475 
ACUS03 KWNS 111900
SWODY3
SPC AC 111859

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
1259 PM CST Thu Dec 11 2025

Valid 131200Z - 141200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Isolated weak thunderstorm activity is possible across near South
Florida and the Keys Saturday night.

...Synopsis...

An upper trough over the eastern U.S. will deepen as the western
upper ridging moves inland through the forecast period on Saturday.
A surface boundary extending along the western and central Gulf
coast vicinity will move offshore by the end of the period. Weak
warm advection and some modestly increasing midlevel westerly flow
in the vicinity of this boundary may support isolated showers from
the TX coast into portions of the central Gulf coast. However,
forecast soundings indicate minimal instability (100-200 J/kg
MUCAPE), largely stunted by warm midlevel temperatures. While
shallow convection is possible, lightning appears unlikely. 

The exception may be across far southern FL and the Keys late in the
period where richer boundary layer moisture will be in place. This
will support greater instability (around 1000-1500 J/kg MLCAPE) amid
modest vertical shear ahead of the upper trough. A few thunderstorms
may approach the Keys and South FL coast in the 08-12z time frame.

..Leitman.. 12/11/2025

$$


File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS03/20251211T1900.txt



163 
ACUS03 KWNS 110733
SWODY3
SPC AC 110732

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0132 AM CST Thu Dec 11 2025

Valid 131200Z - 141200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Scattered, mostly weak, thunderstorm activity is possible across the
Gulf Coast states Saturday into Saturday night.

...Discussion...
Models indicate that the blocking high will generally maintain
strength just to the north of Aleutians through this period.  The
evolution of a lower/mid-tropospheric cyclone to its east, across
the northeastern Pacific, is more unclear, but guidance indicates
that a downstream ridge will broaden eastward, inland of the British
Columbia/Pacific Northwest coast through the southern Canadian
Prairies and northern U.S. Great Plains.  Farther east, it still
appears that a vigorous digging short wave trough will once again
contribute to larger-scale mid-level trough amplification across the
Upper Midwest into Great Lakes and Ohio Valley Saturday through
Saturday night.

An increasingly confluent mid-level regime, in the wake of the
amplifying trough, is forecast to support the southeastward
development of an expanding cold surface ridge to the east of the
Rockies, across much of the Great Plains and Mississippi Valley
through western slopes of the Appalachians.  By late Saturday night,
a strengthening low-level baroclinic zone, near the leading edge of
the colder air, is forecast to approach southern Mid Atlantic
through Gulf coastal areas.

In lower latitudes, beneath a weak branch of westerlies emanating
from the subtropical eastern Pacific, a remnant preceding surface
frontal zone may shift northward across the Florida Keys and
southern peninsula by 12Z Sunday, downstream of broad mid-level
troughing overspreading the Gulf Basin.

...Gulf Coast states...
Although weak lapse rates and rather weak lower/mid-tropospheric
wind fields seem likely to minimize the risk for severe weather, a
substantive increase in boundary-layer moisture, in the presence of
increasing large-scale forcing for ascent, may support increasing
scattered thunderstorm development along the front, near the Florida
Keys and southern peninsula, by late Saturday night.

Elsewhere, guidance suggests that scattered thunderstorm development
is possible near/offshore of lower through middle Texas coastal
areas, at least early Saturday.  Farther northeast, a narrow plume
of elevated moisture return, off the modifying northwestern Gulf
boundary layer, might contribute to weak destabilization sufficient
for convection capable of producing lightning, mainly just ahead of
the front as it approaches the Gulf coast late Saturday night.

..Kerr.. 12/11/2025

$$


File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS03/20251211T0733.txt