Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0102 AM CDT Mon Jul 20 2026

Valid 201200Z - 211200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE UPPER MIDWEST AND GREAT LAKES...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTH
CAROLINA AND FAR SOUTHERN VIRGINIA...

...SUMMARY...
Severe thunderstorms are expected across portions of the Upper
Midwest and Great Lakes vicinity, especially late this afternoon and
tonight. Swaths of damaging winds, large hail, and a few tornadoes
will all be possible. Isolated damaging wind gusts may also occur
over parts of the Carolinas and southern Virginia.

...Upper Midwest/Great Lakes...
A potentially active severe-weather scenario is expected later today
into tonight, although some key uncertainties persist related to the
potential impacts of early day convection and associated cloud
debris.

A substantial shortwave trough over southern Manitoba will continue
to gradually amplify and spread southeastward to the Lake Superior
vicinity through tonight, with a strengthening belt of
mid/high-level west-northwesterly flow overspreading the Upper
Midwest toward the Lake Michigan vicinity, highlighted by 50-70 kt
mid-level winds and 100 kt winds in the upper levels across
Minnesota/Wisconsin. An east/southeastward-advecting plume of steep
mid-level lapse rates will overspread a warm sector with upper 60s
to lower/middle 70s F dewpoints.

Initially, a few early day storms could produce hail and perhaps
some strong wind gusts across east/southeast Minnesota into western
Wisconsin and eastern Iowa, amidst ample elevated instability and
effective shear over 50 kt. This activity may continue to spread
southeastward this morning but tend to wane during the day, leading
to a potential regional break prior to additional/more vigorous
development by late afternoon along the cold front as it progresses
east-southeastward toward Wisconsin/Upper Michigan and
northern/eastern Iowa. 

The initial storms should primarily be supercells given such strong
deep-layer shear. A corridor of large hail and tornado risk is
evident east of the instability axis from Iowa across Wisconsin into
Upper MI. Even while near-surface winds may tend to veer with time,
effective SRH may exceed 300 m2/s2, especially across Wisconsin
toward Upper Michigan as supported by the seasonally very-strong 2-3
km AGL winds (700 mb winds in excess of 50 kt). The degree of SRH
could support a couple strong tornadoes (EF2+), and somewhat higher
tornado probabilities could be warranted in subsequent outlooks as
early day convection details are resolved. While supercells will
persist for a time, several storm clusters will evolve this evening,
with a continued damaging wind and some tornado risk persisting
southeastward this evening prior to storm intensity eventually
waning overnight.

...Carolinas and southern Virginia...
Convection and related cloud debris may persist early today, but a
moist air mass will again diurnally destabilize this afternoon along
and south of a roughly west/east-oriented front. Daytime heating,
70s F dewpoints and surface convergence will aid storm formation and
intensification this afternoon. MLCAPE in excess of 2000 J/kg, PWAT
over 2.00", and mid-level westerly flow aloft of 15-20 kt will lead
to multicellular storm mode with isolated damaging wind gusts during
the afternoon until around sunset.

...Florida...
Tropical Depression Two may gradually strengthen across the
northeast Gulf of America today and tonight. Reference the National
Hurricane Center for the latest development/forecast details. While
various global models support the notion of a strengthening of
southerly winds in the lowest 2-3km AGL, especially across the
western Florida Peninsula, it currently appears that
supercell-related tornado potential should remain low, largely
attributable to the overall weakness of the Depression and weak wind
aloft.

..Guyer/Weinman.. 07/20/2026

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1239 AM CDT Mon Jul 20 2026

Valid 211200Z - 221200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF SOUTHERN INDIANA...NORTHEAST KENTUCKY...SOUTHERN/EASTERN
OHIO...WEST VIRGINIA...NORTHERN VIRGINIA...MARYLAND...AND
PENNSYLVANIA...

...SUMMARY...
Numerous severe thunderstorms are expected across a broad region
from the Ohio Valley into the Mid-Atlantic and Northeast on Tuesday.
All severe hazards are possible, but swaths of damaging wind gusts
should be the primary severe risk Tuesday afternoon into the
nighttime hours.

...Ohio Valley to the Mid-Atlantic and Northeast...

An upper trough will be oriented over the region on Tuesday, with
several shortwave impulses migrating through the larger-scale
system. At the surface, low pressure will move across southern
Ontario into Quebec. A trailing cold front will move across much of
the Midwest through the period, becoming positioned from western PA
to TN and northern AR/OK by Wednesday morning. Ahead of the main
surface front, surface prefrontal troughing is expected to develop
across western/central NY into the Mid-Atlantic vicinity. Rich
boundary-layer moisture will overspread much of the area, with
dewpoints from the mid-60s to low 70s F commonplace. This will aid
in development of moderate to strong instability. 

Deep-layer flow will be strong for this time of year, with 40-60 kt
flow at 500 mb, and 30-50 kt in the 850-700 mb layer. Forecast
soundings indicate supercell wind profiles with favorably curved
low-level hodographs becoming elongated above 2-3 km across much of
the region. Convective evolution remains a bit uncertain, but a mix
of supercells and one or more bowing linear segments are expected
across the Ohio Valley into the Mid-Atlantic. Significant severe (2+
inch hail, 65+ kt winds, etc) potential is unclear, and will largely
depend on storm mode and mesoscale evolution of convection.
Temperatures aloft are relatively warm, around -5 to -7 C at 500 mb,
and this may inhibit sig hail potential. Meanwhile, 65+ kt gusts
could occur if a well-organized bowing structure and stronger cold
pool can develop. Given warm/moist low-levels and limited low-level
lapse rates, confidence in this scenario is low. As a result, the
CIG 1 area from the prior Day 3 outlook has been removed for now.
Where supercells can be maintained, a risk for a few tornadoes also
is possible. 

While details regarding storm mode and evolution remain somewhat
uncertain, the overall environment will support a severe risk across
a broad region on Tuesday/Tuesday evening. Swaths of damaging winds
still appear to be the greatest risk, though all hazards are
possible.

..Leitman.. 07/20/2026

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0221 AM CDT Mon Jul 20 2026

Valid 221200Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
NORTH CAROLINA INTO SOUTHEAST VIRGINIA...

...SUMMARY...
Isolated strong to severe thunderstorms will pose a risk for
damaging wind gusts across parts of southeast Virginia and North
Carolina.

...Mid-Atlantic to New England...

Several shortwave impulses will migrate through persistent upper
troughing over the East on Wednesday. At the surface, low pressure
will lift northeast across Quebec. A trailing cold front will move
east/southeast across portions of the region, become positioned from
the Mid-Atlantic coast into central NC by Thursday morning.
Southerly low-level flow ahead of the front will maintain a
seasonally moist airmass. Moderate destabilization is expected
across parts of the Mid-Atlantic into NC where boundary-layer
moisture is greater and stronger heating may occur. Weak instability
will be located over New England. Around 30-40 kt southwesterly flow
from 850-500 mb will provide sufficient vertical shear for some
organized cells/clusters. Isolated strong to severe storms producing
damaging winds are expected across portions of the Mid-Atlantic into
New England, with the greatest risk across parts of VA/NC and
vicinity.

..Leitman.. 07/20/2026