SPC Dec 16, 2025 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1137 PM CST Mon Dec 15 2025

Valid 161200Z - 171200Z

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

...SUMMARY...
Sporadic severe gusts may accompany isolated thunderstorms across
parts of the Pacific Northwest on Tuesday night.

...Pacific Northwest...
A vigorous shortwave trough will approach the Pacific Northwest
coast through tonight before shifting inland over WA during the
early morning Wednesday. A deepening surface cyclone will move
across southern BC towards southwest AB, with a Pacific cold front
trailing south-southwestward. Low-topped convection is expected to
accompany the front, initially approaching the WA coast by late
evening. Surface-based buoyancy will remain meager, but strong
gradient winds will shift from the southwest to west-northwest as
the front passes. Sporadic lightning flashes and strong to severe
gusts may accompany passage of this low-topped squall before it
subsides inland in western WA/OR.

Intense lower-level flow will likely peak in the overnight to early
morning hours. Buoyancy should remain quite limited along and east
of the Cascades, but most guidance indicates broken low-topped
convection should spread east along/ahead of the front amid
pronounced large-scale ascent. Background gradient winds will likely
be capable of producing severe gusts, and some of these may be
coincident with sporadic lightning flashes.

..Grams/Wendt.. 12/16/2025


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SPC Dec 16, 2025 0100 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 0100Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0656 PM CST Mon Dec 15 2025

Valid 160100Z - 161200Z

...NO THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Thunderstorms are not forecast tonight.

...Pacific Northwest...
Thunderstorms earlier this afternoon over southwest OR have fully
decayed in the past couple hours. A lone storm or two will be
possible tonight within the persistent, but modest low-level warm
conveyor that will shift farther inland to the northern Rockies.
With flimsy elevated buoyancy expected (MUCAPE at or below 100
J/kg), overall thunderstorm probabilities appear negligible.

A few lightning flashes were also detected in the last hour across
northwest WA near a shortwave trough, that will rapidly progress
east across far southern AB/SK tonight. This thunder threat is
expected to remain very isolated and diminish east of the Cascades.

..Grams.. 12/16/2025


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SPC Dec 15, 2025 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1127 PM CST Sun Dec 14 2025

Valid 151200Z - 161200Z

...NO THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Thunderstorm probabilities are low today.

...Pacific Northwest...

100+kt 500mb speed max is forecast to translate inland along the
WA/OR coast around 16/00z. Low-amplitude short-wave trough will
induce strong height falls near the international border ahead of
this feature, coincident with a notable surface front that will
surge inland after 21z. While profiles will cool and steepen at
midlevels, forecast soundings are not particularly buoyant either
side of the trough, and the prospect for deep convection capable of
generating lightning appears low. While the thunderstorm potential
appears low, weak midlevel convection is possible and a flash or two
can not be ruled out. This, however, does not warrant a categorical
risk for thunderstorms during the day1 period.

..Darrow/Wendt.. 12/15/2025


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SPC Dec 15, 2025 0100 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 0100Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0632 PM CST Sun Dec 14 2025

Valid 150100Z - 151200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected tonight.

...01z Update...

Northwesterly flow is deepening across the southern FL Peninsula as
the primary synoptic front surges toward the FL Straits. Isolated
showers are lingering across this region, with even a few flashes of
lightning near West Palm Beach. However, this activity should
continue to wane then focus well offshore over the next few hours.

00z sounding from UIL is quite stable this evening with poor lapse
rates noted through 6km. Late tonight elevated buoyancy may increase
near the WA coast such that weak convection is able to develop ahead
of approaching short-wave trough. If lightning is noted with this
activity it will remain quite sparse.

..Darrow.. 12/15/2025


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