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yoda

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  1. yoda
    Severe Thunderstorm Watch coming soon per SPC MCD
  2. yoda
    Storms entering NW VA increasing in intensity and some hail cores slowly starting to appear
  3. yoda
    1630z disco .Lower OH Valley into the Mid-Atlantic states... Morning surface mesoanalysis places a residual frontal zone draped over central IN/OH with a low-level moisture reservoir (low 60s deg F surface dewpoints) extending from the confluence of the MS/OH rivers northeastward into the lower Wabash Valley. Atop this moisture, a plume of steep 700-500 mb lapse rates (8.0 to 8.3 deg C/km) sampled at the Lincoln, IL and Wilmington, OH raob sites, will overspread the OH Valley eastward into VA today. The richer low-level moisture will likely remain west of the Appalachians across the lower OH Valley where 1500-2500 J/kg MLCAPE is forecast. Widely scattered thunderstorms are forecast to develop by mid afternoon within the moist axis along/south of a stalled front over the OH Valley. Effective shear 25-35 kt will support a mix of supercells and organized line segments capable of hail and wind. Farther east, steep lapse rates from the surface to 500 mb are depicted in forecast soundings by early to mid afternoon (8 deg C/km). Although PW will be lower across the Mid-Atlantic region, a more deeply mixed boundary layer is forecast with strong westerly mid-level flow (40 kt). Initial cellular storms will likely develop over the higher terrain with subsequent development across northern VA. A band of storms posing a risk for severe gusts (60-70 mph) and resultant wind damage is forecast. Given the lapse rate profile coupled with ample mid- to high-level flow and a linear mode, have increased wind probabilities and an upgrade to level 3 categorical outlook this update. The overall severe threat should gradually diminish through late evening with the loss of diurnal heating.
  4. yoda
    Yup And added ENH to our south including EZF into S MD
  5. yoda
    Wonder if the 1630z OTLK will pull the SLGT risk a bit further north and west
  6. yoda
    Mesoscale Discussion 0438 NWS Storm Prediction Center Norman OK 1001 AM CDT Mon Apr 15 2024 Areas affected...portions of eastern West Virginia...northern Virginia and western Maryland Concerning...Severe potential...Watch unlikely Valid 151501Z - 151630Z Probability of Watch Issuance...5 percent SUMMARY...Isolated showers and thunderstorms may produce gusty winds or small hail the next couple of hours across parts of the West Virginia, Maryland and Virginia border vicinity. DISCUSSION...A couple of thunderstorms have developed late this morning ahead of a stationary boundary near the WV/MD/VA border. This activity is likely somewhat elevated. Nevertheless, weak instability (generally less than 500 J/kg MUCAPE) amid steep midlevel lapse rates and modest effective shear could support sporadic small hail. A dry, mixed boundary-layer and light low-level flow also may foster gusty winds around 40-50 mph. This initial thunderstorm activity is expected to remain isolated and the overall severe threat limited over the next couple of hours, and a watch is not expected. The severe threat will increase across portions of Mid-Atlantic later this afternoon, and this later threat will be addressed with additional MCDs in the coming hours. ..Leitman/Smith.. 04/15/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LWX...PBZ...RLX...
  7. yoda
    Area Forecast Discussion...UPDATED National Weather Service Baltimore MD/Washington DC 910 AM EDT Mon Apr 15 2024 .SYNOPSIS... A cold front will drop southward through the area tonight, before returning northward as a warm front on Wednesday. A strong cold front will move through this weekend, with high pressure building in early next week. && .NEAR TERM /THROUGH TONIGHT/... Model trends past 24 hrs have shown storms this afternoon developing further north than anticipated yesterday roughly now from along and south of the US-50 corridor or south of I-70 along a lee-side trof. New 13Z SPC DY1 Otlk has shifted the Slight risk further north into areas south of the Capital Beltway. Hail is expected to be the primary threat given 7.3 C/km mid-level lapse rates and decent CAPE above -20C seen on the 12Z IAD sounding. Storms would also be relatively fast movers with 0-6 km mean winds of 28kt posing a marginal damaging wind threat.
  8. yoda
    SLGT risk pushed north to DC metro... MRGL to near Mason-Dixon line on 1300z SPC OTLK
  9. yoda
    Hmmm... later today surprise? NEAR TERM /THROUGH TONIGHT/... Showers and a few thunderstorms continue to slowly drift southeastward across the northern half of the forecast area early this morning. This remnant activity should continue to weaken over the coming hours, and eventually dissipate prior to daybreak. Clouds associated with this activity may linger for the first half of the morning, but clearing and ample sunshine is expected during the second half of the morning into the early afternoon. A diffuse cold front will continue to slowly drift southward across the forecast area today. Daytime heating will allow instability to build, with around 1000 J/kg of CAPE present by peak heating this afternoon. Additional thunderstorms are expected to develop within the zone of low-level convergence near the surface front later this afternoon. There`s some uncertainty as to where exactly this will occur. Any location in the forecast area has at least a slight chance for a thunderstorm, but the greatest chance should generally be south of I-66/US-50 and east of US-15. Further west, westerly flow and downsloping will act to further dry out an already dry boundary layer, which should limit storm coverage as a result. Further north, they`ll likely end up to the north of the best- low-level convergence, which should also limit the coverage of storms. Where storms do form, they`ll likely be strong to severe. Model soundings show an environment that is more typical of the High Plains than the Mid-Atlantic. Boundary layer moisture will be rather limited, with dewpoints only in the 50s, but lapse rates will be very steep (dry adiabatic in the lowest three kilometers, with mid- level lapse rates around 7.5-8 C/km). Flow will be relatively weak in the boundary layer, but pick up rapidly in the mid- levels, with continued shear through the upper levels. Hodographs are relatively straight, so storm splits may be possible, with both multicells and right/left moving supercells. Model soundings check a lot of boxes in recent research for hail producing storms. That may be the primary threat this afternoon, although the steep lapse rates and DCAPE values around 1000 J/kg should make damaging winds a threat as well. Tornadoes aren`t expected with a dry boundary layer and little to no low- level shear in place. The I-95 corridor south of DC to southern Maryland should stand the greatest chance of seeing a severe stoms. These storms will progress off to the south and east this evening, leading to dry conditions overnight.
  10. yoda
    New Day 1 has SLGT risk in W MD eastward till around HGR, also includes parts of the Panhandle of WV that borders Maryland
  11. yoda
    Could be interesting if any storm can get into our area tomorrow evening .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... Flow aloft will become more zonal in nature tomorrow, with a broad belt of west-southwesterly flow extending from the Upper Midwest toward the East Coast. A shortwave disturbance will descend down in the west-northwesterly flow from the Great Lakes toward Upstate NY. A weak area of low pressure will accompany the shortwave, along with an attendant cold front which will drop southward out of NY into northern PA Sunday afternoon. Locally, it will be a warm day to the south of the boundary, with temperatures climbing into the upper 70s to near 80 beneath partly cloudy skies. Thunderstorms are expected to form near the aforementioned frontal boundary up in PA Sunday afternoon. Much of this activity is expected to remain to our north during the daylight hours. As we move into the evening and the first half of the overnight, these storms are expected to drift southward along with the frontal boundary, eventually reaching northern portions of the forecast area. With loss of daytime heating, the trend should be for these storms to gradually weaken as they move in from the north, but a few stronger storms can`t be ruled out. The environment will be an uncommon one for this part of the country, with steep lapse rates of 7-8.5 C/km in place as an elevated mixed layer moves in aloft. If storms do persist as they track into the area, some instances of large hail may be possible. SPC currently has portions of northern Maryland and the West Virginia Panhandle outlooked in a Marginal Risk for severe thunderstorms.
  12. yoda
    Yay wind URGENT - WEATHER MESSAGE National Weather Service Baltimore MD/Washington DC 1022 PM EDT Fri Apr 12 2024 DCZ001-MDZ005-006-011-013-014-503>508-VAZ053-054-506-526-131030- /O.EXB.KLWX.WI.Y.0015.240413T0400Z-240413T2200Z/ District of Columbia-Carroll-Northern Baltimore- Southern Baltimore-Prince Georges-Anne Arundel- Northwest Montgomery-Central and Southeast Montgomery- Northwest Howard-Central and Southeast Howard-Northwest Harford- Southeast Harford-Fairfax-Arlington/Falls Church/Alexandria- Eastern Loudoun-Northwest Prince William- Including the cities of Washington, Eldersburg, Westminster, Reisterstown, Cockeysville, Baltimore, Bowie, Suitland-Silver Hill, Clinton, College Park, Greenbelt, Laurel, Camp Springs, Glen Burnie, Annapolis, Severn, South Gate, Severna Park, Arnold, Odenton, Germantown, Damascus, Bethesda, Rockville, Gaithersburg, Silver Spring, Lisbon, Columbia, Ellicott City, Jarrettsville, Aberdeen, Reston, Herndon, Annandale, Centreville, Chantilly, McLean, Franconia, Arlington, Alexandria, Falls Church, Leesburg, Ashburn, Sterling, and Haymarket 1022 PM EDT Fri Apr 12 2024 ...WIND ADVISORY IN EFFECT UNTIL 6 PM EDT SATURDAY... * WHAT...West winds 15 to 25 mph with gusts around 45 mph overnight, increasing to 20 to 30 mph with gusts around 50 mph Saturday. * WHERE...Portions of central, north-central, and northern Maryland, The District of Columbia, and northern Virginia. * WHEN...Until 6 PM EDT Saturday. * IMPACTS...Gusty winds could blow around unsecured objects. Tree limbs could be blown down and a few power outages may result.
  13. yoda
    1630z OTLK disco ...Mid-Atlantic States and Carolinas... A less focused and less certain severe risk appears to exist across the region. Cloud cover remains prevalent at midday coincident with low-level upslope flow, although some clearing is noted early this afternoon across the southern Appalachians vicinity. Where modest destabilization does occur this afternoon, long hodographs would conditionally support storm organization with any robust updrafts. Isolated to widely scattered strong to severe storms capable of a threat for damaging gusts and a couple of tornadoes are possible, particularly near the mountains/Blue Ridge, with a lower probability/lesser anticipated storm coverage expected farther east over the coastal plain/Delmarva.
  14. yoda
    30 wind added in SW PA/W WV on 1630z OTLK
  15. yoda
    Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1019 AM EDT Thu Apr 11 2024 .SYNOPSIS... Low pressure will track into the Great Lakes today, with an associated cold front moving through tonight. Upper troughing will linger overhead tomorrow, with a reinforcing cold front moving through tomorrow evening. High pressure will build to our south this weekend. A weak area of low pressure will track to our north late Sunday night into early Monday, before high pressure regains control early next week. && .NEAR TERM /THROUGH TONIGHT/... 1030 AM Update: Showers are starting to approach the area late this morning with some partial clearing happening across western portions of MD and the eastern WV panhandle. Temperatures are already climbing into the mid to upper 60s across the lower elevations. It is worth noting a dry slot building in behind the initial cold front passage affecting areas further south of our CWA. Discrete cells and clouds should begin building back in through the early afternoon with increasing rain chances.
  16. yoda
    Both 12z NAM and NAM NEST have some decent curved and looping hodographs around 06z in the region with 300 m2/s2 with 500 to 1000 SBCAPE
  17. yoda
    1300z SPC OTLK update Mid-Atlantic states into Carolinas... A less focused and more conditional severe risk seems evident for the Carolinas later this afternoon and northward into the Mid-Atlantic states this evening as the upper trough encroaches on the general region. A broad warm-air advection regime north of the FL/GA early-day MCS will slowly destabilize today, aided in part by lower 60 deg F dewpoints north, mid to upper 60s south. Long hodographs will favor storm organization with any robust updrafts. Isolated to widely scattered strong to severe storms capable of a threat for damaging gusts and a couple of tornadoes are possible, mainly over parts of western VA, with lower coverage expected farther east over the coastal plain/Delmarva.
  18. yoda
    Morning AFD from LWX on the threat The upper trough will take on a negative tilt as it moves overhead tonight. At the surface, low pressure will deepen as it tracks into the Ohio Valley. Thunderstorms are expected to form within the zone of strong forcing for ascent ahead of the negatively tilted trough across OH/WV/SW VA late this afternoon into early this evening. These storms should initially reach far southwestern portions of the forecast area during the late evening, before progressing northeastward across the remainder of the forecast area between 10 PM and 4 AM. Instability will increase through the evening as a low level mass response occurs ahead of the approaching trough. CAPE values are expected to increase to around 300-600 J/kg across much of the area. When coupled with an impressive low- level jet and ample deep layer shear present, some of the storms this evening into the overnight may be on the strong to severe side. Damaging winds should be the primary threat, but a brief tornado can`t be ruled out given the strong low-level jet, 0-1 km SRH values increasing to around 200-300 m2/s2, and STP values climbing above 1. Weak stabilization evident on forecast soundings right near the surface may potentially serve as a limiting factor for both the damaging wind and tornado potential. SPC currently has locations to the west of the Blue Ridge outlooked in a Slight Risk for severe thunderstorms, while locations to the east of the Blue Ridge are in a Marginal Risk.
  19. yoda
    Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1247 AM CDT Thu Apr 11 2024 Valid 111200Z - 121200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER OHIO RIVER VALLEY... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE OHIO RIVER VALLEY AND NORTHERN FLORIDA TO SOUTHERN GEORGIA... ...SUMMARY... Severe thunderstorms with a few tornadoes, scattered damaging winds, and isolated large hail are possible across the upper Ohio River Valley and parts of the Appalachians this afternoon. Scattered damaging winds and a couple tornadoes will also be possible across southeast Georgia into northern Florida, mainly this morning through early afternoon. ...Synopsis... 04 UTC surface observations depict a diffuse surface low over the lower MS River Valley. This low is forecast to deepen over the next 24 hours as it lifts northward into the OH Valley/Great Lakes region in tandem with the phasing of an amplified upper-level trough over the MS Valley with an approaching upstream perturbation. A surface cold front currently draped across southeast LA will surge to the east/northeast as the low deepens, and should act to focus thunderstorm development through the late morning and afternoon hours across both the upper OH Valley and Southeast. ...Upper OH River Valley... Recent 925/850 mb analyses and surface observations show a consolidating warm frontal zone draped from the surface low over the lower MS Valley into the upper OH River Valley. The surface low will deepen along this corridor amid a combination of strong height falls and ascent within the left-exit region of a mid-level jet. A plume of low to mid-60s dewpoints will advect northward with the deepening low, establishing a focused warm sector ahead of the approaching cold front by early afternoon across parts of KY, OH, and WV. The current expectation is for sufficient destabilization within the warm sector to support surface-based convection by the 18-21 UTC time frame. A combination of strong synoptic-scale ascent and 40-50 knot deep-layer shear vectors off the cold front should promote a mix of discrete cells and semi-discrete clusters - including the potential for a few supercells. Increasing southeasterly winds through the lowest 1-2 km should yield effective SRH values between 150-300 m2/s2, which will support a tornado threat with the more robust/organized cells as well as a wind threat with more organized clusters. This threat appears greatest across southeast OH into western WV where latest guidance continues to show a focused convective signal. Further to the east into parts of northwest VA, a somewhat weaker convective signal is noted in most CAM guidance, but 50-knot flow in the lowest 2 km will likely pose a substantial wind threat with any storms that can mature. Risk probabilities have been expanded into this region to account for this potential. That said, this scenario appears to be conditional on achieving sufficient low-level warming within the warm sector. While an extensive dry slot is noted in water-vapor imagery across the Mid-South into central IN, the low/mid-level warm advection regime is maintaining mid-level stratus across the region with most ASOS stations reporting overcast skies and ceilings near 6 kft. It is unclear how much clearing will occur through early afternoon given persistent ascent, and a 10 F spread in afternoon high temperatures is noted across OH/WV in recent ensemble guidance. Based on forecast soundings, surface temperatures in the upper 60s may be required to realize 500+ J/kg SBCAPE with minimal inhibition. The median of the temperature distribution appears to reside in the upper 60s, but SBCAPE may still only reach 500-1000 J/kg per ensemble distributions.
  20. yoda
    SLGT risk moved into most of N VA and C MD on new Day 1 for 15 wind and 5 tornado
  21. yoda
  22. yoda
    Still MRGL on 1730z SPC OTLK... but a small ENH risk was added in E Ohio into West Virginia with 10% tor probs added
  23. yoda
    Might get a slight risk upgrade at 1730z
  24. yoda
    Updated morning AFD from LWX now mentions tornado threat SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... Rain chances increase further Thursday morning as a frontal system inches closer to the region, but the bulk of precipitation likely arrives Thursday afternoon. Strong southerly winds are expected to develop ahead of the approaching cold front, which could reach 25 to 35 mph or so. The upper trough that is currently digging into the MS River Valley will lift northeastward towards the Great Lakes, becoming negatively-tilted into Thursday evening/night. Given the amount of pre-frontal showers and clouds, instability looks to be hard to come by, especially with the timing looking to be later in the evening into Thursday night. However, given height falls aloft and anomalous low-level moisture, 200-400 J/kg ML/SBCAPE still looks achievable. This, combined with increasing low-level flow to 50+ kts at a few thousand feet AGL (especially late at night Thursday into early Friday morning) could be enough for low-topped convection capable of bringing down damaging wind gusts or spinning up a brief tornado or two. The greatest potential for any severe weather appears to be Thursday night.
  25. yoda
    SPC AC 100551 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1251 AM CDT Wed Apr 10 2024 Valid 111200Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE UPPER OH VALLEY AND PARTS OF THE SOUTHEAST... ...SUMMARY... Severe thunderstorms with a few tornadoes, scattered damaging winds, and isolated large hail are likely across the Upper Ohio Valley vicinity, mainly during Thursday afternoon. Scattered damaging winds and a few tornadoes will also be possible across southeast Georgia into central Florida, from Thursday morning into the afternoon. ...Synopsis... A full-latitude mid/upper trough will be centered near the MS Valley at 12Z Thursday, comprised of two primary shortwave impulses. The southern-stream impulse should pivot northeast and accelerate as the northern-stream impulse becomes the dominant embedded feature. A steadily deepening surface cyclone will track northeast from the Lower OH Valley to the Lake Huron vicinity during the period. ...Upper OH Valley... A synoptically favorable corridor for a few supercells and organized clustering into short-line segments appears likely to develop east of the gradually deepening surface cyclone track. This region should have a period where an overspreading mid-level dry slot coincides with the diurnal heating cycle, before afternoon convection develops within the left-exit region of the strong mid-level jet across the Southeast and southern Appalachians. MLCAPE should reach 500-1000 J/kg amid a meridional supercell wind profile, before low-level flow becomes veered from the southwest. Consensus of 00Z CAM guidance supports the potential for a few supercells, with some upscale growth into a line segment as convection consolidates northeastward. This may be relatively short-lived as convection outpaces the weak buoyancy plume and likely weakens after dusk. A mesoscale corridor of greater severe probabilities, seemingly in the form of damaging wind, may be warranted in later outlooks. ...Southeast GA to central FL... Extensive deep convection should be ongoing from north FL into GA at 12Z Thursday. The southern portion of this activity will have the best chance to maintain a damaging wind and embedded tornado threat during the late morning into about mid-afternoon as stronger boundary-layer heating occurs across the FL Peninsula. Large-scale ascent will subside with southern extent through the day given the northeastward track of the surface cyclone, in addition to low-level winds becoming more veered in time over the FL Peninsula. ...Carolinas and VA... Overall severe threat appears rather conditional during the daytime hours given extensive convection across at least north FL and GA on Thursday morning. Diabatic surface heating should be quite limited by abundant downstream cloudiness/weak convection north of the deeper convection during the day. Consensus of guidance largely attempts to destabilize on the backside of early-day convection within a plume of at least mid 60s surface dew points. Overall threat will probably consist of sporadic damaging winds and up to a few brief tornadoes within lower-topped convection, mainly from midday through Thursday evening. With the expectation for lesser severe weather coverage relative to areas farther northwest and south, have opted to highlight much of this region with a cat 1-MRGL this cycle. ..Grams.. 04/10/2024
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