055 
fxus66 klox 030606 
afdlox 


Southwest California area forecast discussion 
National Weather Service Los Angeles/Oxnard California 
1005 PM PST Tuesday Dec 2 2008 


Short term (tonight-fri)...marine layer near 1800 feet deep at lax 
this evening. Low clouds have moved inland over much of the coast 
and valleys of vtu/l.A. Counties...but overnight some offshore flow 
should help to push the low clouds back toward the coastal plain. 
Local dense fog is possible in the valleys overnight as well. Low 
clouds will persist on the sba S coast overnight...as well as along 
portions of the central coast. With an easterly flow coming out of 
the Tule fog in the southern San Joaquin Valley...plenty of low 
clouds have spilled into the slow interior valleys this evening and 
will persist overnight. Locally dense fog will also be possible 
tonight in the interior valleys and along the central coast. 
Elsewhere mostly clear skies will prevail. 


A shortwave weak upper ridge will move swiftly through the forecast 
area on Wednesday. An upper level low is expected to develop off the northern 
California coast Wednesday night then move quickly S on Thursday to a position well SW 
of Southern California near 31n/128w. The upper low will slip further S through Friday 
while an upper trough develops over Southern California. There continues to be 
model differences with regard to the movement and evolution of the 
upper low and upper trough development Thursday night and Friday. However...it 
appears that dry weather should prevail through Friday over the district. 
The marine layer forecast will be somewhat problematic during the 
period as the lower level flow will fluctuate between onshore and 
offshore...and the marine layer depth is hard to ascertain as well. 
It does look like at least some low cloud development will occur 
along the coastal plain and into some of the valleys through Thursday 
night...but a somewhat stronger offshore flow is expected late Thursday 
night and Friday morning which should clear the low clouds off the 
coast by middle to late Friday morning. Temperatures over the region are expected 
to be milder Wednesday with some offshore flow in the morning and more sun 
for the coast and valleys...then cool slightly Thursday before rebounding 
to near or sligthly above normal most areas Friday thanks to another 
round of offshore flow. 


..from previous discussion... 


Long term (sat-tue)...still significant uncertainty in the extended 
models handling the cutoff low system off our coast. For now...have 
trended for more clouds and cooler temperatures for the Saturday 
through Monday time frame...and have bumped up probability of precipitation to the 10 to 15 
percent range in gridded forecast. At some point...later shifts may 
need to bump up probability of precipitation a bit more in the Saturday night through Monday 
time frame if models start to converge better. 


&& 


Aviation...03/0600z...IFR to MVFR...and even low IFR conditions for 
ksmx...will prevail at many of the coastal and valley taf sites 
overnight into Wednesday morning...although some offshore flow may bring 
improving conditions to kvny...kbur...and koxr Wednesday morning. All 
areas should clear to VFR conditions by Wednesday afternoon...except MVFR 
visibilities should linger through the afternoon at klax and klgb. 


For klax...MVFR ceilings will prevail through about 21z Wednesday with MVFR visibilities 
persisting the rest of the day. No wind issues are expected. 


For kbur...IFR to low MVFR conditions will prevail through about 19z 
then VFR conditions can be expected for the rest of the day. There 
is a slight chance skies may clear by 15z or 16z due to some 
offshore flow. No wind issues are expected. 


&& 


Lox watches/warnings/advisories... 
Small Craft Advisory (see laxmwwlox). 


&& 


$$ 


Public...sirard/gomberg 
aviation...sirard 


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