Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0127 PM CST Tue Dec 16 2025

Valid 162000Z - 171200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE
PACIFIC NORTHWEST...

...SUMMARY...
Sporadic severe wind gusts may accompany low-topped convection
across parts of the Pacific Northwest tonight into early Wednesday
morning.

...20z Update...
No changes are needed to the D1 Convective Outlook. See previous
discussion for more information.

..Thornton.. 12/16/2025

.PREV DISCUSSION... /ISSUED 1020 AM CST Tue Dec 16 2025/

...Pacific Northwest...
A strong mid-level shortwave trough over the eastern Pacific will
amplify today and reach the coastal Pacific Northwest late tonight.
This trough will be accompanied by an enhanced deep-layer wind
field, with 90-100+ kt winds at 500 mb and around 50-80 kt flow in
the lowest 1-3 km AGL. Low-level moisture should also gradually
increase tonight ahead of an eastward-advancing cold front.
Low-topped convection may accompany the front, initially approaching
the WA Coast by late evening, and then more interior areas
overnight/early Wednesday.

Surface-based buoyancy will remain quite meager due to poor lapse
rates aloft and the time of night. Still, rather strong low-level
gradient winds will shift from the southwest to west-northwest as
the front passes. Sporadic lightning flashes and occasional strong
to severe-caliber wind gusts may accompany the passage of this
low-topped convective line, with the most intense low-level
winds/convective influences expected to peak during the overnight
and early morning hours Wednesday. However, it remains quite
uncertain if these convectively enhanced winds will be substantially
stronger than the background gradient wind field. Therefore, the
Marginal Risk has been maintained with no changes.

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1118 AM CST Tue Dec 16 2025

Valid 171200Z - 181200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Isolated thunderstorms are possible over much of the northern
Rockies on Wednesday, with a greater probability across the Texas
Coastal Plain. Sporadic activity may also occur Wednesday night into
the mid to lower Mississippi Valley. Severe storms are not forecast.

...Synopsis...
A strong upper trough and cold front will move across the Pacific
Northwest and northern Rockies on Wednesday, with substantial
cooling aloft and strong winds. Daytime heating will lead to areas
of weak instability, with scattered lightning possible especially
over ID and western MT/WY. Overnight, a strong cold front will surge
south across the Great Plains, and sporadic lightning may occur with
elevated/weak convection.

Southeast of this system, a low-latitude wave will be located over
southern TX, with cool midlevel temperatures present. This will aid
destabilization despite relatively cool surface temperatures.
Dewpoints in the 60s F will be common across the Coastal Plain and
perhaps toward the ArkLaTex late, however, given the surface high to
the east, low-level trajectories will favor cool surface
temperatures and elevated instability in most areas.

..Jewell.. 12/16/2025

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0124 PM CST Tue Dec 16 2025

Valid 181200Z - 191200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS CENTERED OVER
KENTUCKY AND TENNESSEE...

...SUMMARY...
Isolated damaging wind gusts are possible across portions of the
Lower Ohio and Tennessee Valleys on Thursday.

...Synopsis and Discussion...
A powerful upper trough will move from the Plains into the MS Valley
on Thursday, taking on a negative tilt late in the period as it
moves across the upper OH Valley and lower Great Lakes. Strong
cooling aloft will occur with the greatest large-scale ascent across
the OH and TN Valleys. 

At the surface, low pressure will move from Upper MI eastward into
southwest Quebec, with a cold front trailing south of the low and
reaching the northern Gulf of America overnight.

Ahead of the front, a narrow plume of 50s F dewpoints will extend as
far north as the OH River, with lower 60s F possible near the
ArkLaMiss. Substantial clouds and areas of precipitation will limit
heating over most of the area, and SBCAPE will be quite low.
However, lift immediately along the cold front should at least
result in a low-topped forced line of convection. SBCAPE will be low
even south of I-40, despite higher dewpoints as temperatures aloft
will be warmer.

Despite these mitigating issues, favorable large-scale ascent during
the daytime along with at least marginal instability and strong flow
off the surface may yield locally strong to damaging gusts with
activity along the cold front.

..Jewell.. 12/16/2025