Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0245 PM CDT Fri Jul 11 2025
Valid 112000Z - 121200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM FAR
NORTHEAST MO AND SOUTHEAST IA INTO NORTHWEST IL...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL
AND SOUTHERN HIGH PLAINS...
...SUMMARY...
Severe thunderstorms are expected this afternoon and evening across
the Midwest to southern portions of the Great Lakes region,
accompanied by a risk for damaging wind gusts, hail, as well as some
tornado potential. Severe thunderstorms are also expected across the
central/southern High Plains and Upper Midwest.
...20Z Update...
Minor modifications were made to the ongoing forecast based on
current observations and expected convective evolution. Please see
the previous forecast for additional forecast details.
..Wendt.. 07/11/2025
.PREV DISCUSSION... /ISSUED 1131 AM CDT Fri Jul 11 2025/
...Lower MO and Mid MS Valleys into Great Lakes...
Recent surface analysis places a low over far southeast NE. Residual
cloudiness and showers northeast of this low are helping to
reinforce a warm-front-like baroclinic zone that extends from low
eastward along the IA/MO border through central IL and IN. This
boundary will likely sharpen throughout the day as the cloudiness
and showers persist to its north and temperatures warm into 90s to
its south. As a result, a reservoir of strong buoyancy is
anticipated south of this boundary from southern IA into
northern/central MO and western IL.
Lift associated with the surface low, as well as its parent
convectively augmented shortwave trough, will interact with this
destabilized and buoyant airmass to support thunderstorm development
by the early afternoon. Moderate vertical shear will be in place
throughout the base of the shortwave, helping to organize some of
these storms. However, the corridor of strongest shear is relatively
narrow, with the broader environment characterized by weak mid-level
flow and limited vertical shear. As such, a somewhat messy
convection evolution appears probable.
Initial development is expected over southern IA during the early
afternoon. This activity will likely be elevated just north of the
warm front. Additional warm sector development is also possible
farther east across west-central/northwest IL. This initial
development could be more cellular, with both hail and damaging
gusts as primary risks. However, given the presence of a surface low
as well as the warm front, some tornado risk is possible with these
initially more cellular storms as well.
Convective coverage is expected to increase with overall evolution
towards a more linear mode anticipated with time. Damaging wind
gusts should become the more predominant potential hazard as this
occurs with the line moving east/southeastward this evening. Threat
for brief embedded tornadoes exists within this evolving convective
line as well.
...Central High Plains...
The immediate post-frontal regime should be favorable for severe
storm development this afternoon into evening across southeast WY
and northeast CO into adjacent southwest NE/northwest KS. Some
initial supercells capable of large hail can be expected, and one or
more eastward-moving clusters may evolve by evening with
severe-caliber winds also a possibility.
...Southern High Plains...
Moderate low-level moisture (i.e. dewpoints in the upper 50 to low
60s) is currently in place across eastern NM, which will help offset
some of the mixing anticipated as the airmass heats into the 90s
this afternoon. Thunderstorm development is anticipated across the
higher terrain of central/northern NM and the Raton Mesa, with these
storms then progressing eastward/southeastward into the moderately
moist, deeply mixed, and unstable airmass downstream across the
southern High Plains. Numerous thunderstorms are expected, with the
higher storm coverage likely facilitating cold pool amalgamation and
the development of one or more forward-propagating convective
clusters. Strong wind gusts would be possible within these clusters,
with severe coverage expected to be high enough to merit introducing
15% wind probabilities.
...Upper Midwest...
At least isolated strong to severe thunderstorms can be expected
within a narrow corridor near the east/southeastward-moving front
this afternoon from north-central MN southwestward into eastern SD,
This will be influenced by the amplifying upper-level trough
approaching the Dakotas/northern MN. The strongest winds
aloft/vertical shear will tend to lag the front, but ample
near/pre-frontal buoyancy will support storms capable of hail/wind.
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