Aug 23, 2026 1630 UTC Day 1 Convective Outlook
Updated: Sun Aug 23 16:35:32 UTC 2026 ( | | )
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
Probabilistic Tornado Graphic
Day 1 Tornado Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
Day 1 Wind Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
CIG1
318,297
4,245,690
Salt Lake City, UT...West Valley City, UT...Provo, UT...West Jordan, UT...Billings, MT...
15 %
102,962
2,526,000
Salt Lake City, UT...West Valley City, UT...West Jordan, UT...Billings, MT...Ogden, UT...
5 %
663,599
65,265,928
New York, NY...Phoenix, AZ...Jacksonville, FL...Tucson, AZ...New Orleans, LA...
Probabilistic Large Hail Graphic
Day 1 Hail Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
CIG1
70,681
437,445
Rapid City, SD...Bismarck, ND...North Platte, NE...Mandan, ND...Dickinson, ND...
15 %
62,615
374,438
Rapid City, SD...Great Falls, MT...Dickinson, ND...Pierre, SD...Rapid Valley, SD...
5 %
219,210
8,728,768
Buffalo, NY...Rochester, NY...Springfield, MA...Syracuse, NY...Erie, PA...
SPC AC 231635
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1135 AM CDT Sun Aug 23 2026
Valid 231630Z - 241200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN ROCKIES/PLAINS AND GREAT BASIN...
...SUMMARY...
Thunderstorms capable of producing large hail and severe wind gusts
are forecast across parts of the northern Rockies/Plains this
afternoon and evening. Other thunderstorms with mainly a severe
wind threat are probable over portions of the northern Great Basin.
...Great Basin into the Northern Rockies/High Plains...
Water-vapor imagery this morning shows an eastward-migrating
shortwave trough over the Pacific Northwest. A belt of 40-50 kt of
west-southwesterly mid-level flow will overspread the northern
Rockies and adjacent High Plains of central/eastern MT by this
afternoon. Heating along with ascent attendant to the disturbance
will favor initial storm development over the higher terrain over
southwest/western MT. Steepening lapse rates over the High Plains
will favor the potential for scattered severe gusts as thunderstorms
move/develop over the plains during the late afternoon and evening.
A mix of multicells and supercells may yield a risk for severe hail
early before upscale growth into linear clusters (60-80 mph gusts)
likely evolves during the evening.
A somewhat separate area of convection should develop this afternoon
across parts of the northern Great Basin and Upper Snake Valley.
While mid-level flow will be somewhat weaker across this region
compared to locations farther north, the presence of generally 50s
surface dewpoints across northern UT and vicinity suggests that
sufficient low-level moisture exists to support robust updrafts.
Very steep lapse rates will favor ample evaporative cooling in the
stronger downdrafts. Scattered severe gusts (60-80 mph) are
possible with the stronger thunderstorm cores and outflow.
...Northern/Central Plains...
Morning surface analysis places a moisture plume (lower to mid 60s
deg F dewpoints) extending from the TX-OK Panhandles
north-northwestward through eastern CO/NE Panhandle and into the
Black Hills vicinity. It is within this corridor moderate to strong
instability is forecast by mid-late afternoon along/east of a lee
surface trough. At least isolated thunderstorms should develop by
peak afternoon heating across these areas, with west-northwesterly
flow strengthening with height through mid/upper levels. Around
35-45 kt of deep-layer shear will support supercells and associated
threat for large hail from northeast CO northward into the western
Dakotas.
Farther south, high-based convection is forecast to slowly
spread/move east of the Raton Mesa into the TX-OK Panhandles during
the early evening. Very steep lapse rates and inverted-V profiles
will favor evaporative cooling and an isolated threat for severe
gusts with the stronger downdrafts and outflow surges.
...Northeast...
Midday satellite imagery shows an upper trough/low over Ontario with
a series of embedded shortwave impulses rotating through its base.
A lead disturbance over the Lower Great Lakes will continue to
rotate northeastward across the western portion of the Northeast and
influence scattered thunderstorm development this afternoon.
Heating of an adequately moist airmass but relatively meager
mid-level lapse rate environment will result in weak buoyancy
developing through mid afternoon as convection deepens. Around
30-35 kt of deep-layer shear will support some updraft organization
mainly in the form of bands of storms. An isolated risk for strong
to locally severe gusts is expected across much of this region this
afternoon. Towards early evening, an upstream impulse will approach
the Lake Erie vicinity with some uptick in storm coverage and
perhaps a lingering risk for wind damage before this activity
weakens by the mid evening.
...Southeast...
Isolated to scattered thunderstorms will likely develop along/south
of a weak front draped across the lower MS Valley into the Gulf
Coast states, and continuing northeastward into the Carolinas. An
isolated threat for strong to locally severe gusts may result in
pockets of wind damage with the more intense wet microbursts.
...Northeast Oklahoma/Southeast Kansas into the Ozarks...
Some modest increase in isentropic ascent associated with
a south-southwesterly low-level jet, may aid thunderstorm
development late tonight into early Monday morning across parts of
northeast OK/southeast KS into the Ozarks. Instability is forecast
to remain fairly weak (MUCAPE generally less than 1000 J/kg), but
some clustering may occur with a low chance for localized severe
gusts.
...Arizona...
On the western periphery of a mid-level anticyclone centered over
eastern NM, weak southeasterly mid-level flow will remain across
southern/central AZ. Model guidance only depicts weak buoyancy
across much of central and southern AZ, with the exception of
perhaps over far southern AZ. Nonetheless, hot temperatures and a
deeply mixed boundary layer lend some potential for a localized
microburst risk.
..Smith/Chalmers.. 08/23/2026
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