RSS Mesoscale Discussions from Storm Prediction Center
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 0700Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1152 PM CST Fri Dec 12 2025
Valid 141200Z - 151200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
A few storms are possible across South Florida and the Florida Keys
on Sunday.
...Discussion...
An upper trough will move from the Great Lakes to the western
Atlantic by Sunday night/early Monday. At the surface, strong high
pressure will continue to build south and east from the Midwest to
the Tennessee Valley. This expansive high pressure will push a cold
front into the Atlantic and the Gulf. Richer boundary layer moisture
will remain confined to South Florida and the Keys where showers and
isolated thunderstorms may be ongoing Sunday morning. This activity
may persist into the afternoon while shifting southeast with time.
However, weak instability should limit overall severe weather
potential.
..Bentley.. 12/13/2025
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SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0117 AM CST Sat Dec 13 2025
Valid 151200Z - 161200Z
...NO THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Thunderstorms are not expected on Monday.
...Discussion...
Strong high pressure will dominate much of the eastern 2/3rds of the
CONUS on Monday with strong offshore flow into the Atlantic and the
Gulf, pushing rich moisture well offshore. Therefore, thunderstorm
activity is not expected across much of the CONUS. The only
exception may be across the Pacific Northwest coast where some weak
instability may develop. However, even within this area, lightning
activity should remain limited due to relatively warm air aloft.
..Bentley.. 12/13/2025
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Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0246 AM CST Sat Dec 13 2025
Valid 161200Z - 211200Z
...DISCUSSION...
Moisture return will begin on Tuesday/D4 across Texas with some weak
instability and thunderstorm potential arriving by Wednesday/D5.
Significant differences in the upper-level pattern begin on
Thursday/D6 and beyond which will significantly impact thunderstorm
and severe weather potential.
The ECMWF and AIFS have a sharper mid-level trough farther south on
Thursday/D6. This will result in a stronger cold front and farther
north moisture return ahead of the front. In addition, some weak
instability may develop beneath the stronger mid-level jet. This may
create an environment favorable for a few stronger storms from the
Lower Ohio Valley to the Mid-Mississippi Valley. This stronger
scenario would likely push a strong cold front deep into the Gulf on
Friday and limit thunderstorm potential into the weekend.
A less amplified solution (as shown by the GFS and AIGFS) would not
support much of any strong storm threat on Thursday/D6. However, it
would keep low to mid 60s dewpoints across Texas and the Lower MS
Valley on Friday and into the weekend. This may result in weak to
potentially moderate instability across portions of the southern
Plains and possibly into the Mid-Mississippi Valley through the
weekend. Despite this lingering instability, a mostly zonal
mid-level pattern would not support a significant severe weather
threat.
Overall, severe weather potential remains somewhat low for much of
the period. Some low-end severe weather threat may exist from
Thursday/D6 and beyond as low-level moisture increases, but
significant uncertainties in the evolution of the upper-level
pattern make any forecast for time or location of any potential
low-end threat difficult.
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