Small Craft Advisory 5, NWS San Diego, CA

Area Forecast Discussion
National Weather Service San Diego CA
912 PM PST Wed Mar 2 2022

.SYNOPSIS...
Thursday will be a little cooler than today, then it will turn much
colder Friday as a winter storm moves across the region. Rain and
mountain snow will move into Southern California Thursday night and
Friday along with gusty winds and a slight chance of thunderstorms.
A second trough will bring additional showers and cold weather
Saturday, followed by dry, cool weather Sunday and Monday.

&&

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

Update:

It was another warm day across the region today. Highs ranged from
61 degrees at Big Bear City and Mount Laguna to 92 degrees at
Ocotillo Wells (this was the hottest spot in the nation today!)

Tranquil conditions continue across SoCal this evening ahead of
the winter storm poised to impact the region beginning Thursday
night. Latest HRRR shows rain beginning along the coast at around
midnight tomorrow night spreading east. The latest WRF is a couple
hours earlier. Either way, dry weather will continue tonight and
last through Thursday with cooler conditions. See previous
discussion below for details on the incoming storm systems.

Previous Discussion (Issued at 200 PM PST Wed Mar 2 2022):

The weather will turn sharply colder Friday through Sunday as a
series of shortwaves in cold northwest flow brings rain, wind and
mountain snow. Rain with the first wave will arrive Thursday night
with a cold core low lowering 500 mb temps to -26C and raising CAPE
values to 200 J/kg, high enough for thunderstorms.

Snow levels will fall to 5,000 feet Friday morning, then down to
around 4,000 feet Saturday, prompting a Winter Storm Watch from
Thursday night through early Sunday morning.

In the short term, tomorrow will be a little cooler than today, but
still above average except in the coastal areas where the return of
cool marine air will keep temps in the mid to upper 60s which is
about average. A shallow marine layer will bring low clouds back to
the coast tonight which will steadily deepen Thursday as a coastal
eddy spins up. Increasing onshore gradients ahead of a Pacific
trough will accelerate marine layer deepening so that by Thursday
evening the low clouds will have spread into the valleys.

Part 1 of this winter storm will impact the area Thursday night and
Friday. The GFS and EC operational runs are in general agreement
with the location and intensity of a 550 dm upper low west of Pt
Conception at 00Z Friday. Strong PVA and strong cold air advection
aloft (500 mb temps fall to -26C by 12Z Friday) will trigger an area
of rain with embedded thunderstorms Thursday night into Friday
morning. Part 2 arrives Friday night through Saturday night with a
colder airmass lowering snow levels and bring cold northwest winds
to the area.

The forecast rain and snow totals haven't changed very much since
yesterday. The San Diego County mountains stand the best chance to
see the highest amounts with rain totals of 1.00 to 1.75 inches.
Coastal and valley areas will see from 0.25 to 1.00 inches, greatest
in the valleys and foothills. From 0.10 to 0.25 inches is expected
in the deserts.

Snow levels around 6500 feet Thursday evening will fall to 5000 feet
late by Friday morning with 4 to 8 inches of snow above 6000 feet to
locally around 12 inches above 7,500 feet. Strong winds will also
impact the deserts.

On Saturday a second cold upper low from the northwest will bring
cold weather and scattered showers through Saturday night, most
widespread in the mountains. Rain amounts will range from 0.10 to
0.25" in the coast and valley areas. The snow level will fall to
around 3,500 to 4,000 feet where several more inches of snow will
fall. Highs Saturday will be well below average

The trough moves east Saturday night for dry but cool days and cold
nights Sunday and Monday.

&&

.AVIATION...
030500Z...Low clouds and patchy fog will develop at the coast after
09Z, with bases 500-700 feet MSL. Vis reductions of 4-6 SM expected
in HZ/BR, with lower vis of 2-4 SM over higher coastal terrain.
Bases will rise to 1000-1500 feet after 17Z, with improving vis.
Brief and random scatter out possible after 20Z, though ceilings may
continue through Thursday afternoon.

&&

.MARINE...
No hazardous marine weather is expected through Thursday afternoon.
Northwest winds will increase Thursday night and continue at times
through Sunday morning, with gusts 25-30 kts. These winds will also
produce choppy seas hazardous for small craft, with seas of 8-12
feet at times. There is also a slight chance of thunderstorms
Thursday night and Friday, which could produce gusty erratic winds,
lightning and waterspouts.

&&

.BEACHES...
There is a slight chance of thunderstorms and associated lightning
strikes Thursday night through Friday. Increasing west winds and WNW
swell will also lead to some higher breaking waves late Friday
afternoon through Saturday night, with surf heights potentially
exceeding 6 ft at times on the San Diego County beaches.

&&

.SKYWARN...
Skywarn activation may be requested Friday.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory from noon Thursday to midnight PST Thursday night
     for Riverside County Mountains-San Bernardino County
     Mountains-San Diego County Deserts-San Diego County
     Mountains.

     Winter Storm Watch from late Thursday night through Sunday
     morning for Riverside County Mountains-San Bernardino
     County Mountains-San Diego County Mountains.

PZ...NONE.
&&

PUBLIC...Gregoria (Update)/Moede (Previous Discussion)
AVIATION/MARINE...Connolly