ACUS02 KWNS 130537
SWODY2
SPC AC 130536

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1236 AM CDT Tue May 13 2025

Valid 141200Z - 151200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL TO NORTHERN PLAINS...

...SUMMARY...
Scattered strong to severe thunderstorms are possible mainly over
parts of the Dakotas and Nebraska Wednesday afternoon and evening.
A more isolated severe threat is anticipated across parts of the
Southeast and Mid-Atlantic Wednesday afternoon.

...Synopsis...
An upper trough evident in water-vapor imagery over the Pacific
Northwest is forecast to pivot into the central and northern Plains
over the next 48 hours. As this occurs, strong to severe
thunderstorms are expected to develop ahead of the wave and within a
narrow warm sector in place across parts of the central to northern
Plains. Across the Southeast and Mid-Atlantic, a weakening
upper-level low will continue to de-amplify as it meanders to the
northeast. Residual 25-35 knot mid-level flow will likely contribute
to some storm organization as convection develops within a moist and
weakly capped environment.

...Central to Northern Plains...
Continued deepening of a surface trough is anticipated through the
next 48 hours across the northern Plains. This will maintain a
southeasterly flow regime across the Plains with modest moisture
return anticipated within a narrow plume from NE into the Dakotas by
Wednesday afternoon. A Pacific cold front, evident in late-evening
surface observations across the Intermountain West, is forecast to
progress east and impinge on the narrow warm sector by late
afternoon/early evening. Storm motions and deep-layer shear vectors
largely parallel to the front will favor relatively quick upscale
growth into clusters/linear segments. Although shear will initially
be modest, the high-based nature of the storms should promote a
strong/severe wind threat. With time, strengthening mid to
upper-level flow will elongate hodographs and may support an
increasing hail threat into the evening hours as convection develops
southward along the front. Some guidance hints at a second round of
convection late evening into the overnight hours across southeast SD
into NE as the primary vorticity maximum ejects into the Plains and
promotes additional thunderstorm development along the advancing cold front.

...Carolinas to Mid-Atlantic...
A moist air mass will remain in place across the Southeast and
Mid-Atlantic through the next 48 hours in the absence of any
synoptic fronts or influential gradient winds. Rich moisture through
the lowest 100-200 mb will maintain weak capping and support
diurnally driven convection by late afternoon as surface
temperatures warm into the mid 70s under broken cloud cover. Similar
to previous days, which have produced isolated damaging winds, weak
low-level winds under 25-35 knot mid-level flow will promote
transient storm organization. While a similar
thermodynamic/kinematic environment will be in place across much of
the Southeast on Wednesday, latest CAM guidance suggests the best
severe potential resides across portions of the Carolinas into the
DelMarVa region where thunderstorm coverage should be greatest ahead
of the mid-level vorticity maximum.

..Moore.. 05/13/2025

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