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FXUS66 KSGX 231050

Area Forecast Discussion
National Weather Service San Diego CA
250 AM PST Thu Nov 23 2017

High pressure aloft near the West Coast and very weak offshore
flow will continue record setting heat today inland from the
beaches. The cooling will spread slowly inland for Friday into the
weekend with greater cooling for Sunday and Monday with stronger
and gusty west winds in the mountains and deserts. There is the 
potential for a moderate strength Santa Ana wind event next 
Tuesday into Wednesday with the strongest and most widespread
winds on Tuesday.



High pressure aloft across Southern California will weaken
slightly through Saturday with greater weakening for Sunday and
Monday as a trough of low pressure moves inland along the West
Coast and into the Great Basin.

Record setting heat will continue today away from the beaches
where a return of weak onshore flow will bring some cooling. The
slow cooling developing near the beaches today will spread slowly
inland through Saturday with greater cooling for Sunday and Monday
as the low pressure system moving inland along the West Coast
brings stronger onshore flow for Southern California with gusty
west to southwest winds for the mountains and deserts. 

As that low pressure system moves inland...high pressure aloft
will develop along the West Coast with surface high pressure over
the Great Basin. A period of moderate strength Santa Ana winds is
possible for Tuesday...weakening some on Wednesday. There remain
some timing and intensity differences among the global models.
Those winds combined with a very dry air mass could bring critical
fire weather conditions for Tuesday and Wednesday with the
strongest winds on Tuesday.


231010Z...Mostly clear with unrestricted vis through Friday morning.

No hazardous marine weather is expected through Monday.


Elevated fire weather conditions will continue today for inland
areas with lowest humidities around 15 percent. Northeast winds
near the coastal foothills will be weaker than on Wednesday with
gusts mostly 30 mph or less this morning. Humidities will slowly
recover for Friday through the weekend.

For next Tuesday and Wednesday...a moderate strength Santa Ana
wind event is possible with lowest daytime humidities of 5 to 10 
percent...and with the strongest and most widespread northeast 
winds on Tuesday.


Forecast high temperatures that could be near or exceed existing
record high temperatures through Thanksgiving...

For today... 
Location       Forecast       Current Record
San Diego         86              86 in 1950
Vista             89              83 in 1975
Chula Vista       89              87 in 1924
Riverside         92              91 in 1995
Escondido         92              90 in 1949
El Cajon          94              86 in 1995
Ramona            91              89 in 1995
Alpine            89              86 in 1995
Big Bear Lake     72              68 in 1981 
Idyllwild         76              75 in 1954
Palomar Mountain  77              75 in 1954
Campo             89              82 in 1995 
Palm Springs      91              94 in 1950 
Thermal           91              93 in 1950
Borrego Springs   90              88 in 1989

There will likely also be some record warm minimum temperature
records set...and a few additional high temperature records tied 
or broken on Friday.


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




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