Eskimo Joe Posted April 7, 2020 Share Posted April 7, 2020 40% chance of a WW: https://www.spc.noaa.gov/products/md/2020/md0294.html Quote NWS STORM PREDICTION CENTER NORMAN OK 0157 PM CDT TUE APR 07 2020 AREAS AFFECTED...NORTHEAST WEST VIRGINIA...NORTHERN VIRIGNIA AND PORTIONS OF MARYLAND CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE VALID 071857Z - 072030Z PROBABILITY OF WATCH ISSUANCE...40 PERCENT SUMMARY...THE THREAT FOR SEVERE HAIL AND WIND IS EXPECTED TO INCREASE AFTER 20Z ACROSS PARTS OF THE MID ATLANTIC. DISCUSSION...RECENT SATELLITE IMAGERY SHOWS INCREASINGLY AGITATED CUMULUS ALONG AND AHEAD OF A REMNANT OUTFLOW BOUNDARY ACROSS EASTERN WV AND IN THE VICINITY OF AN EMBEDDED VORTICITY MAXIMA LOCATED IN NORTHERN WV. THESE FEATURES ARE CO-LOCATED WITH A REGION OF MODEST WARM AIR ADVECTION ROOTED BETWEEN 925-850 MB. COMBINED, THESE FEATURES WILL ACT AS THE IMPETUS FOR CONVECTIVE INITIATION ACROSS NORTHEAST WV AND NORTHERN VA IN THE COMING 1-3 HOURS. ALTHOUGH THIS ENVIRONMENT WILL LIKELY FEATURE MODEST INSTABILITY BETWEEN 500-750 J/KG MLCAPE, 45-50 KNOTS OF EFFECTIVE BULK WIND SHEAR AND SUSTAINED FORCING FOR ASCENT MAY BE ABLE TO COMPENSATE FOR THE INSTABILITY AND WILL SUPPORT A HAIL THREAT WITH ANY STRONGER STORMS. ADDITIONALLY, STEEP BOUNDARY LAYER LAPSE RATES ON THE ORDER OF 7-8 C/KM ALREADY IN PLACE ACROSS THE REGION (PER SPC MESOANALYSIS) SUGGESTS THE POTENTIAL FOR STRONG, DOWNDRAFT-DRIVEN WINDS. DUE TO THESE CONSIDERATIONS, A WATCH MAY BE NEEDED IF CONFIDENCE INCREASES THAT SUSTAINED ORGANIZED CONVECTION WILL OCCUR. ..MOORE/HART.. 04/07/2020 Link to comment Share on other sites More sharing options...
yoda Posted April 7, 2020 Share Posted April 7, 2020 LWX afternoon AFD seems to think 2 more rounds to go... one this evening and one overnight NEAR TERM /THROUGH TONIGHT/... Weak frontal zone draped across the area this afternoon with slightly cooler/drier/more stable air to its northeast across northern Maryland. Meanwhile, the remnant of a morning convective cluster in the Ohio Valley is currently crossing northern parts of the area. Along its southern flank it is encountering a slightly more unstable airmass and there has been occasional lightning. This rain, along with dense cloud cover, will likely reinforce the boundary, keeping the idea that the best convective activity will remain near or southwest of the Potomac River through this evening. Additional scattered showers/storms may for south of this cluster where there has been more sun. Mid level lapse rates are actually at their poorest this afternoon, so most activity may tend to struggle to get going. An additional convective complex in the upper Ohio Valley may provide an additional trigger for storms this evening. If steep low level lapse rates remain, it will make locally damaging wind gusts the primary threat with any stronger storms. Severe hail would likely be limited to storms with rotating updrafts (which is possible due to sufficient shear) with instability initially rather meager amongst modest surface dew points. This activity may be assisted as a 700 mb speed max arrives and instability increases with better lapse rates. However, exact convective evolution remains quite uncertain through this evening. There will likely be a bit of a lull during the late evening, but then the disturbance and associated low in the upper Great Lakes will approach late tonight. With a mid and upper speed max and steep mid level lapse rates associated with this disturbance, convection will likely be ongoing to our northwest. While most models are in fairly good agreement with convection existing, the biggest question is how much of it will survive through the diurnal minima, though synoptic forcing and increasing MUCAPE suggest it could. The primary threat with these storms might be hail (a somewhat uncommon occurrence at this time of day in this part of the country). The wind threat with these storms would have to be associated with the strongest downbursts due to nocturnal stabilization. Any storms that are left will likely be exiting or dissipating by daybreak Link to comment Share on other sites More sharing options...
wawarriors4 Posted April 7, 2020 Share Posted April 7, 2020 Really good storm moving through just NW of Fredericksburg right now. Heavy Rain, Lightning, Thunder and just had a 44 mph wind gust. ETA: Severe Thunderstorm Warning just issued https://twitter.com/NWS_BaltWash/status/1247607555137757184/photo/1 2 Link to comment Share on other sites More sharing options...
yoda Posted April 7, 2020 Share Posted April 7, 2020 Looks like the sun is trying hard to come back out here Link to comment Share on other sites More sharing options...
southmdwatcher Posted April 7, 2020 Share Posted April 7, 2020 The sun is going to try to come back, today this is one of the rare events in this region where the sun is not needed but can certainly aid the environment overnight...I am already looking forward to Sunday's event southwest of here and what here could be an overnight storm scenario. Hope the Euro and UK are wrong about Sunday down South. Link to comment Share on other sites More sharing options...
wxdude64 Posted April 7, 2020 Share Posted April 7, 2020 Well, with the 4th shower/storm of the day here I got to make a hail report to CoCoRaHS, nothing major, 1/4 size, but first hail of the season! Link to comment Share on other sites More sharing options...
yoda Posted April 7, 2020 Share Posted April 7, 2020 2000 SPC OTLK states that threat for severe hail and wind should increase as diurnal heating continues and references the MCD Eskimo Joe posted above Link to comment Share on other sites More sharing options...
NorthArlington101 Posted April 7, 2020 Share Posted April 7, 2020 https://m.facebook.com/notes/wxriskcom/major-alert-easter-sunday-looks-dangerous/2881339375246635/Looks like an interesting period of severe WX! Link to comment Share on other sites More sharing options...
Kmlwx Posted April 7, 2020 Author Share Posted April 7, 2020 1 minute ago, NorthArlington101 said: https://m.facebook.com/notes/wxriskcom/major-alert-easter-sunday-looks-dangerous/2881339375246635/ Looks like an interesting period of severe WX! It looks intense - but primarily for the SE. I'm not convinced we see much of anything up our way other than rain maybe. Bears watching for sure. 1 Link to comment Share on other sites More sharing options...
high risk Posted April 7, 2020 Share Posted April 7, 2020 3 minutes ago, Kmlwx said: It looks intense - but primarily for the SE. I'm not convinced we see much of anything up our way other than rain maybe. Bears watching for sure. I generally agree, but it depends on whether the GFS is right with the secondary low forming near the Carolinas. That would keep us well in the cool air for sure. The Euro would at least give us a (small) chance of getting into the warm sector. Link to comment Share on other sites More sharing options...
Rhino16 Posted April 7, 2020 Share Posted April 7, 2020 This is one of those things where you can hear thunder in the distance, but not a single drop of rain... Link to comment Share on other sites More sharing options...
Kmlwx Posted April 7, 2020 Author Share Posted April 7, 2020 Just now, high risk said: I generally agree, but it depends on whether the GFS is right with the secondary low forming near the Carolinas. That would keep us well in the cool air for sure. The Euro would at least give us a (small) chance of getting into the warm sector. And there's plenty of time to move things around. I'm sure we're not at the final setup on the models. We'll see where we stand later in the week. Would suck if most of us miss out on appreciable storms tonight, tomorrow, Thursday and then the weekend too. Link to comment Share on other sites More sharing options...
high risk Posted April 7, 2020 Share Posted April 7, 2020 1 minute ago, Kmlwx said: And there's plenty of time to move things around. I'm sure we're not at the final setup on the models. We'll see where we stand later in the week. Would suck if most of us miss out on appreciable storms tonight, tomorrow, Thursday and then the weekend too. Well, THAT is depressing. If this evening and late tonight fail, I still think we have a good shot at a line of storms Thursday, even if limited instability keeps them sub-severe. Link to comment Share on other sites More sharing options...
MN Transplant Posted April 7, 2020 Share Posted April 7, 2020 The impulse kicking off our next set of storms appears to be in SE Ohio right now. Had 0.33" earlier with a one rumble of thunder. Link to comment Share on other sites More sharing options...
Kmlwx Posted April 7, 2020 Author Share Posted April 7, 2020 21 minutes ago, high risk said: Well, THAT is depressing. If this evening and late tonight fail, I still think we have a good shot at a line of storms Thursday, even if limited instability keeps them sub-severe. Thunder and gusty winds would be fun. Even if we don't see anything locally for Sunday - just seeing some of the guidance for areas of the Southeast is pretty freaky. 1 Link to comment Share on other sites More sharing options...
Rhino16 Posted April 7, 2020 Share Posted April 7, 2020 In the Special Weather Statement, I like how they specifically told the people at the hospitals nearby to take shelter, as well as everyone else. They told people at the hospitals to take shelter. Link to comment Share on other sites More sharing options...
WxUSAF Posted April 7, 2020 Share Posted April 7, 2020 NAM and Hrrr both give me a nice ole. Link to comment Share on other sites More sharing options...
Vice-Regent Posted April 7, 2020 Share Posted April 7, 2020 Our profile and column is getting trashed by the front-running convection but it is very warm in OH valley. Good for warm air advecting our way to victory. Link to comment Share on other sites More sharing options...
yoda Posted April 7, 2020 Share Posted April 7, 2020 Big hail core in the supercell in N WV right now Link to comment Share on other sites More sharing options...
Sparky Posted April 7, 2020 Share Posted April 7, 2020 Just would like to hear thunder and see some lightning in the wee hours tomorrow. Link to comment Share on other sites More sharing options...
yoda Posted April 8, 2020 Share Posted April 8, 2020 LWX states spotter activation maybe needed overnight in their updated HWO Also zones have severe wording in them for overnight and tomorrow morning Link to comment Share on other sites More sharing options...
osfan24 Posted April 8, 2020 Share Posted April 8, 2020 Unless I"m missing something, round two for this evening/tonight is looking really bleak on radar. Link to comment Share on other sites More sharing options...
yoda Posted April 8, 2020 Share Posted April 8, 2020 0100 SPC OTLK mentions MCS complex rolling through overnight with large hail and damaging winds as a threat MCS development is ongoing across the southern Great Lakes region. This large area of storms is forecast to move east-southeastward into the Ohio Valley and central Appalachians this evening into tonight. A threat for large hail and wind damage will likely exist overnight with the stronger thunderstorms within this MCS. An isolated wind damage and hail threat may persist through late tonight as the MCS moves into the Mid-Atlantic region. Link to comment Share on other sites More sharing options...
yoda Posted April 8, 2020 Share Posted April 8, 2020 STWatch issued until 3AM for where the MCS is developing back in OH and MI - https://www.spc.noaa.gov/products/watch/ww0084.html Link to comment Share on other sites More sharing options...
high risk Posted April 8, 2020 Share Posted April 8, 2020 34 minutes ago, yoda said: 0100 SPC OTLK mentions MCS complex rolling through overnight with large hail and damaging winds as a threat It's still on the table for sure. I was super optimistic about this threat in my morning posts, but my enthusiasm has been tempered by multiple CAMs showing the section of the MCS in the DC-Baltimore corridor falling apart just before it arrives, while the sections further east and west persist. Still, some of the solutions have at least some of the system surviving into the metro areas, and the lapse rates aloft are still progged to be terrific, so I'm not ruling out storms with hail very late tonight. Link to comment Share on other sites More sharing options...
yoda Posted April 8, 2020 Share Posted April 8, 2020 15 minutes ago, high risk said: It's still on the table for sure. I was super optimistic about this threat in my morning posts, but my enthusiasm has been tempered by multiple CAMs showing the section of the MCS in the DC-Baltimore corridor falling apart just before it arrives, while the sections further east and west persist. Still, some of the solutions have at least some of the system surviving into the metro areas, and the lapse rates aloft are still progged to be terrific, so I'm not ruling out storms with hail very late tonight. LWX evening AFD update agrees with you NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Other than the single weakening supercell over far western Virginia, showers and thunderstorms have mostly waned due to the stable atmosphere provided across the region in the wake of the earlier convection. Another disturbance and associated low in the upper Great Lakes will approach late tonight. With a mid and upper speed max and steep mid level lapse rates associated with this disturbance, convection is currently ongoing to our northwest. While most models are in fairly good agreement with convection existing, the biggest question is how much of it will survive through the diurnal minima, though synoptic forcing and increasing MUCAPE suggest it could. The primary threat with these storms might be hail (a somewhat uncommon occurrence at this time of day in this part of the country). The wind threat with these storms would have to be associated with the strongest downbursts due to nocturnal stabilization. Any storms that are left will likely be exiting or dissipating by daybreak. Link to comment Share on other sites More sharing options...
high risk Posted April 8, 2020 Share Posted April 8, 2020 00z NAM nest also does the split with the late night MCS around the metro areas, but on the plus side, it looks WAY better for Thursday. The midday line has 2000 j/kg of sfc-based cape to work with and healthy deep layer shear. This is the first cycle to show that good instability, so will need to see it maintain that signal. 2 Link to comment Share on other sites More sharing options...
yoda Posted April 8, 2020 Share Posted April 8, 2020 Wow... impressive PRELIMINARY LOCAL STORM REPORT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1140 PM EDT TUE APR 07 2020 ..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON... ..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE.... ..REMARKS.. 1019 PM HAIL SPOTTSWOOD 37.95N 79.21W 04/07/2020 E1.00 INCH AUGUSTA VA 911 CALL CENTER HAIL ACCUMULATING 2 INCHES DEEP ON I-81 NEAR SPOTSWOOD CAUSED MULTIPLE ACCIDENTS AND PARTIALLY CLOSED THE HIGHWAY && EVENT NUMBER LWX2000890 1 1 Link to comment Share on other sites More sharing options...
yoda Posted April 8, 2020 Share Posted April 8, 2020 https://www.spc.noaa.gov/products/md/md0304.html Mesoscale Discussion 0304 NWS Storm Prediction Center Norman OK 1252 AM CDT Wed Apr 08 2020 Areas affected...Portions of southeastern OH...northern WV...southwestern PA...western MD...and far northern VA Concerning...Severe Thunderstorm Watch 85... Valid 080552Z - 080715Z The severe weather threat for Severe Thunderstorm Watch 85 continues. SUMMARY...A line of strong to severe storms capable of producing mainly damaging winds will continue east-southeastward. Downstream watch issuance is possible. DISCUSSION...Storms have grown upscale across parts of southeastern OH into western PA, with mainly severe/damaging winds being reported, including a gust to 75 mph at the Pittsburgh International Airport. The airmass downstream of this ongoing convection is not particularly unstable given cooler low-level temperatures and less low-level moisture. With MUCAPE generally 500-1000 J/kg, storms may have a tendency to become slightly elevated with time, particularly with eastward extent. Still, given the well-organized nature of the line and strong outbound velocities noted on KPBZ radar, there appears to be a continued strong to damaging wind threat that may extend to the south/southeast of ongoing Severe Thunderstorm Watch 85. Accordingly, another watch may be needed across parts of southwestern PA into western MD and the eastern WV Panhandle. ..Gleason/Thompson.. 04/08/2020 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CTP...LWX...PBZ...RLX... Link to comment Share on other sites More sharing options...
yoda Posted April 8, 2020 Share Posted April 8, 2020 5 hours ago, high risk said: 00z NAM nest also does the split with the late night MCS around the metro areas, but on the plus side, it looks WAY better for Thursday. The midday line has 2000 j/kg of sfc-based cape to work with and healthy deep layer shear. This is the first cycle to show that good instability, so will need to see it maintain that signal. New day 2 from SPC was quite meh unfortunately Link to comment Share on other sites More sharing options...
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