Eskimo Joe Posted May 11, 2018 Share Posted May 11, 2018 Quote .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... The warm front will lift northward into Pennsylvania by Saturday afternoon. This places the region solely in the warm sector, allowing for temperatures to rise into the upper 80s to low/mid 90s with dew points rising into the 60s. This will promote the development of 1000-2000 J/KG of MLCAPE, with shear values increasing markedly as winds at 700 mb approach 50 knots. Forecast soundings indicate that for the vast majority of the day the region will remain capped. Thus, convective evolution will be dependent on convection that will likely already be ongoing across OH/PA that may move into the region from the northwest on westerly flow and a southward moving frontal boundary. While its uncertain how far south the convection can progress, the atmosphere will be primed for a severe weather threat, provided the cap can be broken. The main threat will be damaging winds, with a secondary threat of large hail. The highest risk of severe thunderstorms will be across eastern WV and northern/central Maryland. The Storm Prediction Center has placed this region in an Enhanced Risk for severe thunderstorms, with a Slight Risk south to near the Washington DC metropolitan area. The threat window will be late afternoon and through the evening hours. The frontal boundary will sink further southward Saturday night, and will be bisecting the region by Sunday morning. Southwesterly flow will continue south of the boundary, with northeasterly flow taking over across the cool side. Thus the combination of ongoing convection, frontogentical forcing, increasing precipitable water values, and shortwaves passing through the flow aloft, will promote continued areas of showers and elevated convection. The severe threat will be dwindling during the first half of the night, however attention will then turn to the possibility of heavy rain and a low risk of flooding across the higher terrain of eastern WV and western VA due to repeated convection and upslope west flow. Lows Saturday night will range from the upper 50s to upper 60s. Sunday will be highly dependent on the eventual frontal position, but have shown the boundary between Charlottesville and Dulles, with stable/cooler low levels northeast of this, and very warm and humid air southwest. Forecast soundings and Showalter Indices indicate the potential of elevated convection across all areas, but there is the potential for additional strong to locally severe thunderstorms in the warm sector. Will continue to have to monitor potential for heavy rain as well. Highs will range from the 60s across NE MD to potentially near 90F towards Nelson County VA. Shower chances continue into Sunday night as well. Link to comment Share on other sites More sharing options...
Kmlwx Posted May 11, 2018 Author Share Posted May 11, 2018 We shall see. I'll wait for more data coming in to make an in/out call. Subject to numerous changes Link to comment Share on other sites More sharing options...
yoda Posted May 11, 2018 Share Posted May 11, 2018 Good disco from LWX about tomorrow... I like that we will have a cap in place so we won't lose our chances on morning/early afternoon shower crap. Link to comment Share on other sites More sharing options...
Kmlwx Posted May 11, 2018 Author Share Posted May 11, 2018 Most of the hires models like the ARW/NMM etc keep most stuff north of Mason Dixon. They're out at range for now though. Link to comment Share on other sites More sharing options...
yoda Posted May 12, 2018 Share Posted May 12, 2018 NE of BWI on 00z NAM NEST at 22z THUR nearby Aberdeen, MD... jesus Link to comment Share on other sites More sharing options...
yoda Posted May 12, 2018 Share Posted May 12, 2018 The first Day 1 OTLK from SPC should be interesting to see... I expect something like 5 tor/15 hail/30 wind... but with ML Lapse Rates nearing 7.0 C/KM and even higher in some areas due to an EML in the area... wouldn't be surprised to see a 30% hail tossed in. Tor probs will probably stay at 5% until later in the day Link to comment Share on other sites More sharing options...
Kmlwx Posted May 12, 2018 Author Share Posted May 12, 2018 Still doesn't look particularly noteworthy for DC proper. Good parameters but not a lot ot show until you're north. Maybe it'll adjust south a bit. Or maybe capping is overplayed Link to comment Share on other sites More sharing options...
mappy Posted May 12, 2018 Share Posted May 12, 2018 Overcast this morning after some overnight storms came through. Link to comment Share on other sites More sharing options...
Eskimo Joe Posted May 12, 2018 Share Posted May 12, 2018 Early morning visible shows some clouds but mostly some low level fog and stratus which should burn off. I'm good with this. Link to comment Share on other sites More sharing options...
high risk Posted May 12, 2018 Share Posted May 12, 2018 After being on the southern plains for a week and not even seeing lightning there, I'm ready for this! But, I'm still totally unsure how this will evolve. The best signals in the CAMs are still for southeast PA and far northeast MD. Deep layer shear is terrific, and as has been noted previously in this thread, lapse rates are impressive, so the hail/wind threat is legit. That said, low-level shear is weak, so I don't think that a good tornado threat is shaping up. For DC metro, the CAMs are all over the place, but the most consistent signal appears to be for the late evening hours. Maybe something will go earlier on an outflow boundary, and some guidance has some healthy storms moving through very late at night, so nailing down the time window is unusually complicated. Link to comment Share on other sites More sharing options...
Eskimo Joe Posted May 12, 2018 Share Posted May 12, 2018 I'm liking the boundary of the low level stratus for any TOR risk. South of there should be the biggest wind threat. Should be one of the better severe weather days in these parts. Link to comment Share on other sites More sharing options...
Kmlwx Posted May 12, 2018 Author Share Posted May 12, 2018 Nice and toasty out there. Radar clear for now. MCD to our west. Link to comment Share on other sites More sharing options...
WVclimo Posted May 12, 2018 Share Posted May 12, 2018 Severe Thunderstorm Watch for the northern and western LWX counties until 11:00 p.m. Link to comment Share on other sites More sharing options...
poolz1 Posted May 12, 2018 Share Posted May 12, 2018 I usually sit the sidelines during sever season... I know very little. Love severe but have never taken the time to dig into it. A definite shift in the stability to my west... To my east are clear blue skies. To my west is now starting to bubble. Hoping for a good early season garden soaker... Possibly something even more interesting. Sent from my SAMSUNG-SM-G920A using Tapatalk Link to comment Share on other sites More sharing options...
batmanbrad Posted May 12, 2018 Share Posted May 12, 2018 looks like SPC issued a MD at 4PM for the northeastern parts of our area with 95 percent chance of a watch: http://www.spc.noaa.gov/products/md/md0392.html Link to comment Share on other sites More sharing options...
George BM Posted May 12, 2018 Share Posted May 12, 2018 URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 85 NWS Storm Prediction Center Norman OK 455 PM EDT Sat May 12 2018 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Delaware Central and eastern Maryland Southern New Jersey Southeast Pennsylvania Coastal Waters * Effective this Saturday afternoon and Sunday morning from 455 PM until 100 AM EDT. * Primary threats include... A couple intense tornadoes possible Scattered damaging winds and isolated significant gusts to 75 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Scattered strong to severe storms will spread east towards the Mid-Atlantic Coast through the evening. Low-level wind profiles on the cool side of a quasi-stationary front will favor a few rotating storms with mainly a damaging wind and tornado risk. Link to comment Share on other sites More sharing options...
AlexD1990 Posted May 12, 2018 Share Posted May 12, 2018 I am shocked they went with a tornado watchSent from my SM-G892A using Tapatalk Link to comment Share on other sites More sharing options...
George BM Posted May 12, 2018 Share Posted May 12, 2018 The Severe Thunderstorm Watch includes the District now. WATCH COUNTY NOTIFICATION FOR WATCHES 84/85 NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 504 PM EDT SAT MAY 12 2018 DCC001-MDC031-033-VAC013-059-510-600-610-130300- /O.EXA.KLWX.SV.A.0084.000000T0000Z-180513T0300Z/ THE NATIONAL WEATHER SERVICE HAS EXTENDED SEVERE THUNDERSTORM WATCH 84 TO INCLUDE THE FOLLOWING AREAS UNTIL 11 PM EDT THIS EVENING THE DISTRICT OF COLUMBIA IN MARYLAND THIS WATCH INCLUDES 2 COUNTIES IN CENTRAL MARYLAND MONTGOMERY PRINCE GEORGES IN VIRGINIA THIS WATCH INCLUDES 5 COUNTIES IN NORTHERN VIRGINIA ARLINGTON CITY OF ALEXANDRIA CITY OF FAIRFAX CITY OF FALLS CHURCH FAIRFAX THIS INCLUDES THE CITIES OF ALEXANDRIA, ARLINGTON, ASPEN HILL, BETHESDA, BOWIE, CAMP SPRINGS, CHANTILLY, CLINTON, COLLEGE PARK, FAIRFAX, FALLS CHURCH, GAITHERSBURG, GERMANTOWN, GREENBELT, HERNDON, LAUREL, MCLEAN, POTOMAC, RESTON, ROCKVILLE, SILVER SPRING, SUITLAND-SILVER HILL, AND WASHINGTON. $$ Link to comment Share on other sites More sharing options...
high risk Posted May 12, 2018 Share Posted May 12, 2018 27 minutes ago, alexderiemer said: I am shocked they went with a tornado watch Sent from my SM-G892A using Tapatalk uh, have you looked at the upstream radar? Link to comment Share on other sites More sharing options...
high risk Posted May 12, 2018 Share Posted May 12, 2018 Helicity is maximized over north-central/northeast MD, so I do understand why they went with the tornado watch instead of the severe watch. Link to comment Share on other sites More sharing options...
AlexD1990 Posted May 12, 2018 Share Posted May 12, 2018 uh, have you looked at the upstream radar?Yes I have. From the chatter I've heard on here, didnt seen like a tor was needed. Guess I'm wrong. Im all for woo storms thoSent from my SM-G892A using Tapatalk Link to comment Share on other sites More sharing options...
high risk Posted May 12, 2018 Share Posted May 12, 2018 13 minutes ago, high risk said: uh, have you looked at the upstream radar? sorry about that. I thought I was replying to a different post (that I think the poster deleted) that questioned the need for any watch. Your question was perfectly legit. I wasn't expecting a TOR box either, but the supercell composite values in that area are actually impressive. Link to comment Share on other sites More sharing options...
yoda Posted May 12, 2018 Share Posted May 12, 2018 Lancaster/York County storm has rotation with it per severe tstorm warning Link to comment Share on other sites More sharing options...
WxLaura Posted May 12, 2018 Share Posted May 12, 2018 Have an event with a friend at 7 o'clock around Dover/Middletown De. Any thoughts on storm development by that time Link to comment Share on other sites More sharing options...
Eskimo Joe Posted May 12, 2018 Share Posted May 12, 2018 Tornado Watch is certainly justified. I'm a bit concerned things are going linear too quickly though for an organized tornado threat. Link to comment Share on other sites More sharing options...
Eskimo Joe Posted May 12, 2018 Share Posted May 12, 2018 Nice tongue of CAPE and helicity across the boundary for the severe t'storm and tornado watches. Kinda psyched. Link to comment Share on other sites More sharing options...
Kmlwx Posted May 12, 2018 Author Share Posted May 12, 2018 5 minutes ago, Eskimo Joe said: Nice tongue of CAPE and helicity across the boundary for the severe t'storm and tornado watches. Kinda psyched. Radar trends still significantly favor that tornado watch zone. Looks like the best line will (as expected) go into NE Maryland. Let's see if outflow can trigger anything closer to the DC region. Link to comment Share on other sites More sharing options...
Kmlwx Posted May 12, 2018 Author Share Posted May 12, 2018 2 minutes ago, Kmlwx said: Radar trends still significantly favor that tornado watch zone. Looks like the best line will (as expected) go into NE Maryland. Let's see if outflow can trigger anything closer to the DC region. That said - mesoanalysis is bonkers in a tiny area just ENE of DC. Has very high supercell parameter values there as well as high EHI. Link to comment Share on other sites More sharing options...
yoda Posted May 12, 2018 Share Posted May 12, 2018 STW Northern Carroll/Frederick/Baltimore/Harford counties Link to comment Share on other sites More sharing options...
Kmlwx Posted May 12, 2018 Author Share Posted May 12, 2018 Some tiny cells going up in Southern Carroll and extreme northern HoCo. From looking at them on GR2Analyst - they look capped....struggling to get very high Link to comment Share on other sites More sharing options...
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