2026 Mid-Atlantic Severe Storm General Discussion

[yoda]

Updated afternoon Day 3 SPC disco

Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0227 PM CDT Thu Jul 16 2026

   Valid 181200Z - 191200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
   OHIO VALLEY AND LOWER GREAT LAKES INTO THE MID-ATLANTIC...

   ...SUMMARY...
   Strong to severe thunderstorms are expected across portions of the
   Ohio Valley and lower Great Lakes into the Mid-Atlantic, mainly
   Saturday afternoon into the evening. Some threat may linger into
   late Saturday night.

   ...Ohio Valley into the Mid Atlantic and vicinity...
   Some amplification of a mid/upper-level trough is expected over the
   northeastern CONUS on Saturday, as multiple shortwaves move through
   the base of the trough. The primary surface low is expected to
   deepen as it moves across southern Quebec toward northern Maine. A
   trailing cold front will move through parts of the Ohio Valley and
   Northeast. A remnant surface front initially draped from western PA
   toward the Delmarva region is forecast to lift northeastward as a
   warm front through the period. 

   As deep-layer flow strengthens atop a richly moist and destabilizing
   warm sector, organized severe potential is expected to develop
   across a relatively broad region from the Ohio Valley into the Mid
   Atlantic, with at least an isolated threat potentially reaching
   parts of New England. Uncertainties include the influence of
   early-day convection and potential persistent smoke on the
   northeastward extent of substantial surface-based destabilization. 

   Along the cold front, the greatest relative threat is currently
   expected from the lower Great Lakes into eastern parts of the Ohio
   Valley, where stronger 850-700 mb flow (around 25-40 kt) is
   forecast. Organized cells/clusters capable of damaging wind and
   isolated hail may evolve along/ahead of the front and spread
   eastward. Rich boundary-layer moisture and modest enhancement to
   low-level SRH may also result in some tornado threat, depending on
   storm-mode evolution. Favorable moisture/buoyancy will also extend
   westward along/ahead of the front into parts of the Midwest and
   lower Ohio Valley, but there may be more of a tendency for
   convection to be undercut by the front with westward extent. 

   Farther south/east, organized convection may evolve or reintensify
   near the effective warm front by afternoon into parts of PA/NJ, and
   also develop into parts of MD/VA along/east of a surface trough.
   Very warm temperatures and steepening low-level lapse rates will
   become supportive of damaging-wind potential, and isolated hail may
   also occur. Some tornado threat could also evolve in closer
   proximity to the warm frontal zone. 

   An extensive frontal QLCS may develop by evening, and continue to
   pose some wind-damage threat for as long as it persists into
   Saturday night. 

 

[yoda]

That single storm in SE NJ is packing quite a wallop... 85mph wind gust

Severe Weather Statement
National Weather Service Mount Holly NJ
655 PM EDT Thu Jul 16 2026

NJC005-029-162330-
/O.CON.KPHI.SV.W.0181.000000T0000Z-260716T2330Z/
Ocean NJ-Burlington NJ-
655 PM EDT Thu Jul 16 2026

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 730 PM EDT
FOR SOUTHEASTERN OCEAN AND EAST CENTRAL BURLINGTON COUNTIES...

At 654 PM EDT, a severe thunderstorm was located over Surf City, or
23 miles south of Toms River, moving southeast at 30 mph.

THIS IS A DESTRUCTIVE STORM FOR SHIP BOTTOM AND SURF CITY.

HAZARD...80 mph wind gusts and half dollar size hail.

SOURCE...Trained weather spotters. At 647 PM EDT, a 85 MPH wind gust
         was recorded at the Surf City Yacht Club mesonet station.

IMPACT...Flying debris will be dangerous to those caught without
         shelter. Mobile homes will be heavily damaged. Expect
         considerable damage to roofs, windows, and vehicles.
         Extensive tree damage and power outages are likely.

Locations impacted include...
Barnegat, Tuckerton, Surf City, Brookville, Warren Grove, Penn State
Forest, Beach Haven West, Manahawkin, Ocean Acres, and Waretown.

This includes Garden State Parkway between mile markers 57 and 73.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Prepare immediately for large hail and damaging winds. People outside
should seek shelter inside a well-built structure and away from
windows.

Frequent cloud to ground lightning is occurring with this storm, and
the storm will affect the beaches. For your safety, immediately move
off the beach and seek shelter indoors.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3976 7454 3986 7446 3982 7402 3950 7421
TIME...MOT...LOC 2254Z 301DEG 25KT 3966 7411

THUNDERSTORM DAMAGE THREAT...DESTRUCTIVE
HAIL THREAT...OBSERVED
MAX HAIL SIZE...1.25 IN
WIND THREAT...OBSERVED
MAX WIND GUST...80 MPH

$$

 

[vortex95]

9 hours ago, WxUSAF said:

Why has the NAM just looked like shit for any shower/storm day we’ve had this year from any range >6 hours??

The NAM is woefully outdated as a model.  I do not think it has been updated to tweaked in 10 years or so.  It is mainly for a "quick, early look" and I think that's why I has stuck around for so long!

Generally, I do not use the NAM after 36 hr, as it does odd things.  And the model was never designed for TCs, so never use it for them.

The NAM and all its derivative models are going away in Oct (was going to be Aug but pushed back),  The RRFS will replace it.  The RRFS has its issues, but from what I have seen, it does much better than the NAM.
 

 

[vortex95]

1 hour ago, yoda said:

That single storm in SE NJ is packing quite a wallop... 85mph wind gust

Severe Weather Statement
National Weather Service Mount Holly NJ
655 PM EDT Thu Jul 16 2026

NJC005-029-162330-
/O.CON.KPHI.SV.W.0181.000000T0000Z-260716T2330Z/
Ocean NJ-Burlington NJ-
655 PM EDT Thu Jul 16 2026

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 730 PM EDT
FOR SOUTHEASTERN OCEAN AND EAST CENTRAL BURLINGTON COUNTIES...

At 654 PM EDT, a severe thunderstorm was located over Surf City, or
23 miles south of Toms River, moving southeast at 30 mph.

THIS IS A DESTRUCTIVE STORM FOR SHIP BOTTOM AND SURF CITY.

HAZARD...80 mph wind gusts and half dollar size hail.

SOURCE...Trained weather spotters. At 647 PM EDT, a 85 MPH wind gust
         was recorded at the Surf City Yacht Club mesonet station.

IMPACT...Flying debris will be dangerous to those caught without
         shelter. Mobile homes will be heavily damaged. Expect
         considerable damage to roofs, windows, and vehicles.
         Extensive tree damage and power outages are likely.

Locations impacted include...
Barnegat, Tuckerton, Surf City, Brookville, Warren Grove, Penn State
Forest, Beach Haven West, Manahawkin, Ocean Acres, and Waretown.

This includes Garden State Parkway between mile markers 57 and 73.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Prepare immediately for large hail and damaging winds. People outside
should seek shelter inside a well-built structure and away from
windows.

Frequent cloud to ground lightning is occurring with this storm, and
the storm will affect the beaches. For your safety, immediately move
off the beach and seek shelter indoors.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3976 7454 3986 7446 3982 7402 3950 7421
TIME...MOT...LOC 2254Z 301DEG 25KT 3966 7411

THUNDERSTORM DAMAGE THREAT...DESTRUCTIVE
HAIL THREAT...OBSERVED
MAX HAIL SIZE...1.25 IN
WIND THREAT...OBSERVED
MAX WIND GUST...80 MPH

$$

 

The training on this storm was incredible.  And it was smack dab in the middle of the thick smoke plume, so that did not seem to inhibit things, and maybe enhanced things (cloud condensation nuclei different?).  Smoke as to impacting convection has some studies, and results vary.  One was smoke plumes seem to increase the frequency of +CGs.

I attached the CG plot zoomed up color coded every 20 min going back 2 hr ending 724pm EDT.  The density is wild!

Radar rainfall estimates show up to 6" in some locations.
 

[high risk]

10 hours ago, yoda said:

Hmmmm... sounds like Saturday could be quite interesting... afternoon AFD from LWX on the threat

@wxmeddler @Eskimo Joe @Kmlwx @high risk

KEY MESSAGE 2...A strong cold front brings the threat of severe
weather Saturday, possibly lingering into Sunday to the south.

 

      Early thought is that storms will fire Saturday afternoon along the lee trough in an environment with good shear and at least moderate instability.  (The NAM is likely too moist in the low levels, so toss its extreme instability).  Severe will definitely be a concern, and the high PW environment may support locally intense rainfall, but the fast storm movement should prevent major flooding concerns.   The potential round 2 is highly dependent upon timing.     Right now, consensus seems to favor arrival very late in the evening, which leads to significant weakening (and possibly falling completely apart) before arrival.   The shear will be increasing further after dark, so severe would be possible, but the timing really needs to speed up to make that happen.

[WxUSAF]

5 hours ago, high risk said:

      Early thought is that storms will fire Saturday afternoon along the lee trough in an environment with good shear and at least moderate instability.  (The NAM is likely too moist in the low levels, so toss its extreme instability).  Severe will definitely be a concern, and the high PW environment may support locally intense rainfall, but the fast storm movement should prevent major flooding concerns.   The potential round 2 is highly dependent upon timing.     Right now, consensus seems to favor arrival very late in the evening, which leads to significant weakening (and possibly falling completely apart) before arrival.   The shear will be increasing further after dark, so severe would be possible, but the timing really needs to speed up to make that happen.

0z euro moves that round 2 through around 0z. Most other guidance has it 2-3 hours later so it mostly falls apart before getting to us. 

[WxUSAF]

23 hours ago, WxUSAF said:

Why has the NAM just looked like shit for any shower/storm day we’ve had this year from any range >6 hours??

Bump for the 12z isolated micro-shower tomorrow in the metro area

[Eskimo Joe]

1 hour ago, WxUSAF said:

Bump for the 12z isolated micro-shower tomorrow in the metro area

Code Purple Rain to wash the smoke away.

[jewell2188]

Wouldn’t it be fitting for smoke to put a damper on our severe potential!? We can find every way to fail here whether it’s snow or thunderstorms 

[Eskimo Joe]

30 minutes ago, jewell2188 said:

Wouldn’t it be fitting for smoke to put a damper on our severe potential!? We can find every way to fail here whether it’s snow or thunderstorms 

Plot Twist: the edges of the smoke plumes can act as differential heating boundaries for storms, and the increased particular can act as nucleation for lightning. We saw that in PA/WI/NJ the past few days.

Satellite loop for visual:

 

 

[yoda]

ENH risk introduced on 1730z SPC OTLK 

[yoda]

4 minutes ago, yoda said:

ENH risk introduced on 1730z SPC OTLK 

 

 

 

[yoda]

Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1229 PM CDT Fri Jul 17 2026

   Valid 181200Z - 191200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
   THE LOWER GREAT LAKES INTO THE MID-ATLANTIC...

   ...SUMMARY...
   Severe thunderstorms are expected across portions of the Ohio Valley
   and Lower Great Lakes into the Mid-Atlantic and Northeast, mainly
   Saturday afternoon into the evening. Some threat may linger into
   late Saturday night.

   ...Ohio Valley/Lower Great Lakes into the Mid-Atlantic/Northeast...
   An active severe-weather day is expected Saturday from parts of the
   Ohio Valley and Lower Great Lakes into the Mid-Atlantic, as
   scattered to widespread storms move through an increasingly
   favorable environment. A 45% wind area has been added, resulting in
   a categorical upgrade to Level-3/Enhanced Risk. The Enhanced Risk
   area is a combination of multiple regimes which may eventually
   overlap, with some areas potentially seeing multiple rounds of
   strong to severe storms.  

   A mid/upper-level shortwave trough is forecast to move across the
   northern Great Lakes vicinity through the day, before approaching
   New England by evening. In conjunction with this shortwave trough, a
   deepening surface low is expected to move across southern Quebec
   toward northern Maine, as a trailing cold front moves through the
   Great Lakes and eventually parts of the Mid Atlantic and Northeast.
   A remnant surface front initially draped from southern NJ into
   western PA will lift northeastward as an effective warm front, in
   advance of the surface low and cold front. 

   As strengthening deep-layer wind fields overspread increasingly rich
   moisture, a broad region from the Ohio Valley and Lower Great Lakes
   into the Mid-Atlantic and parts of the Northeast will become
   supportive of organized convection and severe-thunderstorm
   potential. HRRR-based forecasts suggest that smoke will become less
   prominent from west to east by afternoon, which should allow for
   relatively strong diurnal heating and moderate destabilization in
   areas not affected by early-day convection. Effective shear of 35-45
   kt will support organized clusters and possibly occasional
   supercells from the Lower Great Lakes into the northern Mid-Atlantic
   and Northeast, while strong heating and steep low-level lapse rates
   will result in a favorable wind-damage environment within the
   somewhat weaker flow regime across the southern Mid-Atlantic and
   parts of the Carolinas.  

   Elevated convection may be ongoing or else develop during the
   morning across parts of PA/NY, within a warm-advection regime
   associated with the returning warm front. Depending on the timing of
   this convection and downstream heating/destabilization, some
   intensification of ongoing convection may occur by early afternoon.
   Additional development may occur along the southwest flank of
   early-day convection and related outflow, which may intensify and
   move across the northern Mid-Atlantic during the afternoon. In
   addition to a wind-damage threat, some hail and tornado potential
   may also evolve with any supercell development, given the presence
   of favorable effective SRH. 

   Farther north, a broken band of storms is expected to develop along
   the cold front and move across the Lower Great Lakes region,
   eventually reaching a larger part of OH/PA/NY by late afternoon or
   early evening. Additional storms may develop ahead of the frontal
   convection, depending on the extent of heating in the wake of
   early-day storms. Multiple wind-damage swaths may accompany this
   convection, along with some potential for isolated hail. Rich
   moisture and some enhancement to low-level SRH may also support a
   tornado threat with any discrete or embedded supercells, especially
   near the effective warm frontal zone or any remnant outflow
   boundaries from morning convection. 

   An initially separate regime of storm development and severe
   potential is expected to develop along/east of a surface trough
   across parts of the southern Mid-Atlantic into NC. While deep-layer
   flow will tend to weaken with somewhat southward extent, strong
   heating and steepening of low-level lapse rates will provide a
   favorable thermodynamic environment for downbursts and damaging
   outflow winds. 

   Depending on the extent of outflow from prefrontal storms, frontal
   convection may continue to pose at least an isolated severe threat
   through the evening as it spreads southeastward. 

[yoda]

@high risk @wxmeddler @Eskimo Joe 

Can smoke lay boundaries?  I know Eskimo mentioned it in his post above... but is it something that we should be watching tomorrow morning?  Also, doesn't the smoke act like a pseudo cap or EML in a sense in that it keeps the atmosphere from CI?  Finally, wouldn't it also keep the moisture (dewpoints) up?

[WxUSAF]

Need a big fat QLCS to blow and rain all the smoke out 

[wxmeddler]

45 minutes ago, yoda said:

@high risk @wxmeddler @Eskimo Joe 

Can smoke lay boundaries?  I know Eskimo mentioned it in his post above... but is it something that we should be watching tomorrow morning?  Also, doesn't the smoke act like a pseudo cap or EML in a sense in that it keeps the atmosphere from CI?  Finally, wouldn't it also keep the moisture (dewpoints) up?

Smoke can do a bunch of stuff but the two things that you see most often are:

1. Smoke can create differential heating on smoke vs. non smoke areas. Causing pseudo surface cold fronts.

2. Mid/Upper level smoke can absorb sunlight and transfer that energy to the surrounding environment; creating warmer mid-levels while also reducing surface heating. Both combined makes caps more robust than would otherwise be expected. 

[Eskimo Joe]

Just wanted to add for the Maryland folks. The Maryland Department of Environment has some real nerdy pollution meteorologists. Their forecasts are almost always spot on and they regularly coordinate with the various NWS offices. We're very fortunate to have these folks in our state!

[WxUSAF]

3 hours ago, WxUSAF said:

Need a big fat QLCS to blow and rain all the smoke out 

Hugging the Herpderp. Other mesos look like shit.

[vortex95]

4 hours ago, yoda said:

@high risk @wxmeddler @Eskimo Joe 

Can smoke lay boundaries?  I know Eskimo mentioned it in his post above... but is it something that we should be watching tomorrow morning?  Also, doesn't the smoke act like a pseudo cap or EML in a sense in that it keeps the atmosphere from CI?  Finally, wouldn't it also keep the moisture (dewpoints) up?

I think thick smoke can go both ways.  On Tue, big time svr wx (best SCP and SIGTOR parameters I have seen in a long time in the Northeast), was completely squashed during the daylight hours at least.  Otherwise there would likely have been a sig tor event in srn Quebec and nrn New England. Temps were held down a lot.  BOS fcst high as 97, and high was only 90.  PWM fcst high was 93, and only got to 85.  This resulted in CINH remaining stronger over the entire area.

However, ydy we saw a nasty back-building tstm training event in cntrl NJ.  Wind gusts as high as 84 mph at Surf City and they also had 4.37" of rain.  CG LTG was incredibly dense in a narrow swath.  And these storm fired directly within the thick plume of smoke.

One can say w/ high confidence the smoke in the Northeast was the cause for the svr wx bust here, but for what happened in NJ ydy?  Not as clear.  That would be a good case study/research item, re-run models w/o the smoke, and see if intense tstms would have occurred to the degree they did!

The models for tomorrow have smoke in their initialization, unlike what happened on Tue in the Northeast, so it is accounted for.

I am not impressed w/ the 18z HRRR storm coverage tomorrow over the region.  18z RRFS is a little better, and shows an isolated honkin' supercell just N of DC, but the 45% area for wind seems high for the DMV area to me given the *coverage* of storms fcst.  This is important.  The colored SPC outlooks areas are for expected svr wx type coverage, they say nothing about how intense any individual svr wx may be (the hatched areas show that)

So they should be solid svr storms, just the real question is coverage overall.  The thick smoke may be a factor here, but how much in either direction?

We go from weak anticyclonic flow aloft today to solid cyclonic flow tomorrow w/ a s/w coming thru.  500 heights come down as well.  But the NAM shows 500 temps actually increase a bit in the aftn, up to -4 C (yuck!).  The GFS tho shows slight cooling from -5 C tdy to -6 C tomorrow.  Also, the mid-level lapse rates are not as bad as you would think for such warm 500 mb temps.  Looking at the NAM and GFS, it shows lapse rates as high as 7 C/km on the fcst soundings (not using 700-500 exactly here, any thick layer at mid-levels will do).

Fcst K-indices in the area gets as high as 40 on both the NAM and GFS, and that is impressive.  Juiced column for big rains!  NAM has PWATs are high as 2.8" which is likely overdone.  GFS has it as high as 2.5" which is good for this model (not usually that high)!  Anything over 2" is more than enough.

Since DCAPE is fcst high and 0-3 km CAPE low, tor threat seems minimized. 0-6 km shear 35-40 kt, so enough for supercells.