Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 200412
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
912 PM PDT Thu Apr 19 2018

.SYNOPSIS...
Drier weather tonight, with gusty winds diminishing in the
mountains and deserts. High pressure will take hold Friday and
remain in control through early next week, bringing quiet and
warmer weather to the region. Cooler to end next week with the
potential for a trough of low pressure along the West Coast.

&&

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

At 9 PM, water vapor satellite imagery displayed an upper-level
low centered over the NV/UT/AZ border with northwest flow over
southern CA. Surface observations showed wind gusts of 35-45 mph
over portions of the mountains and lower deserts. A few higher
gusts are possible over the next few hours, then winds will
quickly diminish across the area. No extensions of the wind
products are expected at this time. Peak wind gusts so far have
been 64 mph at Volcan Mountain, 63 mph at Harrison Park and
Whitewater and a 56 mph was reported at Palm Springs International
Airport. A few hundredths of an inch of precipitation were
observed earlier today as the trough moved across the area, with a
tenth or two reported along the coastal mountain slopes. Only
minor updates to the sky forecast this evening to account for low
clouds along portions of the coast tonight and tomorrow night.

Weak ridging will develop over the region Friday and remain in
control through early next week. This will bring a rapid warming
trend to the region with afternoon highs returning to 5-10 degrees
above seasonal normals Saturday/Sunday. A weak closed low may
drift over the region Saturday night and Sunday, but impacts
should be limited to a few high clouds. Other than temperatures,
winds will be light, with no impactful weather forecast through
the early next week.

Global models continue hint at the development of a closed low
along the West Coast by late next week. The track/strength of this
low remains in question, with better agreement in recent runs of
the deterministic ECMWF/GFS being undercut by significant spread
in their corresponding ensembles.

&&

.AVIATION...
200330Z...Coast/Valleys...SKC-SCT025 most areas except BKN020-030
near the foothills through 15Z Friday. After 15Z...SKC-SCT030
through 23Z.

Mountains/Deserts...Northwest winds 20-30kt gusting to 45kt down the
eastern slopes into the lower deserts through 08Z. From
08-12Z...winds diminishing to 10-20kt.

West facing mountains slopes and foothills occasionally obscured in
clouds and fog 15Z Friday. After 16Z...mostly clear with
unrestricted visibility.

&&

.MARINE...
Small Craft Advisory in effect until 2 AM for gusty northwest winds
15-25kt and choppy seas associated with a short period wind swell,
primarily over the Outer Waters. No hazardous marine weather is
forecast Friday through Monday.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...High Wind Warning until 2 AM PDT Friday for Coachella Valley-
     Riverside County Mountains-San Diego County Deserts-San
     Diego County Mountains-San Gorgonio Pass Near Banning.

     Wind Advisory until 11 PM PDT this evening for Apple and Lucerne
     Valleys-San Bernardino County Mountains.

PZ...Small Craft Advisory until 2 AM PDT Friday for Coastal Waters
     from San Mateo Point to the Mexican Border and out to 30 nm-
     Waters from San Mateo point to the Mexican Border Extending
     30 to 60 nm out including San Clemente Island.

&&

$$

PUBLIC...JJT
AVIATION/MARINE...Moede



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