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Area forecast discussion
National Weather Service San Diego California
134 PM PDT Mon Oct 14 2019

Synopsis...
a trough of low pressure will spread cooling inland today with
weak offshore flow on Tuesday bringing several degrees of warming
on Tuesday and Wednesday. This will be followed by slow cooling
for Thursday into Saturday with a return of onshore flow.
Stronger offshore winds are possible for Sunday and Monday with
uncertainly on the timing and strength of the northeast winds.

&&

Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
counties...

Short term (tonight through wednesday)...
at 1 PM, water vapor satellite showed an upper-level low moving
across southern CA, and an upper-level ridge pushing into the
Pacific northwest. Low clouds will redevelop along the coast and coastal
valleys overnight, with lower bases than this morning.

Temperatures will quickly change tomorrow as the aforementioned
ridge builds across Southern California Tuesday and Wednesday. This will
help highs to increase back to seasonal normals and create a much
more shallow marine layer across the coast and valleys. Weak east
to northeast winds over coastal mountain slopes and adjacent
foothills Tuesday and Wednesday will help highs increase around 5
degrees above normal for most of the inland Empire. Highest gusts
will be between 20-30mph.

&&

Long term (thursday through monday)...
an upper-level trough quickly swings across Southern California Thursday,
helping to drop highs back below normal and deepen the marine
layer Thursday and Friday. Westerly winds will increase across the
region, with gusts of 30-40 mph and isolated gusts to 50 mph
possible across Desert Mountain slopes into adjacent desert areas
Thursday night. Cyclonic flow remaining over the West Coast will
maintain similar conditions into the beginning of the weekend.

Model ensemble solutions then start to disagree with the pattern
for early next week as high pressure builds to our west and a
trough moves by to the northeast. Depending on the path of the
trough, at least weak to potentially moderate offshore, Santa Ana
winds could develop across the region, with the strongest winds
being on Monday. Current estimates are east to northeast wind
gusts of 30-40 mph with isolated gusts to 50 mph, but until
models become better aligned this will likely change over the next
few days. The offshore flow will be accompanied with low relative
humidity over inland areas, therefore critical fire weather
conditions are possible through the period. Highs early next week
will be around 5 degrees below normal in the deserts to up to 10
degrees above normal along the coast.

&&

Aviation...
141955z...coast/valleys...mostly clear skies this afternoon. Patchy
areas of low clouds will return after 04z with bases 1500-2000 ft
mean sea level. Low clouds will not spread as far inland tonight. Scattered
conditions will return by 16z Tue.

Mountains/deserts...clear with unrestricted vis through Tue.

&&

Marine...
no hazardous marine conditions are expected through Saturday.

&&

Fire weather...
east to northeast winds are possible across the region twice this
week. The first round is expected to be weak Tuesday through early
Wednesday, with inland gusts of 20 to 30 mph along coastal
mountain slopes and through and below mountain passes. Minimum
relative humidity will be between 15-25%, and when combined with
the winds, will elevate fire weather conditions through the
period.

The second round, which has the potential to be stronger, could
develop Sunday into at least Monday as a system moves by to the
east and surface high pressure builds over the Great Basin.
Minimum relative humidity will lower to near 10% by Sunday, with
gusts of 30-40 mph, isolated gusts to 50 mph, possible across the
far inland valleys, along coastal mountain slopes and through and
below mountain passes on Monday. There is less confidence in the
strength and timing of stronger winds, however critical fire
weather conditions may develop on Sunday and continue into at
least Monday, especially for the mountains and valleys.

&&

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

&&

Sgx watches/warnings/advisories...
California...none.
Pz...none.
&&

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