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Area Forecast Discussion (AFD)

Issued by San Diego, CA (SGX)

FXUS66 KSGX 180955

Area Forecast Discussion
National Weather Service San Diego CA
255 AM PDT Mon Jun 18 2018

warming trend this week as high pressure strengthens over 
Southern California. The marine layer will become more shallow 
with less extensive low clouds and fog. Inland temperatures will 
rise to above average Tuesday through Friday. Slightly cooler 
next weekend as high pressure weakens.



Low clouds have once again pushed into the coastal slopes of the
mountains and have pushed through the Cajon Pass this morning. 
Fog may impact travel along 1-15 through the pass through mid- 
morning. Clouds have already begin clearing over the Inland 
Empire. Given how patchy and somewhat thin they are, expect 
earlier and more widespread clearing than previous days. Otherwise
warmer today as the upper level trough begins to lift out of the 

More considerable warming is expected Tuesday through Thursday as
an upper level ridge of high pressure strengthens over Southern CA
and northern Baja. Inland, high temperatures will rise to around 5
to 10 degrees above normal. The low deserts will once again see
high temperatures of over 110 degrees in some areas. Fortunately 
it'll be clear and dry, so it should cool down into the 70s 
overnight. Areas west of the mountains will begin to cool on
Friday as the ridge axis shifts east, though the deserts will
continue to warm. A shallow marine layer will help keep the 
coastal areas cool, with night and morning low clouds and fog 
continuing. Beaches may remain foggy through much of the 
afternoon, especially on Wednesday and Thursday as the ridge is 
the strongest. 

The ridge weakens slightly this weekend in response to an upper 
trough moving through the great basin, bringing minor cooling and
a gradual deepening of the marine layer.  


180930Z...Coast/Valleys/Coastal Mountain Slopes...Multiple low cloud 
decks, with bases from 2800-4000 ft MSL and tops near 4500 ft MSL, 
will become more patchy over the next few hours. Some areas of the 
coastal basin may clear, then have stratus redevelop throughout the 
morning. Bases may also lower a few hundred feet by sunrise. Low 
clouds should clear over inland areas by early afternoon, then 
redevelop along the coast this evening, with bases around 1500 ft 
MSL. VIS may lower to 2-4 SM BR where low clouds near higher 

Desert Mountain Slopes/Deserts...Mostly clear with unrestricted VIS 
through tonight. Gusty northwesterly winds will continue to diminish 
over the next few hours.


Gusty west northwest winds near 20 kt will develop this afternoon 
and evening. Otherwise, no hazardous marine weather is expected 
through Friday.


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