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Area Forecast Discussion (AFD)

Issued by San Diego, CA (SGX)

FXUS66 KSGX 202059

Area Forecast Discussion
National Weather Service San Diego CA
159 PM PDT Fri Apr 20 2018

Tranquil and warmer weather conditions will prevail across
Southern California through the upcoming weekend. The marine 
layer and weak onshore flow will keep coastal temperatures near 
average with areas of night and morning low clouds and fog. For 
Tuesday through Friday...a low pressure system over the eastern 
Pacific will move slowly towards the West Coast. This will bring 
slowly increasing onshore flow and slow deepening of the marine 
layer with night and morning low clouds and fog extending into 
portions of the valleys. Slow cooling will spread into the valleys
with periods of gusty southwest to west winds in the mountains 
and deserts.



The overall weather pattern through the weekend will feature dry
and warm conditions across the area. The overall pattern features
a departing upper level low to the east with heights rising
locally. An upper level trough will move south of the area this
weekend with no consequence. The result will be warm temps
continuing through the weekend along with dry weather conditions.

Marine layer cloudiness and fog is forecast to develop over the
ocean tonight with some clouds and perhaps fog moving in towards
dawn on Saturday. However, confidence in fog is low at this time
with little marine layer stratus even west of the islands.

The pattern next week will feature an upper level trough moving
slowly towards northern and central California. Southwest wind
flow ahead of this trough will result in a more inland penetration
of nighttime and morning marine layer cloudiness. However, it
looks as though Southern California will remain under tranquil
conditions. Winds could pick up in the mountains and deserts as 
this trough finally moves onshore the NorCal coast next Fri-Sat
along with slightly cooler temperatures.


201950Z...Coast/Valleys...Clear with unrestricted vis through this 
afternoon. Patchy low clouds return to the coastal areas after 02Z 
Sat, increasing in coverage after 07Z with bases around 1000 ft MSL. 
Bases could lower to around 700 ft MSL with vis 3-5 miles in fog. 
Confidence in impacts at coastal TAF sites is moderate but timing is 
uncertain. Any ceilings that develop should clear between 14Z and 
16Z Sat.


No hazardous marine weather is expected through Tuesday.


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