Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 040400
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
800 PM PST Sat Dec 3 2016

.SYNOPSIS...
Gusty northeast winds will continue tonight near the mountains and
foothills but continue to decrease elsewhere. Under clear skies, it
will be another chilly night where winds stay light, with fair and
warmer weather on Sunday. Cooler with increasing clouds, higher
humidity, and onshore flow early next week. Offshore winds and
warming will follow for the latter half of next week.

&&

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

...Evening Update...

Winds have diminished greatly this evening. A post-storm map was
issued recently to highlight the areas of high winds that occurred
over the past two days, as well as a storm summary report.

Hi-res HRRR model is showing brief resurgence of Santa Ana winds
later this evening due to a brief enhancement to the offshore
pressure gradient. These strong winds will again decrease before
daybreak Sunday morning.

Sunday will be a bit warmer with lighter winds region-wide. It will
also be abundantly sunny with high pressure still in control of the
synoptic pattern.

No significant changes were made to the evening forecast update.

...Previous discussion, issued at 1252 PM PST...

Surface pressure gradients were relaxing to the deserts late this
morning, but remained at 6 MBS SW NV to KSAN. Weak onshore gradients
were in place to the lower deserts. Peak wind gust reports were all
under 45 MPH at midday.

It will be another chilly night as the dry air gives up what heat it
gathered today. In some of the sheltered valleys temperatures will
fall to near the freezing mark briefly with patchy frost possible.
Where some winds continue, it will be much more mild.

The wind warning/advisory is no longer in effect since winds have
decreased below advisory strength. The northeast winds are likely to
pick up again locally, later this evening over portions of the Santa
Ana and San Diego County Mountains, with some gusts near or above 45
MPH possible.

Strong surface high pressure over the Great Basin will weaken
through Sunday as a cut-off, upper-level low pressure center slips
SE along the west coast of Mexico. This will relax the pressure
gradient across the southland allowing wind to drop off for those
areas that still have wind today. After a sunny and warmer day under
a weak upper-level ridge on Sunday, a broad trough will develop
south across the Rockies and Great Plains. This will turn flow back
onshore with cooler weather and more clouds as the marine layer
rebuilds.

By midweek, the surface flow turns back offshore as high pressure
rebuilds over the Great Basin and Rocky Mountains. This will bring
Fair and warmer weather through Friday.

&&

.AVIATION...
040400Z...Northeast wind gusts of 30 to 40 knots will continue
through early tonight over mountain crests and along coastal
mountain slopes. Local LLWS will occur in the area, along with
strong up/downdrafts. Winds will very slowly decrease tonight.
Otherwise, clear skies and unrestricted vis will prevail through
Sunday.

&&

.MARINE...
No hazardous marine weather is expected through Thursday.

&&

.FIRE WEATHER...
Gusty north to northeast winds have continued to weaken this evening
across the region. A minor surge of Santa Ana winds is still likely
to occur later this evening over the Santa Ana Mountains, and
relative humidity will have very poor recovery once again, with near
critical conditions over the Santa Ana Mountains. Therefore the Red
Flag Warning remains in effect for the Santa Ana Mountains/foothills
until 3 AM PST. Conditions will improve Sunday with lighter winds
and slight RH recovery.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Red Flag Warning until 3 AM PST Sunday for Santa Ana Mountains-
     Including The Trabuco Ranger District of the Cleveland
     National Forest.

PZ...None.

&&

$$

PUBLIC/FIRE WEATHER...JMB
PREVIOUS DISCUSSION...JAD
AVIATION/MARINE...JJT



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