2025 Severe Weather General Discussion

[Kmlwx]

Entirely possible some of us get completely missed today. The NAM nest is a snoozefest for many of us. The 6z HRRR had the good line tonight for mainly southern portions of the area it seemed. It will all come down to how the upstream activity develops and propagates. I sound like a winter weather weenie...but it'll ultimately come down to nowcasting. I'm doubtful ANY model is going to 100% nail the development and movement of any MCS coming from the W or SW 

[Eskimo Joe]

58 minutes ago, WxUSAF said:

Storms? Did not expect a clean sweep on LWX radar when I woke up. That MCS is way up in NW PA. 

Looks like we might miss out completely. I'm okay with this. 

[nw baltimore wx]

Annual Black Eye Susan party starts at 9AM. I’m okay with things holding off until late this evening to chase everyone out.

[WxUSAF]

15 minutes ago, Eskimo Joe said:

Looks like we might miss out completely. I'm okay with this. 

Bbbbbooooorrrrrrriiiiinnnnnnggggg

[Kmlwx]

One unscientific note on the MCS up in PA - previous model runs yesterday had that coming through shaped like a long NW-SE stretching "arm." In reality it looks like a reverse L shape. Had that horizontal part of the L been straight downward like in the prior model forecasts, it likely would have been a closer call for parts of our area. Let's see how the afternoon plays out in terms of instability etc. I'm not "out" but I have tempered my expectations until I see a legit/more certain threat. 

[CAPE]

Hell of a disco from SPC for the moderate risk area. "Pristine" airmass.

[Kmlwx]

I'm yet again spam posting...but this thread isn't generally SUPER active so who cares  

I think if that MCS up in PA can "die" or fade out somewhat near the area - it could spit out/lay down some boundaries to aid in the less clear forcing for later on. Then it will be a question of seeing if the cap holds, or if we can get some isolated activity to pop in the region. The other possibility is (as we've discussed already) - that the upstream convection from the moderate risk could surge through some part of the area later on tonight. Similar to winter...the more chances that are presented - the better the odds of at least one working out. We failed on the morning MCS this AM up in PA. Next we'll see if there's any afternoon initiation (maybe higher terrain?) and then the eyes will be on the overnight stuff. 

While NONE of these are certain to get any of us...I do think the highest overall odds would come with the MCS activity tonight from the west/SW. The question at that point would be whether it becomes elevated convection or remains surface based/severe. 

[high risk]

Regarding the “failed” morning MCS, guidance overnight showed that the far southern flank might ignite after 8 or 9 am this morning in northern MD.  A few showers are now indeed breaking out, so there is clearly at least some forcing.  Model solutions vary between just isolated weak showers and actual robust storms, so I’m unsure how the next few hours will play out, but we clearly do have some sort of forcing mechanism. 

[dailylurker]

27 minutes ago, Kmlwx said:

I'm yet again spam posting...but this thread isn't generally SUPER active so who cares  

I think if that MCS up in PA can "die" or fade out somewhat near the area - it could spit out/lay down some boundaries to aid in the less clear forcing for later on. Then it will be a question of seeing if the cap holds, or if we can get some isolated activity to pop in the region. The other possibility is (as we've discussed already) - that the upstream convection from the moderate risk could surge through some part of the area later on tonight. Similar to winter...the more chances that are presented - the better the odds of at least one working out. We failed on the morning MCS this AM up in PA. Next we'll see if there's any afternoon initiation (maybe higher terrain?) and then the eyes will be on the overnight stuff. 

While NONE of these are certain to get any of us...I do think the highest overall odds would come with the MCS activity tonight from the west/SW. The question at that point would be whether it becomes elevated convection or remains surface based/severe. 

It looks like storms are starting to fire all through Central PA into Northern MD. Maybe late but not denied?

[WxUSAF]

Just now, high risk said:

Regarding the “failed” morning MCS, guidance overnight showed that the far southern flank might ignite after 8 or 9 am this morning in northern MD.  A few showers are now indeed breaking out, so there is clearly at least some forcing.  Model solutions vary between just isolated weak showers and actual robust storms, so I’m unsure how the next few hours will play out, but we clearly do have some sort of forcing mechanism. 

If you squint, looks like a boundary moving through HoCo right now on radar 

[CAPE]

Pretty clear elongated outflow boundary associated with the primary area of convection moving S/SE, as the convection itself is expanding southward.

[Eskimo Joe]

46 minutes ago, CAPE said:

Pretty clear elongated outflow boundary associated with the primary area of convection moving S/SE, as the convection itself is expanding southward.

Latest HRRR tries to fire an impressive MCS on that boundary after it sweeps east of Baltimore. Philly and eastern Delmarva get a solid hit. 

[CAPE]

2 minutes ago, Eskimo Joe said:

Latest HRRR tries to fire an impressive MCS on that boundary after it sweeps east of Baltimore. Philly and eastern Delmarva get a solid hit. 

Yeah it looks like NE MD and southward into DE have the best shot with this initial round.

[frd]

9 minutes ago, Eskimo Joe said:

Latest HRRR tries to fire an impressive MCS on that boundary after it sweeps east of Baltimore. Philly and eastern Delmarva get a solid hit. 

Yep, it has started 

[Kmlwx]

Nice little cell to start the day is passing just to my north along the MC/HC line. Hopefully we clear out and don't deal with remnant clouds all day. Satellite behind this stuff looks fine. 

Places that get a little precip (even if not storms) could "benefit" for storm chances later via the additional  moisture on the ground for higher dewpoints. 

[yoda]

Severe Thunderstorm Watch coming shortly for NE MD and DE/Eastern Shore

https://www.spc.noaa.gov/products/md/md0808.html

 

[JakkelWx]

80% watch probs!

[yoda]

2 minutes ago, JakkelWx said:

80% watch probs!

Mesoscale Discussion 0808
   NWS Storm Prediction Center Norman OK
   0846 AM CDT Fri May 16 2025

   Areas affected...the Lower Mid-Atlantic States

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

   Valid 161346Z - 161545Z

   Probability of Watch Issuance...80 percent

   SUMMARY...A few supercells could develop before midday across parts
   of the Lower Mid-Atlantic region. Large hail and damaging winds
   should be the primary hazards into early afternoon.

   DISCUSSION...An arcing band of convective development is underway
   south of a morning MCS across over central/eastern PA. This arc
   extends southward through central MD towards the DC metro vicinity.
   12Z WAL to PIT soundings sampled a favorable environment for
   supercells with 40-50 kt effective bulk shear, largely driven by
   speed change with height amid unidirectional west-northwesterlies.
   This was coupled with moderate mid-level lapse rates of 6.5 to 7
   C/km. 12Z HRRR and 00Z HREF guidance have a signal for longer-track
   2-5 km UH, with potential for a few supercells. Given the
   orientation of the convective development, this seems probable
   across parts of eastern MD, DE, and far southern NJ. Pronounced
   surface heating in this area, south of persistent cloudiness farther
   north, will aid in further destabilization and increase the risk for
   both large hail and damaging winds by midday.

   ..Grams/Mosier.. 05/16/2025

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

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

   LAT...LON   40727641 40517541 39887448 39177448 38267486 38037544
               38087591 38427700 38917704 39777645 40277652 40727641 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN

[WxUSAF]

MBY got split. Core went a mile south or so.

[yoda]

Watch up

URGENT - IMMEDIATE BROADCAST REQUESTED
   Severe Thunderstorm Watch Number 260
   NWS Storm Prediction Center Norman OK
   1005 AM EDT Fri May 16 2025

   The NWS Storm Prediction Center has issued a

   * Severe Thunderstorm Watch for portions of 
     Delaware
     Far Eastern Maryland
     New Jersey
     Far Eastern Pennsylvania
     Coastal Waters

   * Effective this Friday morning and afternoon from 1005 AM until
     500 PM EDT.

   * Primary threats include...
     Scattered large hail and isolated very large hail events to 2
       inches in diameter possible
     Scattered damaging wind gusts to 70 mph possible

   SUMMARY...Thunderstorms continue to strengthen as they move into
   more of eastern PA and eastern MD. Destabilization is expected
   downstream, with the resulting combination of instability and shear
   supportive of supercells capable of large hail and damaging gusts.

   The severe thunderstorm watch area is approximately along and 55
   statute miles east and west of a line from 15 miles northwest of
   Trenton NJ to 45 miles south of Dover DE. For a complete depiction
   of the watch see the associated watch outline update (WOUS64 KWNS
   WOU0).

 

[dailylurker]

Looks like a snooze fest west of the bay. Oh well.. I didn't need hail. Something interesting would of been nice though. 

[yoda]

Don't usually see the bolded 

rea Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1000 AM EDT Fri May 16 2025

.SYNOPSIS...
A warm front is expected to lift through and to the northeast
of the region today into late afternoon. A low pressure system
will move into the Great Lakes today with a trailing cold front
pushing through the area on Saturday. High pressure will build
in from the north Sunday and Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As expected, a line of moderate to heavy showers has developed
across central MD this morning and is moving east towards the
Chesapeake Bay. This is along a boundary set off by a much
stronger MCS that is ripping across northern PA at this time. It
doesn`t appear that the line will have anything severe over our
area, but a brief downpour can be expected in these areas.

Later this afternoon into this evening, thunderstorms may
develop along remnant outflows from this morning convection in
conjunction with Bay/River breezes. This would be our first shot
at severe thunderstorms today, and would generally be along and
east of I-95 roughly. It seems that we will have no issues with
heating today, along with very high dew points in the 70s, so
this round could be quite strong if it is able to develop. Model
guidance and current obs do depict some westerly mid-level flow,
which could be an inhibiting factor to CI this afternoon.
However, I want to stress that if something does develop in this
environment, all hazards will be possible with any storm that
develops.

Another round of severe weather could be on the horizon later
this evening into the overnight hours. This is still very
uncertain though, and very dependent on an MCS developing to our
west and tracking in such a way that would impact our area.
Since we won`t have our daytime heating, the severity could be
diminished some, but the humidity, nearby trough, approaching
cold front on Saturday could be enough to make it interesting in
terms of severe elements overnight. At this time, would feel
more confident that this occurs across central/southern VA, but
can`t be 100 percent certain at this time. This is very much a
"wait and see what develops" scenario and will be much more in
the way of NOWcasting later today.

Given all of these threats today, the Storm Prediction Center
has our region in a Slight Risk for Severe Thunderstorms today
into tonight. The threats are damaging wind gusts and large
hail. Accompanying these threats will be heavy rain and could
occur over areas that had already taken on a lot of rainfall in
the past few days. A marginal risk for excessive rainfall is
also highlighted for our area today for the localized potential
for some flash flooding.

High temperatures today should push the upper 80s in the eastern
half or even close to 90.

[CAPE]

Most of the 12z Mesos look interesting for later, esp near and east of the bay. 12z 3Km NAM is a bit more scattered/isolated compared to its 6z run though.

[yoda]

14z HRRR blows up some supercells (I'm assuming thats what they are) across the region around 20z 

[Eskimo Joe]

9 minutes ago, yoda said:

14z HRRR blows up some supercells (I'm assuming thats what they are) across the region around 20z 

Got a screenshot for those of us who are mobile?

[Kmlwx]

[Kmlwx]

[Kmlwx]

Many of the CAMS really are not enthused about the overnight stuff locally - perhaps for southern portions of the area. That will be interesting to see if they are correct. 

[Kmlwx]

12z sounding from IAD/LWX

[Kmlwx]

Also of note - overnight CSU MLP wind graphic put the red over us.