Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 281108
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
408 AM PDT Fri Apr 28 2017

.SYNOPSIS...
A Santa Ana Weather Pattern will bring very strong northeast winds
to the mountains, inland valleys and some of the Orange County
Coastal areas tonight through Saturday afternoon. Fair weather
conditions with mainly clear skies Sunday through Wednesday with
temperatures rising a bit above normal.

&&

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

Gusty northerly winds will continue this morning in the western
San Bernardino County Mountains and then gradually diminish this
afternoon. A strong upper level jet dives south along the lee of
the Sierra later today as an upper low inside slider deepens over
the 4 corners area. This will usher in a stronger NE wind pattern
and bring a strong Santa Ana wind event to the coastal slopes of
the San Bernardino Mountains, northern Inland Empire, Santa Ana
Mountains, and portions of the Orange County Coast. Gradients
remain onshore at the immediate coast today but offshore flow will
deepen inland and then become quite strong tonight as the low
deepens to the east. Because of the strong winds expected, the
high wind watch has been upgraded to a warning and a wind advisory
has also been issued for the San Diego Valleys, Mountains, and the
Riverside Mountains, where offshore winds will not be quite as
strong but still likely to reach advisory level.

The strong offshore flow will cause temperatures to spike to well
above normal in the valleys and a few miles inland from the coast
in the most favored areas. A few locations in the valleys will
likely reach into the lower 90s on Saturday.

Santa Ana winds will diminish Saturday evening and night as
onshore flow becomes re-established and an area of high pressure
just off the coast strengthens. For Sunday temperatures near the
coast and in the valleys will cool back down to near normal
levels, but warm air will remain in place over the mountains and
deserts with above normal temperatures continuing there.

Temperatures over the mountains and deserts next week will
continue above normal. Temperatures in the valleys and near the
coast will likely remain near normal as the upper high remains
just offshore with periods of light onshore flow near the
coast. Later in the week the upper level ridge shifts east for
Wednesday into Thursday into the deserts with a widespread warmup
possible across SoCal.

&&

.AVIATION...
281000Z...SCT/BKN stratus, with bases 1200-2000 ft MSL and tops to
2500 ft MSL, will continue along the coast and coastal valley
locations (mainly in San Diego County) this morning. North to
northeast wind gusts of 30-40 kt will develop along coastal mountain
slopes into adjacent foothills of San Bernardino County Mountains
this morning, then stronger and more widespread northeasterly winds
develop along coastal mountain slopes across the region tonight. Mod-
strong uddfs/llws are expected at times over and east of the
mountains. Otherwise, SCT clouds AOA 20000 ft MSL through this
evening.

&&

.MARINE...
Northwest wind gusts of 25-30 kt will continue through late tonight.
A short-period, choppy swell from 290 degrees will also increase to
9-12 ft by this evening. A Small Craft Advisory continues for the
waters through early Saturday morning.

&&

.BEACHES...
An elevated swell from around 290 degrees will create surf of 3-6
ft, with local sets to 7 ft today. Highest sets will be along west-
facing beaches. Surf will begin to lower on Saturday. Strong rip
currents are likely through the period.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory from 10 PM this evening to 2 PM PDT Saturday for
     Riverside County Mountains-San Diego County Deserts-San
     Diego County Mountains-San Diego County Valleys-San
     Gorgonio Pass Near Banning.

     High Wind Warning from 10 PM this evening to 2 PM PDT Saturday
     for Orange County Coastal Areas-Orange County Inland Areas-
     San Bernardino County Mountains-San Bernardino and
     Riverside County Valleys-The Inland Empire-Santa Ana
     Mountains and Foothills.

PZ...Small Craft Advisory until 5 AM PDT Saturday 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...Brotherton
AVIATION/MARINE/BEACHES...JJT



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