Area Forecast Discussion
Issued by NWS San Diego, CA

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516
FXUS66 KSGX 121058
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
258 AM PST Thu Dec 12 2019

.SYNOPSIS...
Building high pressure will bring warmer weather through Friday.
A trough moving over California this weekend will bring cooler
weather along with gusty winds in the mountains and deserts. There
is a slight chance of showers late Saturday, except in the desert.
Offshore flow will bring some northeast winds Monday and Tuesday.

&&

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

Waves of high clouds drift across our skies and there will be a
few patches of low clouds and fog near the coast this morning.
A high pressure ridge builds today and peaks out Friday promising
a warming trend. Fair weather with fewer high clouds and patchy
coastal fog is expected through Friday. The ridge breaks down this
weekend under a hefty trough of low pressure moving through the
West. Most of the energy misses SoCal to our north, but we`ll get
some wind and some December version of a deepened marine layer
Saturday. Winds will be strongest in the mountains, deserts and
coastal waters. Highest gusts in portions of the mountains could
exceed 60 mph, but most mountains and deserts will gust 25-45 mph.
The enhanced marine layer should produce light showers,
particularly in far inland valleys and coastal slopes of the
mountains. Higher mountains, coast and deserts should avoid
measurable precip. A cold front moves through the area early
Sunday for a cooler day. Offshore flow keeps the continental cold
air flowing into the region Monday and Tuesday. Although higher
pressure builds aloft, the warming trend is quite muted because
of the cool offshore flow. Guidance is showing that high pressure
ridge next week doing a good job of deterring any weather system
from bringing us rain. What looked like Wednesday is now looking
like Thursday for the next chance. Ensembles and deterministic
guidance show low pressure to our west and southwest, but no
serious jet power to drive it through the ridge (the GFS is
completely dry for us through 10 days). While most guidance shows
some showers appearing beyond seven days, the pattern change to
wet weather appears halfhearted.

&&

.AVIATION...
120835Z...Coastal areas...Patches of BKN-OVC clouds with bases 200-
700 ft MSL and reduced vis of 1-3 miles at times through 15Z.
Impacts at TAF sites are unlikely. Otherwise, SCT-BKN clouds AOA
25000 feet through Friday.

Elsewhere...SCT-BKN high clouds AOA 25000 FT with unrestricted vis
through Friday.

&&

.MARINE...
A large, west northwest swell with a period of 15-17 seconds could
produce combined seas of 8 to 12 ft Friday through Sunday. West
northwest winds will increase over the outer coastal waters Saturday
through Sunday with gusts up to 30 kt possible. This will create
hazardous boating conditions for mariners.

&&

.BEACHES...
A west northwest swell with a period of 15-17 seconds will bring
elevated to high surf and strong rip currents to the beaches Friday
through Sunday. Current projections are for 5-7 foot surf with local
sets to 8 feet, mainly in southern San Diego County. High tides over
6 feet along with the surf may cause local beach erosion. A Beach
Hazards Statement is in effect from 10 AM Friday through 4 PM Sunday.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement from Friday morning through Sunday
     afternoon for Orange County Coastal Areas-San Diego County
     Coastal Areas.

PZ...NONE.

&&

$$

PUBLIC...MM
AVIATION/MARINE/BEACHES...PG



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