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Kmlwx

2020 Mid-Atlantic Severe Weather - General Thread

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There's one STW by LWX... headed toward DC in an hour or so...

Severe Weather Statement
National Weather Service Baltimore MD/Washington DC
945 PM EST Wed Feb 26 2020

VAC047-113-137-270315-
/O.CON.KLWX.SV.W.0011.000000T0000Z-200227T0315Z/
Madison VA-Orange VA-Culpeper VA-
945 PM EST Wed Feb 26 2020

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1015 PM EST
FOR SOUTHEASTERN MADISON...CENTRAL ORANGE AND SOUTH CENTRAL CULPEPER
COUNTIES...

At 945 PM EST, a severe thunderstorm was located near Orange, moving
northeast at 35 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Damaging winds will cause some trees and large branches to
         fall. This could injure those outdoors, as well as damage
         homes and vehicles. Roadways may become blocked by downed
         trees. Localized power outages are possible. Unsecured
         light objects may become projectiles.

Locations impacted include...
Culpeper, Orange, Gordonsville, Raccoon Ford, Rhoadesville, Rapidan,
Everona, Verdiersville, Madison Run, Montpelier Station, Burr Hill,
Nasons, Winston, Madison Mills, Montford, Mitchells, Old Somerset,
Unionville, Somerset and Locust Dale.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

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930pm AFD from LWX 

NEAR TERM /THROUGH THURSDAY/...
Squall line continues to gell as the surface boundary plows
eastward from WV. Forcing aloft continues to increase, so expect
line to continue to strengthen through midnight before low-level
forcing finally starts to wane. Main threat will be damaging
winds, with a secondary threat of hail, though most hail should
be sub-severe. An isolated tornado still can`t be ruled out
given the shear. Heavy rain will also occur, but should
generally be brief enough to prevent significant flooding. Poor
drainage areas may experience difficulties, however.

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#2

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Baltimore MD/Washington DC
1010 PM EST Wed Feb 26 2020

The National Weather Service in Sterling Virginia has issued a

* Severe Thunderstorm Warning for...
  Northern Stafford County in northern Virginia...
  Northeastern Orange County in central Virginia...
  Southeastern Fauquier County in northern Virginia...
  Southeastern Culpeper County in northern Virginia...
  Southwestern Prince William County in northern Virginia...
  North central Spotsylvania County in central Virginia...

* Until 1100 PM EST.

* At 1010 PM EST, a severe thunderstorm was located 10 miles
  southeast of Culpeper, moving northeast at 40 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Damaging winds will cause some trees and large branches
           to fall. This could injure those outdoors, as well as
           damage homes and vehicles. Roadways may become blocked by
           downed trees. Localized power outages are possible.
           Unsecured light objects may become projectiles.

* Locations impacted include...
  Bealeton, Nokesville, Remington, Catlett, Calverton, Midland,
  Stevensburg, Roseville, Garrisonville, Locust Grove, Flat Run,
  Heflin, Dunavant, Lake Of The Woods, Morrisville, Ruby, Somerville,
  Goldvein, Raccoon Ford and Lois.

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Perhaps the smallest amount of sfc-based instability for that cell to work with down by Culpeper, where sfc temps are 5-6 degrees warmer than around the DC Beltway and points north and east.

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3 hours ago, high risk said:

O storm reports.    Lack of sfc-based instability, ftw!        B)

I see 4 LSR's from LWX from last night

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36 minutes ago, yoda said:

SPC has 4 storm reports from LWX -- https://www.spc.noaa.gov/exper/archive/event.php?date=20200226

 

        well, crap.    Those got added in pretty late, so I guess that LWX had to look pretty hard to find them   :rolleyes:

        but in seriousness, the Culpepper reports don't totally surprise me, but the Fairfax reports do.      I didn't see anyone in this forum report strong winds inside of the Beltway.....

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If the surface low of that mid next week system can track just off to our northwest lots of models have some impressive wind fields. CAPE would be the main question though mainly because of warmer low/mid-level temperatures... and also climo in general (it's still on the early side)...

Though the February 7th system probably has a few choice words for me about that "climo" statement.

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1 hour ago, high risk said:

        well, crap.    Those got added in pretty late, so I guess that LWX had to look pretty hard to find them   :rolleyes:

        but in seriousness, the Culpepper reports don't totally surprise me, but the Fairfax reports do.      I didn't see anyone in this forum report strong winds inside of the Beltway.....

That's the problem with storm reports.  One was a branch down and another was a tree down.  But that doesn't really tell you if the winds were super-strong or whether the trees are in terrible shape.  I gusted higher this morning at my house than last night and I was in a pretty good storm spot last night.

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I thought it was mid july looking at the activity of this thread, until I looked at the trees outside and the temperature

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A low risk of some thunder and perhaps some gusty winds tomorrow depending on the amount of sunshine we can get. Low-level lapse rates look steep... with mid-level lapse rates looking somewhat steep as well. 

1565767111_3022020hrrr_033_38.98--77_39.thumb.png.d39cbf70ed3b6eab7d3ab6aa72e31630.png

 

And FWIW... SPC doesn't even have us in a 10% thunder risk for tomorrow so... :ph34r:

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1 hour ago, George BM said:

A low risk of some thunder and perhaps some gusty winds tomorrow depending on the amount of sunshine we can get. Low-level lapse rates look steep... with mid-level lapse rates looking somewhat steep as well.

And FWIW... SPC doesn't even have us in a 10% thunder risk for tomorrow so... :ph34r:

      This post is spot-on.     I can see why they didn't have any thunder marked around here on the prelim day 1, but the 12z guidance has clearly shifted towards more favorable parameters AND explicit convective signatures in the simulated reflectivity.     It warrants a general thunder outlook in the new day 2 for sure, and it's honestly not that far off from a MRGL.

 

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2 hours ago, high risk said:

      This post is spot-on.     I can see why they didn't have any thunder marked around here on the prelim day 1, but the 12z guidance has clearly shifted towards more favorable parameters AND explicit convective signatures in the simulated reflectivity.     It warrants a general thunder outlook in the new day 2 for sure, and it's honestly not that far off from a MRGL.

 

General thunder added and a disco issued in the 1730 SPC OTLK 

...Middle Atlantic Region...

   Moisture return will be limited in this region which along with
   potential for widespread clouds should contribute to only weak
   instability. However, a couple of CAMs including the RAP indicate
   potential for more significant destabilization. A northern stream
   shortwave trough will approach this region during the afternoon and
   evening and given strength of vertical shear profiles, some threat
   for severe storms could materialize. Given low confidence in more
   substantial destabilization, will not introduce severe probabilities
   at this time, but have expanded the general thunder area.

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18z HRRR has a sfc-based bow echo moving across the areas north of the DC Beltway early Tuesday evening.     It's an outlier solution in terms of having much warmer sfc temps than other guidance, but IF it were correct, it would be a SLGT risk day.

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23 minutes ago, high risk said:

18z HRRR has a sfc-based bow echo moving across the areas north of the DC Beltway early Tuesday evening.     It's an outlier solution in terms of having much warmer sfc temps than other guidance, but IF it were correct, it would be a SLGT risk day.

That is a very impressive sim radar. NAM doesn't look anything like it. 

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3 minutes ago, Kmlwx said:

That is a very impressive sim radar. NAM doesn't look anything like it. 

 

      right.   because the HRRR is 5-8 degrees warmer.....

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24 minutes ago, Kmlwx said:

That is a very impressive sim radar. NAM doesn't look anything like it. 

The 3K has little bit of a line at 30 hr

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End if its run, but 02z HRRR gets us into the mid 60s at 20z tomorrow with storms developing off to the west in WV

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MRGL risk for this afternoon and evening... 2% TOR/5% WIND

...Parts of the central Appalachians to the Mid Atlantic region...
   As a northern-stream upper trough moves quickly eastward across the
   Ohio Valley region through the day, and approaches the central
   Appalachians during the afternoon, modest/low-topped instability
   should support convective development across parts of far eastern
   Ohio/western Pennsylvania/West Virginia.  Given strong/deep-layer
   westerly flow, convection will be fast-moving -- posing low-end risk
   for locally strong/damaging wind gusts.  The convection will move
   quickly across Maryland/northern Virginia/eastern Pennsylvania
   through early evening, likely diminishing gradually as it crosses
   New Jersey and Delaware before midnight.

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pretty crazy pictures coming out of the Nashville area this morning. 7 confirmed deaths so far. 

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28 minutes ago, mappy said:

pretty crazy pictures coming out of the Nashville area this morning. 7 confirmed deaths so far. 

Yea woke to hear about the tornado and have seen the damage and video out of there. 

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I lived in East Nashville for the 1998 tornado. Sometime if you all want I can recount living through that one. My office bldg. downtown was massively damaged and my home also had significant damage. But check out this overlay in this tweet of the Nashville tornados from 1933, 1998 and the one last night. That's...absolutely uncanny:

https://twitter.com/WCM_Krissy/status/1234822047571881984

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1300 SPC OTLK still 2% TOR/5% WIND... but disco has picked up a bit compared to the 0600 one 

..Central Appalachians to Mid-Atlantic this afternoon/evening...
   A northern stream shortwave trough will translate from the MS Valley
   to the OH Valley today, and reach the Mid-Atlantic and New England
   tonight.  An associated surface cyclone will deepen from the lower
   Great Lakes into New England, while a trailing cold front moves
   eastward off the Mid-Atlantic coast by early tonight.  In the wake
   of weakening morning convection and a remnant MCV near southern WV,
   a few cloud breaks and some low-level warming/moistening will
   contribute to weak buoyancy in advance of the cold front from WV
   into parts of PA/VA this afternoon/evening.  Broken bands of storms
   will be possible this afternoon along the front, and the convection
   will spread east-northeastward toward NJ by late evening.  Assuming
   sufficient near-surface destabilization, wind profiles will favor
   organized bowing segments and supercells with some threat for
   isolated damaging gusts and a tornado or two.

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