SPC May 11, 2025 1630 UTC Day 1 Convective Outlook

SPC 1630Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1119 AM CDT Sun May 11 2025

Valid 111630Z - 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 from 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...
Strengthening southwesterly flow aloft is anticipated throughout the
day as the upper low off the Pacific Northwest coast progresses
eastward and a lead shortwave trough pivots through OR/northern CA
into the northern Rockies. Strong heating will help destabilize the
airmass downstream from the northern Rockies into the northern High
Plains. Large-scale ascent attendant to the approaching shortwave
trough, coupled with orographic lift, will help initiate storms 
across the high terrain during the afternoon within this
destabilized airmass. 

Environmental conditions suggest some supercells are possible with
this initial development, with damaging gusts and isolated hail as
the primary risk. A low-probability corridor of tornado potential
exists across southeast ID. The storms should encounter an
increasingly mixed environment with eastern/northeastern extent into
central MT, with strong gusts becoming the primary severe hazard as
storms trend towards more outflow-dominant linear structures.

...Southeast States...
Recent satellite imagery and surface observations continue to show
the vertically stacked low over the Lower MS Valley, with broad
swath of southwesterly flow extending south and east of this low
from the central Gulf into FL. Surface features have become
increasingly diffuse across the Southeast and FL over the past two
days given the persistence of this low and associated precipitation,
but recent surface analysis shows a weak and wavy stationary
boundary extending from the low over the ArkLaMiss southeastward to
the AL/FL Panhandle border before arcing back northeastward across
southern GA. 

Scattered thunderstorms are ongoing and the general expectation is
for scattered to numerous thunderstorms to persist across much of
the region throughout the day. Widespread cloudiness should limit
heating, but ample low-level moisture will still support modest
buoyancy. Shear will gradually increase as the low to mid-level flow
strengthens this afternoon and evening, which could lead to some
transient storm organization, but in general convection is expected
to be disorganized, outflow-dominated multicells. Even so, isolated
damaging gusts are possible. Some low-probability tornado potential
exists as well, particularly along the stationary boundary across
southern GA around 00Z.

Farther northwest across AL/MS and into eastern AR, the airmass is
forecast to destabilize this afternoon as heating occurs beneath
cool temperatures aloft. Even with the cooler temperature aloft,
overall buoyancy will be modest given the somewhat cool low to
mid-level thermodynamic profile. Even so, a nearly unidirectional
southeasterly wind profile with moderate deep-layer speed shear
could support brief updraft organization. As a result, a few cells
may briefly produce marginally severe hail and locally strong gusts,
and possibly some funnel/brief tornado potential, from late
afternoon through early/mid-evening.

..Mosier/Wendt.. 05/11/2025

StormPrep