High Wind in California, November 24 to 25, 2022

Area Forecast Discussion
National Weather Service San Diego CA
945 PM PST Wed Nov 23 2022

.SYNOPSIS...
A Santa Ana weather pattern will bring strong and gusty winds along
coastal slopes and below passes and canyons for Thanksgiving day and
Friday. Some gusty winds will make it across the valleys as well.
The downsloping winds will bring warmer days west of the mountains,
but it will remain cool over the mountains and high deserts. Cooling
will spread inland Saturday and Sunday with the return of onshore
flow. Early next week a low pressure system from the northwest will
bring cooler, breezy weather and a chance for showers.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

Some thin high clouds were drifting south across the region this
evening. There was a small patch of low clouds south of San Clemente
Island too, but that was about it. the sfc pressure gradient from
the high deserts was trending moderately offshore, increasing the NE
winds over the San Bernardino Mts. At 8 PM PDT, peak gusts were
running 35-45 MPH. Our Miramar sounding this afternoon had a solid
shift to northerly winds at 25-40 KTS throughout much of the column.
Those winds will be felt more and more through the night and into
Thursday morning. Wind Advisories are out through Friday morning. No
forecast updates are planned this evening.

From previous discussion...

Lows tonight will not be as cold as last night in most areas,
especially in the Inland Empire below the Cajon Pass and the San
Gorgonio Pass where lows will likely be in the mid 50s as the Santa
Ana winds kick in and keep the atmosphere well mixed.

There are no significant changes to the Santa Ana wind event that
will begin tonight. The models have remained consistent with its
timing and strength. The winds will strongest Thursday, then
gradually weaken Friday. The San Diego County mountains and passes
will likely see the strongest winds with gusts of 70+ mph at a few
back country locations as the gradients and midlevel wind support
are directed in an east-west orientation as opposed to a northeast-
southwest orientation. Motorists on I-8 through the mountains will
experience very strong winds tomorrow.

Temperatures on Thanksgiving day will be several degrees warmer than
today in the coastal areas, but the mountains and high deserts will
be several degrees cooler as cold air advection moves in. Friday
will be another warm day west of the mountains, with little change
in the mountains and deserts.

On Friday night and Saturday the offshore gradients flip back
onshore as the high amplitude ridge over the Southwest collapses
under the weight of a digging jet stream that will drive the storm
track farther south. The first of two shortwaves moves across SoCal
Saturday, bringing a few degrees of cooling west of the mountains as
the onshore flow increases and the cool marine air returns to the
coastal and valley zones. The mountains and deserts will continue to
warm one more day.

On Sunday the cooling spreads farther inland into the mountains and
down into the deserts. Low clouds and fog could return to the coast
in the morning.

The second, stronger wave moving down the coast will bring a chance
for rain and mountain snow Monday and Monday night. Model guidance
has trended drier and a little more inland with this system. This
inside track would reduce the precipitation chances and the
precipitation amounts. It's still five days away though, and as the
storm moves into the high resolution model window the storm
specifics will becoming clearer.

&&

.AVIATION...
240530Z...Areas of FEW-SCT high clouds AOA 15000 ft MSL with
unrestricted vis through tonight. NE-E winds expected through Friday
morning. Peak gusts of 40-60 mph, locally up to 70 mph possible on
the coastal mountain slopes, foothills, and below passes. At the
coastal areas, peak gusts of 30-45 mph possible 14Z Thu-04Z Fri. MOD
up/downdrafts and LLWS possible over and SW/W of the mountains into
Friday morning.

&&

.MARINE...
A few easterly wind gusts near 20 kt possible just off the coast
Thursday. Otherwise, no hazardous marine weather expected through
Monday.

&&

.FIRE WEATHER...
Northeast Santa Ana winds ramping up this evening and spreading into
San Diego County through daybreak tomorrow as the flow becomes
easterly. The strongest winds will surface between 9 AM and 6 PM,
gusting from 55 to 65 mph with higher gusts to 70+ mph in the San
Diego County mountains. The strong winds coincident with humidities
falling to 7-15 percent, will make this time frame the period of
greatest fire weather concern. Thursday night and Friday the winds
will not be quite as strong, but still noticeably windy, strongest
in San Diego County. The winds will diminish Friday afternoon.

Humidity will begin to recover Saturday with greater recovery on
Sunday as onshore flow strengthens.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory from 6 AM to 6 PM PST Thursday for San Diego
     County Coastal Areas.

     Wind Advisory from 10 PM this evening to 10 AM PST Friday for
     Orange County Inland Areas-San Bernardino County Mountains-
     San Bernardino and Riverside County Valleys-The Inland
     Empire-Santa Ana Mountains and Foothills.

     Wind Advisory from 2 AM Thursday to noon PST Friday for San
     Diego County Mountains-San Diego County Valleys.

     Wind Advisory from 4 AM Thursday to 10 AM PST Friday for
     Riverside County Mountains-San Gorgonio Pass Near Banning.

     Wind Advisory from 6 AM to 8 PM PST Thursday for Orange County
     Coastal Areas.

PZ...None.

&&

PUBLIC...10/Moede
FIRE WEATHER...Moede
AVIATION/MARINE...JMB