Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0252 PM CDT Thu Jun 12 2025
Valid 122000Z - 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.
...20z Update...
The primary change for this update is to remove risk probabilities
across parts of eastern TX and western LA in the wake of a gradually
strengthening convective band/MCS where conditions have stabilized.
Low-end risk probabilities have been expanded slightly across south
TX to account for the southeastward propagation of a convective
cluster developing on the outflow of the prior MCS. Recent RAP
mesoanalysis estimates/forecast soundings suggest the downstream
convective environment may be supportive of organized convection
through early evening.
Elsewhere, the forecast largely remains on track with few
adjustments required. Convection developing within the upslope flow
regime across the central High Plains should increase in coverage
and intensity as ascent associated with a weak mid-level
perturbation (currently over northern UT) overspreads the region.
Across the Northern Mid-Atlantic/Northeast, temperatures have warmed
into the mid-80s, which should minimize inhibition based on forecast
soundings; however, satellite imagery continues to show meager
vertical development of cumulus along the frontal zone, which limits
confidence in convective initiation and the overall severe threat.
See the previous discussion (below) and MCD #1260 for additional
details.
..Moore.. 06/12/2025
.PREV DISCUSSION... /ISSUED 1151 AM CDT Thu Jun 12 2025/
...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.
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