2026 Mid-Atlantic Severe Storm General Discussion

[MillvilleWx]

This thread should hopefully spur to life a bit with the overall longwave pattern shifting. Our good friend the WAR will be making a comeback which should open the door with better theta_E advection into the Mid Atlantic. We've been void of persistent southerly flow for a while with the NW flow regime basically a deterrent to any type of warm advection regime in this area of the country. 

[yoda]

Looks like Wednesday, maybe Thursday for a chance of some severe?  Nothing huge of course... just the risk for it

[yoda]

MRGL up out to the NW of the i95 corridor 

[yoda]

Wednesday afternoon up in the air per morning AFD from LWX 

 

A strong area of low pressure moves through the Northeast on
Wednesday, with a cold front extending down the East Coast that will
bring widespread rain and thunderstorm chances to the Mid-Atlantic
in the afternoon/evening. While the center low will be well north of
us, the timing of the front aligning with the diurnal cycle and the
high temperatures seen at the start of the week could still
contribute towards some thunderstorm development in the region.
Potential severity at this time still ranges widely--NCAR`s AI NWP
Convective Hazards Forecast currently has our region outlined in its
45%-60% probability for severe weather to occur, while CSU`s medium-
range probabilities ranks the severe threat much lower. Regardless,
this front will likely result in widespread showers at a minimum as
well as a sharp drop in temperatures seen later in the week. Highs
on Thursday will range in the upper 60s and low 70s, a marked shift
from the mid-90s expected earlier in the week. Lingering rain
showers may still be moving out of the area by Thursday morning,
while a meandering front to the south could bring a few additional
rain showers on Friday.

[Kmlwx]

Even the lower CSU is still in the 15% range for wind. Given how boring things have been - I'll take it for some thunderstorm activity! 

[WxUSAF]

Hhheeelllloooooo 6z RGEM 

[Kmlwx]

45 minutes ago, WxUSAF said:

Hhheeelllloooooo 6z RGEM 

Central MD special  

Now if only I trusted the RGEM at this range more. 

[high risk]

I'm on board for thunderstorms later Wednesday, but the upper level flow looks *really* weak which should reduce the severe potential.  There may still be enough shear lower in the profile to get some wind threat, but the ceiling for this event looks to be low.

[SnowenOutThere]

5 minutes ago, high risk said:

I'm on board for thunderstorms later Wednesday, but the upper level flow looks *really* weak which should reduce the severe potential.  There may still be enough shear lower in the profile to get some wind threat, but the ceiling for this event looks to be low.

Thoughts on today? I listed out some of my thoughts in the Discobs thread but do we have any hope of a boundary causing forcing? 

[Stormchaserchuck1]

Just now, SnowenOutThere said:

Thoughts on today? I listed out some of my thoughts in the Discobs thread but do we have any hope of a boundary causing forcing? 

I just saw my first cloud! 

[high risk]

1 hour ago, SnowenOutThere said:

Thoughts on today? I listed out some of my thoughts in the Discobs thread but do we have any hope of a boundary causing forcing? 

     I haven't seen any guidance bring storms today much further east than the I-81 corridor.   Storm motion won't pull anything towards the Metro area.

[Ellinwood]

I'm losing count of the amount of times SPC has put upper MoCo in the Marginal only for 0 storms to appear this year (granted, I haven't expected anything from these setups yet except the one March system). That said, I do think we get a Slight with Wednesday's setup along/northwest of I-95... low-to-mid level shear is subpar but there's good CAPE and DCAPE for some gusty winds along the cold front.

[yoda]

18 hours ago, Ellinwood said:

I'm losing count of the amount of times SPC has put upper MoCo in the Marginal only for 0 storms to appear this year (granted, I haven't expected anything from these setups yet except the one March system). That said, I do think we get a Slight with Wednesday's setup along/northwest of I-95... low-to-mid level shear is subpar but there's good CAPE and DCAPE for some gusty winds along the cold front.

Add today to the list?

[Ellinwood]

16 hours ago, yoda said:

Add today to the list?

Haha yep. I still think we get Slight-level severe coverage along/NW of I-95 today (even if the SPC keeps it Marginal)... we've been baking since Monday with little to no turnover in the atmosphere and storm coverage looks pretty good today.

[yoda]

1 hour ago, Ellinwood said:

Haha yep. I still think we get Slight-level severe coverage along/NW of I-95 today (even if the SPC keeps it Marginal)... we've been baking since Monday with little to no turnover in the atmosphere and storm coverage looks pretty good today.

LWX seems to think we get a STWatch today.  They mentioned it in their AFD... haven't seen them do that much before 

[dailylurker]

NAM comes in like "what storms today?" Hopefully it's wrong but the pattern we've been in for 5 years says it's right lol

[Kmlwx]

5 minutes ago, dailylurker said:

NAM comes in like "what storms today?" Hopefully it's wrong but the pattern we've been in for 5 years says it's right lol

The 6z NAM and NAM nest on the site I'm looking at have storms. 

[dailylurker]

38 minutes ago, Kmlwx said:

The 6z NAM and NAM nest on the site I'm looking at have storms. 

I'm hugging the HRRR. For the record I feel like today we have a good shot at something fun. At this point I'd be pumped to see some lightning and downpours. 

[high risk]

1 hour ago, dailylurker said:

NAM comes in like "what storms today?" Hopefully it's wrong but the pattern we've been in for 5 years says it's right lol

The overnight NAMs are lit up like Christmas trees.     It's the HRRR that wants to keep all activity today focused north of DC.

[high risk]

3 hours ago, Ellinwood said:

Haha yep. I still think we get Slight-level severe coverage along/NW of I-95 today (even if the SPC keeps it Marginal)... we've been baking since Monday with little to no turnover in the atmosphere and storm coverage looks pretty good today.

        Big downdraft CAPE is our path to severe today, because the shear sucks.   That might be enough to get it done in a few corridors where storms organize, but this would have had some legit widespread material had we achieved better winds aloft.

[dailylurker]

9 minutes ago, high risk said:

The overnight NAMs are lit up like Christmas trees.     It's the HRRR that wants to keep all activity today focused north of DC.

Oops. Had it backwards. I'm hugging the NAM lol. I'm just glad we now have a discussion about it. LFG!

[yoda]

3 hours ago, Ellinwood said:

Haha yep. I still think we get Slight-level severe coverage along/NW of I-95 today (even if the SPC keeps it Marginal)... we've been baking since Monday with little to no turnover in the atmosphere and storm coverage looks pretty good today.

Good call

 

[yoda]

 

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0730 AM CDT Wed May 20 2026

   Valid 201300Z - 211200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE CENTRAL APPALACHIANS INTO THE MID-ATLANTIC AND SOUTHERN NEW
   ENGLAND...AND PARTS OF WEST/SOUTH-CENTRAL TEXAS...

   ...SUMMARY...
   Scattered severe/damaging winds and isolated hail will be possible
   with thunderstorms from the central Appalachians into the
   Mid-Atlantic and southern New England this afternoon and evening.
   Severe thunderstorms with large hail and isolated severe gusts may
   also occur today across parts of west/south-central Texas.

   ...Ohio Valley into the Mid-Atlantic and Southern New England...
   On the southern fringe of upper troughing over eastern Canada and
   the Great Lakes, a weak/convectively augmented mid-level shortwave
   trough will progress northeastward across the OH Valley and central
   Appalachians through the day, eventually reaching the Mid-Atlantic
   tonight. Robust daytime heating of a modestly moist low-level
   airmass (surface dewpoints generally in the low to mid 60s) ahead of
   a surface cold front will aid in the development of moderate
   instability by early afternoon. Ongoing convection across OH/KY this
   morning may eventually strengthen as it encounters this
   destabilizing airmass, and additional thunderstorms are expected to
   develop along/near the cold front by mid afternoon from the central
   Appalachians into portions of the Mid-Atlantic and southern New
   England.

   Stronger flow aloft will tend to lag/remain north of the cold front,
   but modest enhancement to the west-southwesterly mid-level flow
   along/near the front should support around 20-30 kt of deep-layer
   shear. This will be sufficient for some updraft organization with
   mainly multicells expected, although marginal supercell structures
   may occur. Low-level lapse rates are expected to become quite steep
   through the day, evidenced by a general lack of clouds on recent
   visible satellite imagery from central/eastern WV into the
   Mid-Atlantic. This will likely aid efficient downward momentum
   transfer in convective downdrafts, with scattered severe/damaging
   winds possible as multiple clusters spread east-northeastward
   through the afternoon/evening. Isolated hail may also occur with the
   stronger cores. A Slight Risk for severe/damaging winds has been
   introduced from parts of WV to southern New England given increased
   confidence in multiple clusters traversing a narrow zone along/ahead
   of the front.

[Eskimo Joe]

11z HRRR mixes our low level dewpoints out to the upper 50s by initiation time (~2:00 pm), while the NAMNAM Nest keeps the dews in the 60s. 

[SnowenOutThere]

1 hour ago, high risk said:

        Big downdraft CAPE is our path to severe today, because the shear sucks.   That might be enough to get it done in a few corridors where storms organize, but this would have had some legit widespread material had we achieved better winds aloft.

Even yesterday could feel the ability for the DCape to work its magic from the gust front winds alongside gusty winds with a downpour. Just need some taller cells to full take advantage of it. 

[Eskimo Joe]

Per the 12z sounding at IAD, the Conv. Temp is 93°. Hoping to get us into the low 90s to maximize whatever we can today.

[batmanbrad]

alerted on Radarscope of an MCD issued for our area, 80% chance of a blue box coming.

[yoda]

STW coming soon for majority of LWX CWA

[yoda]

https://www.spc.noaa.gov/products/md/md0801.html

 

 

Mesoscale Discussion 0801
   NWS Storm Prediction Center Norman OK
   1123 AM CDT Wed May 20 2026

   Areas affected...portions of the Mid-Atlantic

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

   Valid 201623Z - 201800Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Widely scattered thunderstorms will pose a risk for
   damaging wind gusts and isolated large hail this afternoon and
   evening. A Severe Thunderstorm Watch will be needed soon.

   DISCUSSION...Latest surface observations depict a cold front
   extending from central New York southwestward through north-central
   and western Pennsylvania into southeast Ohio. Ahead of this cold
   front, temperatures are warming into the 90s across portions of the
   Mid-Atlantic, with surface dewpoints in the low/mid 60s F. Continued
   heating of this air mass is supporting 1000-1500 J/kg MLCAPE, with
   further destabilization anticipated through the afternoon hours.

   Recent satellite/radar imagery has shown increasing convective
   coverage ahead of the aforementioned cold front as remaining
   inhibition is eroded. With stronger mid/upper-level flow remaining
   displaced to the northwest, only modest effective shear is analyzed
   across the region (generally 20-30+ kts per latest mesoanalysis).
   This will be sufficient to support updraft organization with
   multicells, and perhaps marginal supercells, likely. Steep low-level
   lapse rates, well-mixed boundary layer profiles, and surface
   dewpoint depressions exceeding 20-25 F will promote the potential
   for damaging wind gusts, particularly with any more organized
   clusters that develop. Isolated instances of large hail may also
   accompany any more robust updrafts despite weak mid-level lapse
   rates (as sampled by the 12z PIT/IAD observed soundings). A Severe
   Thunderstorm Watch will be needed soon.

   ..Chalmers/Hart.. 05/20/2026

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

   ATTN...WFO...PHI...BGM...CTP...LWX...PBZ...RLX...

   LAT...LON   40687798 40987676 40987614 40907587 40747568 40397553
               39967560 39437589 39147621 38927665 38687793 38597862
               38587907 38767959 39117993 39388003 39737992 40107959
               40247926 40687798 

   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN

[high risk]

5 minutes ago, yoda said:

https://www.spc.noaa.gov/products/md/md0801.html

           Definitely consistent with the idea that this is mainly a threat north of 66 (VA) 50 (MD).