2020 Mid-Atlantic Severe Weather - General Thread

[Bodhi Cove]

The piers are under water and Mother Nature is power washing our house.

[osfan24]

Interesting looking cell just southeast of Laurel.

[MN Transplant]

That was very Miller B-like.  The line died out and reformed to my east.  Trace of rain, winds in the 30s.  Dud.

[AlexD1990]

STW for storms moving SE at 95MPH....eek

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[Scraff]

Wow. Complete swing and a miss here. Gusty sprinkles for 30 seconds. Hope everyone else is cashing in on their severe. Lol. 

[A777]

Got sandwiched by rain on 3 sides... nothing here except a few wind gusts to 40

[Stormfly]

Pretty meh here, TBH the strong southerly breezes were more enjoyable today.  Endless leafnados!  Probably picked up a few bushels of big oak and maple leaves in the barn all by itself from having the slider open which faces due south. 

Funny this time of the year we get yellow boxes with no lightning.  There were a few flashes but those weren't from lightning.  (the mother nature kind!) ;-)

[yoda]

Good amount of reports for a late SLGT risk day

https://www.spc.noaa.gov/climo/reports/today.html

 

[CAPE]

That new line along the bay died out apparently, and then another one got going SE of here.

Nothing noteworthy, just 0.14" of rain and a few gusts of maybe 40.

[George BM]

6 minutes ago, losetoa6 said:

Lost a bunch of shingles but it was too dark this morning to really see from where.  Hopefully just from the  shed roof .

Finally a flush hit for you...

 

In all seriousness I hope the damage isn't too bad there.

[toolsheds]

5 minutes ago, losetoa6 said:

Hopefully northern Md crush zone  is back baby ...in time for winter 

I'm pretty sure it's the shingles from my shed . So not too big a deal .

If they are from your house...check with your insurance company.  Might be covered. 

 

[A777]

                                                         A week out but.....

[Kmlwx]

Yeah - SPC does have a mention of that window in the D4-8 outlook. 

 

 One exception may be near the end of the period (days 7-8/23rd-24th)
   in the upper Ohio Valley to Mid-Atlantic/Northeast, if a more
   intensely amplified northern-stream cyclone, as forecast by
   operational ECMWF (but not deterministic GFS/CMC nor several EC
   ensemble members), verifies over the southern ON/lower Great Lakes
   region.  Such a scenario would strengthen frontal forcing under
   intense flow aloft for potential low-topped convective band(s). 
   However, at such a long time range, predictability is very low for
   such a solution.

[A777]

   

Lock it in.

[yoda]

Day 3 MRGL risk (for Monday)

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0226 AM CST Sat Nov 28 2020

   Valid 301200Z - 011200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   FLORIDA/COASTAL GEORGIA INTO THE CAROLINAS AND MID-ATLANTIC...

   ...SUMMARY...
   Isolated strong to severe thunderstorms capable of producing
   damaging winds and perhaps a couple of tornadoes appear possible on
   Monday from parts of Florida and coastal Georgia into the Carolinas
   and Mid-Atlantic.

   ...Florida/Coastal Georgia into the Carolinas and Mid-Atlantic...
   A large-scale upper trough should evolve into a closed low over the
   Midwest/OH Valley and central Appalachians on Monday. A mid-level
   vorticity maximum embedded within this upper trough is forecast to
   move quickly northeastward from the central Appalachians into the
   Mid-Atlantic through Monday afternoon. A deep surface low should
   likewise develop northeastward in tandem with this vorticity
   maximum. A cold front trailing from this surface low will likely
   sweep eastward across much of the FL Peninsula and the East Coast
   through the day. A warm front extending northeastward from the
   surface low will probably make some northward progress across parts
   of the Mid-Atlantic through Monday afternoon as well.

   A line of low-topped showers/storms along or just ahead of the cold
   front should be ongoing at the start of the period from near the
   surface low in WV/western VA southward to northern FL. Although
   instability may remain modest across most of the warm sector ahead
   of this line, generally low to mid 60s surface dewpoints should be
   enough to support weak surface-based instability through the day. A
   very strong (50-60+ kt) south-southwesterly low-level jet should be
   present over the central/eastern Carolinas and southern VA Monday
   morning, and this feature is forecast to shift northward across the
   Mid-Atlantic through the day. 

   Given the strength of the low-level flow and sufficient, albeit
   weak, forecast instability, strong to damaging winds may occur with
   storms that either persist along the cold front or develop ahead of
   it over the open warm sector. A couple tornadoes also appear
   possible, mainly across parts of eastern SC/NC/VA to the Delmarva
   Peninsula and perhaps NJ in associated with the low-level jet and
   potentially greater low-level moisture and instability. Even so,
   there is too much uncertainty regarding sufficient destabilization
   to include higher severe probabilities for now.

   Farther south, low-level convergence along the cold front and
   deep-layer shear are both forecast to be somewhat weaker across
   coastal GA and the FL Peninsula. Still, there may be isolated
   strong/gusty winds with any storms through Monday afternoon.

[high risk]

I've been looking this evening at the Monday threat, and while I'm not too optimistic at our SVR chances, I can't argue with the MRGL.

The warm front looks to move through the area by mid-morning taking the steady rain with it.    There is a period late Monday morning when the progged hodographs should be outstanding, and several CAMs have a more scattered, somewhat cellular nature to the precip, but instability just isn't there in the CAMs right now.    By early afternoon, it *does* appear that we'll get several hundred J/KG of sfc-based CAPE as the dry slot moves overhead and much of the area warms into the mid 60s.      Unfortunately, the low-level winds are progged to veer by then, and the hodographs don't look as good.    That said, there may be a broken line of convection on the cold front (High-res Window ARW2 really shows this), so some severe threat, especially in the form of wind gusts, will exist if we can achieve the higher (500?) CAPE values.     

The faster that the warm sfc air overspreads the area Monday, the better the chance of severe.    Ultimately, the instability and best low-level shear likely won't overlap (keeping the tornado threat fairly low), but with very strong winds just above the surface, there will be an opportunity for at least a few severe gusts if we can heat up by early afternoon.  

 

 

[Kmlwx]

It's essentially December - so we shouldn't expect much of anything. But we'll all keep an eye on it I'm sure  

[Kmlwx]

NAM has 85 knot winds at 850mb over the bay on Monday. Dynamic storm system!

[H2O]

I can’t help but laugh when I see activity in this thread when fall and winter approaches.  My first thought is “oh you severe people still exist?”

[A777]

HRRR gets my area up to 500 CAPE before the line comes through 

[high risk]

several morning CAMs do show a broken line moving through parts of the area during early Monday afternoon, with a few hours of heating prior to arrival.     If that plays out, with several hundred J/kg of CAPE, there is certainly some severe potential.

[Vice-Regent]

5 hours ago, H2O said:

I can’t help but laugh when I see activity in this thread when fall and winter approaches.  My first thought is “oh you severe people still exist?”

We laughing with you because people still think it snows here but of course you being so far NW will get a luxury event.

[Kmlwx]

The NAM twins have been improving the last few runs. The long range 18z HRRR looked good for DC and east as well. 

[southmdwatcher]

0z HRRR is suggesting around 1000 MLCAPE east and south of DC through Richmond and out through most of Delmarva at 18z tomorrow. 

[yoda]

SLGT risk i95 and east into Delmarva for today... 15 percent wind and 5 percent tornado

MRGL risk is basically BR to i95 corridor 

[CAPE]

Mount Holly thoughts this morning-

CAMs continue to indicate scattered, fragmented, multi-mode convection developing across the forecast area. Any robust convection that can get going and maintain itself will have the potential to be of the "power shower" variety. These will have the potential to bring down the stronger winds from just above the surface in the form of damaging straight line wind gusts. If the best instability is realized (>500 J/kg), I wouldn`t be surprised to see a low-topped supercell or two across the coastal plain. In addition to the convective wind potential, low level shear values will be high (40+ kts) with curved low level hodographs supportive of surface based rotation. The tornado potential is certainly non- zero with this environment, but given questionable convective mode the confidence is not particularly high on this potential.

[high risk]

4 hours ago, CAPE said:

Mount Holly thoughts this morning-

CAMs continue to indicate scattered, fragmented, multi-mode convection developing across the forecast area. Any robust convection that can get going and maintain itself will have the potential to be of the "power shower" variety. These will have the potential to bring down the stronger winds from just above the surface in the form of damaging straight line wind gusts. If the best instability is realized (>500 J/kg), I wouldn`t be surprised to see a low-topped supercell or two across the coastal plain. In addition to the convective wind potential, low level shear values will be high (40+ kts) with curved low level hodographs supportive of surface based rotation. The tornado potential is certainly non- zero with this environment, but given questionable convective mode the confidence is not particularly high on this potential.

      That Mt Holly discussion works very well for most of our area too.     Interestingly, progged parameters for early this afternoon have improved, but overall, the CAM simulated reflectivity forecasts for our area have gotten worse.      12z NAM nest stops the bleeding and actually has a nice convective feature and a secondary low center - we'll see if it has the right idea.....

[JakkelWx]

 

[A777]

 

[mappy]

tornado watch