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FXUS66 KSGX 142034

Area Forecast Discussion
National Weather Service San Diego CA
134 PM PDT Mon Oct 14 2019

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. 



At 1 PM, water vapor satellite showed an upper-level low moving 
across southern CA, and an upper-level ridge pushing into the 
Pacific NW. 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 CA 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.


An upper-level trough quickly swings across southern CA 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.


141955Z...Coast/Valleys...Mostly clear skies this afternoon. Patchy 
areas of low clouds will return after 04Z with bases 1500-2000 ft 
MSL. Low clouds will not spread as far inland tonight. SCT 
conditions will return by 16Z Tue. 

Mountains/Deserts...Clear with unrestricted vis through Tue. 


No hazardous marine conditions are expected through Saturday.


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

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



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