Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 240420

Area Forecast Discussion
National Weather Service San Diego CA
920 PM PDT Tue Oct 23 2018

A weak trough will bring seasonal weather through Wednesday. The
weather will turn much warmer Thursday through Saturday as high
pressure aloft builds over the Southwest. The marine layer will
become shallower and the surface winds will turn weakly offshore.
Sunday and Monday will not be quite as hot west of the mountains as
the ridge weakens and a Pacific trough increases the low level
onshore flow.




Highs today ranged from 60 at Baldwin Lake to 95 at Thermal. The
national high was 97 at Death Valley.

Marine layer stratus is impacting parts of the San Diego coast and
valleys, but not so much in Orange County yet. Some high level
cloudiness has moved into that area but is moving fast. Am
expecting still some stratus to form along the OC coast as well,
but not extending as far inland as last night. No significant
changes were made to the forecast this evening.

...Previous Discussion (Issued at 140 PM PDT Tue Oct 23 2018)...

Low clouds surged into coastal San Diego County this afternoon,
which didn`t occur Monday afternoon. These marine layer clouds may
scatter out for a time this afternoon or evening, but then reform
and move back inland overnight. The low clouds probably won`t spread
as far inland tomorrow morning as heights rise from 574 dm this
morning to 578 dm Wednesday morning. There will be even less low
cloud cover Thursday morning as heights rise to 582 dm and high
pressure aloft gains more traction.

A 589 dm high over the eastern Pacific will build over Southern
California Friday and Saturday bringing hot days and weak
offshore flow. The offshore winds will not be very strong, but the
easterly downslope flow will help some of the valleys to warm
into the 90s. Coastal highs will be in the 80s, and mountain highs
will range from the mid 80s at 4000 feet to the mid 60s above
9000 feet. The High Deserts will be in the mid 80s, and the Low
Deserts in the mid 90s.

The high will start to break down Sunday as a trough of low pressure
moves inland to the north. This trough will bring cooler weather
early next week with lower heights and somewhat stronger onshore

The long range models this morning forecast a closed upper low
west of Northern Baja Monday morning, which is a relatively new
development. Right now it is projected to bring upper level moisture
and high clouds into SoCal next Monday and Tuesday.


240330Z...Coast/Valleys...Patchy low clouds have begun to move into
the coastal TAF sites. Low clouds will increase in coverage between
05-06Z tonight and spread 15-20 miles inland. Ceilings between 600-
1000 ft will impact KSAN, KCRQ, and KSNA after 06Z with fog and
reduced visibility of 3-5 miles possible. Scatter out expected 14-
15Z inland and 16-17Z on the coast Wednesday morning.

Deserts/Mountains...Clear skies and light winds through the period.


No hazardous marine weather is expected through Saturday.


Skywarn activation is not needed.




PUBLIC...Gregoria (Update)/Moede (Prev Discussion)
AVIATION/MARINE...Connolly is the U.S. government's official web portal to all federal, state and local government web resources and services.