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


Kmlwx
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Afternoon discussion from LWX about our next chance of severe on Thursday

LONG TERM /WEDNESDAY THROUGH SUNDAY/...
A strong cold front will dive southeastward from the Lower Great
Lakes, across the eastern Ohio Valley and into the mid-Atlantic
region Thursday into Thursday night. A large amount of instability
expected ahead of the front. Mid and upper level energy will be
joined by a strong jet aloft to set the stage for potential strong
or damaging thunderstorms Thursday afternoon and evening. SPC
currently has the eastern three-quarters of our region in a 15%
threat for severe weather. There are timing issues once again as to
when the strongest thunderstorms develop and move through the
region. The GFS is 12 to 18 hours faster than both the NAM and EURO
deterministic models. The GFS has the main event from mid-morning
through late afternoon Thursday. The NAM and EURO have it mid-
afternoon through about midnight. Nonetheless, whichever model you
believe, the instability ahead of the front and the lift from the
surface front, mid-level energy and jet aloft could cause for an
active Thursday afternoon and evening. Temperatures will be a couple
degrees above average, reaching the middle 80s with humid conditions.
 
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19 minutes ago, SnowenOutThere said:

Wonder if we get a day two enhanced? What's the main fail method with this severe event and what should we look for in the models to determine if the threat is looking more threatening or not.  

Mid-level lapse rates suck on the NAM. 

Timing could also adjust since we are several days out. 

NAM does give us sunshine that morning (for now) 

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Mount Holly's latest take on the severe threat for Thursday-

With stalled frontal boundary remaining situated over the region, there will likely be an appreciable temperature gradient once again with cooler highs in the upper 70s for the northern half of the region and upper 80s to near 90 south of the front. The front will attempt to move northward as a warm front ahead of the incoming shortwave trough and attendant surface low. The greatest risk for severe thunderstorms remains south of the front, which looks to be mostly south of the PA Turnpike and AC Expressway (Philadelphia suburbs southward). The Storm Prediction Center has a Slight Risk for Severe Weather south of Philadelphia Thursday. With CAPE values forecast to be in the 1000 to 2000 J/kg range (perhaps upwards of 3000 J/kg MUCAPE in areas that see enough sun to the south). The greatest threats look to be hail and damaging wind with deep CAPE well above the freezing level and some modest dry air aloft leading to forecast DCAPE values from 500 to 1000 J/kg. LL shear looks to be supportive of at least some supercells initially that will morph into a broken line or QLCS.

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Definitely on board with a SLGT tomorrow.     Chances of multiple widespread rounds of SVR appear to have dropped a lot, but most guidance has an organized system rolling through during the late afternoon hours.   With decent CAPE, good downdraft CAPE, and storm organization, there is a good chance of a bunch of wind reports.    We'd need better instability and shear to get ENH.

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3 hours ago, Kmlwx said:

12z NAM nest focuses the activity south of DC 

18Z still like south of DC for multiple rounds, but it gives one round to most of us.   I'd take it.   HRRR is again showing a couple of rounds for most.

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Afternoon AFD from LWX suggests maybe some late night storms north of DC metro as well

As we head into the overnight hours, showers and strong to
severe thunderstorms over western and central PA will try to
push southeastward into western and central Maryland and parts
of northern West Virginia. This activity, despite being in
the middle of the night, could be on the strong side. Gusty
winds and hail possible with this activity.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
A strong cold front dropping southeastward out of the Lower
Great Lakes and eastern Ohio Valley will slide across our region
on Thursday and pass through the region Thursday night. Morning
showers and thunderstorms may fizzle some and become more
isolated and weaker. However, as daytime heating evolves and the
front comes closer to the mid-Atlantic region, showers and
strong to severe thunderstorms will likely develop ahead of and
along the cold front. The more persistent and heaviest
thunderstorm activity should be from mid-afternoon through mid-
evening, such as 2pm to 8pm. There could be two rounds of
intense showers and thunderstorms Thursday afternoon and
evening. One would be near or east of US 15 to the Chesapeake
Bay and the second would be over the western mountains that
would eventually propagate eastward during the course of the
early evening hours. The main threats will be damaging winds and
large hail. A close second in terms of threats would be flooding
rains due to training thunderstorms. An isolated tornado cannot
be ruled out later Thursday afternoon. Showers and thunderstorms
should exit the area by midnight Thursday night with high
pressure building in Friday and Friday night. The high pressure
will lead to dry conditions and seasonable temperatures just in
time for the weekend.
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there's two types of weather we do pretty well here...

1) post-mid-latitude cyclone clouds/breezy conditions (when often times the forecast is just partly cloudy).

2) thunderstorms during or at the tail end of a stagnant, classic summer-like, swampy airmass.

it's game time.

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Morning AFD from LWX has an intriguing statement

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
354 AM EDT Thu Jun 2 2022

.SYNOPSIS...

A strong cold front will cross the area tonight and bring some
severe thunderstorms this afternoon and evening. High pressure
returns shortly thereafter heading into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...

Cdfnt extends southwest from a low pressure center over
northeast Ohio. Numerous to widespread showers and thunderstorms
are expected across the area from late this morning through mid
evening. Given strong instability and moderately strong mid-
level flow, thunderstorms will be capable of producing damaging
winds. Main severe threat looks to be from 11 AM until 8 PM.
Could see a SVR TSTM Watch issued as early as 10AM. Given mid-
level flow perpendicular to sfc front, storms should be fairly
progressive with storm motions around 30kt. Despite the fast
flow, very localized flooding can`t be completely ruled out
over the highly urbanized areas of DC to Baltimore given
possibility of intense, but brief, rainfall rates.

Convection should start winding down around 8PM and exit the
entire area by midnight tonight.
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Repeat later today? Daughter lives a few miles south of me and said it was a wild hour or so in the early morning. I didn't hear a thing!

Anne Arundel First Alert

#Update | Severe Storm Damage | #Overnight | Pictures are coming in showing the destruction in Herald Harbor | Around 1:30 AM the isolated storm came through the Crownsville area causing severe damage | Crews are working to restore power | Unknown on injuries | Use extreme caution if you find a downed wire or tree into the wires
285754339_1942833795920305_6359221860225
 
 
285818526_1942833822586969_5577270310151
 
 
285743867_1942833812586970_3606706206713
 
 
285702640_1942833832586968_1203638441459
 
 
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There still seems to be a south-favored nature of today's threat on the models. Not to say stuff isn't north of the Potomac, but I'd say best shots at something above the severe criteria is south of DC. We'll see! 

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
500 AM EDT THU JUN 02 2022

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0129 AM     TSTM WND DMG     1 N CROWNSVILLE         39.03N  76.59W
06/02/2022                   ANNE ARUNDEL       MD   911 CALL CENTER

            TWO TREES BLEW DOWN INTO HOUSES. NUMEROUS OTHER TREES
            AND BRANCHES DOWN BETWEEN CROWNSVILLE AND HAROLD HARBOR.


&&

EVENT NUMBER LWX2203648
 
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3 hours ago, Kmlwx said:

There still seems to be a south-favored nature of today's threat on the models. Not to say stuff isn't north of the Potomac, but I'd say best shots at something above the severe criteria is south of DC. We'll see! 

This feels off to me. 

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