2026 Mid-Atlantic Severe Storm General Discussion

[canderson]

1 minute ago, MN Transplant said:

The HRRR wanted initiation to happen already, but so far there is only one new cell up west of Gettysburg.  Things can change quickly in this environment, though.

Quite a lot of popcorn ongoing around HBG and they all instantly became quite strong. 

[TSSN+]

3 minutes ago, canderson said:

Quite a lot of popcorn ongoing around HBG and they all instantly became quite strong. 

Hrrr now says it’s a dc south day. Not much for northern Md or southern pa. Nothing new there though. Haven’t had much of anything for months. 

[midatlanticweather]

 Mesoscale Discussion 1691
   NWS Storm Prediction Center Norman OK
   1253 PM CDT Tue Jul 21 2026

   Areas affected...portions of the Mid-Atlantic

   Concerning...Severe potential...Watch likely 

   Valid 211753Z - 211930Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Multiple rounds of numerous, strong to severe
   thunderstorms will bring a risk for primarily damaging wind gusts to
   portions of the Mid-Atlantic through this evening, with a couple of
   brief tornadoes and isolated large hail also possible.

   DISCUSSION...Scattered thunderstorms have developed along the Blue
   Ridge as of 1750 UTC ahead of a mid-level shortwave trough that is
   progressing eastward across the upper Ohio Valley. Expectation is
   for this activity to spread eastward this afternoon with additional
   thunderstorms likely to progress into the region from the northwest
   this evening. Filtered heating of the downstream environment has
   resulted in temperatures warming into the upper 80s/near 90 F. With
   dewpoints in the low/mid 70s, this is supporting moderately strong
   buoyancy across the region. While effective shear of 35-45+ kts will
   favor storm organization, widespread thunderstorm development and
   cold pool consolidation are anticipated to yield a
   multicellular/outflow-dominant storm mode, with damaging to severe
   wind gusts the primary risk. A couple of brief tornadoes and
   isolated large hail will also be possible.

   Additionally, guidance suggests that air mass recovery will occur in
   the wake of these initial storms, which may allow the severe threat
   to persist into this evening as additional convection progresses
   southeastward into the region. Given this severe potential, watch
   issuance will likely be needed in the next hour or two.

   ..Chalmers/Mosier.. 07/21/2026

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

   ATTN...WFO...PHI...AKQ...LWX...RNK...

   LAT...LON   37348031 38057950 39047840 39467763 39467704 39397660
               39147596 38857550 38557536 38147544 37417580 37067629
               36927689 36917711 36747834 36737931 36818019 37078049
               37218043 37348031 

   MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN

[AlexD1990]

MCD out, 80% watch issuance. Technically im outside of both circles 

[batmanbrad]

1 hour ago, Kmlwx said:

Would think a mesoscale discussion would be coming in the next 1-2 hours. But only guessing. 

we just got one, so good guess!

[SnowenOutThere]

22 minutes ago, Kmlwx said:

That's one thing that during our heat stretches this year...the dewpoints haven't been mixing down as low as they have in prior heatwaves. That makes a ton of difference for sensible weather...sure we hit 100 sometimes but often the dews would drop back into the 60s. Being up near the century mark and having dews stay well into the 70s is nasty. 

Radar looks meh for the DC region for now - but that activity down deep in VA looks decent. Will have to see if anything more substantial pops up closer in. Some of the CAMs yesterday had a sort of gap in the activity between SEPA and Central VA/Southern Maryland leaving some of us high and dry (relatively speaking). 

The first part of this point is super important when it comes to our severe ability. Convective instability isn’t really because it’s hot out with some humidity, it’s a measure of how much energy a parcel can release as it traverses the atmosphere. Water carries a lot of heat with it, so despite us being clouded over since it’s so wet out we have 3000+ CAPE over the region. Additionally, airs ability to hold water increases exponentially, it’s why a dewpoint change from 40 -> 50 feels fine, but 60 -> 70 is rough. Hence, we have a ton of energy stored through all that extra water. The issue without heating is that you need forcing to cause storms as you don’t get natural convective currents to help out. I’m not qualified to know if our Lee trough will be enough to pop storms, but In some ways I wonder that a lack of heating could help our severe odds today. Since we don’t have a cap traditionally storm overcrowding could be a fail mode, but with poor level lapse rates maybe it will mitigate overcrowding.  

[87storms]

Humidity is on point, but radar out west looks more like heavy rainers than the electrical show we had Saturday…which I’m kinda craving again because it was awesome.

[Kmlwx]

Hopefully the VA storms don't rob energy - I think they have enough separation. That severe cell back in WV may be awfully far away to be our threat...will have to see if anything can trigger along the ridges and such. 

[alexj7]

24 minutes ago, TSSN+ said:

Hrrr now says it’s a dc south day. Not much for northern Md or southern pa. Nothing new there though. Haven’t had much of anything for months. 

It's crazy I've had nothing this year. Every single event is a miss.

[SnowenOutThere]

Just now, Kmlwx said:

Hopefully the VA storms don't rob energy - I think they have enough separation. That severe cell back in WV may be awfully far away to be our threat...will have to see if anything can trigger along the ridges and such. 

We have a small Lee trough signature out along I-81 I think. It’s pretty weak though. 

[frd]

TORNADO WATCH OUTLINE UPDATE FOR WT 507
NWS STORM PREDICTION CENTER NORMAN OK
205 PM EDT TUE JUL 21 2026

TORNADO WATCH 507 IS IN EFFECT UNTIL 900 PM EDT FOR THE
 FOLLOWING LOCATIONS

DEC003-220100-
/O.NEW.KWNS.TO.A.0507.260721T1805Z-260722T0100Z/

DE
.    DELAWARE COUNTIES INCLUDED ARE

NEW CASTLE
$$

[AlexD1990]

Just now, frd said:

TORNADO WATCH OUTLINE UPDATE FOR WT 507
NWS STORM PREDICTION CENTER NORMAN OK
205 PM EDT TUE JUL 21 2026

TORNADO WATCH 507 IS IN EFFECT UNTIL 900 PM EDT FOR THE
 FOLLOWING LOCATIONS

DEC003-220100-
/O.NEW.KWNS.TO.A.0507.260721T1805Z-260722T0100Z/

DE
.    DELAWARE COUNTIES INCLUDED ARE

NEW CASTLE
$$

missed me by two counites..petty  

[Eskimo Joe]

That cell coming out of central WV is probably going to be the main show in these parts. Already visible on LWX radar and it's had a tornado warning on it a short time ago. Must be some little vort max swinging around the base of the trough?

[Kmlwx]

11 minutes ago, Eskimo Joe said:

That cell coming out of central WV is probably going to be the main show in these parts. Already visible on LWX radar and it's had a tornado warning on it a short time ago. Must be some little vort max swinging around the base of the trough?

It's beyond the echo tops product range for LWX too! Impressive that it's showing so strongly. Must have a heck of an updraft...

[wxmeddler]

The best looking hodographs come in around 20z and last through about 3z. Eastern shore looks thermodynamically best right now given the satellite but the are better hodographs west.

Convective temperatures are around 95F -ish, and we're not gonna get there in N/W of I-95 with the clouds. This is all for semi-isolated supercell stuff... if you just want a thunderstorm, you'll get a good chance of that everywhere later.

[WxUSAF]

5 minutes ago, wxmeddler said:

The best looking hodographs come in around 20z and last through about 3z. Eastern shore looks thermodynamically best right now given the satellite but the are better west. Convective temperatures around 95-ish, and we're not gonna get there in N/W of I-95 with the clouds. This is all for semi-isolated supercell stuff... if you just want a thunderstorm, you'll get a good chance of that everywhere later.

Euro has been insistent on a broad QLCS through the area well after dark and 12z continues that 

[Kmlwx]

A little shower popping near Brunswick now. 

[SnowenOutThere]

27 minutes ago, Eskimo Joe said:

That cell coming out of central WV is probably going to be the main show in these parts. Already visible on LWX radar and it's had a tornado warning on it a short time ago. Must be some little vort max swinging around the base of the trough?

If you look on RadarScope right now it seems to have a debris ball possibly? May just be wind kicking up leaves but I’m not sure. The cell isn’t even TOR warned though… 

[Eskimo Joe]

Severe Thunderstorm Watch for everyone until 10 pm tonight. 

[yoda]

10 minutes ago, Eskimo Joe said:

Severe Thunderstorm Watch for everyone until 10 pm tonight. 

 

   URGENT - IMMEDIATE BROADCAST REQUESTED
   Severe Thunderstorm Watch Number 509
   NWS Storm Prediction Center Norman OK
   245 PM EDT Tue Jul 21 2026

   The NWS Storm Prediction Center has issued a

   * Severe Thunderstorm Watch for portions of 
     District Of Columbia
     Delaware
     Maryland
     Far Northwest North Carolina
     Virginia
     The Eastern West Virginia Panhandle
     Coastal Waters

   * Effective this Tuesday afternoon and evening from 245 PM until
     1000 PM EDT.

   * Primary threats include...
     Scattered damaging wind gusts to 70 mph likely
     Isolated large hail events to 1.5 inches in diameter possible
     A tornado or two possible

   SUMMARY...Multiple rounds of strong to severe thunderstorms are
   expected across the region today and tonight, beginning with the
   ongoing storms across central Virginia. Environmental conditions
   support robust updrafts, with all severe hazards possible, including
   damaging gusts and isolated hail. A low-probability tornado risk
   exists with any afternoon development as well. Another round of
   storms is possible along a cold front later tonight, with damaging
   gusts as the primary risk. A low-probability, line-embedded tornado
   risk exists with these more linear storms as well.

[yoda]

I'm assuming we are also watching the storms in SE OH entering WV?

[Eskimo Joe]

Looks like the storms NW of RIC may be choking off the inflow for anything local to DC or Baltimore. 

[Kmlwx]

1 minute ago, Eskimo Joe said:

Looks like the storms NW of RIC may be choking off the inflow for anything local to DC or Baltimore. 

This sort of thing has happened before. But also somebody noted a little further up that Convective Temps are like 95 today. So without the better forcing from the front we might not have much going on until later. 

Also @yoda - I'd think so - but quite of bit of seemingly stratiform junk in front of that stuff as well. A messy radar picture as a whole other than the organized stuff down south. 

[Kmlwx]

Kind of impressive that the SE OH cells are showing a bit on the LWX radar (in GR2AE3)

[Eskimo Joe]

Just now, Kmlwx said:

Kind of impressive that the SE OH cells are showing a bit on the LWX radar (in GR2AE3)

A number of tornado warnings in that watch box to our west. Wonder if SPC upgrades that?

[vortex95]

3 hours ago, high risk said:

  It might temper the severe threat somewhat, but getting significant storms seems to still be on track.   Each HRRR cycle this morning has been catching on to the fact that we won't get the amount of heating previously expected, and it still initiates widespread heavy convection.

I.m little concerned about the immediate DC area.  Seems like the "split" is already evident on radar w/ the large area near RIC and the isolated cells along the PA border.  A lot of clouds now before we get any solid storm development! 

What the 15z HRRR fcst for 19z for the DC metro is *way* off.  Storm cluster fcst vs. zip!

That being said, isolated discrete storms are starting develop now in the area, so that's what was shown last night and then big line in the evening is still fcst.  So it may yet work out?

Only got a svr box, no tor box, despite 5% tor probs.  Usually w/ 5% tor probs we get a tor box.  Perhaps SPC did that b/c they noted what I pointed out above (too much cloud cover in the risk area)?
 

 

[vortex95]

1 hour ago, Kmlwx said:

Hopefully the VA storms don't rob energy - I think they have enough separation. That severe cell back in WV may be awfully far away to be our threat...will have to see if anything can trigger along the ridges and such. 

Yes, I do not like to see a big cluster of storms S of an area of interest.  It seems more often than not, that means the area to the N is ripped off!

[TSSN+]

Whiff lol. 

[Eskimo Joe]

9 minutes ago, vortex95 said:

I.m little concerned about the immediate DC area.  Seems like the "split" is already evident on radar w/ the large area near RIC and the isolated cells along the PA border.  A lot of clouds now before we get any solid storm development! 

What the 15z HRRR fcst for 19z for the DC metro is *way* off.  Storm cluster fcst vs. zip!

That being said, isolated discrete storms are starting develop now in the area, so that's what was shown last night and then big line in the evening is still fcst.  So it may yet work out?

Only got a svr box, no tor box, despite 5% tor probs.  Usually w/ 5% tor probs we get a tor box.  Perhaps SPC did that b/c they noted what I pointed out above (too much cloud cover in the risk area)?

4,700 SBCAPE on the 18z sounding, but the convective temp is 88 degrees. With this thick cirrus shield in place at peak heating, I doubt we get enough sunshine to reach this. Perhaps south of US 50 and the eastern shore, as @wxmeddleralluded to works out, but this is shaping up to be an ugly bust here in the metros.

[MN Transplant]

Based on the CAMs, we were all hoping that this would be a two-round day, with discrete cells out front before the organized stuff gets here later.  We just didn't get initiation and now have to wait for the stuff in Ohio to come together.  18z HRRR brings it in around 10pm, but there is a risk of it being south.