SPC Apr 13, 2025 Day 4-8 Severe Weather Outlook

Day 4-8 Outlook

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0351 AM CDT Sun Apr 13 2025

Valid 161200Z - 211200Z

...DISCUSSION...
An active severe weather pattern is expected late week into next
weekend.

...D5/Thursday...
Guidance has converged to a signal of severe-storm threat centered
on Thursday evening as a deep surface cyclone becomes established in
the KS vicinity, downstream of a longwave trough in the West. An
enriching low-level moisture plume will be advected nearly due north
from the western Gulf towards the Lower MO Valley. A stout EML
should limit convective development along much of the dryline. But a
strengthening low-level jet should support thunderstorm development
to the northeast of the surface low amid strong deep-layer shear.

...D6/Friday...
A rather broad swath of 50+ kt 500-mb southwesterlies appears likely
to become established from the southern High Plains to the Great
Lakes, downstream of a broad trough in the Southwest and a separate
northern-stream wave around northern ON. While the deep cyclone over
the KS vicinity will weaken, it should track towards the central
Great Lakes in response to the northern wave. Along its trailing
cold front, extensive thunderstorm development is anticipated Friday
afternoon/evening. Given the aforementioned strong mid-level flow
regime, a broad corridor of severe threat is warranted. 

...D7-8/Saturday-Sunday...
Predictability for a 15 percent highlight wanes somewhat next
weekend, but areas will probably be needed in later outlooks.
Saturday may consist of confined, bimodal threat areas across the
Lower Mid-Atlantic States and southern High/Great Plains. For the
former, the degree of instability and position of a southeast-moving
cold front on the periphery of a fast zonal flow regime are the main
uncertainty drivers. For the latter, timing of the pivot and
eastward ejection of the Lower CO Valley shortwave impulse into the
south-central states will be critical. Based on latest guidance, it
appears Sunday could have a broader corridor of severe potential.

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