Day 1 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0312 PM CDT Tue Aug 12 2025
Valid 122000Z - 131200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
GREAT LAKES REGION...
CORRECTED FOR NDFD
...SUMMARY...
Strong to locally severe thunderstorms are possible over parts of
the Great Lakes/Midwest this afternoon with both damaging winds and
hail possible.
...20Z Update...
Given the weak mid/upper-level flow, the potential for organized
severe wind gusts appears very limited in southeast
Arizona/southwest New Mexico. Steep low-level lapse rates may still
support strong/gusty outflow however. Elsewhere only minor update
the general thunderstorm area were made. See the previous discussion
for additional details.
..Wendt.. 08/12/2025
.PREV DISCUSSION... /ISSUED 1128 AM CDT Tue Aug 12 2025/
...Great Lakes/Midwest...
Midday satellite/radar composite show a weakened thunderstorm band
moving east-northeast across the eastern part of Lower MI. Surface
analysis indicates rain-cooled air north of a gust front/outflow
that has become draped from southeast Lower MI into the Michiana
region. Heating south of this boundary has resulted in temperatures
warming through the mid-upper 80s with dewpoints in the lower 70s.
Additional storms will probably develop along the trailing outflow
and gradually move east-northeast with the mean wind. Considerably
weaker deep-layer shear is present across the eastern part of the
Corn Belt into the Lower MI vicinity compared to farther north over
the U.P. of MI in closer proximity to a shortwave trough.
Nonetheless, scattered thunderstorms will gradually develop within a
moist/destabilizing airmass and pose a risk for isolated strong to
perhaps locally severe/damaging gusts this afternoon.
Farther north in WI into the U.P. of MI, a weak cold front will move
into the region later this afternoon. Model guidance shows widely
scattered storms developing as filtered sunshine leads to a
destabilizing boundary layer. A few stronger thunderstorms are
possible and could yield a localized risk for marginally severe hail
and damaging gusts during the mid afternoon to early evening period.
...Southeast AZ/southwest NM...
Strong heating should result in widely scattered thunderstorms
developing near terrain-favored areas. Weak shear will result in
disorganized storms, but the development of very steep surface to
500-mb lapse rates will promote strong evaporative cooling with the
more intense downdrafts. Isolated severe gusts are possible.
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