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2011 - Mid-Atlantic Severe Storm Thread


Kmlwx

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The severe threat looks to be pretty marginal overall for the region Monday afternoon into Tuesday morning, with the key issue being timing as the cold front works with limited/no instability. West Virginia has the greatest risk for severe as a few pre-frontal storms and a QLCS (quasi-linear convective system) move into the westernmost parts of the region the late afternoon and evening hours. The line of storms will weaken and push east during the overnight hours, moving off of the coast by late morning or early afternoon. These storms are currently modeled to hit the DC/BWI region around morning rush hour, depending on the overall speed of the line. During the overnight hours, these storms are expected to be rather weak and/or elevated, but a loose line should be able to make its way through the coastal areas.

A positively-tilted upper-level trough will become neutral as an UL vort. lifts N+E through the region. At the same time, an UL jet will intensify just W of the cold front, putting the Mid-Atlantic in the right-exit region of the jet. The dynamics that we need for severe weather are there because of these UL features along with the surface front, but without any thermal instability that potential could be lost for most of the region as the storms skirt by. Directional shear isn't terribly impressive for most of the region, with largely unidirectional winds out of the SW. The biggest threat will be from wind as a LL jet with a speed max of 70-80 kts around 900mb orients itself over the region. It would take minimal surface-based convection to bring severe-level gusts of 50+ kts to the surface, but getting surface-based convection will prove to be difficult once the late evening hits. Dry air out ahead of the front will also hurt instability as the column tries to saturate just ahead of the front. The risk for hail and tornadoes is minimal threat for most of the region, with an isolated risk for those in the western parts of WV.

18z NAM and GFS showing somewhat better potential for strong/severe winds tomorrow night into Tuesday morning compared to previous runs with weak instability in the mid-levels... will continue to monitor possible nocturnal instability as just a small amount is needed for the severe winds to occur.

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I actually went and checked that forum for the first time ever, and that "discussion" you mention is simply just a bunch of copypasta of model images and verbatim descriptions with virtually no interpretation and analysis beyond "it's different from the other run." That's what the snow weenies do, and this region's severe group is good enough to not need a thread filled with these virtually useless posts.

My discussion is coming shortly... fell asleep again and missed the end of the race :arrowhead:

Excellent.

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The slight risk area has extended farther east covering most of WV now. Timing looks good for maximum heating for W. WV. CRW mentioning good potential for severe, mainly wind.

Wind Avisory issued for gusty SW winds up to 40-50 mph this afternoon ahead of the front.

From CRW...lots going on today and tonight...as a very strong cold front with

impressive dynamics and increased instability on newest model runs

threaten an eastward moving squall line of strong to possibly severe

thunderstorms...mainly later this afternoon and evening. Model guidance has trended slightly

slower in the progression of the front...as a weak wave of low

pressure forms in the eastern Tennessee Valley and lifts up along

the front. This trend reflects the Euro model which has been rather

persistent with this wave...

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Monday has been looking interesting, but we could have timing issues yet again. GFS brings the storms through late morning and early afternoon, with the Euro bringing storms through early Tuesday morning. I'm staying closer to the GFS timing at this point. The upper-level are doing some funky stuff with this system as it hits the East Coast, so we'll have to wait until d+3 to get a decent idea of what's going to go down.

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Monday has been looking interesting, but we could have timing issues yet again. GFS brings the storms through late morning and early afternoon, with the Euro bringing storms through early Tuesday morning. I'm staying closer to the GFS timing at this point. The upper-level are doing some funky stuff with this system as it hits the East Coast, so we'll have to wait until d+3 to get a decent idea of what's going to go down.

We need some excitement :(

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The slight risk area for severe storms extends into western WV for this afternoon. A stationary front is stretched east to west across the area bisecting the state.

SPC Statement:

LATEST MODEL GUIDANCE SUGGEST STRONG BOUNDARY LAYER HEATING WILL BE NOTED

ACROSS SRN IL INTO NRN KY/SRN OH. THIS SHOULD ENHANCE THE PROSPECT

FOR CONVECTIVE DEVELOPMENT WITHIN STRONGLY SHEARED ENVIRONMENT

FAVORABLE FOR SUSTAINED ROTATING UPDRAFTS. FORECAST SOUNDINGS FAVOR

SUPERCELL DEVELOPMENT EARLY IN THE CONVECTIVE CYCLE AND THIS SEEMS

REASONABLE GIVEN THE WEAK FORCING. WITH TIME STORM MERGERS AND

CONVECTIVE INTERFERENCE COULD LEAD TO STORM CLUSTERS AS MEAN WIND

VECTOR DRIVES TSTMS SEWD AT ROUGHLY 30KT. FOR THIS REASON IT

APPEARS THERE WILL BE A THREAT FOR LARGE HAIL...DAMAGING WINDS AND

PERHAPS EVEN A FEW TORNADOES AS BOUNDARY LAYER MOISTURE AND RH

VALUES WILL HAVE RISEN SIGNIFICANTLY BY THIS TIME.

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Monday draws closer...the suspense builds. Will BethesdaWx endure massive damage and 100mph winds?! Only time will tell.

I'll pass on that. Yard looks too nice, Weeping cherry blossoms in full bloom now.

Considering I've never seen a gust that high...I'd say it definitely won't happen! :o

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The long track supercell that crossed far western West Virginia with large hail put down a damaging tornado in southwest Virginia

PRELIMINARY LOCAL STORM REPORT

NATIONAL WEATHER SERVICE BLACKSBURG VA

239 AM EDT SAT APR 09 2011

..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...

..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....

..REMARKS..

0735 PM TORNADO 1 SW PULASKI 37.04N 80.81W

04/08/2011 PULASKI VA EMERGENCY MNGR

*** 6 INJ *** SEVERE DAMAGE...TOWN OF PULASKI

VIRGINIA...DAMAGE PATH EXTENDS SE ACROSS INTERSTATE 81 AT

THE EXIT 92 INTERCHANGE VNTY OF DRAPER VIRGINIA PULASKI

COUNTY. VDEM INITIAL REPORTS ARE THAT 5 TO 6 BLOCKS IN

THE TOWN OF PULASKI ARE SEVERELY DAMAGED. THE NATIONAL

GUARD ARMORY IS REPORTED DESTROYED. ROADWAYS ARE CLOSED

DUE TO FALLEN TREES. 4700 CUSTOMERS WITHOUT POWER.

SHELTER OPEN AT PULASKI ELM SCHOOL. ROADS INTO THE TOWN

OF PULASKI ARE CLOSED AND DETOURS ESTABLISHED. NWS WILL

CONDUCT SURVEY SATURDAY.

http://www.weather.gov/view/prodsByState.php?state=VA&prodtype=public

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The timing and upper-levels continue to be an issue with this storm... I may be able to get a discussion in-between unpacking tonight/tomorrow.

The 21z SREF run on the SPC site is looking better than previous runs. Not really sure about what changed (only took a brief glance) but it looks a good bit better.

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Wish we had a better chance with this. Seems like the storms want to come through overnight but take a look at the 09z SREF run params - if we could get something earlier in the evening/late afternoon it would have this to work with (these have improved over the last few runs)

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Wish we had a better chance with this. Seems like the storms want to come through overnight but take a look at the 09z SREF run params - if we could get something earlier in the evening/late afternoon it would have this to work with (these have improved over the last few runs)

It's always something to screw our chances.

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