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Area Forecast Discussion (AFD)

Issued by San Diego, CA (SGX)

FXUS66 KSGX 162105

Area Forecast Discussion
National Weather Service San Diego CA
155 PM PDT Thu May 16 2019

The persistent west coast trough continues to be the strong driver 
for the weather in the southwest. Persistent, mainly onshore flow 
will continue to weaken and strengthen at times due to Pacific 
frontal systems moving through the main trough position and into 
Southern California. Periods of showers should accompany the mainly 
weak Pacific storms. Decreasing showers this evening and Friday 
morning is expected, with additional drying expected Friday into 
Saturday, but then then another similar low will bring another 
period of cooling, gusty winds, and precipitation for Sunday into 
early Monday. By late Monday drying and warming is expected. Yet 
another low pressure system is expected for the middle part of next 
week that will bring more cooling, gusty winds, and additional 
chances of precipitation Southern California.



.SHORT TERM (Today through Saturday)...
The west coast trough has pretty much decided that winter weather 
will continue deep into spring in SOCAL as the the jet remains 
rather robust in the area. The mainly decaying cold fronts are 
remaining strong enough to bring some light to moderate 
precipitation to the area at times. Occasional showers will linger 
near the mountains into the evening and for areas of San Diego 
County from the coast tonight into Friday morning. Additional 
amounts should generally be around a trace. 


.LONG TERM (Sunday through Wednesday)...
Ensembles and the local WRF model continue to indicate that the next 
low pressure system is expected to arrive on Sunday bringing another 
round of cooling, precipitation, and gusty winds for Sunday and 
early Monday. For late Monday into Tuesday, it will be drier and a 
little warmer under weak high pressure. For Wednesday and Thursday, 
the mean trough of low pressure will be centered in the vicinity of 
the southwest states with below average temperatures, gusty winds in 
the mountains and deserts, and additional chances of precipitation. 


162000Z...Coast/Valleys/Coastal Mountain Slopes: 
Coastal TAF sites are beginning to scatter out at this hour, and 
clouds will continue to scatter out west to east this afternoon. SCT 
cloud bases will be around 2500-3500 ft MSL. The main band of rain 
has moved through the area, however, a few scattered showers are 
possible through the afternoon. Some low clouds redeveloping in the 
Inland Empire and in San Diego County overnight with bases around 
2500 feet. Scatter out expected after 17Z Friday. 

Desert Slopes/Deserts: Clouds in the desert slopes with bases down 
to 10000 feet MSL through 22Z with light rain near higher terrain, 
clearing shortly thereafter. West wind gusts reaching 45-50 kts, 
strongest after 23Z. MOD-SVR UDDFS likely.  


Strong westerly winds this afternoon through Friday evening with 
gusts 25-30 kts. A Small Craft Advisory is in effect through 11 PM 
Friday evening. Brisk winds Saturday afternoon will gust over 20 
kts, but winds will increase more on Sunday through Monday with 
hazardous boating conditions possible again.


CA...Wind Advisory until 11 AM PDT Friday for Apple and Lucerne 
     Valleys-Coachella Valley-Riverside County Mountains-San 
     Bernardino County Mountains-San Diego County Deserts-San 
     Diego County Mountains-San Gorgonio Pass Near Banning.

PZ...Small Craft Advisory from 11 AM this morning to 11 PM PDT Friday 
     for Coastal Waters from San Mateo Point to the Mexican 
     Border and out to 30 nm-Waters from San Mateo point to the 
     Mexican Border Extending 30 to 60 nm out including San 
     Clemente Island.