SPC Jan 21, 2025 0600 UTC Day 1 Convective Outlook

SPC 1200Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1046 PM CST Mon Jan 20 2025

Valid 211200Z - 221200Z

...NO THUNDERSTORM AREAS FORECAST...

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

...Discussion...
Ridging to the north of the blocking mid-level high centered over
the mid-latitude eastern Pacific is rebuilding, as an initially
suppressing short wave perturbation progresses inland across British
Columbia.  The latter feature is forecast to dig through the
northern U.S. Rockies and adjacent Great Plains by 12Z Wednesday,
reinforcing large-scale troughing now encompassing much of central
and eastern North America.  As this occurs, a pair of initially
digging downstream short wave perturbations will be forced
east-northeastward, into and through strong, confluent flow between
a prominent mid-level ridge centered over the subtropical western
Atlantic and a broad cyclonic circulation centered over the far
northeastern Canadian provinces.

Although down slope flow may contribute to moderating temperatures
across the northern and central Great Plains, seasonably cold air
associated with surface ridging entrenched across much of the
southern Great Plains through Atlantic Seaboard will generally be
maintained.  It appears that the shallow leading edge of this cold
air mass will remain south and east of the Florida Peninsula and
Keys, with little in the way of surface frontal wave development
across the west central through southeastern Gulf of Mexico due to
lack of mid/upper support.

...Northwestern Gulf coast...
In the presence of steepening mid-level lapse rates associated with
differential thermal advection, it still appears that elevated
moisture return will contribute to weak destabilization (rooted in
the 800-700 mb layer) as far northwest as upper Texas/Louisiana
coastal areas by 12-15Z this morning.  This probably will provide
support for a period of increasing convective development, with
thermodynamic profiles possibly become conducive to at least some
lightning production before diminishing by early afternoon.  There
remains substantive spread concerning this potential, however, and
thunderstorm probabilities will be maintained at less than 10
percent, based on objective calibrated guidance from both the NCEP
SREF and HREF.

..Kerr.. 01/21/2025

Read more