2026 Mid-Atlantic Severe Storm General Discussion

[Roger Ramjet]

Socked in the clouds here. Smoke visibility has not changed at all in the last 24 hours.

[frd]

Significant cloud cover to the North, East and West of DC presently. The area of storms in PA really has a crazy outflow as previously mentioned. 

 

[WxUSAF]

5 minutes ago, SnowenOutThere said:

Did the models account for this or are we failing as per usual?

Dunno. I assume fail lol. Maybe if the warm front can push through we can partially clear for a few hours?

[high risk]

37 minutes ago, WxUSAF said:

Dunno. I assume fail lol. Maybe if the warm front can push through we can partially clear for a few hours?

       It's very warm to our south, so a fast warmup could absolutely occur, but I'm worried.  While the guidance is all over the place, most initiate storms along the lee trough or some other boundary this afternoon.   That said, the models have most of the area getting into the 90s, so if the clouds from the PA activity retard heating, we could end up with limited / weaker storms.   It's also worth noting that the RRFS really wants to clock us late evening with the line dropping south out of PA, even though most over guidance has it falling apart.  Bottom line is that I'm cautiously optimistic for rainfall today, and the severe threat is real if we get some heating, but there is definitely a path to many of us getting nada.

[SnowenOutThere]

10 minutes ago, high risk said:

       It's very warm to our south, so a fast warmup could absolutely occur, but I'm worried.  While the guidance is all over the place, most initiate storms along the lee trough or some other boundary this afternoon.   That said, the models have most of the area getting into the 90s, so if the clouds from the PA activity retard heating, we could end up with limited / weaker storms.   It's also worth noting that the RRFS really wants to clock us late evening with the line dropping south out of PA, even though most over guidance has it falling apart.  Bottom line is that I'm cautiously optimistic for rainfall today, and the severe threat is real if we get some heating, but there is definitely a path to many of us getting nada.

Can tell you the pool deck in chantilly suddenly got hot in the past 20 minutes as there’s a break in the clouds. Shot up from humid and cool to hot and extremely uncomfortable quick. 

[yoda]

Its "sunny" here in Springfield... just you can't tell with the smoky haze 

[yoda]

S winds being reported on the 11am obs up to BWI... 84/75 S at 9 at DCA... C VA like CHO, Culpepper, EZF already upper 80s

[WxUSAF]

Just now, yoda said:

S winds being reported on the 11am obs up to BWI... 84/75 S at 9 at DCA

Sky has brightened 

[batmanbrad]

visible does seem to show some decent clearing as you get west of MoCo...

 

[yoda]

Should be getting a MCD soon, probably in next hour

[yoda]

@high risk could there be some differential heating boundaries later?  I'm assuming that with the rain/storms in PA, the WF will not push as far north and increase risk for a few tornadoes?

[canderson]

From your N in PA. It had been years since we have had constant deep thunder like we have had all morning. 
 

Like @yoda asked I’m curious if all this here shoves south the hatch area. 

[high risk]

1 hour ago, yoda said:

@high risk could there be some differential heating boundaries later?  I'm assuming that with the rain/storms in PA, the WF will not push as far north and increase risk for a few tornadoes?

        It's worth watching, for sure.   With the westerly flow aloft, even 190 or 200 degree winds (SSW) at the surface might be enough to make things interesting.   Most of the guidance veers us to more fully southwest ahead of storm development, though, and surface wind speeds may not be particularly strong.   If that's wrong, yes, a tornado or two would be possible.   My guess now is that we'll have some supercell structures (and a tornado warning or two) with the favorable deep-layer shear but not enough low-level shear for tornadoes.

[yoda]

TW up from CTP on a storm moving ESE... would be near HGR in a few hours 

[JakkelWx]

What a surprise storm this morning. Some of the loudest thunder ever. 0.3"

[yoda]

1 hour ago, yoda said:

Should be getting a MCD soon, probably in next hour

Sounds like leaning towards Tornado Watch 

 

[DDweatherman]

Growing concerned looking at the parameters and sun is beating down nicely at the moment. Lots of little boundaries as well that could enhance some supercells.. assuming development continues upstream. 

[yoda]

https://www.spc.noaa.gov/products/md/md1648.html

Mesoscale Discussion 1648
   NWS Storm Prediction Center Norman OK
   1150 AM CDT Sat Jul 18 2026

   Areas affected...portions of southern Pennsylvania...eastern West
   Virginia...northern Virginia...much of
   Maryland...Delaware...southern New Jersey

   Concerning...Severe potential...Watch likely 

   Valid 181650Z - 181815Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Thunderstorms are expected to increase in coverage and
   intensity through early-mid afternoon. Damaging winds will be the
   primary concern as storms evolve into eastward-moving clusters and
   line segments.  A watch is likely prior to 18z.

   DISCUSSION...Strong boundary-layer heating of a very moist air mass
   is ongoing across the discussion area as of 1645z, contributing to
   moderate/pockets of strong surface-based instability. Thunderstorms
   will continue to increase in coverage across the higher terrain, and
   along a north-south confluence zone across southern PA south into
   northern VA, during the next few hours. As coverage continues to
   increase and low-level lapse rates steepen, the potential for
   damaging gusts will increase across the discussion area this
   afternoon and early evening. Additionally, low-level shear will
   remain locally enhanced in the vicinity of a warm front across
   southeast PA/southern NJ. Deep-layer shear will be supportive of
   supercell structures, and the risk for tornadoes, potentially
   strong, will be maximized in this area.

   Convective trends will continue to be monitored, and a watch is
   likely prior to 18z.

   ..Bunting/Thompson.. 07/18/2026

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

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

   LAT...LON   39077931 40007859 40547698 40477526 40267451 39987411
               39137439 38627538 38437699 38487839 38647934 39077931 

   MOST PROBABLE PEAK TORNADO INTENSITY...100-125 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN