034 
fxus66 ksgx 072031 
afdsgx 


Area forecast discussion 
National Weather Service San Diego California 
230 PM PDT Thursday Aug 7 2008 


Synopsis...moisture in southeast flow aloft will cause scattered 
showers and thunderstorms in the mountains and deserts...mainly 
during the afternoons...decreasing Friday and Saturday. A shallow 
marine layer and onshore flow will bring coastal low clouds and fog 
during the nights and mornings...extending locally inland. 
Otherwise...fair under high pressure. 


&& 


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


Short term (today-sun)...there was lots of middle level moisture and 
clouds today. Isolated showers and thunderstorms...mainly in the 
mountains and deserts but a few also developed in the inland valleys 
near the foothills. Status was extensive offshore. Early afternoon 
acars soundings indicated an inversion based near 1200 feet with weak 
southeast to S winds aloft. Onshore gradients to the east with about 5 mb 
san-ipl. 


The pattern of upper level high pressure over the SW with a 
weakening trough to the northwest will prevail through the short term. The 
moist unstable air mass...combined with weak winds aloft...will 
bring a chance of slow moving thunderstorms to the mountains and 
deserts through the remainder of this afternoon. As a result...a 
Flash Flood Watch is in effect until 8 PM. A few showers could also 
drift into the inland valleys during the remainder of this 
afternoon. Models have been inconsistent on the moisture fields. 
There should be a little drying Friday and then the moisture may 
increase again Sat in S to southeast winds aloft. NAM bring more moisture 
sun but GFS and European model (ecmwf) show drying. Will indicate a slight chance of 
thunderstorms Friday and Sat afternoons in the mountains and high 
deserts and increase the cloud cover on sun. The marine layer should 
be less disrupted by middle level clouds and moisture after tonight 
with low clouds and patchy fog into most coastal areas and the western 
San Diego inland valleys. Temperatures will be near seasonal in most areas 
Friday then slightly below Sat and sun as thickness and local 850 mb 
temperatures decrease a little. 


&& 


Long term (mon-thu)...broad upper level high pressure will continue 
over the SW and another trough will move past to the north. This will 
result in minor changes in the marine layer and temperatures. Middle level 
moisture may increase again toward middle week. Will indicate more 
afternoon clouds over the mountains...but no thunderstorms for now. 


&& 


Aviation... 
071900z...marine layer depth remains around 1200 feet. Marine layer 
depth will show little change through Friday. Stratus is not 
expected to be much of a problem at coastal airports through the 
afternoon and evening but could move over coastal airports late 
tonight. Breakup on Friday should be between 15z and 17z. 


Above the marine layer including the mountains and deserts...main 
issue through the evening will be the scattered thunderstorms over 
the mountains and adjacent deserts and valley areas. Bases of the 
thunderstorms will be at or above fl080 with tops to fl450. 
Thunderstorms could impact the baret four arrival and border five 
departure routes for ksan at times. Most activity should end around 
sunset but additional thunderstorms are possible over the mountains 
Friday afternoon. Horton 


&& 


Sgx watches/warnings/advisories... 


Flash Flood Watch until 8 PM today for the mountains and deserts. 
See laxffasgx. 


&& 


$$ 


Public...atkin 
aviation...Horton