High Wind and Dense Fog in California, February 12 to 18, 2021

Area Forecast Discussion
National Weather Service San Diego CA
812 AM PST Fri Feb 12 2021

.SYNOPSIS...
A compact low pressure system moving southward through the area
today will bring cooling with gusty west to northwest winds in
the mountains and deserts and with scattered mostly light showers
from the coast into the mountains. The next low pressure system
moving southeastward across the area will bring strong gusty west
winds for the mountains and deserts for Saturday into Saturday
evening with a slight chance of light showers for the mountains in
the late afternoon and early evening. Gradually warmer for Sunday
through Thursday with gusty northwest to north winds on Tuesday
and locally gusty northeast winds on Wednesday.

&&

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

Showers and winds have begun to track through Southern California
as a compact and somewhat energetic trough of low pressure moves
from northwest to southeast this morning. Pockets of strong winds
in the ridges and mountain passes have exceeded 40 mph in spots.
Showers were rather isolated earlier this morning, but now have
organized into a band of showers moving through the region. This
band will continue to track southeast through the morning. Winds
will decrease late this morning and showers will be out by early
afternoon. Amounts will total less than 0.10 inch, but locally
higher in foothills. Coastal areas should get decent sunshine
this afternoon. A few low clouds will continue tonight into
Saturday in the coastal basin. The next trough or wave of low
pressure will arrive Saturday. This has a more inland track, less
moisture, but more energy for strong winds. A High Wind Watch is
in effect for Saturday afternoon and evening, when gusts in the
mountains and adjacent desert slopes should exceed 55 mph, with
isolated gusts reaching 70 mph. There is just enough moisture for
a slight chance of showers in the mountains Saturday afternoon
and evening. But the winds will be the bigger impact, and blowing
dust is probable for the deserts. The winds weaken quickly
Saturday night into Sunday, and even turn weakly offshore for a
period early Sunday. More sunshine is expected Sunday and Monday,
but with variable thin high clouds. The next wave arriving Tuesday
looks a lot like Saturday's wave, taking an interior track.
Again, winds will produce the bigger impact, becoming rather
strong in mountains and deserts. But there is a tiny chance of
precip too, mainly in mountains. In the wake of that wave,
offshore flow develops Wednesday and continues Thursday. This will
produce northeast winds, but right now they don't appear very
strong. High pressure aloft will team up with the offshore flow
for clearer skies and warmer weather Wednesday and Thursday.

&&

.AVIATION...
121530Z...Coasts/Valleys/Mountains...Scattered showers to continue
off and on through 21Z. Low clouds with bases 1200-2000 feet MSL
expected through this afternoon, with locally lower cigs near 500
feet MSL in areas of SHRA. Clouds gradually scattering out from
north to south late this afternoon, with bases generally above 3000
feet MSL after 21Z.

Desert Mountain Slopes/Deserts...Increasing west winds with gusts 30-
40 kts through 22Z. Isolated gusts near 45 kts possible below the
San Gorgonio Pass. Strong up/downdrafts and rotors possible
over/east of the mountains. Winds gradually weakening this
afternoon. Otherwise SCT-BKN clouds at/above 15,000 ft MSL and
unrestricted vis through this evening.

&&

.MARINE...
Northwest winds with gusts 20 to 25 kt to increase this morning over
the outer coastal waters and continue through this evening. A Small
Craft Advisory remains in effect from 10 AM through 7 PM this
evening. Stronger winds expected over the coastal waters Saturday,
with gusts of 35 to 40 kts and seas of 8 to 12 feet possible. A Gale
Watch has been issued for the inner and outer coastal waters from
Saturday afternoon through late Saturday night.

&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...High Wind Watch from Saturday morning through Saturday evening
     for Apple and Lucerne Valleys-Riverside County Mountains-
     San Bernardino County Mountains-San Diego County Deserts-
     San Diego County Mountains-San Gorgonio Pass Near Banning.

PZ...Gale Watch from Saturday afternoon through late Saturday night
     for Coastal Waters from San Mateo Point to the Mexican
     Border and out to 30 nm-Waters from San Mateo point to the
     Mexican Border Extending 30 to 60 nm out including San
     Clemente Island.

     Small Craft Advisory until 7 PM PST this evening for Waters from
     San Mateo point to the Mexican Border Extending 30 to 60 nm
     out including San Clemente Island.

&&

PUBLIC...MM
AVIATION/MARINE...Connolly