2022 Mid-Atlantic Severe Wx Thread (General Discussion Etc)

[MN Transplant]

11 minutes ago, yoda said:

Kinda wondering where our MCD is lol

The same place as our good mid-level lapse rates?

[mattie g]

0-15-5, which pretty much means we'll get some gusty winds, lightning, and heavy rain followed by 30-45 minutes of stratiform rains. No need to expect anything more...and I'm perfectly fine with that!

[mappy]

sooooo just another day in the mid atlantic with severe chances?

[yoda]

11 minutes ago, MN Transplant said:

The same place as our good mid-level lapse rates?

Well played good sir

[mattie g]

10 minutes ago, mappy said:

sooooo just another day in the mid atlantic with severe chances?

Basically. We so rarely do real severe, so it's probably just another run-of-the-mill thunderstorm day.

[mappy]

1 minute ago, mattie g said:

Basically. We so rarely do real severe, so it's probably just another run-of-the-mill thunderstorm day.

I just need a good rain shower to knock down the pollen. 

[H2O]

12 minutes ago, mappy said:

I just need a good rain shower to knock down the pollen. 

I just need storms in the 4-5pm range. Make that happen please

[Kmlwx]

There's an MCD now. I'm at work and can't post. 

[biodhokie]

Mesoscale Discussion 1013
   NWS Storm Prediction Center Norman OK
   1204 PM CDT Thu Jun 02 2022

   Areas affected...Portions of the central Appalachians into the
   Mid-Atlantic

   Concerning...Severe potential...Watch likely 

   Valid 021704Z - 021900Z

   Probability of Watch Issuance...80 percent

   SUMMARY...The severe weather threat will increase through the
   afternoon with a threat for damaging winds and marginally severe
   hail.

   DISCUSSION...Temperatures have already warmed into the upper 80s to
   near 90 across much of Virginia and Maryland with slightly cooler
   temperatures across southern Pennsylvania where cloud cover is
   present. Modifying the IAD 12Z RAOB for current surface conditions
   shows MLCAPE around 750 J/kg which matches SPC mesoanalysis.
   Continued heating will lead to additional destabilization and MLCAPE
   around 1500-2000 J/kg by later this afternoon. 

   A few storms have already started to develop over the higher terrain
   in eastern West Virginia, where the inhibition has been eroded and a
   mid-level shortwave trough is traversing the region. Eventually
   expect storms to move off of the higher terrain with additional
   development likely across Maryland, Virginia, and southern
   Pennsylvania as ascent moves east. The 12Z IAD RAOB showed 0-6km
   shear around 37 knots with at least some increasing mid-level flow
   forecast this afternoon. Therefore, shear should be sufficient for
   storm organization including the potential for some rotating
   updrafts. However, scattered to numerous storms are anticipated in
   the uncapped atmosphere this afternoon which could lead to colliding
   storms and a more clustered storm mode. 

   A watch will likely be needed within the hour as more robust/better
   organized storms develop.

   ..Bentley/Guyer.. 06/02/2022

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

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

   LAT...LON   38127541 37747729 36997951 36798079 36978104 37298109
               37738076 38047989 38297961 38887920 39537856 40597640
               39547415 38107502 38127541 

[Eskimo Joe]

Despite decent downdraft CAPE, low level lapse rates, and respectable shear, the CAMS still really unenthused with any real beefy storms today. 

[H2O]

mix of sun/clouds now that the CU has started to pop

[vastateofmind]

17 minutes ago, Kmlwx said:

There's an MCD now. I'm at work and can't post. 

Which is interesting...because LWX has taken a more measured tone with their updated afternoon forecast WRT severe...there was a lot less "slight" and "possibly" in there this morning.

[mattie g]

4 minutes ago, vastateofmind said:

Which is interesting...because LWX has taken a more measured tone with their updated afternoon forecast WRT severe...there was a lot less "slight" and "possibly" in there this morning.

That's confusing. I think they mean that there's a slight chance early on, then 90% chance of rain later with a chance of storms.

[Kmlwx]

6 minutes ago, vastateofmind said:

Which is interesting...because LWX has taken a more measured tone with their updated afternoon forecast WRT severe...there was a lot less "slight" and "possibly" in there this morning.

Remember that those are the grids. Often the language is better in the zone forecast product. 

[yoda]

Can someone clarify for me regarding this part in the MCD?

"

The 12Z IAD RAOB showed 0-6km
   shear around 37 knots with at least some increasing mid-level flow
   forecast this afternoon. Therefore, shear should be sufficient for
   storm organization including the potential for some rotating
   updrafts. However, scattered to numerous storms are anticipated in
   the uncapped atmosphere this afternoon which could lead to colliding
   storms and a more clustered storm mode. "

 

Now when they state rotating updrafts, that means cellular activity with potential for severe hail, correct?  Especially since they state in the next sentence about colliding storms?

[Eskimo Joe]

SPC issues Severe Thunderstorm Watch until 01:00 UTC.

[weatherCCB]

Storms starting to fire to the west.

[high risk]

19 minutes ago, yoda said:

Can someone clarify for me regarding this part in the MCD?

"

The 12Z IAD RAOB showed 0-6km
   shear around 37 knots with at least some increasing mid-level flow
   forecast this afternoon. Therefore, shear should be sufficient for
   storm organization including the potential for some rotating
   updrafts. However, scattered to numerous storms are anticipated in
   the uncapped atmosphere this afternoon which could lead to colliding
   storms and a more clustered storm mode. "

 

Now when they state rotating updrafts, that means cellular activity with potential for severe hail, correct?  Especially since they state in the next sentence about colliding storms?

       It means that the deep layer shear supports a few supercells, which would of course ramp up the threats for hail and wind.    The issue is that they expect widespread storms due to the forcing and lack of cap, and that will prevent the potential for longer-track supercells which are more likely when the storm mode is more discrete.      Regardless, I still expect a modest number of wind reports today with the pretty good downdraft cape and decent combo of CAPE/deep layer shear (despite the meh lapse rates).

[MN Transplant]

Something trying to fire near Fairfax City.

[yoda]

Severe Tstorm Watch till 9pm for all in LWX CWA (except Alleghany and Garrett counties in W MD)

[Eskimo Joe]

4 minutes ago, MN Transplant said:

Something trying to fire near Fairfax City.

Seems like there may be some local boundary setting up. Ft. Belvoir (KDAA), DCA, and College Park (KCGS) all have SE winds, while everything else is W or SW winds. Wonder if that plays into anything later.

[yoda]

1 minute ago, yoda said:

Severe Tstorm Watch till 9pm for all in LWX CWA (except Alleghany and Garrett counties in W MD)

URGENT - IMMEDIATE BROADCAST REQUESTED
   Severe Thunderstorm Watch Number 303
   NWS Storm Prediction Center Norman OK
   155 PM EDT Thu Jun 2 2022

   The NWS Storm Prediction Center has issued a

   * Severe Thunderstorm Watch for portions of 
     District Of Columbia
     Delaware
     Central and Eastern Maryland
     Southern and Central New Jersey
     Southeast Pennsylvania
     Virginia
     Far Eastern West Virginia
     Coastal Waters

   * Effective this Thursday afternoon and evening from 155 PM until
     900 PM EDT.

   * Primary threats include...
     Scattered damaging wind gusts to 65 mph likely
     Isolated large hail events to 1 inch in diameter possible

   SUMMARY...Strong to severe thunderstorms are expected to develop and
   further increase, initially near/just east of the mountains through
   mid/late afternoon. These storms will spread east-southeastward and
   eventually reach near-coastal areas by evening. Damaging winds are
   likely to be the most common hazard with some hail possible as well.

 

[North Balti Zen]

I’ve decided to run a victory lap.

[MN Transplant]

First thunder.  Think that cell is going to slide just to the south of me.

And EJ is right, there is definitely some sort of boundary just hanging around.

[yoda]

Cellular activity going up pretty fast last 15 mins around i81 corridor

[Eskimo Joe]

9 minutes ago, MN Transplant said:

First thunder.  Think that cell is going to slide just to the south of me.

And EJ is right, there is definitely some sort of boundary just hanging around.

Yea there's a couple of cells firing in SE DC and along US 50 in Prince George's County.

[Eskimo Joe]

Southern MD and lower Delmarva looks like the place to be for today. Much better instability than from DC north.

[arlwx]

Special Marine warning for the tidal Potomac.

[vastateofmind]

53 minutes ago, mattie g said:

That's confusing. I think they mean that there's a slight chance early on, then 90% chance of rain later with a chance of storms.

Right? It was an armageddon forecast early this AM, they tempered it somewhat in the late morning disco update and midday grid forecast, and now it's back to this morning's grid since the watch was issued. Odd, given that conditions seemed to support increased chance of severe throughout the day.

 

[dailylurker]

Severe in Mid Atlantic meaning to me: 

Today there's a chance I won't have to water my garden. Severe around here is like last night. Some random cell produces a micro burst. Organized widespread Severe has happened like twice in my 43 years of life here.