Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Mon Aug 03 2026
Valid 032000Z - 041200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS INTO THE UPPER MIDWEST...AND SOUTHERN ARIZONA...
...SUMMARY...
Scattered severe thunderstorms are possible today into tonight
across parts of the eastern Dakotas into northern Minnesota, as well
as across portions of southern Arizona.
...20Z Update...
The MRGL Risk in the Northeast was trimmed behind an eastward-moving
band of frontal convection. This activity will continue to pose a
risk of damaging wind gusts and possibly a brief tornado this
afternoon, before moving into an increasingly stable air mass
sampled by the CAR 18Z sounding and/or moving off the southern New
England Coast.
Farther west, the latest surface analysis depicts a surface low at
the intersection of a cold front and lee trough in far northeast CO.
Current thinking is that high-based thunderstorms will develop in
the vicinity of this feature and spread east/northeastward into a
deeply mixed boundary layer in southwestern NE this evening -- where
a robust warm layer is present at the base of the EML (per LBF 18Z
sounding). There is some potential that this environment supports a
localized corridor of enhanced severe wind gusts (some upwards of 75
mph). However, the aforementioned capping and spatially limited
corridor casts uncertainty on the overall risk -- precluding an
upgrade at this time.
Elsewhere, the forecast remains on track and no changes were made
with this update.
..Weinman.. 08/03/2026
.PREV DISCUSSION... /ISSUED 1130 AM CDT Mon Aug 03 2026/
...Northern/Central Plains into the Upper Midwest...
Post-frontal thunderstorms occurring this morning across ND have
remained mostly sub-severe over the past couple of hours. A stout
low-level inversion noted on the observed 12Z INL sounding will
likely inhibit surface-based thunderstorms from developing until
late this afternoon or early evening across the eastern Dakotas into
northern MN. Still, gradual airmass destabilization is anticipated
across this region along/ahead of a cold front through the
afternoon. Large-scale ascent attendant to an ejecting mid-level
shortwave trough from MT into ND will eventually aid scattered
convective development along/near the front, most likely by 22-01Z.
Moderate instability coupled with strong deep-layer shear will
support some threat for supercells and large hail initially, before
upscale growth into clusters supports an increasing severe/damaging
wind threat with eastward extent into northern MN this evening. A
tornado or two may also occur as low-level shear gradually increases
in a narrow corridor ahead of the front this evening.
Isolated to widely scattered thunderstorm development is forecast
with southward extent into the central High Plains. A hot and very
well-mixed low-level airmass ahead of the front/surface trough
across this area may support occasional severe gusts with convective
outflow. But, weaker mid-level winds and related modest deep-layer
shear should result in only loosely organized clusters/cells. This
activity should weaken with the loss of daytime heating.
...Southwest...
Around 15-25 kt of east-northeasterly mid-level winds will persist
today across far southern AZ/NM, to the south of prominent upper
ridging that will remain anchored over the Southwest. Recent visible
satellite imagery shows mostly clear conditions across southeast AZ,
with latest surface observations showing ample low-level moisture
present (surface dewpoints generally in the low to mid 60s across
lower elevations). Ample heating of this moist airmass will support
moderate instability by mid afternoon. Current expectations are for
thunderstorms to initially develop over the higher terrain of
southeast AZ as convective temperatures are reached, and
subsequently spread west-southwestward into the lower deserts
through the evening. Some organization/clustering appears possible
with this activity, and the Slight Risk for severe wind gusts up to
60-75 mph has been maintained with no changes. Isolated hail may
also occur with the strongest cores that develop initially.
...Northeast/Northern Mid-Atlantic...
An upper trough with enhanced mid-level south-southwesterly flow
will advance eastward across the Northeast and northern Mid-Atlantic
today. A weak surface low should develop northward into southern
Quebec, with a trailing cold front advancing eastward across the
Northeast this afternoon/evening. Filtered daytime heating of a
seasonably very moist airmass (reference 12Z observed soundings from
OKX/ALB/GYX) will support modest MLCAPE up to 500 J/kg, even though
mid-level lapse rates remain quite poor. Thunderstorms developing
along and ahead of the cold front may pose an isolated threat for
damaging winds given the enhanced flow present at low/mid levels. A
brief tornado or two could also occur across parts of New England
where effective SRH may be locally greater in tandem with a
southerly low-level jet. Still, the overall poor thermodynamic
environment should limit a greater severe wind threat from
developing this afternoon.
Read more CHECK UPDATE ZOOM GRAPHIC
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