SPC Apr 29, 2025 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0737 AM CDT Tue Apr 29 2025

Valid 291300Z - 301200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
WEST TX INTO SOUTHWEST OK...AND FROM THE OH VALLEY INTO THE LOWER
GREAT LAKES...

...SUMMARY...
Scattered severe thunderstorms are possible within a broad swath
from the Lower Great Lakes to the southern High Plains, mainly
during this afternoon to evening. Corridors of greater threat are
expected over the Upper Ohio Valley/Lower Great Lakes and in parts
of west Texas into southwest Oklahoma.

...Synopsis...
Recent satellite imagery shows a well-defined shortwave trough
moving through northwest Ontario and the adjacent Upper Midwest, and
a mature cyclone centered over the central UT/AZ border. The
northern shortwave trough is forecast to move eastward across the
Great Lakes and eastern Canada today while also transitioning to a
more negative tilt. The UT/AZ cyclone is expected to progress
southeastward across AZ and into western NM as an embedded shortwave
trough moves through its base across northern Mexico and into the
southern High Plains.

Early morning surface analysis places a low over eastern Lake
Superior, with a cold front extending southwestward from this low
into central OK where another, weaker surface low exists. The front
continues westward from this second low across the TX Panhandle and
through central NM. The northern low is forecast to progress
eastward across eastern Canada, moving just ahead of its parent
shortwave trough, ending the period over the Canadian Maritimes. The
attendant cold front will also push eastward moving through the OH
and TN Valleys, and much of the Northeast. Southern/western portion
of the front will make limited southerly/southeasterly progress,
with its position becoming more regulated by repeated convective
outflow throughout the day.

Numerous thunderstorms, some severe, are anticipated along the
eastward progressing cold front from the OH Valley into the Lower
Great Lakes and Northeast, as well as farther southwest across the
southern Plains near the stalled boundary.

...Ohio Valley into the Lower Great Lakes...
Ongoing cluster across northeast OK will continue through the Ozarks
this morning before reaching the Lower OH Valley this afternoon. It
seems probable that this cluster will reintensify as it interacts
with the destabilizing airmass over the region. Additional
thunderstorm development appears likely along the front north of
this cluster throughout much of the OH Valley into the Lower Great
Lakes. 

Strong low/midlevel flow will support development of organized storm
clusters, along with some potential for discrete or embedded
supercells. Scattered damaging winds will be possible, with some
potential for swaths of more concentrated wind damage if any
organized linear segments develop. The strongest low-level flow will
be displaced north of the region, but 35-50 kt in the 850-700 mb
layer will support sufficient low-level shear for some supercell
and/or line-embedded tornado threat. Isolated hail could also
accompany any persistent supercell structures.  

...West TX into the Ozarks...
Complex convective evolution is underway across OK this morning as a
northeastward progressing convective cluster interacts with the
thunderstorms that developed along the front over
northwest/north-central OK. Current trends and recent guidance
suggest that an MCS will evolve and then track northeastward across
the Ozarks. The airmass downstream is expected to remain supportive
of damaging gusts and large hail for at least the next few hours.

Another round of thunderstorms is anticipated this afternoon both
along the outflow-modulated cold front in OK and northwest TX and
along the dryline in West TX as the airmass destabilizes. Strong
buoyancy and shear will support supercells, particularly from west
TX into southwest OK during the late afternoon where low-level
convergence will be strongest. Large to very large hail will be the
primary threat initially, but strong cold pools and close storm
proximity should result in several clusters capable of strong to
significant gusts. A mesoscale corridor of greater tornado potential
may materialize just east of the surface low where stronger
southeasterly low-level flow and higher low-level moisture may
overlap. Current guidance suggests this would be over northwest TX,
but uncertainty exists regarding the outflow/cold front and surface
low positions, precluding the confidence needed to outlook higher
tornado probabilities.

..Mosier/Jewell.. 04/29/2025

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