ACUS01 KWNS 112000
SWODY1
SPC AC 111959

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Sun May 11 2025

Valid 112000Z - 121200Z

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

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

...20Z Update...
The only noteworthy change with this update was a southwestward
expansion of the Slight Risk area into northern UT, driven by
15-percent severe wind probabilities. Here, ample diurnal heating
has resulted in a deep/dry boundary layer supportive of scattered
severe wind gusts accompanying high-based storms. Reference Severe
Thunderstorm Watch #245 for more details. Farther east, isolated
severe storms capable of producing locally damaging winds and
marginally severe hail remain possible across the Southeast into
this evening. Reference MCDs #766/767 for details.

..Weinman.. 05/11/2025

.PREV DISCUSSION... /ISSUED 1119 AM CDT Sun May 11 2025/

...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.

$$
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