SPC May 13, 2025 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook

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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