Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 252147
AFDSGX

AREA FORECAST DISCUSSION
National Weather Service San Diego CA
247 PM PDT WED MAY 25 2016

.SYNOPSIS...
An upper level low over Southern California will move into Arizona
tonight with westerly winds increasing across the mountains and
deserts behind it. There is a slight chance of showers or
thunderstorms developing in the mountains through early this
evening. Weak ridging will build into the area slowly through
Friday before another trough moves into California for the
upcoming weekend. However, moisture will continue limited with
tranquil conditions forecast. Benign weather will continue into
next week along with slow warming as a ridge begins to build across
the area then.

&&

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

An upper level low over Southern California will move into Arizona
tonight. While colder air aloft has moved over the area, instability
is very limited with CAPE at only 100 J/KG now over parts of the
mountains. Moisture is very limited as well. So it is highly
uncertain in whether or not any showers or thunderstorms will
manage to get going over the next few hours over the far inland
valleys or mountains. Maintained the mention in the forecast as it
is low probabilities anyways and the potential, albeit low, still
is there.

It will turn windy tonight on the mountain tops and into parts of
the deserts, especially the desert slopes, as the low departs the
area to the east. Issued a Wind Advisory for these areas for
areas of gusty winds in the 40-50 mph range. Hi res model
consensus shows winds increasing across these areas this evening
then gradually subsiding late in the night.

As the upper low moves away, very weak ridging slowly builds Thu-
Fri before yet another trough moves down the state. This is a
weaker trough and will have limited moisture again. GFS does show
some light rain accumulations inland for the upcoming weekend, but
the ECMWF keeps it dry. Have favored the drier solution at this
time...given the limited moisture expected and low confidence in
any showers this weekend.

The latest run of the GFS keeps the upper trough hanging around
into early next week as it closes off into a low, while the ECMWF
is more progressive. Eventually, both show a ridge building in
from the Pacific by the middle part of next week...and either way
it looks to continue dry with the typical marine layer stratus
impacting the coasts/valleys each night and morning throughout the
period.

Temperatures will continue to run below average, but with slow
warming away from the coast. /Gregoria

&&

.AVIATION...
251945Z...Coast/Valleys...Mainly Broken clouds based around 3500-
5000 feet MSL with tops to near 7000 feet MSL. After around 26/02Z
low cloud bases re-developing below 3000 feet MSL. Risk of broken
low clouds below 3000 feet this afternoon is low.  Confidence in
broken low clouds below 3000 feet MSL returning overnight is moderate
to high but timing is low to moderate.

Mountains/Deserts...Mountain slopes obscured at times in clouds.
From 25/19Z til about 26/02Z thunderstorms possible with CB
tops to near 25000 feet MSL. West winds with gusts of 30-40 knots
will produce weak to moderate up/down drafts over and east
of the mountains through tonight.

&&

.MARINE...
100 PM...Wind gusts to around 20 knots this afternoon and evening.
Otherwise, no hazardous marine conditions are expected through Sun.


&&

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

&&

.SGX Watches/Warnings/Advisories...
CA...Wind Advisory from 5 PM this afternoon to 3 AM PDT Thursday for
     Coachella Valley-Riverside County Mountains-San Diego
     County Deserts-San Diego County Mountains-San Gorgonio Pass
     Near Banning.

PZ...None.
&&

$$

PUBLIC...Gregoria
AVIATION/MARINE...Small


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