686 
fxus66 ksgx 081714 
afdsgx 


Area forecast discussion 
National Weather Service San Diego California 
930 am PST Thursday Jan 8 2009 


Synopsis...a weak upper level trough of low pressure will move past 
to the north early Friday causing areas of coastal low clouds and 
patchy dense fog. Offshore flow will cause local strong gusty Santa 
Ana winds Friday afternoon through Sunday...mainly through and below 
mountain canyons and passes. The offshore winds will gradually 
weaken next week. Clear skies this weekend through the middle of 
next week with warmer days...especially west of the mountains 
Sunday and Monday. 


&& 


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


Short term (today-sunday)...there were areas of stratus along the 
coast with patchy dense fog this morning. Just a few high clouds 
elsewhere. The 12z nkx sounding had a surface based inversion with 
weak Ely winds in the low levels and SW winds aloft. Weak offshore 
gradients from the north and onshore to the east. 


A few high clouds will move in from the SW today. A weak trough 
approaching from the northwest will deepen the marine layer tonight for 
more widespread coastal low clouds and fog. Even with the deeper 
marine layer...there will still be locally dense. The flow will 
rapidly turn offshore from the north to NE Friday becoming strong by 
afternoon. The strongest winds will initially be through and below 
the Cajon Pass and into the Santa Ana Mountains but will turn more 
NE to east and spread into Riverside and San Diego counties Friday 
night and Saturday morning. The strongest and potentially damaging 
winds will likely be early Saturday with local gusts to about 80 miles per hour 
possible in the windiest areas...mainly below the Cajon Pass and in 
the Santa Ana Mountains. Warmer west of the mountains...especially 
Sunday with local maximum temperatures in the low to middle 80s. There will 
initially be some cooling in the mountains and deserts Friday due to 
cold air advection but the ridging aloft will eventually bring 
warming to those areas as well Saturday...but more so on Sunday. 


&& 


Long term (monday-thursday)...the offshore gradients will slowly 
weaken. There will still be local gusty winds...especially 
Monday...but they should mostly remain below advisory strength. 
Local heights aloft should peak on Monday which will be another 
warm day west of the mountains. Cooler Tuesday through Thursday with 
maximum temperatures getting back to near seasonal in most areas by Thursday. 


&& 


Aviation... 
081550 UTC...shallow marine layer below fl006 will persist for 
another 20-26 hours before moderate to strong northeast winds push 
it offshore. Expect very low ceilings/visibility due to stratus/fog 
to affect coastal airports through 1800 UTC this morning and again 
after 09/0200 UTC this evening...clearing north of kokb after 
09/1400 UTC and south of kokb after 09/1800 UTC. Other aviation 
weather concerns will be low level wind shear over inland valley 
airports Friday morning before nocturnal inversion breaks and winds 
surface...best estimate on timing is between 09/1400-09/1800 UTC. 
Also expect moderate to occasional severe turbulence over and in Lee 
of mountains Friday evening through Saturday with sustained 
northeast winds 30-40kt below fl100 and gusts to 75kt through and 
below canyons/passes. 


&& 


Sgx watches/warnings/advisories... 


High wind watch from Friday afternoon through Sunday afternoon 
for the San Bernardino County mountains...the inland Empire and 
Santa Ana Mountains and foothills. See laxnpwsgx. 


&& 


$$ 


Public...atkin 
aviation...Balfour