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.