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Rtd208

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  1. Picked up 0.20" of rain for the day. Final storm total 4.92"
  2. @wdrag Current Mt. Holly discussion for the late week storm. Still not hitting the wind potential to hard but coming around to the heavy rain idea. Upton has similar thoughts. .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... A mid and upper level short wave ridge briefly builds over our region on Thursday, resulting in tranquil and dry conditions. An onshore northeasterly/easterly flow through the day will mean temperatures may be a degree or two lower than today, but still near normal with highs from the mid 50s to mid 60s. After Thursday, our attention turns to the next closed low. This low will be taking an inland track from the lower Mississippi Valley to the northeastern U.S. from Thursday into Saturday. Compared to the model runs 24 hours ago, there are some stark differences with the latest runs. For one, most guidance is a bit slower with the precip entering our region, as much of the region may stay dry through Thursday night. The most notable change though was that many of the operational models now show a brief period of cyclogenesis on Friday as the low is centered to the SW of our region (with yesterday`s run, the low was filling/weakening as it approached our region). This could set the stage for a low level southeasterly jet on the order of 40 to 60 kt progressing over our region from Friday afternoon to Friday evening. If this happens, that would result in significant moisture transport coincident with the best synoptic scale lift, resulting in an increased risk for heavy rain and flash flooding. Not surprisingly, model soundings show precipitable water values well above normal and mean RH values close to 100 percent through this time. If this solution develops, the area most at risk for heavy rain would likely be the 95 corridor, and locations just south and east of the fall line (as the low level jet impacting the fall line could result in additional lift due to orographic lift). Thus, I have added in a mention of heavy rain in the grids generally along and SE of the 95 corridor. If there is a silver lining in this solution it is that the area most at risk with this event should be south and east of areas that were the most impacted with the Monday night/Tuesday rain. The other thing to watch for in these patterns is the potential for the winds in the low level jet to mix down to the surface resulting in strong winds. At this point, momentum transfer during this period looks poor, so even if this solution were to develop, it appears unlikely that there would be widespread wind gusts of 45 mph+ (wind advisory criteria) on land. All that being said, I have hesitation going completely with this solution. In addition to this being a new trend, it is also highly dependent on the location of the entire vertical profile of the low. Small changes in the position, even in just one level of the atmosphere could result in big changes of the net impacts. Thus, will hold off on any flood watches or additional messaging for at least another model run cycle to see if this trend continues. &&
  3. Picked up 4.69" of rain for the day. Current storm total 4.72"
  4. @wdrag Mt. Holly doesn't seem to be overly impressed with the next system per their morning discussion. .LONG TERM /FRIDAY THROUGH MONDAY/... The main focus through this period is on the closed low that will be progressing from the lower Mississippi Valley into the northeastern U.S.. This should bring a round of rain starting possibly as early as Thursday night and continuing until the dry slot arrives on Saturday or Saturday night. At this point it doesn`t appear to be as high impact as our current coastal low since this low will not only be taking an inland track, but should also be weakening and filling as it crosses the Mid Atlantic. Once this system lifts away, a cold front could approach our region early next week, though it may not arrive until Tuesday or Tuesday night of next week. &&
  5. That would cause big time flooding issues. Good thing we did get a chance to dry out for a while after Ida but if that happens I don't think that it would matter.
  6. Upton also hitting the late week/weekend system hard in their Hydrology Discussion. Rainfall of at least 1 to 3 inches, and possibly as high as 2 to 4 inches, will accompany a slow moving low pressure system late Thursday night through Saturday night. The potential for the heaviest rainfall looks to be Friday night into Saturday afternoon. Impacts will depend greatly on antecedent conditions from the storm impacting the region early this week. At least minor impacts can be expected.
  7. Discussions from Mt. Holly and Upton. Mt. Holly: .NEAR TERM /THROUGH TUESDAY/... This remains a low confidence but potentially high impact forecast. The main features to watch over the next 24 to 36 hours are the closed low currently over the mid Mississippi Valley, the warm front currently bisecting our region, and a mid level short wave trough which was over AL/GA as of the 00Z soundings. The interaction of these features is what is expected to result in cyclogenesis later today off the GA/SC coast which will become the coastal storm to impact our region tonight continuing through Tuesday. As mentioned above, this is a low confidence forecast. The warm front is much slower than any of the models had depicted even with the 00Z runs. I am also concerned that at least some models appear to have initialized with the center of the mid level low too far south and east compared to what 00Z soundings and satellite trends would suggest. If there is in fact more separation (distance wise) between the mid level short wave trough and the closed low, then it is possible the coastal low will develop further off shore. Cyclogenesis occuring entirely off the coast is already a notoriously high uncertainty pattern, and the previously mentioned trends just add to my uncertainty with this forecast. That being said, this has the potential to be high impact for our region, so here is a summary of the potential hazards through Tuesday: Heavy rain: Heavy rain at this point is my biggest concern, and the area of concern hasn`t changed much, generally favoring coastal NJ. There is potential that the axis of heaviest rain could be slightly further south along the southern NJ shore, so Cape May and Atlantic counties were added in to the watch. Additionally, based on guidance trends, increased the QPF slightly. Severe Thunderstorms: Limited instability, but significant shear (both speed and directional shear) means that there is potential if any thunderstorms (or even just showers with a stronger updraft) develop, that stronger winds could mix down to the surface. As far as timing, expect most of today to be dry, but some initial showers could move in or develop (especially if the warm front is still in the area) by late in the afternoon. The bulk of the rain should be from late this evening through much of the day on Tuesday. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... Major storm just off the coast will be in the process of pivoting eastward Tuesday night and Wednesday as a digging vort max reaches the Mid-Atlantic. As it reaches the base of the longer-wave trough around 12z Wednesday, the orientation of the vorticity maximum will allow for the increase in eastward momentum of the main upper low by Wednesday afternoon. Of course, a number of questions remain about this process, since the interactions among the various perturbations and the predecessor impacts of widespread precipitation/convection in tandem with the rapidly deepening low are generally low- predictability phenomena. Nevertheless, with the notable model trends on keeping the low closer to the coast and for a little while longer, suspect stronger winds will linger near the coast for a time Tuesday night and Wednesday morning, with gusts exceeding 35 to 40 mph probable along the immediate coast. Not out of the question a wind advisory will be needed for these areas. Additionally, showers will likely rotate south-southeastward on the west side of the low in much of the area Tuesday evening, slowly shifting eastward as the low begins its inevitable acceleration offshore. By Wednesday, most if not all of the precipitation should be done for the region, with breezy north winds also gradually declining during the day. Highs on Wednesday should range from the mid 50s in the Poconos to the mid 60s in Delmarva. Sky cover may diminish Wednesday night as north to northeast winds slowly decrease, which may be favorable for some stronger cooling than on the previous night. Still, think winds will not completely decouple, so forecast lows are mainly in the mid 40s to around 50. && Upton: .NEAR TERM /THROUGH TONIGHT/... With a warm front north of the area for today, some mid level ridging will be allowed to momentarily take place. A deep layered southwesterly flow regime sets up for today allowing temperatures to warm. As a result dew points readings will get into the lower and even a few middle 60s, which is rather humid for late October. There will be some instability into the afternoon and early evening, however due to an overall lack of forcing not expecting really anything impactful in terms of sensible weather through the day. By this evening the jet axis begins to round the base of the upper level trough off to our west as it swings east. As this occurs the stronger mid and upper level forcing will begin to get underway. This should result in moderate to heavy rain to develop towards and after midnight across the area. Much of the guidance has a potent mid level shortwave pivoting through during the the overnight period, followed quickly by strong PVA at 500 mb into Tuesday morning. The winds at 850 mb also begin to back from the south to more out of the east. A strong LLJ gets into the region into the day on Tuesday with a double barrel low type structure. The exact placement and interactions of the low(s) will determine the intensity of the LLJ, thus determining where the axis of heavier rainfall will take place. Also there is the potential for strong winds. With the low levels becoming more stabilized it will be difficult to get the stronger winds down to the surface, at least initially. With some elevated instability and a strong LLJ developing into Tuesday morning expect more organized heavy rainfall along with embedded convective elements, a few rumbles of thunder are possible, if not likely. Over an inch of rain widespread across the area is looking increasingly likely from midnight to the Tuesday morning commute. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... Strong forcing due to a strong WAA pattern and the potential for 50 kt or greater easterly winds at 850 mb, along with strong PVA as the upper level trough axis and 500 mb low gets just south of the area. This should keep the best lift over the area with periods of heavy rain throughout much of the day on Tuesday. Some guidance does have some drying occurring in the mid levels late Tuesday into Tuesday evening. This will depend on the exact placement of the area of low pressure. If the low gets further north then some dry slotting may occur which could bring some of the heavier rain to an end maybe a few hours earlier than expected. In any event, a significant rainfall event looks like a proverbial lock due to the deep and strong WAA / Carlson conveyer belt set up. A strong LLJ gets going during the day on Tuesday, with the model guidance of the LLJ placement and intensity varying. Have issued a Wind Advisory for far eastern sections of CT and LI for late Tuesday and Tuesday night. There is the potential as the low deepens further and one low begins to take over that the winds could peak at 45 to 50 mph across far eastern sections with the winds more out of the northeast and north. The mostly likely time for this would be during Tuesday evening and into the first half of the overnight as the low may get slightly further to the east. The heavier rain would then end from west to east based on the latest timing. With the center of circulation potentially getting further east as the low gets more vertically stacked the storm should get to its peak in terms of intensity and lower surface pressure readings. Rainfall totals as this time look to be on the order of 2 to 4 inches. HREF 24 hr. PMM QPF has localized amounts of 5 to 7 inches which is tough to come by. Hopefully this scenario does not come to fruition as this would lead to widespread flooding issues. Thus continuing with the Flood Watch across the entire area for tonight into the day on Tuesday. On Wednesday the low will gradually get further offshore, especially by the afternoon. The current thinking has chance POPs giving way to slight chance POPs from west to east through the day as the back edge of any rainfall begins to pivot off to the east. With completely dry conditions returning by the late day and evening with mostly cloudy skies giving way to some clearing during this time frame. A gusty northerly flow will have temperatures running near normal with mainly lower 60s for afternoon highs. &&
  8. With the potential for several inches of rain over the 7 days we are actually lucky things dried out for a while after Ida. With that said flooding still looks like a concern with storm #1 and potentially storm #2.
  9. Overnight low of 41 here. Current temp 42
  10. Overnight low of 41 here. Current temp 42
  11. The GFS keeping putting down a swath of 3-5" rainfall amount right over NE NJ and the NYC metro especially on the 06z run. Otherwise widespread 1-3" amounts throughout the region. Pretty strong storm overall at 975 mb.
  12. The NYC metro should see a widespread 1-3" rainfall w/locally higher amounts especially as you head further north and east. Severe weather also possible tomorrow night into the first half of Tuesday. I think the SPC may eventually go with a slight risk for the area. We'll see. Wednesday could be a windy day behind the system. Storm #2 Friday into Saturday details TBD but potentially stronger and more impactful then storm #1?? The fuse was light and the active pattern has now exploded after an extended break post Ida.
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