Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 301022
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
322 AM PDT Thu Mar 30 2017

...Severe potentially damaging winds later today and this evening
over the mountains and deserts...

.SYNOPSIS...
For today a deep low pressure trough moving across the Great
Basin will bring strong and potentially damaging west winds to
the mountains and deserts. Cooler Friday behind the trough with
winds shifting to the northeast. High pressure rebuilding over
the region Saturday will bring sunny and warm weather this
weekend. Cooler early next week as another trough moves in from
the northwest.

&&

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

Low clouds and patchy fog have formed early this morning just off
the Rosarito coast. This will likely spread north and affect the
SD and Orange County coasts through mid morning.

A shortwave is quickly dropping SSE over the NorCal coast early
this morning and is rapidly strengthening per water vapor
satellite. This trough will deepen into a closed low later today
over the Great Basin and will be starved for moisture but will
introduce a very strong pressure gradient over Socal. Upper jet
support with 120 kt+ through about 06z this evening will support
very strong W-NW winds over the mountains and into the Mojave and
Coachella Valley and SD Deserts along with the possibility of
significant blowing sand and dust in the deserts. A high wind
warning remains in effect for this afternoon and evening.

As the low shifts to the east winds will shift to the north late
tonight and into Friday morning. There may be another period of
strong winds through Friday morning, although not nearly as
severe as what we are expecting with the WNW. Northerly winds
will continue through Friday night although not nearly as strong
but a wind advisory may be necessary to cover this period after
the threat for high winds has ended.

Ridging and moderating temperatures and lighter winds will build
in for Saturday and Sunday. An inside slider trough will bring
another cooldown Monday and Tuesday as well as another threat for
strong winds. Another ridge will build in for Wednesday and
Thursday for another period of moderating temperatures.

Mid latitude moisture transport and Pacific Jet will bring the
potential for widespread precipitation to Norcal by the end of
next week although it is looking like this system will not make it
down to Southern California. Will keep an eye on this though for
late season precip potential.

&&

.AVIATION...
300930Z...Patchy fog along the coast not likely to impact coastal
airports, and if so only briefly this morning. Bases would be around
500 feet msl with vis 3-5sm. Otherwise mostly clear skies today.
Coastal low clouds to develop and spread rapidly inland this evening
after 00Z, mostly in San Diego County. Bases will be rising 1000-
2000 feet msl.

Winds in mountains and deserts will increase this afternoon and
continue through tonight. Areas of winds 25-35 KT gusts 40-50 KT
after 20Z near mountain crests, desert mountain slopes and some
lower elevation desert locations. Some strong winds could occur at
KPSP and KTRM, with peak winds likely to be 23-04Z this
afternoon/eve, and KPSP could have a rotor at times with lighter
easterly winds. LLWS and strong up/downdrafts will also occur and
isolated vis reductions in blowing dust/sand in the deserts. Winds
will diminish after 06Z.

&&

.MARINE...
Strong west and northwest winds will develop this afternoon and
continue into early Friday, particularly in the outer coastal
waters. A small craft advisory contains the details on winds and
seas. In the outer waters winds will gust over 30 knots in spots and
seas will build to over 10 feet. Winds and seas will diminish Friday
morning. No hazardous marine weather is expected through Sunday, but
strong winds could return 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 from noon today to 11 PM PDT this evening for
     Apple and Lucerne Valleys-Coachella Valley-Riverside County
     Mountains-San Bernardino County Mountains-San Diego County
     Deserts-San Diego County Mountains-San Gorgonio Pass Near
     Banning.

PZ...Small Craft Advisory from 1 PM this afternoon to 8 AM PDT Friday
     for Waters from San Mateo point to the Mexican Border
     Extending 30 to 60 nm out including San Clemente Island.

&&

$$

PUBLIC...Brotherton
AVIATION/MARINE...MM



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