Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 260550 AAA
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
934 PM PST Thu Feb 25 2021

.SYNOPSIS...
Friday will be a sunny, mild day. A Catalina Eddy will form over the
coastal waters Friday and it will spin up low clouds near the coast
Friday night into Saturday. Saturday will be a little cooler as the
marine layer deepens and the onshore flow increases ahead of an
approaching trough. After the trough passes Saturday evening, strong
northeast winds will once again impact the mountains and foothills
through Sunday. Monday will be dry. There is a chance for light
precipitation Tuesday and Wednesday.

&&

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

Evening Update:

The Santa Ana wind event was a strong one, as highlighted on the
wind report issued earlier this afternoon, and headlined on social
media and our website. Otherwise quiet weather will be expected for
the remainder of tonight, and into Friday. Onshore flow late Friday
will bring in marine enhanced air to the coastal strip and patchy
fog. No changes were necessary this evening.

Remainder of the previous forecast discussion, issued at 240 PM PST:

Santa Ana winds peaked this morning with gusts above 70 mph at the
wind prone areas in San Bernardino and Orange County Mountains.
Marshall Peak in the San Bernardino Mountains had a gust to 98 mph,
and CSU San Bernardino had a gust to 81 mph. Several big rigs were
overturned on the I-15 and I-210 below the Cajon Pass. Winds also
gusted to 58 mph at Desert Hot Springs last night.

The winds will decrease this afternoon as gradients weaken. Friday
will be a little warmer than today in most areas. A Catalina Eddy is
forecast to spin up Friday night which will deepen the marine layer
and spread low clouds and fog into the coastal zones Saturday
morning, perhaps as far inland as the western San Diego Valleys.
Saturday will be a cooler day with lower heights and stronger
onshore flow associated with a fairly strong inside slider
racing across the Great Basin and into Arizona Sunday.

Gradients turn quickly offshore Saturday night and that will bring
in another round of Santa Ana winds Saturday night and Sunday. This
Santa Ana event won`t be a strong today`s, but it will still
generate northeast winds from 40-60 mph in the mountain and
foothills, and that may require a High Wind Watch or Wind Advisory.
Sunday will be a colder day is all areas. Marine layer clouds and
fog in San Diego County Sunday morning will slowly erode as the
drier offshore flow make its way southwestward.

Monday will be a dry and warmer day with generally sunny skies and
weaker offshore flow.

The Tuesday and Wednesday outlook is a murky as it was yesterday.
All of the deterministic and the ensemble runs continue to show a
large model spread next week. The variability ranges from dry and
warm with ridging (ECMWF) to wet and cool troughing (GFS). The
Canadian model is also supporting and cooler, wetter solution.
Forecast confidence remains very low for this time period.

&&

.AVIATION...
260400Z...Local breezes with gusts 20-30 MPH this evening across the
mountains will continue to subside through tonight. Otherwise,
mostly clear with VFR conditions through Friday.

&&

.MARINE...
No hazardous marine weather expected tonight through Saturday.
Northeast winds expected starting early on Sunday morning through
Sunday night with some gusts over 20 knots possible.

&&

.SKYWARN...
Skywarn activation will not be needed Friday.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.

&&

$$

PUBLIC...Moede/JMB
AVIATION/MARINE...APR



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