SPC Apr 12, 2025 0730 UTC Day 3 Severe Thunderstorm Outlook

SPC 0730Z Day 3 Outlook

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0221 AM CDT Sat Apr 12 2025

Valid 141200Z - 151200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE UPPER OH
VALLEY AND CENTRAL APPALACHIANS...

...SUMMARY...
Scattered severe thunderstorms are possible on Monday afternoon and
evening across parts of the Upper Ohio Valley and central
Appalachians.

...Synopsis...
A shortwave trough will further amplify over the Upper Great Lakes
eastward towards the Ottawa Valley through early Tuesday. In its
wake, a separate shortwave impulse and attendant mid-level jetlet
will dive southeast across the northern Great Plains towards the
Lower OH Valley. This will yield a broadening upper trough from the
north-central into the eastern CONUS. At the surface, the lead wave
will foster a near 990-mb cyclone tracking from Lake Superior to the
ON/QC border. A cold front will arc south across the Lower Great
Lakes and then southwestward through the Mid-South by late Monday. 

...OH Valley to the Mid-Atlantic States...
A high shear-low CAPE setup is anticipated on Monday afternoon and
evening, despite the presence of an expanding EML across the region.
Poleward moisture quality beneath the EML should remain sub-optimal,
but will be improved relative to prior days. The drier spectrum of
guidance appears more reasonable with mid to perhaps upper 50s
surface dew points advecting as far northeast as the Upper OH
Valley, ahead of the surface cold front. 

Guidance is reasonably consistent that at least isolated
thunderstorms should develop in early to mid-afternoon across the
Central OH Valley vicinity as mid-level height falls overspread the
confined but destabilizing warm/moist sector. With already strong
700-500 mb southwesterlies strengthening further, fast-moving/highly
sheared convection is anticipated. Despite veered surface winds,
low-level hodograph curvature should be moderately enlarged. This
setup may yield a few supercells that consolidate into a cluster
spreading east across the central Appalachians. A couple tornadoes
and damaging winds appear to be the primary hazards. East of the
higher terrain, remnant steep low-level lapse rates may support a
threat for isolated damaging gusts given the strong wind fields,
before convection becomes increasingly elevated Monday night.

..Grams.. 04/12/2025

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