SPC May 13, 2025 1630 UTC Day 1 Convective Outlook

SPC 1630Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1122 AM CDT Tue May 13 2025

Valid 131630Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTH CAROLINA INTO THE SOUTHERN MID-ATLANTIC...CENTRAL GULF COAST
STATES...AND NORTHERN PLAINS...

...SUMMARY...
Isolated strong to severe thunderstorms appear possible today and
tonight across parts of North Carolina into the southern
Mid-Atlantic, central Gulf Coast states, and northern Plains.

...North Carolina into the Southern Mid-Atlantic...
A closed mid/upper-level low will continue to slowly meander from
the TN Valley towards the central Appalachians through the period.
An embedded mid-level shortwave trough will rotate northward across
the Carolinas into the southern Mid-Atlantic by this evening.
Stronger low/mid-level flow will tend to remain across the eastern
Carolinas into southern VA today, with generally weaker winds aloft
in closer proximity to the mid/upper low. A moist low-level airmass
will remain in place over much of the Carolinas, central
Appalachians, and southern Mid-Atlantic. But, poor mid-level lapse
rates will tend to limit any more than weak instability from
developing through this afternoon. Deep-layer shear away from the
coast will also tend to remain muted, which should keep overall
thunderstorm organization modest. Even with these forecast
thermodynamic and kinematic limitations, some organization may occur
with thunderstorms that develop and spread northward this afternoon.
Isolated damaging winds appear to be the main threat with any
loosely organized clusters that can form, but marginally severe hail
could also occur with the strongest cores. A tornado or two also
appears possible along a pseudo-warm front across northeast NC into
southeast VA and vicinity, where low-level flow and shear are
forecast to be modestly enhanced compared to locations farther west.

...Mississippi/Alabama...
Morning showers and related cloudiness will temper diurnal
destabilization to some extent across northern MS/AL this afternoon.
But, renewed thunderstorm development still appears possible later
today across this region, on the southern fringe of the slowly
moving mid/upper low. Weak low-level westerly winds are expected to
veer to northwesterly and gradually strengthen with height though
mid levels. Related 30-40 kt of deep-layer shear will conditionally
support organized updrafts, including the potential for a supercell
with an associated hail/wind threat. The overall severe risk should
remain quite isolated, which warrants maintaining the Marginal Risk
with this update.

...Northern Plains...
An amplified mid/upper-level trough will move eastward over the
western states through tonight. A surface cold front is forecast to
decelerate and eventually stall over parts of the Dakotas by this
evening. Stronger mid/upper-level flow is expected to remain
displaced to the west of this surface boundary. Even so, there are
some indications in guidance that elevated thunderstorms posing a
threat for isolated hail may impact parts of the northern Plains
this evening into tonight. Weak instability should tend to limit the
overall severe threat.

..Gleason/Wendt.. 05/13/2025

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