SPC Jan 20, 2025 0600 UTC Day 1 Convective Outlook

SPC 1200Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1101 PM CST Sun Jan 19 2025

Valid 201200Z - 211200Z

...NO THUNDERSTORM AREAS FORECAST...

...SUMMARY...
The risk for thunderstorms appears negligible across the U.S. today
through tonight.

...Discussion...
A significant short wave perturbation is forecast to continue
progressing through the crest of blocking larger-scale mid-level
ridging centered over the northeastern Pacific, eventually digging
across the Canadian Rockies and adjacent Pacific Northwest by late
tonight.  Downstream, short wave ridging likely will overspread the
Canadian Prairies, northern U.S. Rockies and Great Basin, in the
wake of digging short wave troughing across the northern Great
Plains through upper Mississippi Valley/Great Lakes region and
across the Southwest/southern Rockies and adjacent international
border vicinity.  Farther east, it appears that strong, confluent
southwesterly mid/upper flow will be maintained between a prominent
ridge centered over the subtropical western Atlantic and a broad,
cold cyclonic circulation centered east-northeast of Hudson Bay.

Beneath this regime, surface troughing likely will develop and
deepen across the Canadian Prairies into the lee of the northern
U.S. Rockies.  Otherwise, though its center is forecast to shift
from the lee of the northern through southern Rockies, expansive
cold surface ridging will generally be maintained across much of the
interior U.S, with another high center building across the Allegheny
Mountains/Mid Atlantic vicinity.  The frontal zone demarcating the
leading edge of this cold intrusion probably will begin to stall and
weaken east/southeast of the Florida Peninsula into the southeastern
Gulf of Mexico, well in the wake of a rapidly deepening cyclone
migrating across and northeast of the Canadian Maritimes.

...Texas coastal areas...
Models do indicate that weak troughing will form on the southern
flank of the cold surface ridge, from the southwestern toward
northwestern Gulf of Mexico today through tonight.  Any associated
boundary-layer destabilization likely will remain focused well
offshore of the lower Texas coast.  However, elevated moisture
return may contribute to weak CAPE rooted around the 700 mb level as
far north as the upper Texas coast by 12Z Tuesday.  RAP and NAM
forecast soundings suggest that it might not be out of the question
that convection, supported by ascent associated with
lower/mid-tropospheric warm advection, might become capable of
producing some lightning.  But, due to lingering uncertainties,
thunderstorm probabilities will be maintained at less than 10
percent, at least for now.

..Kerr.. 01/20/2025

Read more