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2020 Mid-Atlantic Severe Weather - General Thread


Kmlwx
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Mid Atlantic is on Great Plains schedule. Hurry up and wait! Actually it's bullish for tornadoes to maximize heating. 700 mb temps seem just right there.

HRRR finally got itself together. Believe late morning runs initialized poorly due to West Virginia clouds. Issue seems to have resolved. Such high resolution giveth and taketh.

Morning Kentucky shortwave is approaching, as seen with things percolating over in West Virginia. The lift is coming...

Another reason for the Plains wait might be the left front/exit of a jet max passed. Now await the right rear/entrance lift. That's the KY/WV wave and progged 700 mb vort.

Other than tough terrain, I really wish I'm in FREDERICK today, with road options from there. Google Maps terrain looks no more difficult than here in East Tenn.

High dewpoints should promote supercells. Virginia might veer a bit. However SRH will be more than enough on that Maryland boundary and into far northern Virginia.

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9 minutes ago, nrgjeff said:

Mid Atlantic is on Great Plains schedule. Hurry up and wait! Actually it's bullish for tornadoes to maximize heating. 700 mb temps seem just right there.

HRRR finally got itself together. Believe late morning runs initialized poorly due to West Virginia clouds. Issue seems to have resolved. Such high resolution giveth and taketh.

Morning Kentucky shortwave is approaching, as seen with things percolating over in West Virginia. The lift is coming...

Another reason for the Plains wait might be the left front/exit of a jet max passed. Now await the right rear/entrance lift. That's the KY/WV wave and progged 700 mb vort.

Other than tough terrain, I really wish I'm in FREDERICK today, with road options from there. Google Maps terrain looks no more difficult than here in East Tenn.

High dewpoints should promote supercells. Virginia might veer a bit. However SRH will be more than enough on that Maryland boundary and into far northern Virginia.

you just made a bunch of weenies hearts flutter. ;) 

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Mesoscale Discussion 1673
   NWS Storm Prediction Center Norman OK
   0206 PM CDT Thu Sep 03 2020

   Areas affected...the Mid-Atlantic

   Concerning...Severe potential...Tornado Watch likely 

   Valid 031906Z - 032100Z

   Probability of Watch Issuance...95 percent

   SUMMARY...A tornado watch will be needed this afternoon as a
   damaging wind and tornado threat increases.

   DISCUSSION...A broad area of shower activity extends from the Ohio
   Valley into Pennsylvania and New York amid a belt of strong
   mid-level flow. Areas south and east of this activity have slowly
   destabilized through the day with temperatures now in the upper 80s
   to low 90s in northern Virginia, eastern Maryland, and Delaware. In
   addition, the boundary layer is very moist with dewpoints in the mid
   to upper 70s. This has yielded moderate MLCAPE ranging from 1000 to
   2000 J/kg across the region despite very weak mid-level lapse rates
   (5 C/km per 18Z IAD RAOB). Expect at least a few strong storms to
   develop in the eastern periphery of the cloud shield in the next 1-2
   hours as destabilization continues and deep-layer ascent increases
   ahead of a shortwave moving out of West Virginia. 

   Once storms develop, they will likely become supercellular, at least
   initially, given 40-45 kts of effective shear (per KLWX VWP and 18Z
   IAD RAOB). 18Z IAD RAOB showed relatively weak flow in the lowest
   1.5 km, but upstream VWP from KRLX shows strong (40 kt) flow at 1km.
   Once this overspreads northern Virginia, Maryland, and Pennsylvania
   in a few hours, the damaging wind threat will increase and low-level
   shear will increase which should increase the tornado threat. The
   best tornado threat will likely be across northern Virginia,
   southern Maryland, and far southern Pennsylvania where there has
   been less mixing and surface winds remain southerly or
   south-southeasterly.  

   A tornado watch will likely be needed in the next hour or two as
   storm coverage/intensity increases.

   ..Bentley/Grams.. 09/03/2020

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...PHI...AKQ...CTP...LWX...RNK...PBZ...RLX...

 

mcd1673.gif

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1 hour ago, juliacarolecat said:

Sorry for a silly question, I’m new to posting but a lurker for years.

Is the tornado threat for north/central Maryland and then it will switch to more of a wind threat as it becomes more linear moving East? Ik bowing line segments can produce tornadoes but always thought they were more associated with high winds.

The thinking is more linear as it moves eastward towards the coast, and reading the discussion from Mount Holly they think the most likely place for a tornado is in Cecil over into Newcastle in DE up into SE PA. Possibly some interaction with the warm front lying across that area, backing the flow some is my guess. Bigger overall  threat will be damaging straight line winds, with fairly strong winds aloft and decent Dcape. Bowing segments generally produce straight line winds but can also produce tornadoes as vorticity sometimes develops on the north/south end of the line. How far north are you?

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