SPC Dec 13, 2025 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0640 AM CST Sat Dec 13 2025

Valid 131300Z - 141200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today or tonight.

...Discussion...
Large-scale trough amplification will occur over the Midwest/East
through tonight, with expanding surface high pressure across the
Plains and Midwest in the wake of a cold front progressing
south-southeastward toward the Lower Mississippi Valley and Gulf
Coast by late tonight and early Sunday. Preceding the front, weak
warm/moist advection should allow for northeastward-expanding
thunderstorm development across southeast Texas and Louisiana today,
with potential persisting until the frontal passage tonight.

A low-latitude disturbance crossing the Gulf and a northward
moisture flux ahead of it will contribute to thunderstorm potential
across the Florida Keys/Florida Straits today, and also across the
southern Florida Peninsula tonight. Severe thunderstorms are
unlikely with these scenarios.

..Guyer/Lyons.. 12/13/2025


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SPC Dec 13, 2025 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1137 PM CST Fri Dec 12 2025

Valid 131200Z - 141200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Isolated weak thunderstorm activity is possible across portions of
the Texas and Louisiana coasts, as well as South Florida and the
Keys this afternoon into Saturday night.

...Discussion...

Strong midlevel height falls will spread across the Ohio
Valley/Middle Atlantic during the day1 period as a pronounced upper
trough digs across the Great Lakes/OH Valley. This evolution
warrants surface pressures rising across the interior CONUS east of
the Rockies, ultimately forcing a cold front toward the upper TX/LA
Coast by the end of the period. Prior to the frontal passage, weak
low-level warm advection will aid some convective threat due in part
to the influence of a low-amplitude short-wave trough that will
eject across the western Gulf basin. Otherwise, lightning may
accompany frontal convection as the wind shift surges into this
region. In addition to isolated thunderstorms across the upper
TX/LA Coasts, moisture/buoyancy is expected to gradually advance
north across the FL Keys into the southern FL Peninsula. Weak
disturbance should encourage isolated thunderstorm development
across this region as well. In both scenarios, severe threat appears
negligible.

..Darrow/Wendt.. 12/13/2025


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SPC Dec 13, 2025 0100 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 0100Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0625 PM CST Fri Dec 12 2025

Valid 130100Z - 131200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Isolated thunderstorms are possible in the vicinity of the Lower
Texas Coast later tonight.

...01z Update...

Low-amplitude short-wave trough is embedded within the southern
stream over deep South TX. This feature is shearing east toward the
northwestern Gulf basin where it is expected to encourage isolated
thunderstorm development, primarily off the south TX Coast later
tonight. 00z sounding from BRO was notably capped with strong
inhibition around 2km. Latest model guidance suggests inhibition
will gradually weaken which may allow isolated offshore convection
to gradually approach the coast later tonight. Even so, this
activity should remain weak with the greater concentration holding
offshore.

..Darrow.. 12/13/2025


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SPC Dec 12, 2025 1630 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1020 AM CST Fri Dec 12 2025

Valid 121630Z - 131200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Isolated thunderstorms are possible in the vicinity of the Lower
Texas Coast early Saturday morning.

...Discussion...
Morning water-vapor imagery indicates an upper-level jet streak
moving eastward across northern MX. The core of this feature will
advance into the western Gulf tonight -- remaining south of TX. In
response, a modest increase in southerly low-level flow will deepen
boundary-layer moisture/erode inhibition and yield weak
surface-based buoyancy over the western Gulf and Lower TX Coast
overnight. While most deep convection should be confined to the
higher low-level theta-e plume offshore, strengthening coastal
convergence amid the deepening low-level moisture may support a
couple storms over the immediate coastal areas in the 08-12Z time
frame. A remnant warm layer aloft and weak low/mid-level flow should
limit updraft intensity over land areas.

..Weinman.. 12/12/2025


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