SPC Jun 12, 2025 1630 UTC Day 1 Convective Outlook

SPC 1630Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1151 AM CDT Thu Jun 12 2025

Valid 121630Z - 131200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTH-CENTRAL PLAINS...

...SUMMARY...
Scattered areas of severe thunderstorm development are possible
today into tonight, accompanied by potential for severe hail and
wind across parts of the Great Plains, the Upper Midwest, the Texas
coastal plain into the Lower Mississippi Valley, as well as a
portion of the northern Mid-Atlantic.

...North-central Plains including Nebraska/South Dakota...
A low-amplitude shortwave trough and associated speed max will
progress eastward over the northern High Plains, from southeast
Montana/northeast Wyoming toward the Dakotas. Related forcing for
ascent and a moderate belt of mid-level westerlies will overlie a
wavy frontal zone across southern South Dakota and western Nebraska.
At least widely scattered thunderstorms are expected into mid/late
afternoon, with moderate buoyancy and 35-45 kt effective shear
(especially northern Nebraska northward) supportive of supercells.
Large hail and severe-caliber wind gusts are the primary hazards.

...South/East Texas to Lower Mississippi Valley/Mid-South...
An extensive MCS and prominent outflow remain primary forecast
factors today, with outflow now having progressed off the
middle/upper Texas coast. An enhanced low/mid-level wind field on
the eastern periphery of the convectively augmented upper low will
continue to contribute to some supercell/tornado risk within a moist
environment, although cloud cover and thermodynamic limitations may
persist. Damaging winds may also occur on a sporadic/relatively
limited basis regionally.

...Southeast/southern Appalachians...
Strong heating is expected today across parts of Georgia into the
Carolinas, where temperatures in the upper 80s F and dewpoints near
70F are forecast. This will lead to widespread moderate CAPE values
and the development of scattered afternoon thunderstorms. Vertical
shear is weak, but a few weakly organized thunderstorm clusters may
reach severe intensity with gusty/damaging winds.

...Northern Mid-Atlantic/Northeast...
With full insolation, moderate destabilization will steadily develop
this afternoon near/south of a southward-moving front. While
ingredients are severe-storm supportive, the extent of deep
convective development may be limited by modest overall
forcing/low-level convergence, but at least isolated damaging
winds/hail will be possible where storms do develop. Favorable
deep-layer shear (40+ kt effective) is conditionally supportive of
well-organized storms including supercells. In a relative sense,
severe storm development currently appears most probable across
eastern Pennsylvania, northern New Jersey, and potentially toward
the Great NYC Metro vicinity/far southeast New York.

..Guyer/Thornton.. 06/12/2025

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