Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1259 AM CDT Tue Jul 21 2026

Valid 211200Z - 221200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE UPPER OHIO VALLEY INTO THE MID-ATLANTIC...

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

...Ohio Valley into the Mid-Atlantic...
A broad area of 40-50-kt midlevel west-southwesterly flow will
overspread the OH Valley into the Mid-Atlantic as a large-scale
trough shifts across the northeastern CONUS. Scattered to numerous
thunderstorms are expected to develop ahead of an eastward-moving
cold front across the OH Valley and along a pre-frontal trough over
the Mid-Atlantic. In the base of the trough, a convectively
augmented midlevel impulse moving from the lower OH Valley into the
Mid-Atlantic may also serve as a focus for convective development. 

Diurnal heating within cloud breaks, combined with upper 60s to
lower 70s dewpoints, will support moderate surface-based instability
across the broad pre-frontal warm sector. The most favorable overlap
of this instability and 40-50 kt of effective shear is expected from
the lower OH Valley into the Mid-Atlantic, where a mix of organized
clusters and supercells should evolve and spread eastward through
the day. Swaths of damaging wind gusts will be the primary severe
hazard, though severe hail will also be possible with any sustained
supercells. Additionally, a gradually strengthening and expanding
30-kt low-level jet will contribute to clockwise-curved low-level
hodographs, and a few tornadoes may occur.

...Mid-South into the Tennessee Valley...
Greater instability is expected southwestward into portions of the
Mid-South and TN Valley, although somewhat weaker deep-layer shear
(around 30-40 kt of effective shear) may temper storm organization 
compared to ares farther northeast. Nevertheless, widely scattered
thunderstorms capable of organizing into multicell clusters and
occasional supercell structures will pose a risk of damaging wind
gusts and isolated severe hail ahead of the cold front during the
afternoon and early evening hours.

...Northeast...
Increasing midlevel height falls/forcing for ascent preceding the
upper trough will support scattered thunderstorm development near an
effective warm front moving northward across portions of the
Northeast. While poor midlevel lapse rates and weaker instability
should limit the overall severe risk compared to areas farther
south, around 40 kt of effective shear will still support organized
storm structures. Damaging wind gusts will be the primary concern,
though isolated severe hail and a tornado or two will also be
possible.

..Weinman/Jirak.. 07/21/2026

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1215 AM CDT Tue Jul 21 2026

Valid 221200Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN MID-ATLANTIC...

...SUMMARY...
Isolated severe thunderstorms will pose a risk for damaging wind
gusts across parts of the southern Mid-Atlantic. Additional
thunderstorms are expected northward across New England, some of
which could produce locally strong wind gusts.

...Mid-Atlantic into New England...

Several shortwave impulses are forecast to move through large-scale
upper troughing across the Northeast on Wednesday. Relatively strong
deep-layer winds for mid/late July are forecast, characterized by
500 mb southerly flow around 45-60 kt, 35-55 kt at 700 mb, and 25-35
kt at 850 mb. At the surface, low pressure will lift northeast
across Quebec, with a surface trough extending southward into the
Mid-Atlantic. A cold front is forecast to be located from eastern NY
to the central Appalachians and the TN Valley Wednesday morning. The
northern extent of the front will be rather progressive as it moves
across New England and the northern Mid-Atlantic through the
afternoon and evening. The southern extent of the front will more
slowly sag south/southeast across VA/NC. Ahead of the front,
southerly low-level flow will maintain a seasonally moist airmass
beneath the moderately strong deep-layer wind fields. 

While the boundary layer will be moist, strong heating will be
limited due to cloud cover and poor lapse rates. This will limit
instability, especially with northward extent into New England.
Nevertheless, sufficient instability coupled with the stronger
deep-layer flow will support organized clusters capable of wind
damage. The greatest risk will be focused across the southern
Mid-Atlantic where instability will be greatest (1000-1500 J/kg
MLCAPE).

..Leitman.. 07/21/2026

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0126 AM CDT Tue Jul 21 2026

Valid 231200Z - 241200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorm potential appears low on Thursday. However,
locally gusty winds could occur with thunderstorms across the
central High Plains into the northern Rockies.

...Central High Plains...

Scattered thunderstorms are expected to develop over higher terrain
in the central Rockies during the afternoon. Easterly low-level flow
across the adjacent High Plains will transport modest boundary layer
moisture westward across western KS and eastern CO. Meanwhile, a
weak surface boundary may develop south across the central High
Plains as convection moves off higher terrain into the High Plains.
Forecast soundings indicate generally weak midlevel lapse rates, but
steep low-level lapse rates within modest instability (MLCAPE up to
1000 J/kg). This could support gusty outflow winds with storms
across the Plains. However, effective shear values in the 20-25 kt
range and very weak flow below 500 mb suggests organized severe
convection is unlikely amid the weakly unstable airmass. 

...Northern Rockies...

Some enhancement to upper flow is forecast as a shortwave upper
trough moves across Alberta and Saskatchewan, and an upper low
persists off the Pacific Northwest coast. Forecast soundings show a
deeply-mixed boundary layer with steep 0-3 km lapse rates. Steep
midlevel lapse rates will be sufficient for weak destabilization,
and isolated thunderstorms are expected during the
afternoon/evening. Given weak vertical shear and limited
instability, organized severe potential is low, though gusty outflow
winds could occur.

..Leitman.. 07/21/2026