Day 3-8 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0357 PM CST Sat Jan 18 2025

Valid 201200Z - 261200Z

...Southern California - Days 3-4/Monday-Tuesday...
On the upstream side of a highly amplified, positive-tilt
large-scale trough over the West, an embedded shortwave trough and
belt of strong low/midlevel northerly flow will overspread southern
CA. At the same time, an amplified upper ridge will shift slowly
eastward over the eastern Pacific, while surface high pressure
strengthens over the Intermountain West. As a result, the offshore
pressure gradient will rapidly tighten across southern CA, with
magnitudes indicative of a strong Santa Ana wind event. 

Guidance is in good agreement, depicting a LAX-DAG gradient around
-7 to -8 mb, with some guidance showing the gradient as low as -10
to -11 mb (peaking around 12Z-14Z on Day 4/Tuesday). This gradient,
coupled with the strong upper-level support, will yield very
strong/gusty northeasterly surface winds amid single-digit to lower
teens RH from Day 3/Monday night into Day 4/Tuesday. 70-percent
Critical probabilities remain in place for the typical wind-prone
Santa Ana corridor, and the potential for Extremely Critical
conditions is increasing over portions of western Los Angeles County
into Ventura County. Critical probabilities have also been expanded
southward into San Diego County, where confidence in strong offshore
winds and low RH has increased.

From Day 5/Wednesday into Day 6/Thursday, high pressure will rebuild
over the Intermountain West, potentially favoring another increase
in the offshore pressure gradient across southern CA. Current
indications are that the upper-level support and gradient will be
weaker than Days 3-4/Monday-Tuesday, though elevated to critical
conditions will be possible.

..Weinman.. 01/18/2025

...Please see www.spc.noaa.gov/fire for graphic product...