504 
fxus66 ksgx 210845 
afdsgx 


Area forecast discussion 
National Weather Service San Diego California 
100 am PST Friday Nov 21 2008 


Synopsis...a shallow marine layer will cause patchy coastal low 
clouds and fog during the nights and mornings. There will also be 
variable high cloudiness in westerly flow aloft. Upper level low 
pressure approaching from the west will bring more clouds and 
cooling next week with a chance of showers by middle week. 


&& 


Discussion...for southwest California including San Diego... 
Orange...southwest San Bernardino and West Riverside counties. 


Considerable high cloudiness is inhibiting nocturnal radiation 
resulting in minimal fog and low cloud coverage this morning. 
Developing offshore flow will also encourage early clearing. 
Variable high cloudiness will continue in west to SW flow aloft. 


The weak offshore flow will cause local gusty NE winds below passes 
this morning. Strongest gusts to 35 miles per hour will be below the Cajon Pass 
and in the Santa Ana Mountains. The brief dry offshore flow will 
locally increase fire weather hazard today but critical fire weather 
conditions are not expected. Gradients will become weak Sat then 
onshore sun. The marine layer will return and deepen a little 
tonight with more deepening Sat night. Warmer west of the mountains 
today due to offshore flow then a little cooler Sat. Maximum temperatures will 
still be about 5 to 10 degrees above seasonal inland Sat. More 
cooling sun as onshore flow increases. The cooling trend and 
deepening marine layer will continue Monday. 


An upper low off the coast will slowly shift east on Tuesday and could tap 
into tropical moisture. The low will cause more clouds and cooling 
with a chance of showers late Tuesday and Wednesday. The snow level will start 
very high due to mild SW flow ahead of the trough. The system could 
produce substantial rainfall on SW facing mountain slopes. Colder 
with a lowering snow level Thursday as the low moves through. Showers 
should taper off Thursday PM. 


&& 


Aviation... 
210900...high clouds will continue over socal through Saturday. 
Marine layer about 800 feet. Areas of dense fog along the coast and 
mesas this morning to about 5sm inland. Bases around 400 feet mean sea level. 
Offshore flow increasing through this morning...weaker Saturday 
morning. Offshore gradients should force fog/stratus out to sea 
early this morning in the north part with some hanging along the 
South Coast until around 16z-17z. Fog/stratus with marine layer 
remaining the same...returning this evening in the south part with 
none in Orange County. 


&& 


Sgx watches/warnings/advisories...none. 


&& 


$$ 


Public...mackechnie 
aviation...Whitlow