2023 Mid-Atlantic Severe Wx Thread (General Discussion)

[yoda]

1300z SPC OTLK seems to be tossing the HRRR and RAP... and @Kmlwx describes tonight pretty well too

 

Mid-Atlantic to TN/KY...
   Several episodes of strong-severe thunderstorms are possible across
   this corridor, with enough spatial overlap between them to warrant
   maintaining a continuous area of severe probabilities similar to
   those outlined in the previous outlook. 

   A broad area of ongoing precip with embedded thunderstorms --
   initially over portions of KY/TN -- largely should remain non-severe
   while shifting eastward into the central Appalachians today. 
   However, increasing deep-layer flow and favorable low-level moisture
   will precede the associated UVV plume, along with muted diurnal
   heating of a moist airmass with weak CINH from parts of WV across
   the nearby Blue Ridge and Piedmont of VA, eastward toward Chesapeake
   Bay and over the Delmarva Peninsula.  This may support strong-severe
   gusts and hail with thunderstorms forming during the afternoon over
   higher terrain and shifting eastward to northeastward toward the
   coast.  Of note:  progs with RAP basis -- including HRRR -- appear
   to be mixing and drying the boundary layer excessively over the
   Piedmont and coastal plain, leading to potential underproduction
   and/or muting of convection.

   After several hours of warm advection and increasing surface heating
   behind the morning activity, the best organized overall severe
   threat should develop this afternoon from parts of middle/eastern TN
   to southern OH/WV, and shift eastward over the adjoining
   Appalachians.  MLCAPE should range from around 2000-3000 J/kg across
   middle/eastern TN -- where strongest heating/recovery is probable
   but deep flow/shear somewhat weaker -- to around 500-1000 J/kg near
   the Ohio River and northern WV.  Effective-shear magnitudes around
   40-50 kt should be common over eastern KY and WV, with modest 0-1-km
   SRH but around 150-250 J/kg effective SRH.  This suggests an
   eastward-moving corridor of convection containing blend of
   supercells, multicell clusters and quasi-linear segments with
   sporadic bow/LEWP features will be possible, with accompanying
   threat for damaging to severe gusts, isolated hail, and at least
   marginal/conditional tornado potential. 

   The northern part of this convective plume may persist overnight
   into an airmass east of the mountains -- across parts of the
   Piedmont and coastal plain of the Mid-Atlantic -- supportively
   recovered via theta-e advection from any earlier activity not far to
   the south and east.  The parameter space should be favorable for
   severe well after dark, with 40-50 kt effective-shear magnitudes,
   locally enlarged hodographs with 200-300 J/kg effective SRH, and
   around 1000-2000 J/kg MLCAPE.  Convective coverage is uncertain, but
   all hazards will be possible. 

[Kmlwx]

I hope they have a fix for the HRRR over mixing in the works. It seems to do it EVERY time. 

[yoda]

1630z SPC OTLK still has the 5 percent tor probs with no change 

[Kmlwx]

12z ARW2 brings some cells/line through around 5 or 6 and then has a rogue super cellular type thing doing what @Eskimo Joe mentioned earlier lol

ETA: It shows it in the 02-04z timeframe. 

[high risk]

2 hours ago, Kmlwx said:

I hope they have a fix for the HRRR over mixing in the works. It seems to do it EVERY time. 

      There will be no upgrades to the HRRR since it's slated for retirement.

[batmanbrad]

49 minutes ago, yoda said:

1630z SPC OTLK still has the 5 percent tor probs with no change 

does look like they cut back the 5% hail area quite a bit to only western VA and most of WV.

[Kmlwx]

6 minutes ago, high risk said:

      There will be no upgrades to the HRRR since it's slated for retirement.

Now I recall hearing that. Guess we'll just have to keep assuming it is overtaxing in these situations. 

[batmanbrad]

well, even if the wind/hail/tornado potential isn't the greatest for tonight/tomorrow, Sterling thinks highly enough of the heavy rainfall possibilities to issue a flood watch for parts of the area

[jewell2188]

Radar looks ehh. Seems to be also fairly progressive. 

[WxUSAF]

Flash flood watch was also issued 

https://x.com/nwswpc/status/1691165283065696257?s=46&t=JYOHM881b6groqc0-RqtxA

 

[EastCoast NPZ]

And another one bites the dust (literally).

[southmdwatcher]

And another train of storms incoming down here

[southmdwatcher]

Rotating storm east of Nanjemoy MD in Charles County heading for LaPlata and St. Charles

[southmdwatcher]

Tornado Warning for Charles County

[MN Transplant]

5 minutes ago, southmdwatcher said:

Tornado Warning for Charles County

(Insert La Plata comment here)

 

[southmdwatcher]

Thunder is booming and waiting to see if there are any rising motions with this storm as it approaches

[MN Transplant]

@yodaand @H2O

Looking good for you.

[southmdwatcher]

Tornado Warning Fairfax/Alexandria and Arlington 

[nj2va]

Geez, phone just lit up with the emergency notification about the Tornado Warning.

[mappy]

Nice looking radar for y’all down south

[mappy]

Oh man @H2O under a tornado warning 

[jbakerman]

3+ inches of rain from the storm as it passed through Burke, and going. Not surprised it was just warned for tornado, nasty stuff. 

[Eskimo Joe]

3 hours ago, Kmlwx said:

12z ARW2 brings some cells/line through around 5 or 6 and then has a rogue super cellular type thing doing what @Eskimo Joe mentioned earlier lol

ETA: It shows it in the 02-04z timeframe. 

Am in Tysons. Sky is mordor black to my south. Constant thunder. Definitely some boundary working.

[BlizzardNole]

Wishing today was my in-office day in DC so I could see this.  Another split for good ol' Germandesert

[MN Transplant]

2 minutes ago, jbakerman said:

3+ inches of rain from the storm as it passed through Burke, and going. Not surprised it was just warned for tornado, nasty stuff. 

Kudos to LWX to hit the Flash Flood Warning early.  I was skeptical based on radar, but these are efficient as hell.  I’m at 0.61” despite being on the periphery.

[nj2va]

LWX added a Severe thunderstorm warning in addition to the Tornado Warning. Torrential rain at the moment. 

[mattie g]

7 minutes ago, southmdwatcher said:

Tornado Warning Fairfax/Alexandria and Arlington 

That's the cell that blew the hell up right over me.

4 minutes ago, jbakerman said:

3+ inches of rain from the storm as it passed through Burke, and going. Not surprised it was just warned for tornado, nasty stuff. 

Yeah...that storm was wringing out every last ounce of moisture it could.

[WxUSAF]

11 minutes ago, mappy said:

Oh man @H2O under a tornado warning 

Oldmanyellsat(funnel)cloud.jpg

[Chinook]

There two tornado warnings near DC a few minutes ago. Now, mostly 50dBz over the area with a lot of lightning in some areas

 

[Kevin Reilly]

20 minutes ago, Eskimo Joe said:

Am in Tysons. Sky is mordor black to my south. Constant thunder. Definitely some boundary working.

I think that would be a warm front pushing NNE the main low is leaving Ohio and moving into Western PA.