SPC May 11, 2025 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0754 AM CDT Sun May 11 2025

Valid 111300Z - 121200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN ROCKIES AND MONTANA HIGH PLAINS...

...SUMMARY...
Scattered severe wind gusts are expected across the northern Rockies
to Montana High Plains fom mid-afternoon into the evening. Isolated
severe thunderstorms are also possible across the Southeast today
through tonight.

...Northern Rockies/High Plains and northeast Great Basin...
The leading portion of an eastward-transitioning upper-level trough
will overspread the northern Rockies and northern Great Basin later
today and tonight, with preceding height falls and a regionally
strengthening 60-80 kt southwesterly mid-level jet. These trends in
conjunction with orographic influences/differential heating will
lead to another round of isolated to scattered thunderstorms by
mid/late afternoon.

Similar to Saturday, severe-caliber wind gusts will be the primary
hazard as storms develop in association with deeply mixed boundary
layers, especially with eastward extent from southeast Idaho to
central/eastern Montana. Corridors of modest buoyancy, coupled with
moderate to strong deep-layer southwesterly speed shear, could yield
a few high-based supercell structures producing small to marginally
severe hail. This should be focused from the Oregon/Washington/Idaho
border vicinity into central Montana, and separately over southeast
Idaho into Yellowstone.

...Southeast States...
A persistent, slow-moving, and essentially vertically stacked low
will persist, centered over the ArkLaMiss vicinity, with a preceding
belt of moderately strong mid-level winds extending over the
northeast Gulf to the coastal Southeast. This will overlie a
moderately moist warm sector to the east of the surface cyclone and
along/south of the eastward-extending stationary front (or
slow-moving warm front).

Scattered thunderstorms are ongoing regionally this morning,
including semi-extensively over the northeast Gulf. A 30-40 kt
southerly low-level jet is expected to sustain adequately enlarged
low-level hodographs within this corridor, but especially towards
the coast and near the warm front. But convection is expected to be
within a messy, outflow-dominated mode at times. Regardless,
isolated damaging wind and tornado potential is apparent. While the
severe risk does not appear as semi-focused as yesterday, portions
of far northern Florida to southern/southeast Georgia in vicinity of
the stationary/warm front will be reevaluated for a potential Slight
Risk upgrade.

Farther west in Alabama and Mississippi, despite somewhat cooler
mid-level temperatures closer to the upper cyclone, lapse rates
still appear modest. But deep-layer speed shear will be moderately
favorable amid a nearly unidirectional southeasterly wind profile. A
few cells may briefly produce marginally severe hail and locally
strong gusts, and possibly some funnel/brief tornado potential,
mainly from late afternoon through early/mid-evening.

..Guyer/Dean.. 05/11/2025

Read more