Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0228 AM CST Sun Dec 14 2025

Valid 161200Z - 171200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
A few thunderstorms are possible in the Pacific Northwest on Tuesday
and Tuesday night.

...Discussion...
As high pressure moves from the Southeast into the Atlantic, and
weak lee troughing develops across the High Plains, southerly return
flow returns across the Plains on Tuesday. Some showers may develop
within weak isentropic ascent across east Texas on Tuesday night,
but most guidance shows minimal instability until after 12Z
Wednesday. Therefore, thunderstorm activity is not expected.

Thunderstorms are possible in western Washington and far northwest
Oregon on Tuesday and Tuesday night as a strong mid-level trough
approaches the coast. Weak instability is expected during the
afternoon, but most forecast soundings suggest the equilibrium level
will be too low for charge separation which may keep any lightning
potential isolated. However, by late Tuesday night/early Wednesday,
as cold air aloft overspreads the region, sufficiently deep
instability is expected for lightning across western Washington and
perhaps into northwest Oregon. During this time, more frequent
lightning may be possible with a line of convection along the
surface front.

..Bentley.. 12/14/2025

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0356 AM CST Sun Dec 14 2025

Valid 171200Z - 221200Z

...DISCUSSION...
Northward moisture return is expected to persist through the period
on D4/Wednesday as a strong surface low moves across the northern
Plains and Upper Midwest and strong southerly flow expands across
much of the warm sector. Despite the moisture advancing well inland,
warm air aloft should limit strong thunderstorm potential on
D4/Wednesday. 

By D5/Thursday, weak to moderate instability is expected from East
Texas to the Mid-Mississippi Valley. Strong shear will be present
north of I-20 as a mid-level trough amplifies and a strong mid-level
jet overspreads the warm sector. Despite the presence of strong
shear and weak to moderate instability, updraft intensity may still
struggle due to weak lapse rates/warm air aloft. Only weak height
falls/cooling temperatures aloft are forecast south of the MO
Bootheel. Thunderstorms are likely from the Mid-Mississippi Valley
northward, where forcing will be stronger, but these regions will
remain well north of the more favorable instability. Therefore, any
severe weather threat would likely be marginal.

The cold front, associated with the storm system on D5/Thursday,
will move off the East Coast early on D6/Friday. Some marginal
severe weather may be possible Friday morning, but otherwise, severe
weather potential will be low as high pressure builds east of the MS
River in its wake. 

By this weekend, return flow is anticipated across portions of the
southern Plains, but destabilization remains uncertain. A zonal
mid-level pattern with multiple embedded shortwave troughs is
currently forecast during that timeframe which commonly results in
considerably low predictability. Regardless of the exact outcome
over the weekend, there is general consensus for zonal flow and a
ridge building across the western CONUS and into the Plains. In
general, this will likely not support a significant severe weather
threat.