yoda Posted August 18, 2021 Share Posted August 18, 2021 SLGT risk on new Day 1 from N VA north into C PA 1 Link to comment Share on other sites More sharing options...
yoda Posted August 18, 2021 Share Posted August 18, 2021 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1234 AM CDT Wed Aug 18 2021 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE MID-ATLANTIC... ...SUMMARY... A few tornadoes will be possible today across portions of the central Appalachians and Mid-Atlantic. Thunderstorms associated with strong winds and hail may also occur across parts of the Intermountain West, and over portions of the Mid-South/Tennessee Valley. ...Mid-Atlantic... The remnants of Tropical Depression Fred are forecast to move north across the central Appalachians and Mid-Atlantic, with the center of circulation located over West Virginia by the start of the period. Deep tropical moisture will advect northward with low to mid 70s surface dewpoints expected by early afternoon. Some cloud breaks and modest surface heating should be more than enough to support MLCAPE of 500-1000 J/kg through the day. High-resolution and regional guidance are in good agreement that surface wind fields in the northeastern quadrant of the remnant low will remain strong through much of the day. A 40 kt mid-level speed max should also enhance low- and mid-level shear across much of PA, MD, and northern VA, where model soundings show 0-1 km SRH of 200-300 m2/s2. The combination of sufficient buoyancy and strong low-level shear should support multiple supercells with the potential for a few tornadoes and isolated strong wind gusts through the afternoon/early evening. Link to comment Share on other sites More sharing options...
yoda Posted August 18, 2021 Share Posted August 18, 2021 Link to comment Share on other sites More sharing options...
Newman Posted August 18, 2021 Share Posted August 18, 2021 Link to comment Share on other sites More sharing options...
mattie g Posted August 18, 2021 Share Posted August 18, 2021 I'm never a fan of being on the southern end of probability outlooks. Link to comment Share on other sites More sharing options...
Kmlwx Posted August 18, 2021 Author Share Posted August 18, 2021 3 minutes ago, mattie g said: I'm never a fan of being on the southern end of probability outlooks. Maybe you can score a tail-end charlie Link to comment Share on other sites More sharing options...
yoda Posted August 18, 2021 Share Posted August 18, 2021 MD out... 40 percent chance of watch. For BR into i81 corridor Link to comment Share on other sites More sharing options...
MN Transplant Posted August 18, 2021 Share Posted August 18, 2021 8 minutes ago, mattie g said: I'm never a fan of being on the southern end of probability outlooks. Everything has pointed to PA being the best location, but it’ll be interesting to see if we can get anything going down here. Link to comment Share on other sites More sharing options...
yoda Posted August 18, 2021 Share Posted August 18, 2021 Mesoscale Discussion 1550 NWS Storm Prediction Center Norman OK 0746 AM CDT Wed Aug 18 2021 Areas affected...Parts of the eastern West Virginia Panhandle...northern Virginia...central Maryland and adjacent south central Pennsylvania Concerning...Severe potential...Watch possible Valid 181246Z - 181445Z Probability of Watch Issuance...40 percent SUMMARY...The development of occasional isolated supercell structures with the potential to produce tornadoes (generally short-lived) may increase through 11 am-1 pm EDT, mainly west through northwest of the District of Columbia into the higher terrain around Martinsburg, WV and Hagerstown, MD. It is not yet certain a watch will be needed, but trends are being monitored for this possibility. DISCUSSION...The remnant surface low of Fred has migrated northward into areas south/southeast of Parkersburg, WV during the past few hours. As this has occurred, very moist boundary layer has advected northwestward across the Mid Atlantic region. This includes dew points as high as the mid 70s F into the higher terrain centered around the Martinsburg, WV vicinity, where low-level convergence is becoming focused, and an area of enhanced mid/upper forcing for ascent is forecast to overspread through 15-17Z. Beneath a narrow belt of 30+ kt southerly flow around 850 mb, this also appears likely to coincide with where clockwise-curved low-level hodographs will become maximized, with the terrain contributing to the maintenance of backed/southeasterly near surface flow. As breaks in the overcast allow for insolation to contribute to boundary-layer destabilization, it appears that the environment may become increasingly conducive to supercell structures with the potential to produce relatively short-lived tornadoes. ..Kerr/Edwards.. 08/18/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CTP...LWX... Link to comment Share on other sites More sharing options...
mappy Posted August 18, 2021 Share Posted August 18, 2021 Sky has brightened considerably the last few minutes. Link to comment Share on other sites More sharing options...
Kmlwx Posted August 18, 2021 Author Share Posted August 18, 2021 I'm already semi intrigued by the cell near CHO. Link to comment Share on other sites More sharing options...
Eskimo Joe Posted August 18, 2021 Share Posted August 18, 2021 Pretty early to be meso'd, but yesterday there were confirmed tornadoes from showers that produced almost no lightning. Looks like our chance for local tor/spinnies is the activity that's currently south of I-64. 1 Link to comment Share on other sites More sharing options...
yoda Posted August 18, 2021 Share Posted August 18, 2021 SLGT risk extended southward on 1300z OTLK towards RIC 5% tor moved south as well 1 Link to comment Share on other sites More sharing options...
Eskimo Joe Posted August 18, 2021 Share Posted August 18, 2021 Everyone pour one out for the SPC servers that are getting killed by all the weenies hitting F5 on their keyboards. 1 Link to comment Share on other sites More sharing options...
yoda Posted August 18, 2021 Share Posted August 18, 2021 2 minutes ago, Eskimo Joe said: Everyone pour one out for the SPC servers that are getting killed by all the weenies hitting F5 on their keyboards. That's what the kamala website is for lol The 1300z OTLK is up on there now Link to comment Share on other sites More sharing options...
MN Transplant Posted August 18, 2021 Share Posted August 18, 2021 Seems to be that the parameters look good from central PA down to northern VA, but the models are consistently putting the mini supercells (as indicated by UH) mostly in PA. So it’ll be interesting to see whether the explicit simulations win out or not. Link to comment Share on other sites More sharing options...
Eskimo Joe Posted August 18, 2021 Share Posted August 18, 2021 Cell near orange is starting to put CG down and getting a bit of a kidney bean look. Link to comment Share on other sites More sharing options...
H2O Posted August 18, 2021 Share Posted August 18, 2021 44 minutes ago, MN Transplant said: Seems to be that the parameters look good from central PA down to northern VA, but the models are consistently putting the mini supercells (as indicated by UH) mostly in PA. So it’ll be interesting to see whether the explicit simulations win out or not. To be a weenie for a sec, the short range models have sucked for sim the last few days. Haven’t modeled things well IMO 1 Link to comment Share on other sites More sharing options...
Eskimo Joe Posted August 18, 2021 Share Posted August 18, 2021 I-83 jackpot Link to comment Share on other sites More sharing options...
high risk Posted August 18, 2021 Share Posted August 18, 2021 NAM Nest seems to be an outlier with its very sparse coverage of cells this afternoon. 1 Link to comment Share on other sites More sharing options...
Kmlwx Posted August 18, 2021 Author Share Posted August 18, 2021 5 minutes ago, high risk said: NAM Nest seems to be an outlier with its very sparse coverage of cells this afternoon. Interesting that it tends to be the HRRR that is lackluster due to the low dews on that model. Link to comment Share on other sites More sharing options...
mappy Posted August 18, 2021 Share Posted August 18, 2021 23 minutes ago, Eskimo Joe said: I-83 jackpot oh goodie. never seen that model before tho? Link to comment Share on other sites More sharing options...
high risk Posted August 18, 2021 Share Posted August 18, 2021 2 minutes ago, Kmlwx said: Interesting that it tends to be the HRRR that is lackluster due to the low dews on that model. Yeah, but those HRRR low dew points that we usually see are due to mixing, and even the HRRR can't overmix a tropical air mass like this. 1 Link to comment Share on other sites More sharing options...
Kmlwx Posted August 18, 2021 Author Share Posted August 18, 2021 Radar still is pretty tame. We'll see how the next hour or two unfolds. There is a warning NW of us up in PA. Link to comment Share on other sites More sharing options...
WxUSAF Posted August 18, 2021 Share Posted August 18, 2021 2 minutes ago, Kmlwx said: Radar still is pretty tame. We'll see how the next hour or two unfolds. There is a warning NW of us up in PA. This sunshine can’t hurt given how soupy it is outside. Link to comment Share on other sites More sharing options...
Eskimo Joe Posted August 18, 2021 Share Posted August 18, 2021 Just now, mappy said: oh goodie. never seen that model before tho? It's a machine learning account that pulls from the short term meso guidance. Still an uncalibrated account but something worth peeking at, IMO. Link to comment Share on other sites More sharing options...
Kmlwx Posted August 18, 2021 Author Share Posted August 18, 2021 That Baltimore cell even looks a little interesting. 1 Link to comment Share on other sites More sharing options...
mappy Posted August 18, 2021 Share Posted August 18, 2021 2 minutes ago, Eskimo Joe said: It's a machine learning account that pulls from the short term meso guidance. Still an uncalibrated account but something worth peeking at, IMO. Got it, thanks. And there is Reed. lol Not sure about an outbreak per say, but who knows. 1 Link to comment Share on other sites More sharing options...
Kmlwx Posted August 18, 2021 Author Share Posted August 18, 2021 Gotta love the all caps and danger red font. Link to comment Share on other sites More sharing options...
mappy Posted August 18, 2021 Share Posted August 18, 2021 1 minute ago, Kmlwx said: Gotta love the all caps and danger red font. I know, right? Seems alarmist to me. Link to comment Share on other sites More sharing options...
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