ACUS01 KWNS 121243
SWODY1
SPC AC 121241

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0741 AM CDT Mon May 12 2025

Valid 121300Z - 131200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
MONTANA AND NORTHWEST NORTH DAKOTA...

...SUMMARY...
Isolated severe thunderstorms are possible across parts of the
Southeast today, where a tornado or two, localized damaging winds,
and hail could occur. Isolated severe wind gusts are also possible
in northeast Montana to northwest North Dakota around early evening.

...Southeast States...
The persistent vertically stacked mid/upper low that has been nearly
stationary over the Sabine Valley/Lower Mississippi River Valley
will finally accelerate northeastward towards western Tennessee
through tonight. A jetlet of cyclonically curved mid-level
southerlies over the northeast Gulf and Florida Panhandle will
dampen somewhat as it becomes centered on north Florida to southeast
Georgia vicinity this afternoon. More probable diurnal thunderstorm
development is anticipated from the left-exit region of this jetlet
westward towards the cold-core of the stacked low.

Deep-layer vertical shear will relax with westward extent, yielding
more of a pulse strong-storm environment from Middle Tennessee to
western Alabama and Mississippi. Despite the meridional deep-layer
wind profile, effective shear should be sufficient for multicell
clusters and transient updraft rotation centered on eastern Alabama
and Georgia into north Florida. Pockets of modest buoyancy should
support a mix of small to marginally severe hail and strong gusts
capable of isolated damaging winds. Along the eastern periphery of
this activity, a tornado or two is possible where there remains some
overlap with the western belt of enhanced low-level flow, including
South Carolina into both western and near-coastal North Carolina.

Farther south, a more nebulous convective scenario is anticipated
amid extensive ongoing convection across the Florida Peninsula and
Keys. Guidance differs markedly with the degree of destabilization,
as adequate boundary-layer heating will be required amid poor
mid-level lapse rates near 5 C/km. But some guidance suggests south-central/southern Florida has the best chance at recovery by
afternoon, although low-level winds will tend to be veering with a
likely diminishing trend of low-level SRH.

...Northeast Montana/northwest North Dakota...
Another day of rather deeply mixed thermodynamic profiles is
expected across the region. Isolated thunderstorms are most probable
from mid-afternoon into evening with development near/behind an eastward-advancing front. Overall convective coverage off the higher
terrain of southern Montana should be substantially less than in
recent days, amid deep-layer southwesterly wind profiles. The
potential will exist for a few dry microbursts producing localized severe-caliber wind gusts.

..Guyer/Dean.. 05/12/2025

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ACUS01 KWNS 131252
SWODY1
SPC AC 131250

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0750 AM CDT Tue May 13 2025

Valid 131300Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE MID-ATLANTIC...NORTHERN GREAT PLAINS...AND DEEP SOUTH...

...SUMMARY...
Isolated severe thunderstorms are possible: 1) today in vicinity of Virginia-North Carolina-West Virginia, 2) during the late afternoon
to mid-evening over a portion of the Deep South, and 3) this evening
into early morning Wednesday in parts of the northern Great Plains.

...NC/VA/WV vicinity...
The upper-level low centered near the mid-Mississippi Valley will
continue to lift east/northeast through tonight, as a notable
shortwave trough rotates northeast across the Mid-Atlantic region.
Generally weak surface-based instability (MLCAPE at or below 1000
J/kg) will exist across the coastal plain as a belt of stronger 850
mb flow lifts northeast across eastern sections of NC/VA. This will
contribute to enlarged low-level hodograph structures and support
the continued potential for transient areas of rotation and a few
short-lived tornadoes associated with stronger convective elements.
See recently issued Mesoscale Discussion 774 for details on
short-term convective trends.

Farther west into WV/western VA and NC, subtle large-scale forcing
for ascent with the approaching upper low will contribute to
thunderstorm development. Although deep-layer shear will tend to
relax with westward extent, slightly more favorable mid-level lapse
rates and 1000-locally 1500 J/kg MLCAPE will result in the potential
for isolated strong/severe gusts and hail.

...AL/MS/TN vicinity...
Some hi-res guidance continues to suggest a supercell or two may
develop to the west of the departing mid-level trough, where a
corridor of differential boundary-layer heating may support a
favored zone for late afternoon through mid-evening storm
development. Some veering of the wind profile should yield modest
hodograph curvature. This, coupled with moderate mid-level
west-northwesterly flow, will favor a conditional supercell threat.

...Northern Great Plains...
An upstream upper-level trough over the western U.S. will move
steadily east, resulting in strengthening southerly mid-level flow
across the northern Plains. A Pacific cold front will make modest
eastward progress today before becoming quasi-stationary across the western/central Dakotas, however the stronger mid-level flow will
remain generally displaced to the west. Weak elevated buoyancy and
sufficient deep-layer shear may still result in scattered storms,
including supercells, with potential for severe hail. Some risk for strong/severe gusts may also exist with storms closer to the surface front.

..Bunting/Dean.. 05/13/2025

$$
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