RSS Mesoscale Discussions from Storm Prediction Center
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1120 PM CST Fri Dec 19 2025
Valid 201200Z - 211200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Isolated lightning flashes may occur near coastal sections of
Washington today.
...Synopsis...
A mid-level trough will progress across the eastern CONUS while
upper ridging builds west of the Rockies, resulting in surface high
pressure overspreading the Midwest as a surface trough impinges on
the Pacific Northwest Coastline. Cooler temperatures aloft will
overspread a marine boundary layer over the Washington coast,
resulting in scant buoyancy, which may favor a few convective
updrafts that may deepen enough to produce isolated lightning
flashes. A weakening surface low will also drift southward across
the southern Plains, promoting low-level moisture return inland from
the western Gulf. However, considerable convective inhibition should
limit convective development through the Day 1 period.
..Squitieri.. 12/20/2025
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SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1148 PM CST Fri Dec 19 2025
Valid 211200Z - 221200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe thunderstorms are not expected Sunday.
...Discussion...
Progressive/generally zonal upper-level flow will prevail over the
CONUS on Sunday. A low-amplitude shortwave trough will move inland
over the Pacific Northwest, with thermodynamic profiles potentially
becoming conducive for a few low-topped thunderstorms mainly for
coastal portions of Washington. East of the Rockies, surface high
pressure and continental trajectories will be prevalent with
essentially nil thunderstorm potential. Gradual air mass
modification and low-level moistening will occur over the western
Gulf. However, a limited forcing regime and residual capping are
currently expected to preclude thunderstorms along the Texas coast.
..Guyer.. 12/20/2025
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SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0126 AM CST Sat Dec 20 2025
Valid 221200Z - 231200Z
...NO THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe thunderstorms are not expected on Monday.
...Discussion...
The large-scale pattern will undergo modest amplification on Monday
via additional upper ridging over the south-central CONUS and
northern Mexico. As a surface high continues to transition
east-southeastward along the Eastern Seaboard/Southeast, moderate
low-level moistening will occur north-northeastward across
Louisiana/eastern half of Texas toward the ArkLaTex. A few
thunderstorms could occur within this warm/moist advection regime,
but it currently appears that upper ridging and related mid-level
capping should considerably limit thunderstorm potential. In the
Pacific Northwest, a few lightning flashes could occur near coastal
Washington, but this potential should remain limited/isolated while
also trending less thermodynamically favorable by late in the day.
..Guyer.. 12/20/2025
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Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0236 AM CST Sat Dec 20 2025
Valid 231200Z - 281200Z
...DISCUSSION...
The large-scale pattern next week will be highlighted by prominent
upper ridging and anomalously high 500-mb heights over much of the
central to eastern CONUS, with upper troughing developing toward the
West Coast by mid/late week. This pattern should considerably limit
deep convective potential over much of the CONUS, even while a
relatively warm/moist airmass will exist across the Plains and
Midwest.
With the approach of a low-latitude upper trough and increasing
moisture, thunderstorm potential, potentially including some
strong/locally severe storms with gusty winds, could occur across
coastal portions of central and southern California during the last
half of Wednesday/Day 5 into Thursday/Day 6 Christmas. However, the
degree of destabilization and some synoptic-related forecast details
remain uncertain.
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