SPC May 15, 2025 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0752 AM CDT Thu May 15 2025

Valid 151300Z - 161200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS
EAST-CENTRAL MINNESOTA...MUCH OF WISCONSIN...SOUTHERN AND WESTERN
LOWER MICHIGAN...NORTHEAST ILLINOIS...NORTHERN INDIANA AND NORTHWEST
OHIO...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
VIRGINIA AND NORTHEAST NORTH CAROLINA...

...SUMMARY...
Severe thunderstorms are expected across parts of the upper
Mississippi River Valley and Great Lakes this afternoon and evening.
Tornadoes, some of which could be strong, and very large hail and
damaging winds will be possible. Severe thunderstorms are also
expected through the lower Ohio River Valley, Ozarks and in parts of
the Mid-Atlantic.

...Mid to Upper Mississippi Valley/Great Lakes/Ohio Valley...
A deepening surface low will gradually consolidate as it moves north
across the eastern Dakotas today, and a warm front will lift north
through the OH Valley and into WI/Lower MI late this afternoon. As
strong large-scale ascent develops in association with a
northeast-moving/negatively-tilted upper trough and left exit region
of a 300-mb jet streak, rapid thunderstorm development, or
re-intensification of ongoing storms, is expected from near the
surface low east/southeast along an arcing occluded/cold front over
central MN/western WI/northeast IL. A broken line of semi-discrete
cells is anticipated within a strongly unstable and amply-sheared
environment supporting supercell storm structures. Large hail,
possibly very large and in excess of 2.5 inches in diameter, will be
possible in addition to damaging wind gusts. Low-level shear will
support the potential for tornadoes with mature supercells, and the
risk for strong tornadoes will exist, especially towards evening as
low-level shear increases. Storms should tend to merge into clusters
or line segments with time, especially across southern lower
MI/northern IN/OH, where significant severe wind potential will
exist with an eastward moving complex of storms. The 30% wind/sig
severe wind area was extended east into southeast lower MI based on
latest hi-res guidance.

...Ozarks...
Thunderstorms have developed along the Red River in southeast
OK/western AR this morning, along the southern periphery of stronger
mid-level flow and with moderate elevated buoyancy. Although
larger-scale forcing remains nebulous, these storms may continue to
intensify and become surface based with time with the onset of
diurnal destabilization. Strong southwesterly flow will contribute
to ample deep-layer shear for supercells or a small cluster. Severe
hail and perhaps wind will be the primary severe hazards as storms
move across AR towards the mid-Mississippi Valley, and the Slight
(Level 2) Risk has been extended southwest across northern AR for
this potential.  

...Central Appalachians/Mid-Atlantic...
Scattered thunderstorms are expected to develop in response to
diurnal heating and across the higher terrain this afternoon, and
move southeast within an environment of moderate/locally strong
surface-based instability and 35-40 kts of northwesterly deep shear.
In this parameter space, supercell structures and clusters will be
possible and pose a risk for large hail and damaging winds.  Trends
in the 00z HREF and early morning hi-res guidance were the basis for
extending the Slight (Level 2) Risk southeast across portions of
northeast NC.

..Bunting/Dean.. 05/15/2025

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