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000 
FXUS66 KSGX 261638
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
930 AM PDT Sun Mar 26 2017

.SYNOPSIS...
Low clouds this morning will clear slowly today west of the 
mountains where temperatures will be a little below normal, with 
mostly sunny skies in the mountains and deserts and temperatures 
near normal. A low pressure trough will bring cooling Monday and a 
slight chance of showers along with locally gusty west winds. 
Offshore flow will develop Tuesday and bring gusty northeast winds 
below passes and canyons and fair warmer weather Tuesday through 
Wednesday. A low pressure trough will move by to the northeast 
Thursday or Friday and bring cooling again and gusty west winds 
followed by possible northeasterly winds again next weekend.

&&

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

Skies were mostly cloudy west of the mountains and mostly sunny 
elsewhere at mid-morning. Marine layer was 3500-4000 feet deep but 
with a weak inversion, but the depth of the marine layer may keep 
some areas mostly cloudy for awhile this afternoon west of the 
mountains. Temps will be a little below normal west of the mountains 
as a result of the deep marine layer.

A broad area of low pressure is currently off the Pac NW coast, and 
the trough will move E/SE and dig into So-Cal by Monday morning. 
Moisture will be rather limited here and be mostly under 850 MB, so 
any precip that occurs will be light, with best chances in San Diego 
County due to better westerly flow from over the water. We will 
maintain the slight chances of precip for now for Monday. Local wind 
gusts over 50 MPH could occur in the mountains and deserts Monday 
afternoon/evening due to the gradients aloft, though this will only 
be in the usual windy locations just east of the mountain crests and 
through San Gorgonio Pass. After the trough moves east late Monday 
night/Tuesday morning, a surface high from the Pacific will spread 
into Nevada and result in some weak to moderate offshore flow. We 
will likely need a wind advisory Tuesday below passes and canyons. 
Ridging from the west combined with the marine layer becoming either 
very shallow or non-existent will result in warmer days 
Tuesday/Wednesday.

By Thursday, the next trough will dig south over the interior 
western US, but the inland track will mean that precip chances will 
be quite low here, unless the trough ends up further west than what 
the models show. The main effects here will be the cooler weather 
and windy areas in the mountains and deserts. If the trough shifts 
east without closing off over the weekend, we should have fair 
warmer weather but with a possibility of offshore flow next weekend.

&&

.AVIATION... 
261455Z...BKN-OVC clouds filling the coast, valleys and locally into 
the lower mountain elevations, with bases 1500-2500 ft msl, tops 
around 3000 ft msl, local vis 3-5 sm, and possible mountain 
obscuration of lower coastal slopes, will gradually clear through 
1900 UTC, while elsewhere P6SM vis and FEW-SCT clouds AOA 20000 ft 
msl continues. 1900-27/0300 UTC, P6SM vis and SCT-FEW clouds AOA 
20000 ft msl all areas. 27/0300-1500 UTC, BKN-OVC stratus gradually 
re-developing in the coast, valleys and lower coastal mountain 
slopes, with bases 2000-3000 ft msl, tops 4000-4500 ft msl and local 
vis 3-5 sm.

After 27/0000 UTC, W to NW winds strengthening, becoming 15-25 kt 
with gusts 35-40 kt over the mountain ridges, desert slopes, 
passes/canyons and into wind-favored desert areas, resulting in mod-
strong up/downdrafts and LLWS over and east of the mountains.

&&

.MARINE...
Northwest winds will strengthen late today through Monday as a low 
pressure system passes across the region. Gusts of 25 kt are 
possible beginning this evening (mainly in the outer waters) and 
then gusts could reach 30 kt on Monday in both the inner and outer 
waters, in addition to combined seas rising to near or above 10 ft. 
Locally strong and gusty northwest winds may continue through most 
of Tuesday before diminishing that evening. A Small Craft Advisory 
goes into effect at 5 pm today and continues through early Tuesday 
evening.

&&

.BEACHES...
West-northwest swells from around 285-290 degrees will create 
elevated surf of 3-6 feet today through most of this week. Sets of 7 
feet will be possible at times. These surf conditions will be 
accompanied by an increased risk of strong rip currents through the 
period. 

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 5 PM this afternoon to 8 PM PDT 
     Tuesday 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.

&&

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