Area Forecast Discussion
Issued by NWS San Diego, CA

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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.

&&

$$

PUBLIC...Maxwell
AVIATION/MARINE/BEACHES...Harrison



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