Jump to content
  • Member Statistics

    17,502
    Total Members
    7,904
    Most Online
    Weathernoob335
    Newest Member
    Weathernoob335
    Joined

2021 Mid-Atlantic Severe Weather - General Discussion


Kmlwx
 Share

Recommended Posts

Looks to me like Thursday afternoon has a good chance to eventually become a SLGT.     Lapse rates aren't great, but the timing looks favorable, and the shear/instability combo as current progged would likely generate SVR.     Expecting a very heavy rain threat too, particularly as additional rounds of convection move over the area after dark.

  • Like 1
Link to comment
Share on other sites

1 hour ago, Kmlwx said:

Heck of a 12z NAM nest run for the close-in metro area :lol: - Blows up a huge cell or line segment - good UH swath and sim IR frames

Thanks to my experience in snow forecasting I know that this is the only model that will be correct and I should cling to it no matter what the other ones say, ITS NEVER GONE WRONG BEFORE*.

 

*Citation Needed

  • Haha 1
Link to comment
Share on other sites

1 hour ago, Kmlwx said:

Heck of a 12z NAM nest run for the close-in metro area :lol: - Blows up a huge cell or line segment - good UH swath and sim IR frames

       yeah, even if we don't focus on potential significant UH swaths, the signal for widespread, organized convection in the early/mid afternoon hours tomorrow is robust across the CAMs.  The shear/instability profile combo should be sufficient for some of that to become severe.     The only "concern" is weak lapse rates shown in several models, but I like our chances of being upgraded to SLGT in the new day 2 outlook.     

  • Like 2
Link to comment
Share on other sites

The 12z GFS in fantasy land (post 300hrs) dumps a sizeable EML into our area. That would be a game changer. It wasn't on the 0z or 6z, though - so it's probably going poof by next run. And even on this run, it focuses any threat well north and west of us. 

Link to comment
Share on other sites

3 minutes ago, yoda said:

@Kmlwx @high risk @Eskimo Joe

Watch up for parts of MD and NW VA till 10pm

BULLETIN - IMMEDIATE BROADCAST REQUESTED
   SEVERE THUNDERSTORM WATCH OUTLINE UPDATE FOR WS 330...RESENT
   NWS STORM PREDICTION CENTER NORMAN OK
   445 PM EDT WED JUN 30 2021

   SEVERE THUNDERSTORM WATCH 330 IS IN EFFECT UNTIL 1000 PM EDT
   FOR THE FOLLOWING LOCATIONS

   MDC001-013-021-043-010200-
   /O.NEW.KWNS.SV.A.0330.210630T2045Z-210701T0200Z/

   MD 
   .    MARYLAND COUNTIES INCLUDED ARE

   ALLEGANY             CARROLL             FREDERICK           
   WASHINGTON           


   PAC001-041-043-055-071-075-099-107-133-010200-
   /O.NEW.KWNS.SV.A.0330.210630T2045Z-210701T0200Z/

   PA 
   .    PENNSYLVANIA COUNTIES INCLUDED ARE

   ADAMS                CUMBERLAND          DAUPHIN             
   FRANKLIN             LANCASTER           LEBANON             
   PERRY                SCHUYLKILL          YORK                


   VAC043-069-840-010200-
   /O.NEW.KWNS.SV.A.0330.210630T2045Z-210701T0200Z/

   VA 
   .    VIRGINIA COUNTIES INCLUDED ARE

   CLARKE               FREDERICK           


   VIRGINIA INDEPENDENT CITIES INCLUDED ARE

   WINCHESTER           


   WVC003-027-037-057-065-010200-
   /O.NEW.KWNS.SV.A.0330.210630T2045Z-210701T0200Z/

   WV 
   .    WEST VIRGINIA COUNTIES INCLUDED ARE

   BERKELEY             HAMPSHIRE           JEFFERSON           
   MINERAL              MORGAN              


   ATTN...WFO...LWX...CTP...
  • Like 1
Link to comment
Share on other sites

14 minutes ago, yoda said:

@Kmlwx @high risk @Eskimo Joe

Watch up for parts of MD and NW VA till 10pm

         It's worth watching, but by the time it gets here, we will be losing instability (although we'll still have a decent amount of CAPE to work with), and the shear is not nearly as good here as it is further northwest.    Heck, the shear isn't even very good where the watch just got issued.   If, however, a sfc cold pool can become established, the line can organize better. and we would have some modest severe potential in a few hours.   The HRRR runs haven't been too excited, but the 18z NAM nest looks robust.

  • Thanks 1
Link to comment
Share on other sites

Slight risk for I-95 east and southward.

...Mid Atlantic... Mid/upper flow and deep-layer shear along the axis of stronger destabilization within the surface troughing may be fairly modest to weak, at least initially. However, strengthening of southwesterly winds to 30-40 kt in the 850-700 mb layer may be sufficient to contribute to one or two organizing clusters of storms by late this afternoon. Given the magnitude of the forecast CAPE, coupled with relatively steep low-level lapse rates, it appears that the environment will be conducive to potentially damaging surface gusts. This may be associated with locally strong downbursts initially, then with strengthening cold pools in upscale growing, northeastward and eastward propagating convection into this evening.

I just want a dose of heavy rain, and maybe get a shot of a shelf to add to my collection.

Link to comment
Share on other sites

Mesoscale Discussion 1139
   NWS Storm Prediction Center Norman OK
   1045 AM CDT Thu Jul 01 2021

   Areas affected...Portions of far eastern WV...northern/central
   VA...DC...MD...DE...southeastern PA...and central/southern NJ

   Concerning...Severe potential...Severe Thunderstorm Watch likely 

   Valid 011545Z - 011745Z

   Probability of Watch Issuance...80 percent

   SUMMARY...The threat for scattered damaging wind gusts is expected
   to increase this afternoon, and one or more Severe Thunderstorm
   Watches will likely be needed.

   DISCUSSION...Mid-level west-southwesterly flow over the Mid-Atlantic
   associated with an upper trough/low across Ontario, Quebec, and the
   Great Lakes is not as strong today compared to yesterday. Still,
   about 25-40 kt is present generally around 3-6 km AGL based on
   recent VWP estimates from area radars. An area of precipitation with
   embedded isolated lightning flashes extends from northeastern MD
   into eastern PA as of 1545Z. There is concern that this
   precipitation and its associated widespread cloudiness may tend to
   limit destabilization and steepening of low-level lapse rates early
   this afternoon, particularly across eastern PA into NJ and vicinity.
   Still, there will probably be some clearing behind this initial
   activity, as evidenced by recent cloud breaks across parts of
   south-central PA.

   Better prospects for robust boundary-layer destabilization this
   afternoon will likely be realized across parts of northern/central
   VA into MD and the Delmarva Peninsula where clouds are less
   prevalent. Even though mid-level lapse rates will remain poor,
   around 1500-2000 J/kg of MLCAPE should develop this afternoon across
   this region through diurnal heating of a moist low-level airmass.
   Weaker destabilization, with MLCAPE generally ranging from 500-1500
   J/kg, will probably develop farther north into eastern PA and NJ
   owing to the influence of the ongoing precipitation. Storms will
   probably increase in coverage over the next couple of hours
   along/east of the Blue Ridge Mountains and into south-central PA as
   a weak/decaying MCV moves eastward from WV. 30-40 kt of effective
   bulk shear will likely foster some storm organization, with multiple
   clusters likely moving eastward through the afternoon. The greatest
   threat for scattered damaging wind gusts should develop where
   heating of the boundary layer can steepen low-level lapse rates and
   encourage efficient downdraft accelerations.
  • Like 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...