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Area Forecast Discussion (AFD)

Issued by San Diego, CA (SGX)

FXUS66 KSGX 140442

Area Forecast Discussion
National Weather Service San Diego CA
845 PM PST Thu Dec 13 2018

A weak trough of low pressure will bring occasional high clouds 
through Sunday. There is a small chance for light showers on Monday 
when a stronger trough moves inland across the region. Then a Santa 
Ana pattern will bring warm, dry weather Wednesday through Friday. A 
high surf event is expected early next week.



Gusty offshore winds were confined to the mountains and foothills 
Thursday with a peak gust of 61 mph at Sill Hill. This was a very 
localized gust as the second highest gust was 46 mph at Buckman 
Springs. Lighter offshore winds made there way into the coastal 
areas and the warm, downslope flow produced highs in the 70s and 
80s. Fullerton, Anaheim, and Santa Ana all had a high of 80 degrees. 
The San Diego Airport had a high of 78 at 1 PM with a low RH of 22%. 
Just one hour later the temperature had fallen to 68 and the RH 
jumped to 63% as the afternoon seabreeze pulled cool marine air into 
the coastal zones.   

The atmosphere is still quite dry this evening with a PWAT of 0.35" 
on the NKX sounding, but this value will increase Friday as high 
level moisture moves in from the southwest. The IR satellite showed 
a large swath of thick high clouds advancing toward SoCal this 
evening that will overspread the area tonight and Friday. Saturday 
may feature a little more sun with weak ridging aloft, then more 
clouds return Sunday ahead of a stronger trough that will move 
inland on Monday. This second trough will bring greater cooling, a 
deeper marine layer, and the chance for a few light showers west of 
the mountains on Monday. 

After the trough moves east on Tuesday, a building ridge of high 
pressure over the Great Basin with bring moderately strong offshore 
flow Wednesday through Friday with warmer days and gusty Santa Ana 


140350Z...Increasing clouds AOA 20000 ft MSL and unrestricted vis 
through Friday evening. Areas of NE-E surface wind gusts of 20-30 kt 
will continue through Friday morning mainly below mountain passes 
and near the foothills.


No hazardous marine weather is expected through Sunday. A large WNW 
swell Monday and Tuesday will likely generate seas of 10-13 feet, 
highest in the outer coastal waters.


A 11-13 ft/18-20 sec west-northwest swell from 290 degrees is 
forecast to arrive Monday and continue through Tuesday. Surf of 6-12 
feet with locally higher sets is possible, highest in southern San 
Diego County. Strong rip currents and dangerous swimming conditions 
are likely at all beaches.


Skywarn activation will not be needed Friday.