2023 Mid-Atlantic Severe Wx Thread (General Discussion)

[George BM]

Happy Ten Year Anniversary, weenies!

[Eskimo Joe]

12 minutes ago, George BM said:

Happy Ten Year Anniversary, weenies!

For those of your unaware: https://www.spc.noaa.gov/exper/archive/event.php?date=20130613

[George BM]

Classic intense WNW flow mid-June severe potential today. Moderate risk for wind issued by SPC.

"A series of mid/upper shortwave impulses are expected to shift east
   across the Lower MS Valley and Southeast today in strong
   west/southwesterly mid/upper flow. Consistency among various
   forecast guidance shows at least 40-50 kt west/southwest flow
   between 850-700 mb with 60+ kt at 500 mb. A plume of very steep
   lapse rates will overspread the region, and 500 mb temperatures
   around -10 to -11 C will be common. Forecast soundings indicate
   midlevel lapse rates around 8-8.5 C/km over the region..."

"...strong
   destabilization with MLCAPE values exceeding 3000 J/kg..."

"...Locations may see a mix of supercells
   and intense bowing segments during the day, with potential for a
   derecho developing..."

The upper Midwest can sure be interesting this time of year wi- one sec... Wait this is for the deep-south?!

 

 

[yoda]

Whens the last time we saw a PDS STW?

[Kmlwx]

Marginal for Friday.

[yoda]

8 minutes ago, Kmlwx said:

Marginal for Friday.

But mentioned isolated supercells in its discussion too.  Only game in town probably for a while... let's get that upgrade to SLGT lol

[yoda]

Even the morning AFD from LWX is intriguing 

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As the mid-energy pivots across the northern half of our region
on Friday, additional showers and thunderstorms are likely to
develop. The amount of any sunshine Friday morning and midday
will make a difference on how intense Friday afternoon
thunderstorms become when they develop and move east. As of now,
SPC has the eastern two-thirds of our CWA in a Marginal Risk of
thunderstorms. A weak surface cold front will aid in the lift
of convection with the biggest threats from stronger
thunderstorms being strong wind gusts and hail (due to steep
low-level lapse rates and moderate shear). Moderate shear
profiles in our region could get the strongest thunderstorms
rotating into supercells.

&&

[frd]

The morning discussion from Mount Holly indicates that some of the parameters for severe weather are getting a little more robust for Friday. 

Also the WPC has increased rainfall totals in the northern Mid-Atlantic early next week. 

This comes in a backdrop of another dive in the Arctic oscillation and the NAO.  

[Scraff]

19 minutes ago, frd said:

The morning discussion from Mount Holly indicates that some of the parameters for severe weather are getting a little more robust for Friday. 

Also the WPC has increased rainfall totals in the northern Mid-Atlantic early next week. 

This comes in a backdrop of another dive in the Arctic oscillation and the NAO.  

If only this was February. 

[Kmlwx]

OT - But wouldn't it be comedic if the ultimate result locally of climate change turns out to be less exciting weather during our severe season(s) and less snow during the winter? Watch us just turn into a mild-mannered weather area entirely. Guess we have to rely on once per lifetime 5.9 earthquake events from now on for our excitement.

[George BM]

16 hours ago, yoda said:

Whens the last time we saw a PDS STW?

Off the top of my head I believe there was one last year on May 12th in the Plains.

[WxWatcher007]

2 hours ago, Kmlwx said:

OT - But wouldn't it be comedic if the ultimate result locally of climate change turns out to be less exciting weather during our severe season(s) and less snow during the winter? Watch us just turn into a mild-mannered weather area entirely. Guess we have to rely on once per lifetime 5.9 earthquake events from now on for our excitement.

This is a horrifying, yet hilarious, thought. 

[Eskimo Joe]

2 hours ago, Kmlwx said:

OT - But wouldn't it be comedic if the ultimate result locally of climate change turns out to be less exciting weather during our severe season(s) and less snow during the winter? Watch us just turn into a mild-mannered weather area entirely. Guess we have to rely on once per lifetime 5.9 earthquake events from now on for our excitement.

Stop. I can only take so much boredom and 34 and drizzle.

[Kmlwx]

The 12z NAM nest shows activity on the earlier side that intensifies east of 95 - some isolated stuff pops up later in the day as well - but seems like this could be a case where early stuff stabilizes much of the area. We'll see how it unfolds tomorrow. 

Best threat probably E of 95...

[yoda]

MRGL risk pushed back west to i81 corridor on 1730z SPC OTLK.  SLGT risk for i95 corridor and east to the Delmarva introduced 

[yoda]

LWX still likes tomorrow per afternoon AFD

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...

Closed 500 mb low will be moving across Pennsylvania Friday and
help trigger additional showers and thunderstorms with muliple
rounds of showers/t-storms expected. As opposed to last Monday,
this time mid-level lapse rates look significantly steeper and
cloud cover thinner with plenty of heating contributing to
moderately unstable conditions. Risk of severe wx looks greater
than last Monday particularly east of I-95. Convection is
likely to persist well into the evening over eastern areas, but
the severe threat is likely to wane quickly after 7PM.

[Kmlwx]

Still an early-ish arrival on the 18z NAM nest but I like how it looks better than the last run. It's a little more "clean" and actually gets MBY good storms. 

[yoda]

Storms in OH are packing a punch with 2" hail and confirmed tornadoes

[Eskimo Joe]

No KLWX tomorrow. Down for turn table maintenance or something.

[southmdwatcher]

7 minutes ago, Eskimo Joe said:

No KLWX tomorrow. Down for turn table maintenance or something.

Rolling the dice.

[Kmlwx]

37 minutes ago, southmdwatcher said:

Rolling the dice.

If there was any radar in the country to gamble with - it would be KLWX. We have TIAD, TDCA and TBWI in the area that can provide coverage for the immediate metro and many surrounding areas. Buy yeahhh - that's not ideal. 

[Kmlwx]

@Eskimo Joe - Was it this? Was it moved up - because they originally showed June 20-30ish

 

[yoda]

6 minutes ago, Kmlwx said:

@Eskimo Joe - Was it this? Was it moved up - because they originally showed June 20-30ish

 

More about it -- https://nwschat.weather.gov/p.php?pid=202306142127-KLWX-NOUS41-PNSLWX

[Eskimo Joe]

1 hour ago, Kmlwx said:

@Eskimo Joe - Was it this? Was it moved up - because they originally showed June 20-30ish

 

Yes. Part of the national service extension.

[yoda]

Well written discussion this morning from LWX 

NEAR TERM /THROUGH TONIGHT/...
A potent upper-level shortwave is moving through the Ohio Valley
into Tennessee early this morning. In fact, you can see a
reflection to the surface in the form of low pressure. Increased
divergence aloft has caused weak low pressure to develop around
a boundary near the Virginia Piedmont. Light southeast winds
have developed in response to this low, causing a little
moisture advection as well as low-level convergence around the
Piedmont and east of Interstate 95. A few showers and
thunderstorms have developed across these areas early this
morning, and this may continue. The threat for severe storms
seems low since instability is still limited, but small hail and
gusty winds are possible.

Numerous showers and thunderstorms are also associated with the
potent shortwave/low pressure over southeastern Ohio into WV and
PA. This activity will move into the area from the northwest
early this morning. There is a relative min in instability
across northern VA, the Potomac Highlands and eastern WV, so
while there will be showers with perhaps a few thunderstorms,
the probability for severe storms is low. A stronger storm may
impact areas west of the Allegheny Front between 5 and 8 AM this
morning where instability may be a bit higher on the western
side of the mountains.

The shortwave will move through our area later this morning into
this afternoon, and a band of showers along with a couple
thunderstorms will continue to gradually push southeast during
this time. Latest guidance continues to show activity
strengthening along the outflow boundary of this system late
this morning into this afternoon. This is due to falling heights
and daytime heating ahead of it. With stronger shear profiles
and steep low-level lapse rates, this suggests that some storms
may be severe with damaging winds and large hail being the
primary threats. Exactly how far north and west the severe
threat makes it with the first round is uncertain, but it does
appear that the best chance for strong to severe storms will be
across central Virginia south of Interstate 66 and east of
Interstate 95 across central MD into the Baltimore Metropolitan
area as well as northeastern MD between 15 to 18z, and around
18-21z for southern MD.

However, the potent shortwave will lag behind, passing through
our area late this afternoon and evening. The cold front
associated with this system will due so during this time as
well. Therefore, there will be a period where the atmosphere can
recharge around mid to late afternoon ahead of the cold front.
This is tough to do, but given the longer days this time of year
and cold air aloft, it seems likely at this time. Therefore,
more showers and thunderstorms are likely to develop ahead of
the cold front (best chance near and east of Interstate 81)
around mid to late afternoon before propagating eastward toward
the Bay this evening. More severe storms are possible due to
steep low-level lapse rates and strong shear profiles as well
as more DCAPE during this time as well. Damaging winds and large
hail are the primary threats.

The cold front will move off to the east later this evening
into the early overnight while the upper-level trough axis
swings through. A northwest flow will gradually dry things out
during this time, and it will turn out cool and less humid
overnight with falling dewpoints.

[Kmlwx]

A lot of the guidance is pretty emphatic on the idea of weakening the stuff to the west as it approaches and the intensifying it once it's east of many of us - @CAPE being the exception and anyone else mainly east of I-95 but really even east of the bay. A mix of the guidance still shows some cells popping up during the afternoon behind the initial activity...but we all know how this story goes. Despite what LWX says about the atmosphere recharging...I have my doubts. Current SPC SLGT area looks solid to me. Hoping for a good storm IMBY - but I have my doubts. 

[Eskimo Joe]

Just want some rain.

[CAPE]

18 minutes ago, Kmlwx said:

A lot of the guidance is pretty emphatic on the idea of weakening the stuff to the west as it approaches and the intensifying it once it's east of many of us - @CAPE being the exception and anyone else mainly east of I-95 but really even east of the bay. A mix of the guidance still shows some cells popping up during the afternoon behind the initial activity...but we all know how this story goes. Despite what LWX says about the atmosphere recharging...I have my doubts. Current SPC SLGT area looks solid to me. Hoping for a good storm IMBY - but I have my doubts. 

I expect most of the activity will be east/SE/NE of my yard. In that betwixt and between groove.

[Eskimo Joe]

9 hours ago, Kmlwx said:

@Eskimo Joe - Was it this? Was it moved up - because they originally showed June 20-30ish

 

Ugh, I totally whiffed on the start date of the service. My bad.

[Kmlwx]

11 minutes ago, Eskimo Joe said:

Ugh, I totally whiffed on the start date of the service. My bad.

All good! Though - you might have spoken it into existence - KLWX has been having issues lately it seems. Lots of downtime recently.