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

[mattie g]

I think what we should do is forecast on our own, and ignore everything SPC says.

[yoda]

Sneaky severe Friday afternoon?  Updated Day 2 OTLK discussion from SPC... right now it's just north of DC into N MD including Baltimore and S PA into NJ/DE...

 

..Mid-Atlantic...
   A remnant MCV from earlier convection should be present over PA at
   the start of the period Friday morning. Some strong to perhaps
   isolated severe thunderstorms may develop ahead of this circulation
   across parts of southern PA/northern MD into DE and southern NJ
   Friday afternoon. If convection can form, it would pose a threat for
   all severe hazards given gradually increasing instability and a
   favorable kinematic parameter space related to the MCV. Confidence
   in thunderstorms redeveloping is not particularly high, but there is
   enough of a signal in guidance to include a small Marginal Risk.

[Kmlwx]

7 hours ago, yoda said:

Sneaky severe Friday afternoon?  Updated Day 2 OTLK discussion from SPC... right now it's just north of DC into N MD including Baltimore and S PA into NJ/DE...

 

..Mid-Atlantic...
   A remnant MCV from earlier convection should be present over PA at
   the start of the period Friday morning. Some strong to perhaps
   isolated severe thunderstorms may develop ahead of this circulation
   across parts of southern PA/northern MD into DE and southern NJ
   Friday afternoon. If convection can form, it would pose a threat for
   all severe hazards given gradually increasing instability and a
   favorable kinematic parameter space related to the MCV. Confidence
   in thunderstorms redeveloping is not particularly high, but there is
   enough of a signal in guidance to include a small Marginal Risk.

I saw a few model runs with good parameters but not much to show for it in terms of potential sensible weather. Maybe another day where we get one or two good cells but most of the area is meh. 

[yoda]

MRGL risk for just north of DC into most of N and C MD on new Day 1 OTLK... best chance in PA where there is slight risk... 2/5/15

[high risk]

As noted, that MCV is going to be a big player today, but it looks like most of the activity will be in PA.    I wouldn't be surprised, based on the latest HRRR runs, if they go ENH there.    Looks like less of a chance for the DC/Baltimore areas, but these MCVs can be tricky to model.

[Kmlwx]

17 minutes ago, high risk said:

As noted, that MCV is going to be a big player today, but it looks like most of the activity will be in PA.    I wouldn't be surprised, based on the latest HRRR runs, if they go ENH there.    Looks like less of a chance for the DC/Baltimore areas, but these MCVs can be tricky to model.

I'd feel better being up in @mappyland

[high risk]

2 minutes ago, Kmlwx said:

I'd feel better being up in @mappyland

         for sure, but the show may still be well north of there too.

 

[mappy]

30 minutes ago, Kmlwx said:

I'd feel better being up in @mappyland

Better chance than you, but I think it will still miss me north. 

[Kmlwx]

5 minutes ago, mappy said:

Better chance than you, but I think it will still miss me north. 

Yep - definitely seems to be the case. Like @high risk said - only thing left for us is that it could be poorly modeled - but agreement has been pretty solid on the show being up in PA. No reason to expect otherwise right now. 

[Stormfly]

I can almost toss a stone into that yellow box from my deck.

After Monday's atrocity, I'll take my chances.  Even if some high reaching boomers pass through York county, we usually enjoy the lightshow here. Since we have (yet) to see fireflies here, I'll take them inside mashed potatoes in the sky!  

[mappy]

24 minutes ago, Stormfly said:

I can almost toss a stone into that yellow box from my deck.

After Monday's atrocity, I'll take my chances.  Even if some high reaching boomers pass through York county, we usually enjoy the lightshow here. Since we have (yet) to see fireflies here, I'll take them inside mashed potatoes in the sky!  

Yes! Same here. 

[WxWatcher007]

Watch coming for N MD

Mesoscale Discussion 0838
   NWS Storm Prediction Center Norman OK
   0939 AM CDT Fri May 20 2022

   Areas affected...much of central Pennsylvania into far northern
   Maryland

   Concerning...Severe potential...Watch likely 

   Valid 201439Z - 201615Z

   Probability of Watch Issuance...80 percent

   SUMMARY...The severe threat is increasing across portions of central
   PA into MD. Damaging gusts and perhaps a few tornadoes may accompany
   the strongest, longer lived storms. A WW issuance will be needed
   within the next couple of hours.

   DISCUSSION...A remnant mid-level MCV (evident via water vapor
   imagery and 700-500 mb objective analysis fields) is currently
   located just west of the OH/PA border and continues to track
   eastward towards central PA, and is expected to support more robust
   convective initiation in the next few hours. Immediately ahead of
   the MCV center lies a highly sheared low-level environment, with
   recent PBZ VAD data showing relatively long, curved low-level
   hodographs and over 300 m2/s2 of associated 0-1km SRH. At the
   moment, buoyancy remains scant across portions of western into
   central PA. However, modest breaks in the clouds are contributing to
   modest surface heating, with mid 60s F surface temperatures already
   noted across central PA, with low 70s F along the PA/MD border. With
   surface dewpoints around 60F across several locales, RAP forecast
   soundings suggest temperatures need to warm into the lower 70s for
   appreciable buoyancy to develop given the presence of relatively
   poor (5.5-6.5 C/km) low and mid-level lapse rates.

   While buoyancy is expected to initially be marginal (i.e. at or
   below 1000 J/kg MLCAPE), localized deep-layer ascent and strong
   low-level shear associated with the approaching MCV should support
   at least a few strong to severe storms developing early this
   afternoon. Damaging gusts and perhaps a few tornadoes will be the
   primary concerns, though a brief instance or two of marginally
   severe hail cannot be completely ruled out with the longer-lived,
   persistent rotating updrafts. A WW issuance will be needed within
   the next couple of hours to address the severe threat.

   ..Squitieri/Hart.. 05/20/2022

 

[Kmlwx]

Maybe worth mentioning - or may be nothing - but that line entering western Maryland has not been well modeled on the short range guidance. Latest HRRR doesn't even have that line where it actually is. Probably will have a tendency to get tugged back into PA - but the area in the MCD could still get something out of this. 

[WxWatcher007]

Maybe I’m invested in this because it’s faux tropical in appearance lol, but here’s HM.

 

[WxWatcher007]

Nice line trying to bow west of Cumberland.

[Kmlwx]

Yeah some of the guidance looks absolutely nothing like the actual radar at the moment. 

[WxWatcher007]

4 minutes ago, Kmlwx said:

Yeah some of the guidance looks absolutely nothing like the actual radar at the moment. 

Love these kind of days. The sneaky setups often produce. I think the IR will look great when there’s more instability this afternoon in PA.

[yoda]

Tornado Watch up

TORNADO WATCH OUTLINE UPDATE FOR WT 251
NWS STORM PREDICTION CENTER NORMAN OK
1135 AM EDT FRI MAY 20 2022

TORNADO WATCH 251 IS IN EFFECT UNTIL 700 PM EDT FOR THE
 FOLLOWING LOCATIONS

WVC003-027-037-057-065-202300-
/O.NEW.KWNS.TO.A.0251.220520T1535Z-220520T2300Z/

WV
.    WEST VIRGINIA COUNTIES INCLUDED ARE

BERKELEY             HAMPSHIRE           JEFFERSON
MINERAL              MORGAN
$$

 

TORNADO WATCH OUTLINE UPDATE FOR WT 251
NWS STORM PREDICTION CENTER NORMAN OK
1135 AM EDT FRI MAY 20 2022

TORNADO WATCH 251 IS IN EFFECT UNTIL 700 PM EDT FOR THE
 FOLLOWING LOCATIONS

MDC001-005-013-015-021-023-025-027-043-510-202300-
/O.NEW.KWNS.TO.A.0251.220520T1535Z-220520T2300Z/

MD
.    MARYLAND COUNTIES INCLUDED ARE

ALLEGANY             BALTIMORE           CARROLL
CECIL                FREDERICK           GARRETT
HARFORD              HOWARD              WASHINGTON


MARYLAND INDEPENDENT CITIES INCLUDED ARE

BALTIMORE CITY

[mappy]

oh hello tornado watch

[yoda]

40/20 tor probs

30/30 hail probs 

70/20 wind probs 

[mappy]

Balt Co is out 3hrs yearly today, which is good if severe weather is coming, but I do hope they don't cancel after school activities/child care again. The kid has big plans for her half day with movies and outside play with friends. 

[Stormfly]

Looks like it's going to be north of us.
Isn't this the activity the models had forecast severe for NC two days ago?

Winds picked up considerably, feels like summer.  Someone pass the clicker so I can FF to Veteran's Day!

[Eskimo Joe]

Headed to Cumberland for the weekend. Surprised at the red box. Hopefully I catch something in the mountains.

[osfan24]

That all looks like it is going way north of us. 

[yoda]

Tornado Warning for Allegheny County 

[yoda]

 

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Baltimore MD/Washington DC
1241 PM EDT Fri May 20 2022

The National Weather Service in Sterling Virginia has issued a

* Tornado Warning for...
  Northwestern Washington County in north central Maryland...
  East central Allegany County in western Maryland...
  Northwestern Morgan County in the Panhandle of West Virginia...

* Until 115 PM EDT.

* At 1240 PM EDT, a severe thunderstorm capable of producing a
  tornado was located near Barnes Gap, or 9 miles west of Hancock,
  moving east at 50 mph.

  HAZARD...Tornado and quarter size hail.

  SOURCE...Radar indicated rotation.

  IMPACT...For those in the direct path of a tornado touchdown,
           flying debris will be dangerous to those caught without
           shelter. Damage to roofs, siding, and windows may occur.
           Mobile homes may be damaged or destroyed. Tree damage is
           likely.

* This dangerous storm will be near...
  Hancock around 1255 PM EDT.

Other locations impacted by this tornadic thunderstorm include Little
Orleans, Lineburg and Green Ridge.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

[Eskimo Joe]

Sitting at Ott House in Emmittsburg and it definitely has //that feel// up here.

[osfan24]

Seems like the models have a good grasp of what things look like right now. Rough Monday and Friday for forecasters for our area. Swing and a miss.

[Scraff]

Waiting for wedges in HoCo. #Nothappening 

[high risk]

2 hours ago, osfan24 said:

Seems like the models have a good grasp of what things look like right now. Rough Monday and Friday for forecasters for our area. Swing and a miss.

       Totally get where you're coming from on this, but I'll throw out 2 counterpoints:

   1)   For today, remember that SPC has to have boundaries on their watches *somewhere*, and if you're in one of those "last counties", unless you've got an adjacent watch box on the other side of the box, your threat is pretty low.    They typically make the watches slightly bigger than needed to allow for some margin for error.   The chances of SVR today extending all the way south to Howard were always pretty low.    

   2)    Monday was frustrating, but the big hail-producing cell that crushed the southern DC burbs shows that high-end potential did exist.    The failure was overpredicting the coverage, which happened after the poorly-modeled midday convection screwed up the environment for a lot of us.