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Quincy

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  1. Quincy
    Here is a snowfall map that I created using reports from various sources. Many of the reports came from this forum and the National Weather Service. Only social media reports that passed through quality control were considered. All reports gathered were carefully considered and compared before being included.
    Light rain developed during the morning hours on November 26th and mixed with some sleet inland. Wet snow initially confined to the far northwestern corner of the state. As steadier precipitation moved in, a slight southeast shift of the snow/sleet line was observed with some modest evaporational cooling. However, much of coastal and southeastern Connecticut stayed predominantly rain.
    The main reason for the mixed precipitation and sleet was a warm layer in the atmosphere around 700mb. As precipitation became heavy, sleet fell across much of central Connecticut. Wet snow continued across northwestern Connecticut and rain moved as far northwest as Meriden and Hartford with some warming aloft nudging into the valleys. Even in those areas, the 2-meter temperature hovered around 34 degrees for much of the event, which did not allow for significant amounts of snow to accumulate.
    Precipitation tapered off to scattered snow showers by early evening. As cooler air gradually funneled in, a light additional accumulation of snow was reported in many areas. A few broken, but locally enhanced bands of snow continued into the early morning hours on the 27th.
    The greatest snowfall totals were in the range of 6 to 10 inches across northwestern Connecticut. Totals dropped off fairly quickly to the south and east. A narrow area of 3 to 6 inches was observed near and just northwest of I-84. Just southeast of there, 1 to 3 inches was reported and the southeastern third of the state generally saw less than one inch of snow. Where the snow did accumulate, it had a very high water content, especially those areas that battled between a mixture of snow, sleet and rain.

  2. Quincy
    The United States has a greater frequency of tornadoes than most other counties. For many factors, the vast majority of tornadoes occur east of the Rocky Mountains across the continental U.S. Although the central and southern Plains region is widely considered to be "Tornado Alley," there are other areas that see just as many tornadoes, if not even more.
    The two graphics below are adaptations of NOAA/NWS SPC graphics found in their Tornado Environmental Browser. A broad area from the east slopes of the Rockies east to the west slopes of the Appalachians typically see the most days with tornadoes per year. Two local maximums can be identified in northeastern Colorado and central Florida. While these areas may see numerous tornadoes in any given year, they are generally low on the EF-scale. The central Appalachians feature a local minimum of tornadoes, but as one travels east, the frequency of tornadoes increases.

    While terrain by itself will generally not have much of an effect on a tornado, especially a significant (EF/F-2 or stronger) one, there are reasons why terrain affects tornado frequency. In the Plains, lee cyclogenesis combined with a surge of warm, moist air from the Gulf of Mexico and drier air from the Rockies tends to create a favorable setup for severe thunderstorms and tornado development. Across the East Coast, there is less real estate to work with when considering the proximity to the Atlantic Ocean. Also, wind out of the south to southeast in the lower levels will often mitigate the risk of severe thunderstorms, especially in the spring and early summer months from the mid-Atlantic region into the Northeast. The placement of a "Bermuda" high and/or a "southeast ridge" of high pressure will tend to limit the formation of strong non-tropical low pressure systems along the East Coast during the warmer months, as the jet stream is often displaced further northwest.
    The frequency of days with significant tornadoes is in some ways similar to, but also has differences in comparison with the frequency of days with all tornadoes. While portions of Colorado and Florida may see the most tornadoes overall, there are two distinct areas that feature a much greater frequency of significant tornadoes. The southern Plains into Dixie Alley (lower to mid-Mississippi Valley) will on average experience the most significant tornado outbreaks. Here, there are three factors that are probably most responsible for this. First, their proximity to warm, moist air from the Gulf of Mexico fill favor higher dew-points and greater instability. Second, the tornado season is a bit elongated here. While April into May have featured the most significant tornadoes in Dixie Alley, the late fall into winter months have also included several major tornado outbreaks. Finally, there may be at least some influence from tropical systems. While tropical storms and hurricanes often do produce tornadoes, it should be noted that most of these tornadoes are generally not significant.

    Eastern Nebraska into the Midwest also averages an elevated number of days per year with significant tornadoes. Here, while the tornado season typically peaks in June, at least some fall tornado events have spawned significant tornadoes this far north. In 2013, October 3rd-4th recorded six significant tornadoes from eastern Nebraska into Iowa, with the major tornado outbreak of November 17th featuring 32 significant tornadoes in the Midwest.
    Other noteworthy observations:
    Missouri is an interesting case. The western portion of the state is often considered to be in tornado alley and some maps will place southeastern Missouri in Dixie Alley. The state has seen plenty of significant and even violent tornadoes, with the Joplin tornado of 2011 being one of the more recent examples. However, a small section of central Missouri features a local minimum in terms of both tornadoes and significant tornadoes. One possible explanation can be their location being in a "dryslot" of sorts for tornadoes. For storm systems developing just east of the Rockies, the eastward extent of associated severe weather will often fall short of central Missouri. Likewise, systems developing in the lower Mississippi Valley often form a bit too far east to target central Missouri with the most tornadoes.
    West Virginia has less tornadoes than most states east of the Rockies. One factor that immediately comes to mind would be the population density and terrain, which may limit some tornado reports. However, their location along the Appalachians certainly plays a role in the lower frequency of tornadoes. The higher elevations will typically have less instability. Likewise, moisture pooling will typically favor higher dew-points west and east of the Appalachians, leaving West Virginia in another tornado dryslot. According to the NWS, West Virginia has no recorded EF/F-4 or 5 tornadoes. With that said, a long-track F-5 tornado in southeastern Ohio narrowly missed passing into West Virginia before lifting. Also, an F-4 tornado that dropped southeast of Pennslvania into Maryland also lifted shortly before it would have passed into West Virginia.
  3. Quincy

    Severe Weather Sunday

    By Quincy,

    Severe thunderstorms are likely today across portions of the Plains and Mississippi River Valley.
    Ongoing thunderstorms early this morning may be marginally severe across portions of Iowa, northern Missouri and Illinois. Additional showers and thunderstorms are likely from late morning into the early afternoon hours further south before a more serious threat develops.
    Sunday afternoon, low pressure will be in the vicinity of the central border between Texas and Oklahoma. An upper level shortwave will begin to rotate through the area with a vortmax swinging into eastern Oklahoma. Thunderstorms will likely fire just ahead of a dryline during the afternoon hours. These thunderstorms can explosively develop, producing large hail, damaging winds and at least a few tornadoes.
    The greatest potential for tornadoes will be from extreme northeast Texas into eastern Oklahoma. There is some uncertainty with respect to how far north this threat will extend, but the area south of the KS/OK/MO tri-state border has the highest probability of seeing tornadoes. There is high confidence that there will be numerous severe reports, but it is not clear over how large of an area the most intense storms will extend.
    Climatology suggests that the tornado threat could extend further east into Arkansas and southern Missouri late Sunday night into early Monday. Although this is possible, a loss of heating and a cold front overtaking the dryline should mitigate the risk after 12 a.m. Monday.
  4. Quincy
    Following up a cold winter across much of the country, April has proven to be a transition month. Although the month started mild for a large portion of the country, much cooler air has moved in for the middle of the month. There are signs, however, that any negative temperature departures after April 20th into the start of May will be relatively insignificant.
    Before looking at May, it makes sense to look at the April forecast. For the most part, everything is going to plan from the forecast that was made on March 15th. Although portions of the Northeast have been milder than forecast for the month as a whole, one and perhaps two shots of cool air to finish the second half of April will likely counteract the present offsets. As far as the models go, the Euro MJO prediction of moving into phase 2 and 3 verified very well, although the MJO has since looped back around into phase 5 an 6.
    Click here for a follow-up to the April forecast.
    Going forward, there continue to be signs of the remnant winter pattern of troughs across the East Coast breaking down. The Euro shows no clear move with the MJO, although it tries to keep it in the vicinity of phases 4-6 to even neutral. Each of those phases would suggest near to slightly above average temperatures for much of the center and eastern portion of the country with slightly below average temperatures across portions of New England. The GFS ensembles move toward phase 8 and 1, suggesting more of a northern Plains warm-up with near to even below average temperatures near the Gulf States.
    With no strong signals with respect to the MJO, focus shifts toward the Euro and CFS. The Euro weeklies show a fairly zonal pattern with only near to slightly above average temperatures for much of the area. Much like the MJO projections, such a pattern could yield near average temperatures across the Gulf States. The CFS is robust with warming across the upper Plains and yields near to slightly above average temperatures for most other areas. While the CFS keeps the upper Great Lakes below average, this may be overdone due to below average water temperatures.
    Final considerations and forecast:
    The thinking is that the persistant drought across the desert Southwest and adjacent lower Plains will continue. This will especially be the case if the CFS is correct with pronounced ridging in the area. The dry soil will tend to favor above average daytime temperatures. So while there may only be substantial confidence in slightly above average temperatures in the range of 1 to 2F across the mid-Mississippi and Ohio Valleys, a +2 to +3F anomaly forecast has been introduced for portions of the western lower Plains. Ridging could extend into the Great Lakes, but still below average water temperatures should mitigate any warming, especially downwind of a prevailing west-southwest flow. There is moderate confidence in some cooler than average temperatures hanging on across northeast New England, so a small area of -1 to -2F anomalies are included for Maine.
    Severe thunderstorms:
    A forecast graphic is not being made for this outlook with respect to severe thunderstorms. The year 2014 continues to follow a near-record low number of severe thunderstorm events and tornadoes. A series of severe weather events, which may or may not be significant, are possible between April 23rd and 25th. Beyond that, a fairly zonal flow with some above average heights in the Plains and Midwest does not look overly impressive for severe activity. However, the pattern will favor at least an increase to near average activity through the month of May. In summary, the severe thunderstorm forecast is close to climatology and has little confidence in specifics. Prior years that saw very low activity through mid-April did see an increase in activity by late April. A close analog to 2014 is 2010. That season saw an uptick in severe reports between the end of April and through the month of May.

  5. Quincy
    Here is a snowfall map using reports from various sources. Many of the reports came from this forum and the National Weather Service. Only social media reports that passed through quality control were considered. All reports gathered were carefully considered and compared before being included.
    This event was spread out over three days as low pressure passed along a frontal boundary, draped from the Ohio Valley into southern New England. On the first day, Saturday, February 7th, occasional flurries and a few bands of light snow passed through Connecticut. Snowfall totals on this day were generally an inch or less around the state.
    On Sunday, February 8th, scattered snow showers and flurries continued. During the evening hours, a band of heavier snow developed from roughly Danbury to Meriden. Outside of that band, daily snowfall totals were mainly less than two inches. Snow across Connecticut, especially northern portions of the state, became steadier after midnight.
    Snow, heavy at times, continued through much of the day on Monday, February 9th. The heaviest snowfall affected the northern portion of the state. Snow finally tapered off during the evening hours in Windham County. The majority of the total snowfall from this event occurred on Monday.
    Through the event, there was some mixing with sleet, graupel and freezing drizzle across the southern half of Connecticut. Mixed precipitation was the dominant precipitation type in lower Fairfield County and much of New London County.
    Some shadowing of snowfall totals can be noted west of the hills in northwestern Connecticut and across the Connecticut River Valley. There, snowfall totals were generally 4 to 8 inches. Some localized 8"+ snowfall amounts were reported in west-central Connecticut and across some of the higher elevations in Tolland and Windham counties.

  6. Quincy
    Here is a snowfall map using reports from various sources. Many of the reports came from this forum and the National Weather Service. Only social media reports that passed through quality control were considered. All reports gathered were carefully considered and compared before being included.
    Periods of light snow developed across Connecticut between late morning and early afternoon on March 1st. The snow became moderate to briefly heavy at times during the evening hours.
    Snow tapered off across northwestern Connecticut by midnight, but lingered in eastern areas until the pre-dawn hours on March 2nd. The heaviest snow affected the I-95 corridor and a bit further north into eastern Connecticut.
    This event resulted in a general 3 to 6 inch snowfall around the state. The lowest amounts were reported in far northwestern Connecticut with near or just under 3 inches. A few spots in the southeastern half of Connecticut saw 6 to 7 inches of snow.

  7. Quincy
    A major snow storm is projected to bring blizzard conditions to much of New England Monday night through Tuesday. When all is said and done, many areas in and around the Boston area can expect two feet of snow with locally higher amounts.
    Despite the European model staying the course with greater snowfall amounts for areas around New York and New Jersey, it appears that most other data favors sharply decreasing snowfall amounts west of southern New England. As low pressure rapidly intensifies and moves toward Cape Cod and the islands, snow will become heavy with strong winds and blizzard conditions along the I-95 corridor from New York City to Boston and downeast Maine.
    As low pressure nearly stalls and does a loop, similar to historic blizzards in the past, a band of intense snowfall should drop excessive to possibly historic snowfall amounts. It appears that the likely positioning of this band would be on a SSW to NNE axis between central/eastern Connecticut and interior eastern Massachusetts. This may include the Boston metropolitan area. Although mesoscale details of such a band are not 100% clear, the potential exists for some 30"+ totals where this band sets up. Snow in this area will persist through the second half of Tuesday, before finally winding down early Wednesday morning.
    Here is the thinking for this storm.

    The greatest bust potential lies across far western New England, New York State, New Jersey and points west. Although this forecast leans closer to the more eastern GFS/NAM/RGEM solutions, it will still be interesting to see how the 00z Euro trends. It is very rare for the Euro to cave to the other models inside of 72 hours, but it is also hard to believe that it will stay as far west with the heavy snow as previous runs have.
    Another consideration is that liquid to snow ratios, especially across the interior high terrain, will be greater than 10:1. Ratios in the range of 14-18:1 across western and central Massachusetts should help offset some lower precipitation amounts with a considerable fluff factor.
    8:30 a.m. Monday edit:
    The models have compromised a bit overnight, but the RGEM is still rather light with snowfall amounts across western New England and points west.
  8. Quincy
    This isn't really a big event, but due to the amount of discussion it's had, I felt a map was warranted.
    Low pressure moving through the Great Lakes brings an usual push of generally light snow towards the Appalachians. A new area of low pressure is forecast to form east of the mid-Atlantic region, enhancing snowfall amounts ever so slightly around the coastal plain. This map does not show it, but light snow should extend southward into Virginia.
    I believe that most areas will see an inch or less of snowfall, with interior Mass. seeing little or no snow at all. I'm not even all that confident for 3" amounts, but I added them as a potential outcome for northern Pennsylvania, the outer Cape (Cod) and the Islands of southeastern Massachusetts.
    The column is fairly cold, from the surface right up through 850mb and 700mb, promoting snow growth and higher than "typical" liquid to snowfall ratios. I could see 15:1 ratios on the shoreline and 20:1 further inland. The end result is a light, fluffy snow that pretty much sticks on contact to most surfaces.
    Basically, most areas may see up to an inch, with the highest probability of 1"+ amounts occurring along and south of a line from Binghamton to Bridgeport to Groton to Providence to Taunton.
  9. Quincy
    The image is comprised of snowfall totals from various sources, some of which include the New England forum on here. Snowfall totals across Connecticut were pretty uniform around 3-4", although slightly lower amounts occurred along I-95 and there were a few isolated amounts around 5".
    I'll post a contoured color map within the next 12 to 18 hours.
  10. Quincy
    Here is a snowfall map using reports from various sources. Many of the reports came from this forum and the National Weather Service. Only social media reports that passed through quality control were considered. All reports gathered were carefully considered and compared before being included.
    Snow developed during the afternoon on March 20th across Connecticut. Dry air in place prior to the event resulted in several hours of virga until ground observations finally reported snow early in the afternoon. Snow overspread the state, but the snow was heaviest across southwestern sections. The snow continued overnight as low pressure developed east of New Jersey.
    Periods of light snow continued into the morning hours on March 21st. There was some enhancement of the snow across central Connecticut before the snow tapered to flurries statewide by midday.
    Snowfall totals ranged from 4 to 7 inches across southwestern Connecticut to just under 2 inches in northeastern Connecticut. Much of interior Connecticut reported 2 to 4 inches with a few isolated higher amounts in north-central portions of the state. A narrow band across the higher elevations of Fairfield County, just northwest of the Merritt Parkway, reported locally 7 to roughly 8 inches of snow.

  11. Quincy
    Here is a snowfall map using reports from various sources. Many of the reports came from this forum and the National Weather Service. Only social media reports that passed through quality control were considered. All reports gathered were carefully considered and compared before being included.
    Areas of weak low pressure moved through the Ohio Valley along a frontal boundary on February 21st and periods of light snow moved into Connecticut during the afternoon. The snow gradually became moderate to briefly heavy at times during the evening.
    Due to the frontal boundary being west of the state, winds were generally out of the south to southwest ahead of low pressure, through the event. This led to temperatures rising into the lower 30s overnight. Snow changed to sleet, roughly as far northwest as I-84. A narrow corridor of freezing rain was reported just to the northwest of I-95. Some areas changed to plain rain south and east of I-95 along the coast and east of I-395 in far eastern Connecticut.
    Precipitation changed back to snow in all areas before ending on the morning of the 22nd.
    Most of the state reported a 4 to 8 inch snowfall. A few totals just over 8 inches were reported in Litchfield and Tolland counties. Snowfall totals along and southeast of the I-395 to I-95 corridor were generally in the range of 2 to 4 inches. The immediate shoreline in southeastern Connecticut reported around or just under 2 inches.

  12. Quincy
    Here is a snowfall map using reports from various sources. Many of the reports came from this forum and the National Weather Service. Only social media reports that passed through quality control were considered. All reports gathered were carefully considered and compared before being included.
    As low pressure moved east from the Great Lakes, some modest warm advection light snow developed around Connecticut during the morning and afternoon on February 14th. The snow was intermittent and amounts were generally less than two inches during the daylight hours.
    The storm system rapidly intensified east of New England overnight and some bands of moderate to heavy snow rotated through eastern Connecticut. The snow tapered off on Sunday, during the morning in most areas, but not until early afternoon near the Rhode Island border.
    Snowfall totals ranged from less than two inches across far western and southwestern Connecticut, to four to eight inches across most eastern portions of the state. A few totals up to nine inches were reported, across the hills of Tolland County and across southeastern Windham County.

  13. Quincy
    Recapping May: On the heels of a relatively active month for severe weather and tornadoes in April, May 2015 continued the pace. Although the month started slow with no tornadoes for the first two days and only a handful through the 5th, the greatest single day tornado event of 2015 occurred on May 6th. This was actually expected to be proceeded by a much more significant event on the 9th, but the former won out with 59 tornado reports, as the 9th did not fully live up to the hype/potential*.
    The first third of May paced at a somewhat above average count of tornadoes. Steady tornado events continued fairly regularly through the middle and latter portion of the month. Although there was no “defining” tornado outbreak after May 10th, there were multiple instances of picturesque tornadoes. While the previous forecast for May hinged on a near-average month, it looks like the period will end up at least slightly above average. The analog May of 1991 turned out to be the best fit among the four analogs from the 1990s. It was also the most active one of those four. The very persistent troughing across the Inter-mountain West to High Plains was well-indicated in both the forecast ensembles and analog data. Long-range forecasts may not always work out that well, but in this case, the verification speaks for itself. Only four days in the month reported no tornadoes, 5/1, 5/2, 5/12 and 5/31**, which includes an 18-day streak of reported tornadoes from the 13th to 30th.

    To quickly touch on the Plains long-term drought, it has been reduced significantly. Consistent bouts of heavy rain and convective activity have eliminated most of the drought area in the central to southern Plains. It now covers just a fraction of an area that it had before. In terms of tornado activity, the moisture transport northward has boosted the storm potential, but in a way, has also hampered the ability to easily storm chase. Without much EML (elevated mixed layer) influence this May and a tendency for storms to congeal into MCSs (mesoscale convective systems), countless tornadoes have been produced by high-precipitation supercells. Many of those tornadoes were rain-wrapped and/or difficult to see. Portions of Oklahoma reported a record-breaking 20 inches of more of rainfall in the month of May this year. A large portion of the southern Plains came in with precipitation anomalies of +8 inches or more for the month. That essentially means an extra two to three months worth of rain fell, if not more. This has caused major flooding in much of the region.
    June 1st through 10th: A general continuation of the recent pattern should continue through at least the first week of June. While the month begins with ridging across the southern Plains, the short-range models and global models alike are in strong forecast agreement with the upper level pattern. A trough is progged to dig into the West Coast with ripples of shortwave energy swinging into the central/northern Plains from June 1-3. Even though neither one of those three days appears particularly significant in terms of tornado potential, multiple severe reports, including tornadoes, should occur each day. After that, the parent trough is expected to continue digging and beyond that is where the forecast gets a little bit tricky. When looking back at the ensemble forecasts, the models had a ridge bias and did not really pick up on the trough becoming as amplified as it may. (For example, the most recent run, May 28th, of the Euro Weeklies looks much different for the second half of the first week of June, in comparison to the May 31st Euro ensemble run, which is more amplified) The trough could also become cutoff as some model projections indicate. The current expectation is that the trough axis may be just a little bit too far west to favor an outbreak-type severe setup in the Plains. With that said, whether the trough eventually ejects east to cause a significant event, or rather just a string of steady days (much like April and May of this year), there should be fairly consistent tornado threats through about the 7th or 8th of June. Rounding out the period, whatever is left of negative height anomalies in the West should relax to near climatology.
    Verdict: Somewhat above average tornado activity between June 1st and 10th. Fairly consistent bouts of severe weather, including tornadoes, are expected through the first week of June. Much like the previous six to eight weeks, while there may not be a higher-end severe setup on any particular day, tornado reports should be observed on most of these days.
    June 11th through 30th: Fighting with climatology and the computer model forecasts, there is only so long that relatively amplified troughing can dominate the pattern across the western half of the U.S. Starting with analog guidance, the results are fairly mixed. The general pattern assessed in the top four analogs (based off of GEFS 8-14 day prog from 00z 5/31 and extending out 20 days) is characterized as featuring ridging across the western U.S. to central/southern Plains and some troughing across the Great Lakes. It sounds a bit like what happened to start 2015. However, the individual four analogs (based on early June 2015 forecasts) diverge greatly in the period 10 to 20 days following. The 1991 analog, which was a strong match to May 2015, continues to show up. That June featured slightly below average tornado counts. Another analog that was also mentioned in the May 2015 tornado forecast is 1990. This one also shows up for the month of June and that particular month was well above average in terms of tornadoes. On the flip side, the other two analogs showed well below average tornado counts. The expected pattern to start June 2015 resembles late June 2006. That June finished fairly quiet and was followed up by one of the quietest months of July on record in terms of tornado activity. The final GEFS-based analog is 2002. That June was even quieter than 2006 and July of that year was also well below average for tornadoes.

    What can be made out of these mixed signals? Based on persistence and trends observed so far this spring, the computer forecast models have generally erred on the side of too much ridging occurring too quickly in a long-range forecast. It is inevitable that ridging will eventually prevail, but that does not entirely shut off the tornado season. In fact, it is very possible, if not probable, that troughing across the Great Lakes and/or Northeast could enhance the threat of severe weather from the Midwest into the Ohio Valley. A northwest flow regime tends to favor tornadoes in that region, especially the Ohio Valley. The expectation with this forecast is that mid-June should feature decent tornado potential, but that late June may not be as active. All four of the analogs above were eventually followed by a sharp drop-off in the tornado season, whether that came in late June or July. Also, one cannot forget June 16-18, 2014, in which an otherwise quiet tornado season become extremely active seemingly out of nowhere.

    Moisture return cannot be overlooked and this sets June 2015 apart from recent months of June. The soil moisture content across much of the Plains is much higher than it has been in at least two to three years. The period from May 1-29, 2015 featured slightly to somewhat above average soil moisture content from the Southwest into most of the Plains. This available moisture alone would tend to favor tornadoes, even if upper air and kinematic support are marginal. If the jet stream can stay active and provide enhanced flow aloft, a setup like mid-June 2014 could be possible sometime in June 2015. If such a setup did occur, available moisture would probably not be a concern at all. The bigger question becomes, can the Plains and Midwest eventually see more EML influence? That may be the difference between another “climo month,” versus a more memorable month for tornadoes.
    So far in 2015, it has been an active tornado season in two areas. One lies from north Texas/Red River Valley into central Oklahoma. The other is across the central to southern High Plains. Looking ahead to June 2015, early June features tornado prospects from the central/northern High Plains eastward into the Dakotas and Nebraska. Later in June, signs point toward Siouxland eastward through the Midwest and into portions of the lower Great Lakes/Ohio Valley.
    Verdict: Near to slightly average tornado activity between June 11th and 30th.

    June 1-10 forecast: Somewhat above average tornado counts in the U.S.
    June 11-20 forecast: Near average tornado counts in the U.S.
    June 21-30 forecast: Slightly below average tornado counts in the U.S.

    June 2015 tornado estimate: 255 tornadoes in the U.S. (slightly above average)
    *As has been the case many times this year, morning convective activity and MCS dominance have mitigated the frequency of discrete supercells.
    **This is subject to change as it may take a day or two for official reports to come in for May 31st.
  14. Quincy
    There is the potential for a regional severe weather event on June 22nd. The threat zone extends from portions of the middle/upper Mississippi Valley into the western Great Lakes. All severe weather hazards are possible and given the nature of the setup, forecast trends are being closely monitored.
    As at least two pieces of shortwave energy rotate from the upper Midwest into the Great Lakes on Monday, a surface low is forecast to deepen from Iowa/Minnesota into Wisconsin. Impressive wind fields for this time of the year will combine with strong instability to create an environment favorable for severe weather. As it stands right now, two rounds of storms are expected. The first round would most likely be in the form of a mesoscale convective system (MCS) Monday morning, moving into the Great Lakes by midday and early afternoon. The second round develops in the wake of this activity, at and shortly after peak heating, later in the afternoon.
    The setup is a bit complicated and there are reasons to believe that two rounds of mixed intensity are favored over one robust atmospheric punch. The MCS during the first half of the day could pose a threat for primarily damaging winds and isolated hail. Once that system moves out, there should be modest air-mass recovery. The issue is that wind fields in the lower levels begin to veer, causing a more unidirectional shear pattern. This will likely dampen the tornado potential somewhat. Nonetheless, even forecasts on the more conservative end of the spectrum indicate a setup favorable for at least a few tornadoes. The afternoon to early evening threat may feature fairly widespread damaging winds, if storms were to merge into a linear system. Supercells still appear probable and they may extend into the early evening. However, for the reasons listed above, this does not look like an ideal setup for a major severe weather outbreak.
    Trends for this event tend to move the surface low a bit quicker, which also speeds up the veering of winds. The best wind fields may also become somewhat displaced to the northeast of stronger instability to the south. The Euro has joined the GFS/NAM in developing strong instability, as earlier it was showing a less unstable setup. The RGEM is also on-board and all of the models are in general agreement in terms of timing and geographic placement.
    Wisconsin is the target for the initial MCS on Monday. That system should weaken as it moves into portions of upper and lower Michigan. Later in the day, the target becomes southern Wisconsin and northern Illinois. Portions of lower Michigan and northwestern Indiana may also get in on some action. Damaging winds should be the predominant threat. The stronger cores can produce large hail and a few tornadoes seem probable.
    At least one of the following scenarios would need to occur to more fully maximize the tornado threat: First, outflow from the morning MCS could work to set up one or more boundaries to locally enhance a tornado threat. If the MCS decays faster than projected, that could lead to less disruption of the wind field and even stronger instability. A mesoscale low and/or a main low tracking further south into southern Wisconsin (instead of northern sections) may maintain more backing in the lower level wind fields through the threat zone.
    It should be noted that even with the projected wind fields, at least a few tornadoes remain likely. Given both a strong low level jet and 0-6km shear in excess of 50 knots, there is at least some potential for strong tornadoes. All of the factors currently forecast likely place Monday into more of a mid-range (SPC moderate risk) severe weather threat, as opposed to a higher-end (SPC high risk) outbreak. Stay tuned to later forecasts to see how the forecast setup evolves.
    The NAM forecast below for 21z Monday shows winds veering substantially across Wisconsin and Illinois:

  15. Quincy
    The relatively active month of May looks to heat up again in the coming days. After a lot of severe thunderstorm activity last week, the first few days of this week have been on the quieter side. I am looking ahead to three days in particular for the next notable severe weather threats.
    Sleeper Thursday: This day has not been on the radar for most, but offers some potential, even if it is lower-end and in a relatively small area. I am focused on western Texas for isolated supercell/severe potential late Thursday afternoon into the evening hours. A small perturbation/vorticity lobe is modeled to pivot from eastern New Mexico into western Texas late Thursday. At the surface, modest daytime heating will likely result in an area of 1000-2000 J/kg SBCAPE, coupled with approximately 30 knots of 0-6km shear. Although the shear is somewhat marginal for supercell potential and the aerial extent of overlapping parameters is small, the higher resolution models do favor clusters of storms developing in this area.
    Some red flags include weaker winds aloft and storm mode/coverage, but an increasing low-level jet and backing winds around 00z may provide a small window for tornado development. What gets my attention about this event is that it is under the radar and in favorable chase terrain. I do not expect a lot of people to be out and the High Plains have featured several beautiful structure and tornado events this season, so I am not sure I can pass it up. Worst case, I would bail and head north, to get into closer position for Friday.

    Localized outbreak on Friday:
    The model guidance continues to show a strong signal for a severe weather on Friday, with an increased tornado potential across portions of the central Plains. Due to the models speeding up the system just a bit, more forcing and a favorably placed, developing surface low, Friday will probably feature the greatest potential in the otherwise multi-day threat. With the surface low moving into the central High Plains Friday afternoon, the models show strong instability developing across Kansas and Nebraska. The focus appears to be Nebraska, where multiple boundaries/fronts will locally enhance a tornado threat. The warm front is an obvious focus point, as it lifts through Nebraska late in the day. Moving toward late afternoon, the 4km NAM fires a line of discrete storms along a dryline, which will advance eastward through Nebraska and adjacent Kansas ahead of the developing surface low. Look for severe storms along this line, with an isolated to scattered tornado threat. This may extend as far south as sections of north-central Kansas. Along the warm front, the focus narrows in closer to the surface low and warm front/dryline intersection. I would watch the first or second cell closest to that point for a tornado threat. Aside from at least 2000-3000 J/kg SBCAPE (NAM is more like 3000-4000 J/kg), 35-45 knots of 0-6km shear (a bit higher via NAM) and favorable forcing for ascent all favor this severe threat. I imagine that the threat level will be upgraded to Moderate Risk by the Storm Prediction Center (SPC). What makes the threat here a bit more robust than some previous days is that we are not seeing a strong signal of convective debris or MCS activity overturning the atmosphere prior to peak heat. If there should be any convection in the morning, it would likely be limited in coverage, and outflow from that activity may only serve to further enhance the threat by leaving additional boundaries in place. Another quick note is that depending on how wrapped up the surface low becomes, the threat may punch northward into southern portions of South Dakota, especially into Friday evening.
    It is hard to really outline any significant red flags for Friday. There is the question of storm coverage, but a higher-end event in this case is actually favored when storms are more isolated. Precipitable water values are also expected to be lower than some recent events, so that further mitigated an MCS threat. I suppose there could be storm mergers and some messy storm mode eventually, but all in all, I think this is a bonafide threat and certainly a day to get out and chase.

    Messy mayhem on Saturday:
    The setup, overall, has a lot of similarities to last Saturday. It is likely that some junk convection and MCS activity in the morning will mitigate the threat. Also, the mid to upper level flow looks rather southerly, which is not ideal, as forecast soundings show veer-back-veer issues. With that said, if there are pockets of moderate instability, as the models indicate, there should still be corridors of an enhanced severe threat. This includes tornadoes, as 0-6km shear looks to be at least 40-50 knots and probably higher across some western areas of the threat zone. The red flags win out here, but there is time for this to change. In terms of chase potential, it will take some patience and strategy. Even last Saturday did result in clusters of tornadoes. With this threat being furthest out and potentially disappointing, I will not spend too much time focusing on it at this point. Of course, trends will be monitored and the threat will continued to be monitored.
  16. Quincy
    The April tornado forecast was a trial run and a lot has been learned since it was made. After some success with that forecast, I will be incorporating a lot more statistical analysis (analog data) into coming up with a forecast for the month of May.
    Quickly recapping April:
    Overall, April was a fairly steady month for tornado reports across the U.S., with 21 out of 30 days reporting tornadoes. April 1-9 was very active, including a notable, early season EF-4 tornado in northern Illinois. April 10-18 was relatively inactive, but had tornadoes reported in all but two of those days. April 19-27 was rather active, but no single day featured a major or significant outbreak. Most of the tornadoes in the month were EF-1 or weaker, although the April 9th EF-4 was an exception. Preliminary tornado counts indicate that the month was near to slightly below average in tornado activity. The prior forecast issued on March 31st predicted slightly above average tornado counts. Once the numbers become official, I will get into more detail with comparing the forecast vs. actual.
    Before we get into May, there are some things to consider with the current state of the U.S. Although a long-term drought continues for much of the Plains, heavy rainfall throughout April reduced drought conditions considerably across portions of Oklahoma and Texas. This is critical, because relative tornado inactivity during the first half of spring 2014 across the Plains was at least partially attributed to a lack of available moisture. When we think about creating environments that support tornadoes, moisture is key and that moisture source can originate in Texas. Yes, the Gulf of Mexico is another player, but that moisture must also be able to track hundreds of miles inland, across the big state of Texas.
    Additionally, the overall atmospheric pattern has shifted somewhat, as although there has been continued troughiness across eastern Canada and the Northeast, we are seeing a trend toward more ridging developing. This will have many implications on how the tornado season evolves into May. With less blocking across northeast Canada toward the North Pole, that should tend to favor positive height tendencies as well. (Not to mention seasonality helps with that as well)
    For this outlook, the focus will be split into two portions. May 1-10 and May 11-31. I will still include breaking the month down into thirds at the end of the outlook, but keep in mind that specifics beyond May 10th lack the confidence needed to get into extreme detail in that time period. May is also a potentially volatile month, as one outbreak or even one day for tornadoes can effectively skew the big picture. It would be difficult to nearly impossible to predict any such outbreak more than 10 days in advance. The point of this outlook is to look at May as a whole.
    May 1st through 10th:
    After a quiet finish to the tornado season in April, the first few days of May look to continue that theme. This should not last long, though, as both the operational and ensemble forecast models are in strong agreement with the expected pattern. On paper, it looks encouraging for severe weather prospects. An upper level trough and surface low should exit the New England area may May 3rd, leaving the Lower 48 with a relatively zonal pattern, at least for a short-time. Downstream ridging across the East should give way to a digging trough across the West Coast by May 4th to 5th. With some blocking across eastern Canada, we are looking at western U.S. trough that will persist for several days, with potentially multiple impulses rotating around from the Intermountain West into the Plains.
    This could ultimately evolve in many ways. At this point, the most probable scenario would appear to be two to three, perhaps four, days that are conducive for minor to moderate severe weather events, including tornadoes. I would not want to write off the potential for a big event just yet, but it seems more likely that we will have a series of smaller events, kind of how April panned out. What will be working in the favor of severe weather will be the bonus of a better moisture source across the southern Plains and moderate to strong instability ahead of approaching shortwaves. It is the details that get somewhat muddled out, with the amount of clearing/destablization, storm mode, locally backed winds, etc. Essentially, the pattern looks favorable for severe weather and tornadoes, particularly between May 5th and 8th. As mentioned before, maybe only two of those days wind up decent for severe, but if the pattern lines up just right, there could be multiple tornadoes each day.
    Verdict: Near average tornado activity between May 1st and 10th. The period should begin quiet, but then see multiple days with at least modest tornado activity. The period may close out with a couple of quiet days as the pattern trends more zonal, assuming the model projections are correct.
    May 11st through 31st:
    I have put a lot of time into assessing analog data for this period and not so heavily relying upon forecast model ensembles, as was the case with the April tornado outlook. What has been most alarming lately is that the longer-range models have really struggled beyond day 10 over the past several weeks and have often showed little to no skill in the period of days 15 to 30. This means that the models have flip-flopped back and forth, giving little meaningful insight to what might lie ahead. Now, I am not totally discounting the models here. Sometimes they can struggle during a large scale pattern change, much like what we may be seeing into May. I put a fair amount of stock into the European ensembles/weeklies, but I think taking a look at the past will help shed some light on what might happen in the future.
    To come up with analogs, I have looked at two things in particular. First, I assessed the short-term model analogs for May 1-2. Secondly, I looked at the day 6-10 ensemble predictions from the GEFS and those analogs. There was some overlap and plenty of similarities to note. In the broad scheme, the analogs began with the western troughing/eastern ridging that we are expecting to see into the first week of May. The analogs are then in strong agreement with positive height anomalies along and east of the Rockies from the 2nd week of May, pretty much through the entire month. After gaining visibility to the latest 00/30 Euro Weeklies, pretty much the same is the case here. That only increases confidence in this forecast. I pretty much disregarded the CFS entirely for this outlook, as its members are all over the place for May and as an ensemble system, has not had a good track record as of late.
    Going back to the ridge axis, that is the key thing to consider. The indications, in general, point toward a mean ridge axis setting up somewhere between the Missouri River and the Mississippi River. The latter, or a further east ridge axis, would be more supportive of tornadoes, allowing for troughs to dig a bit further south and west into the Plains. Even the former would be encouraging, as it would tend to favor High Plains activity. That region has not had a great chase season in a while. Based on the reports, it appears as if 2010 was the last solid year there and 2008 was decent too, particularly across western Kansas. Either way, since we are looking at a broad period here and kind of splitting hairs, there is nothing necessarily stopping from a rogue, deep trough to swing through, although it would appear that if that was going to happen, it would tend to favor late May over mid-May. As a result, I am leaning toward a somewhat more active end to May, even though I do expect a fair amount of activity in the middle of the month as well. (When I say fair amount of activity, I expect several days with scattered severe reports, again, in some ways similar to what April featured)
    Verdict: Near average tornado activity between May 11th and 31st. The middle of May holds some potential, but is forecast to feature slightly below average tornado reports. Into late May, there are some indications that tornado activity could rebound to near to slightly above average levels with more potential activity.
    When looking at some of the recent analogs (over the past 25 years), 3 out of 4 had slightly to moderately below average tornado counts in May. On the flip side, they tended to favor average to even very active months of June. Since May 2015 does not appear to be a particularly close match to any of those analogs, I would take that information with a grain of salt. If anything, it does give at least some additional confidence in the thinking that May could end more active and lead into another active June. I do not want to get ahead of myself here, so we will hold off on further discussion about June until the next monthly tornado forecast.
    May 1-10 forecast: Near average tornado counts in the U.S.
    May 11-20 forecast: Slightly below average tornado counts in the U.S.
    May 21-31 forecast: Near to slightly above average tornado counts in the U.S.

    May 2015 tornado estimate: 260 tornadoes in the U.S. (near to slightly below average)
    For those wondering, the top 5 analogs are as follows, beginning with the given date and extending out 20 days: 4/28/1994, 5/12/1991, 4/28/1957, 5/10/1993 and 5/18/1977, in that order. The “recent” analogs mentioned earlier in the post were 1990, 1991, 1993 and 1994.
  17. Quincy
    Over a 50-year span from 1962 to 2011, the most violent (F/EF-4 and F/EF-5) tornadoes occurred over Oklahoma and Mississippi. The maximum grid-points reported 16 over that period, with two of those grid-points in central Oklahoma and one in central Mississippi.
    While a broad area from the Plains to the mid-South sees the most tornadoes overall across the United States, there are three sub-areas with the most violent tornadoes. Much of Oklahoma falls into that category, as it is widely considered to be in the heart of tornado alley. Further north into Iowa is another area that has seen the most violent tornadoes during the period. The third area falls across Mississippi, where the tornado season is relatively elongated from the heart of winter into mid-Spring. The tornado season in Oklahoma generally occurs in a narrower window in mid-Spring. The season in Iowa tends to fall from mid to late spring with a secondary peak in the fall. A smaller and less significant maximum for violent tornadoes can also be identified across the upper Ohio Valley. While the tornado season tends to peak there in mid-Spring, a few events have also occurred in the fall.
    An interesting tornado minimum occurs in a small portion of central Missouri. Among multiple factors is the unique geographical area Missouri falls into. The classic tornado setup in the Plains is driven largely by lee-side cyclogenesis and the dryline. As storm systems move across the Plains, the bulk of the violent tornadoes tend to occur west and northwest of Missouri. Also, the dryline tends to have trouble advancing enough east to penetrate far into Missouri. Likewise, typical tornado events in the mid-South tend to thrive off of moisture from the Gulf of Mexico, producing tornadoes east of Missouri. With that said, higher instances of violent tornadoes have been noted across northwestern Missouri (tornado alley), far southeastern portions of the state (Dixie alley) and the devestating EF-5 tornado in Joplin, in far southwestern Missouri in 2011.
    East of the Appalachians, violent tornadoes are fairly uncommon. However, two particular regions have reported three or more violent tornadoes from 1962 to 2011. Portions of the Carolinas fall into that category. Further north, grid-points in the mid-Hudson Valley into southwestern New England have reported four violent tornadoes in that same span.

  18. Quincy
    Here is a snowfall map using reports from various sources. Many of the reports came from this forum and the National Weather Service. Only social media reports that passed through quality control were considered. All reports gathered were carefully considered and compared before being included.
     
    Spotty light rain impacted portions of Connecticut on February 4th as a frontal boundary slowly advanced east through the area. As the front became nearly stationary near the coast, a wave of low pressure developed over eastern North Carolina early on the 5th. As low pressure organized, colder air filtered in and precipitation changed to snow across Connecticut.
     
    The storm system moved swiftly to the northeast, but there were several hours of moderate to heavy snow across parts of southern and eastern New England, as well as Long Island. The heaviest snow in Connecticut was observed from New Haven County, northeastward into interior periods of eastern Connecticut. Some of the hill towns in northeastern Connecticut reported just over a foot of snow. Snow came to an end between late morning and the afternoon hours on the 5th.

  19. Quincy
    A severe thunderstorm threat is expected to develop late this afternoon into the evening hours across portions of the northern Plains. The setup includes an area of surface low pressure ejecting from Wyoming toward the Nebraska/South Dakota border late today. At the same time or shortly thereafter, an embedded upper level shortwave swing through the Dakotas. The combination of kinematic support and strong instability will likely result in several severe thunderstorms with all severe weather hazards possible. The severe weather threat may continue well into the night as storms shift east-southeastward.
    The computer models are in good agreement with the synoptic setup and even most of the mesoscale details seem fairly clear. The HRRR/NAM/RAP show an area of low pressure moving into east-central Wyoming by late afternoon with isolated thunderstorm development across much of eastern Montana. The initial development is closer to the upper level forcing at the time and in association with a frontal boundary interacting with moderate instability and modest wind shear. Further east, although stronger surface heating/instability are progged, a fairly strong cap should limit convection for most of the afternoon.
    Between about 22z and 00z, surface heating looks sufficient to begin breaking the cap. At this time, robust thunderstorm development appears likely across southeastern Montana and far northeastern Wyoming. In the immediate downstream environment, a secondary warm front/differential heating boundary is showing up with the high resolution guidance. As it looks now, that should be draped roughly near the I-90 corridor from far northeastern Wyoming into the western half of South Dakota. It is here that strong instability and increasing wind fields should be very favorable for severe thunderstorms. Any discrete thunderstorms between 23z and 02z near this secondary boundary are expected to have the highest probability to produce tornadoes. The higher end instability scenarios appear overdone, but even the less dramatic GFS shows in excess of 2500 J/kg MLCAPE overlapped with 60 knots of bulk shear through much of western South Dakota.
    Given such instability, the initial threats appear to be large to very large hail, followed by isolated tornadoes. A more substantial damaging wind threat likely develops during the evening hours further east. As the low level jet really ramps up and upper level winds increase, the kinematic environment should support a significant MCS, possibly a derecho. The exact placement of this convective system develops on how and where thunderstorms grow upscale. It appears that beginning in northwestern and moving into central South Dakota is where the model consensus stood as of this morning. This is also supported by an intense inflow environment with moderate elevated instability and a vigorous low level jet (in excess of 50-60 knots) ejecting from northern Nebraska into portions of South Dakota. While the convection-allowing models differ slightly with solutions, they all show an elevated threat of fairly widespread damaging winds into early Saturday morning across much of South Dakota.
    This is a fairly interesting case, as this portion of the (western) northern High Plains does not have many significant tornado cases dating back to the early 1960s. One of the red flags for tornado development includes storm coverage as a result of capping. Nonetheless, regardless of geographic region, it is possible for a strong tornado to develop given the expected environment. If a strong tornado were to form, this would most likely be in western South Dakota or perhaps far southeastern Montana/far northeastern Wyoming. Compared with climatology, the projected severe weather parameters tonight fall into the high end of prior tornado cases for the region. Although wind fields intensify into the evening hours, a gradual loss of heating and a trend toward storm mergers may also mitigate the threat. The threat of most widespread impact will likely end up being damaging winds, even if a derecho does not form. For what it’s worth, the 09z SREF derecho probabilities are in excess of 50% for a large portion of South Dakota by 06z Saturday. A few severe thunderstorms are also possible across southern North Dakota and a rogue supercell cannot be ruled out in the Nebraska panhandle either.


  20. Quincy
    Here is a snowfall map using reports from various sources. Many of the reports came from this forum and the National Weather Service. Only social media reports that passed through quality control were considered. All reports gathered were carefully considered and compared before being included.
    Periods of light snow and flurries began on the morning of Monday, January 26th and continued through the afternoon. It wasn't until after dark that the snow became heavy at times, particularly across the eastern half of the state. Although western sections hung on to a steady snow, it was generally light to moderate.
    A band of intense snowfall set up near I-395 in eastern Connecticut during the early morning to predawn hours on the 27th. The band of snow dropped 2 to 4 and occasionally 5 inches per hour for a few hours. During the day on the 27th, periods of light to occasionally moderate snow continued across eastern Connecticut, while only a few stray flurries affected western portions of the state. A couple of bands of briefly heavy snow hit northeastern Connecticut on the night of the 27th. The last flurries ended early on the morning of the 28th across Windham County. This is where the highest amounts were found.
    I-91 was an approximate divide between less than a foot to the west and over a foot to the east. Over two feet of snow was common from northern New London County into much of Windham County. For some of these communities, this was the most significant snowfall since the Blizzard of 1978.

  21. Quincy
    Here is a snowfall map that I created using reports from various sources. Many of the reports came from this forum and the National Weather Service. Only social media reports that passed through quality control were considered. All reports gathered were carefully considered and compared before being included.
    Light rain, with light snow across the higher elevations, developed across Connecticut during the evening hours of November 13th. The steadiest and heaviest snow fell around midnight and tapered off during the pre-dawn hours on November 14th. Most locations eventually changed to snow, with the exception being the immediate shoreline and urban coastal corridor from New Haven down toward the New York border.
    On average, the hills saw anywhere from 1 to 3 inches of snow, with generally an inch or less across the valleys and shoreline. The highest amounts around and just over 3 inches were reported in Litchfield County.

  22. Quincy
    A localized threat of severe thunderstorms, including possible tornadoes, targets Arkansas Sunday afternoon into the evening hours. A compact shortwave trough approaches from Oklahoma during the afternoon, with a modestly warm, moist flow from the south to southeast streaming up the lower Mississippi Valley.
     
    Computer forecast models have been quite consistent with this general threat for quite some time and now that Sunday is approaching, some high resolution, short-term guidance has been reviewed. Clusters of severe thunderstorms are expected to form during Sunday afternoon and track east to northeast across the region. Large hail and a few tornadoes are expected, along with damaging wind gusts and some localized flooding, mainly where any heavy rain falls over already saturated, or even flooded, areas.
     
    With the environment across the Arklatex vicinity being largely undisrupted, a corridor of moderate instability is progged from the Arkansas/Oklahoma border, southeastward across Arkansas and northern Louisiana. The focus for thunderstorm initiation will be immediately head of a weak surface low crossing over from Oklahoma into Arkansas.

    The 4km NAM has been consistent for several runs now, showing discrete cells forming on a northwest to southeast axis from approximately Fort Smith to Malvern and southward into southern Arkansas by mid-afternoon. Given the environment, supercells are likely with large hail being the initial threat, given cold air aloft and relatively steep mid-level lapse rates. By late afternoon, the tornado threat will likely increase due to several factors, including locally backed near-surface winds, an increasing low-level jet and terrain influences.
     
    The greatest apparent tornado threat will be from central to east-central Arkansas, given very good model agreement with the most robust cells forming in this location, just ahead of the surface low. There is also a possibility that moisture return may also be slightly underestimated by the models given recent rainfall across the region.

    Nonetheless, the setup may also take advantage of channeling of low level flow in the Arkansas Valley, as has been seen many times in the past, meaning that a tornado or two could also be possible between Conway and Fort Smith, on either side of I-40. The confidence in thunderstorm initiation decreases with southward extent, particularly from far southern Arkansas into northern Louisiana. Although some convection may fire here, the most robust storms are likely to remain farther north.
     
    Into the evening, the cells will mature and move northeastward, perhaps reaching the Memphis area before merging/weakening overnight. Both high resolution guidance and the GFS agree in a swath of heavy rain/convection from roughly Little Rock to Memphis. This means that some localized flooding may be possible here. Given the thermodynamic and kinematic environment, a strong tornado cannot be ruled out. Model QPF swaths all support the idea of discrete or semi-discrete convection, particularly from 21-03z from central to eastern Arkansas.
     
    One last note is that although models have been in strong agreement, there may be a very slight slowdown of the system, but this will not have major impacts on the outcome. It does mean that a few strong to perhaps severe thunderstorms may fire in eastern Oklahoma early in the event and that the severe threat will decrease with eastward extent, to the east of the Mississippi River.
  23. Quincy
    Here is a snowfall map using reports from various sources. Many of the reports came from this forum and the National Weather Service. Only social media reports that passed through quality control were considered. All reports gathered were carefully considered and compared before being included.
    Occasional flurries developed on Sunday, February 1st across Connecticut. A steadier snow moved in after midnight with some moderate to heavy snow during the morning hours on February 1st.
    By 7 to 8 a.m., precipitation changed to sleet across lower Fairfield County. Snow mixed with and changed to sleet in most areas up to roughly I-84 from mid to late morning. There was some spotty freezing rain as well, mainly for a short time near the I-95 corridor.
    As colder air worked in behind a low pressure system passing by east of Long Island, precipitation quickly changed back to all snow across the state. An intense band of heavy snow formed across western Connecticut and moved from west to east across the state. This band of snow was producing 2″+ per hour snowfall rates. Snow quickly tapered off by mid-afternoon in western Connecticut and by early evening near the Rhode Island border.
    The majority of the state saw anywhere from 8 to 12 inches of snowfall. Locally higher amounts were reported in the northwestern and northeastern hills. Southeastern Connecticut, where there was the longest period of sleet and freezing rain, had anywhere from about 5 to 8 inches of snowfall.

  24. Quincy
    Thanks to some feedback, I cleaned up this map and added a few additional reports.
    There are still some gaps in Litchfield County, a report of 4.0 inches in Torrington made more sense based off of observations and radar imagery for that area. You can see how the higher amounts were generally confined to the higher terrain, with lower amounts in the Conn. River and Shetucket River valleys.
    Below is a color, contoured map I put together:

  25. Quincy
    I don't really expect much snowfall at all tonight. For some continuity and a slight amount of uncertainty, I painted the entire area with 2" or less of snow. Eastern Conn. and northern R.I. have perhaps a 50/50 shot at 1-2": of snow, while the rest of the area has a high probability of receiving less than 1".
    Temperatures and moisture look very marginal and although some precipitation should back southern sections of southern New England, I don't see it being a big deal. There may be a few slushy roads for the Thursday morning commute.
    I don't think it's fair to make a total snowfall map for both events. The coastal plain should rise several degrees above freezing during the day on Thursday with most inland areas also cracking 32F. Also, western areas that may see no accumulation at all tonight could easily end up with some of the higher amounts tomorrow night.

    The snow Thursday night into Friday morning ("Round 2") looks a bit more significant. It gets tricky nailing down enhanced snow along an inverted trough across eastern N.Y. and western New England. At the same time, precipitation closer to a center of low pressure well south of Cape Cod may bring a period of snow to northeastern Conn., northern R.I. and interior eastern Mass. Here, it's a big question mark where totals could verify either low or high. The computer models are having issues nailing down precipitation totals, while some say widespread amounts over 6" could be realized in my eastern 3-6" zone. I don't see it happening, but take that for what it's worth.
    The confidence for the latter forecast is only moderate, but this will be my last snowfall map for the period. Confidence is higher for the first round.
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