Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 262043

Area Forecast Discussion
National Weather Service San Diego CA
143 PM PDT Thu Apr 26 2018

Gradually cooler through the weekend, with increasing low clouds
spreading inland to the coastal mountain slopes. Expect stronger
onshore flow with strong and gusty southwest to west winds in the
mountains and deserts during the afternoons and evenings. For
Monday and Tuesday...cooler with stronger onshore flow and gusty
northwest to west winds in the mountains and deserts, further
deepening of the marine layer with small chances for light
precipitation along and west of the mountains.



This afternoon...mostly clear, except over the coastal waters
where some areas of low clouds remain. Sfc pressure gradients
continue to trend onshore with 5.0 mb SAN-TPH and 8.5 mb SAN-TRM.
Low clouds should once again spread inland tonight.

From previous discussion...
A low pressure system currently off the coast of northern
California will move slowly inland during the weekend. This will
bring stronger onshore flow to Southern California with slow
cooling spreading inland. The low pressure system will draw
subtropical moisture with some mid and high clouds into Southern
California today...decreasing tonight and Friday. As the marine
layer slowly deepens...night and morning low clouds and fog will
spread inland to the coastal slopes Friday through the weekend.
Stronger onshore flow will also bring periods of gusty southwest
to west winds in the mountains and deserts during the afternoons
and evenings.

For early next week...the global models are in better agreement
with a low pressure system from the northwest that will move into
Southern California Tuesday. This will bring additional cooling
for Monday and Tuesday. There will be stronger and gusty
northwest to west winds in the mountains and deserts. The marine
layer will deepen onto the coastal mountain slopes. There are
small chances for light precipitation west of the mountains early
Monday and slightly greater chances for light precipitation along
and west of the mountains for Tuesday into early Wednesday.

For next Thursday and Friday...An upper level ridge building in
from the west will bring fair and warmer weather with lighter
winds and a shallower marine layer.


262030Z...Coast/Valleys...Mostly VFR conditions through early
evening. Stratus, with bases around 1500 ft MSL and tops to 2500 ft
MSL, will redevelop along the coast this evening and spread into the
far inland valleys overnight. Low VIS of 2-4 SM HZ will develop
inland where low clouds near higher terrain. Stratus will clear
towards the coast by late Fri morning.

Mountains/Deserts...Local surface west northwest wind gusts of 30-40
kt will occur late this afternoon through tonight over portions of
the desert mountain slopes and through San Gorgonio Pass.


No hazardous marine conditions are expected through tonight. West to
northwest winds will strengthen Friday, with gusts of 25 to 30 kt
possible through Saturday evening over the outer waters. Combined
seas will also increase to 6-9 ft. A Small Craft Advisory has been
issued for the period.


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


PZ...Small Craft Advisory from 2 PM Friday to 10 PM PDT Saturday for
     Waters from San Mateo point to the Mexican Border Extending
     30 to 60 nm out including San Clemente Island.



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