586 
fxus66 ksgx 192009 
afdsgx 


Area forecast discussion 
National Weather Service San Diego California 
130 PM PDT Sat Jul 19 2008 


Synopsis... 
increasing moisture in southeast flow aloft will bring a chance of 
thunderstorms to the mountains and deserts late today through early 
next week. A few storms could drift west of the mountains Sunday and 
Monday. The marine layer and onshore flow will continue coastal low 
clouds and fog during the nights and mornings...extending locally 
inland. 


&& 


Discussion...for extreme southwestern California including Orange... 
San Diego...western Riverside and southwestern San Bernardino 
counties... 


Mdcrs soundings this afternoon continue to show the depth of the 
marine layer to be around 2500 feet. Stratus is holding solid along 
the coast with only partial clearing expected through the afternoon 
before moving back inland. 


The earlier surge of moisture into the southern deserts was showing 
signs of diminishing with dew points back down into the low 60s at 
Palm Springs and thermal. Some moisture is expected to move into the 
southern deserts later tonight into Sunday morning. Have mostly 
followed the 12z NAM guidance although the 12z GFS MOS guidance GOES 
along with the NAM solution. 


12z models continue to bring an increase in middle and high level 
moisture to the area from the southeast late tonight into Sunday and 
Monday...similar to earlier model runs. 12z NAM positive buoyancy energy 
graphics indicate very unstable for the mountains and eastern 
deserts early Sunday morning with energy approaching 1500 j/kg by 
18z and lifted indecies between minus 4 and minus 6 during the 
period. Later shifts may need to issue a Flash Flood Watch for the 
mountains and eastern desert areas for Sunday. Monday does not 
appear to be as active with most activity shifting north to the 
northern mountain areas but still expect some convection on Monday. 
A further decrease in activity is expected on Tuesday. 


For the extended period...models continue to keep a ridge over the 
southwest with a broad trough along the Pacific northwest coast 
through the period. The ridge should keep the area under a southerly 
flow aloft which should continue to allow afternoon convection over 
the mountains during the period. Temperatures should be near 
seasonal during the period. Another increase in middle and high level 
moisture is expected late in the week. 


&& 


Aviation... 
192030z...areas of broken stratus along the immediate coast will 
continue this afternoon with some afternoon cumulus clouds over the 
mountains and deserts. Subtropical moisture increases tonight with the 
potential for thunderstorms over the mountains and deserts late tonight 
and sun. Thunderstorms would produce heavy rain lowering visby as 
well as hail and strong gusty winds. On sun the marine layer will 
become disrupted by the increasing moisture aloft and stratus should 
clear from coastal airports between 15-17z. Mm 


&& 


Marine... 
192030z...a moderate south swell will increase through sun with a 
period of 16 seconds. Surf along Orange Colorado beaches is forecast to be 
5 to 7 feet with sets as high as 9 feet. There will be strong and 
dangerous rip currents through early next week. 


&& 


Sgx watches/warnings/advisories... 
California...high surf advisory from 9 PM this evening to 2 am PDT Tuesday 
for Orange County coastal areas. 


Pz...none. 


&& 


$$ 


Public...Horton 
aviation/marine...mm 


National Weather Service on the web at weather.Gov/sandiego