984 
fxus66 ksgx 200436 
afdsgx 


Area forecast discussion 
National Weather Service San Diego California 
930 PM PST Wednesday Nov 19 2008 


Synopsis...a shallow marine layer will cause areas of coastal low 
clouds and fog during the nights and mornings. Fog will be locally 
dense tonight and Thursday morning. Variable high cloudiness in 
westerly winds aloft. Upper level low pressure will bring more 
clouds and cooling next week. 


&& 


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


Short term (tonight-sat)...there were areas of low clouds and dense 
fog in the San Diego coastal areas this evening. Clear elsewhere. 
The 00z nkx sounding had a weak inversion based below 1000 feet with 
dry westerly winds aloft. Weak offshore gradients from the north and onshore 
to the east. 


An upper trough will move past far to the north on Thursday followed by flat 
or weakly cyclonic flow aloft through Sat. The marine layer will 
remain shallow and mostly confined to the coastal areas with local 
dense fog during the nights and mornings. Offshore flow will develop 
from the north Friday and turn offshore from the NE Sat. The offshore flow 
will be mainly gradient driven and weak. The strongest winds will be 
trough and below the Cajon Pass and in the Santa Ana Mountains where 
they could gust to about 35 miles per hour Friday morning...becoming even weaker 
Sat morning. The offshore flow will reduce the marine layer 
cloudiness...especially in Orange County. A little cooler Thursday...but 
maximum temperatures will still be 5 to 10 degrees above seasonal inland. Minor 
temperature changes or slight cooling in the mountains and deserts Friday and 
Sat but a little warmer west of the mountains due to the weak offshore 
flow. Westerly winds aloft will bring variable high cloudiness. 


&& 


Long term (sun-wed)...an upper trough in the eastern Pacific will slowly 
approach the West Coast. This will bring more clouds and cooling. There 
will be a small chance of showers by late Tuesday or Wednesday but there is 
still a lot of uncertainty that far out and will only indicate low 
probability of precipitation for now. 


&& 


Fire weather...higher relative humidities and lower temperatures at 
the coast will be spread inland as the offshore flow continues to 
weaken. The moistening and cooling trend will continue into Thursday. The 
flow reverses Friday..and weak offshore flow will develop...with the 
main effects in the mountains and valleys. Although conditions will 
be dry and warm...critical fire weather values are not expected to 
be reached. 


&& 


Aviation... 
200430z...areas of stratus and fog will occur along the coast 
overnight...most prevalent in San Diego County. Bases will generally 
be around 400-500 feet mean sea level with areas of dense fog expected over The 
Mesas...higher immediate coastal terrain and locally over lower 
terrain as well. Ksan will have visible mostly above 2 miles 
overnight...but kcrq will likely have visible below 1/2 mile by 07z. 
Ksna could have dense fog...with visible below 1/2 mile...after 11z. Most 
areas should clear by 17z Thursday. Stratus/fog could again impact 
immediate coastal areas Thursday night...especially in San Diego County. 


Above the marine layer...mostly clear skies with unrestricted 
visibilities will continue through Thursday. 


&& 


Sgx watches/warnings/advisories...none. 


&& 


$$ 


Public...atkin 
aviation...Maxwell