SPC AC 121234
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0734 AM CDT Sat Oct 12 2024
Valid 121300Z - 131200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe thunderstorms appear unlikely today and tonight.
...Synopsis and Discussion...
Within broad upper troughing over central/eastern Canada, an
embedded mid-level perturbation will gradually amplify as it moves
southeastward over the Upper Midwest and Great Lakes through the
period. At the surface, a weak low will gradually develop eastward
across the Midwest and eventually reach the northwest OH vicinity by
late tonight. An associated cold front will continue moving
southward across the central Plains and upper/mid MS Valley, while a
warm front extending eastward from the surface low remains across
northern IL/IN/OH through this evening.
Limited low-level moisture and weak large-scale forcing across the
warm sector suggest that surface-based thunderstorm potential should
remain low today across the Great Lakes/OH Valley region. However,
most guidance does show some elevated convection developing by late
afternoon/early evening across southern Lower MI and vicinity.
00/06Z NAM runs show much more instability present compared to most
other guidance, with a general consensus that around 500 J/kg of
MUCAPE may exist when convection initiates.
Even with strong shear in the cloud-bearing layer, the weak
instability forecast should tend to limit the threat for severe hail
with any thunderstorms that can form over Lower MI and subsequently
spread east-southeastward across northern IN/OH this evening and
overnight. Still, small hail may occur with the more robust cores.
Occasional gusty winds may also be able to reach the surface given
the forecast strength of the low/mid-level flow, presence of a
somewhat dry sub-cloud layer/weak DCAPE, and relatively shallow
near-surface stable layer.
..Gleason/Jewell.. 10/12/2024
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