Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 220520
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
920 PM PST Sun Jan 21 2018

.UPDATE...
At 9 PM PST, water vapor satellite showed an upper-level trough
moving across northern California, with northwest flow aloft
across southern California. Lows overnight will be a few degrees
below normal, with patchy frost possible over some inland areas,
especially in the Inland Empire. Portions of the High Desert will
dip into the upper 20s overnight, with some high elevation
mountain cities lowering into the teens. No updates needed to the
forecast this evening.

&&

.SYNOPSIS...
High pressure will bring dry weather with a significant warming
trend through Wednesday with gusty northeast winds near the
coastal foothills and below passes and canyons at times...and some
passing high clouds at times. A fast moving Pacific low pressure
system will move inland through California on Thursday, bringing
cooling...strong gusty west winds in the mountains and
deserts...and a chance of light precipitation. Dry with a warming
trend for Friday through next weekend as high pressure aloft will
strengthen near the West Coast. Surface high pressure over the
Great Basin will bring periods of gusty northeast winds near the
coastal foothills and below passes and canyons.

&&

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

.PREV. DISCUSSION FROM 232 PM THIS AFTERNOON...
Breezy offshore winds will develop late tonight and continue
through Monday morning near the coastal mountain slopes and
canyons with gusts around 15-25 mph in the most wind favored
locations. Light offshore gradients will continue Monday and
become a little stronger Tuesday and Wednesday with some isolated
wind gusts over 40 mph possible in the most wind favored
locations. In addition the combination of high pressure and
offshore flow will bring above normal temperatures Tuesday and
Wednesday with many locations likely to reach around 10
degrees...and in isolated locations 15 degrees above normal with a
few readings around 80 degrees possible in the inland valleys.

A vigorous upper level trough will bring some light precip to the
mountains, coast and valleys on Thursday, along with some strong
and gusty westerly winds which will likely reach advisory level in
wind favored locations.

Strong ridging next weekend with offshore flow developing again
and dry conditions with above normal temperatures likely once
again.

&&

.AVIATION...
220330Z...Light winds, unrestricted visibility and SCT-BKN AOA
20,000 ft MSL through 06Z Tuesday.

&&

.MARINE...
Hazardous marine conditions are not expected through Wednesday.
Thursday into Friday, a Pacific storm system may bring another round
of strong northwest winds of 25 KTS or more, accompanied by rough,
elevated seas.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&

$$

UPDATE...JJT
PUBLIC...Brotherton
AVIATION/MARINE...Albright


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