725 
fxus66 klox 211831 
afdlox 


Southwest California area forecast discussion 
National Weather Service Los Angeles/Oxnard California 
1030 am PST Sat Nov 21 2009 


Updated aviation section 


Synopsis...temperatures will remain cool today and tonight as a 
cold front exits the region. On Sunday...high pressure will build 
back into the area and offshore flow will establish...quickly 
warming temperatures back to seasonal normals. This pattern will 
persist through the week...with locally breezy conditions over the 
mountains and above normal temperatures for the Thanksgiving Holiday. 
&& 


Update...will make a few updates to the ongoing forecast package 
mainly for cloud cover this morning and isolated showers continuing 
over the Santa Barbara and Ventura County mountains. Winds are also 
a little stronger across the Antelope Valley than current forecasts. 


A cold front pushed across Southern California overnight with some 
light showers over the northern counties with totals mainly under 
0.10 inch...but a couple of reports over 0.20 inch across the Santa 
Barbara County mountains. Winds have not been too strong...but 
isolated locations in the mountains continue to squeak into advisory 
level this morning. Will let the advisory ride through 11am. 
Temperatures are running 10-20 degrees colder than 24-hours ago 
especially for the mountains and interior valleys. 


Another storm system approaching the pacnw today but it will have a 
hard time making much southward progression on Sunday. Model data 
shows some middle to high level moisture for Santa Barbara and San Luis 
Obispo counties...continued dry but with some cloud cover at times. 
Will take a look at wind speeds for tonight and early Sunday across 
the mountains...could be advisory level again. Temperatures will 
start to rebound tomorrow and then stronger warming begins early 
next week. 
&& 


..from previous discussion... 


Long term...with offshore flow firmly taking hold over the area next 
week...a warming trend will become more pronounced for midweek. Good 
model agreement exists between the flow pattern gaining strength on 
Monday night into Tuesday morning...and continuing into Thanksgiving 
day. There is chance that advisory level winds could develop with 
the pattern...and possibly fire weather conditions could reach 
critical levels for midweek. The package was warmed for the period 
as NAM-WRF and GFS solutions push the thermal trough well offshore 
by Tuesday. Temperatures were warmed up especially for the central 
coast on Tuesday...and kept warm for the valley area and coastal 
areas south of Point Conception into Thanksgiving day. 


For the remainder of the Holiday weekend...models continue to 
diverge on the developing the storm system for late next week. 
GFS solutions remain less aggressive while the European model (ecmwf) and Gem push 
a trough south over central California. Reasonably good agreement 
exists between all the solutions through Thursday night with a 
trough developing along the West Coast. However...the GFS dampens 
the wave a little too quickly versus the European model (ecmwf) and Gem. With the 
Gem and European model (ecmwf) in better agreement through the weekend...the 
forecast was hedged towards a cooler solution for the remainder 
of the weekend. 


&& 


Aviation...21/1800z. 


Middle/upper level ridge of high pressure will build over the area. 
Moderate upper level northwest winds will prevail while moderate middle 
level north winds become light to moderate after 22/03z over area. A 
moderate northerly pressure gradient will become moderate to strong 
after 22/06z. 


Klax...very likely scattered low clouds will clear early. There is a 
chance visibility will become 5sm haze after 22/11z and persist for several 
hours. It is likely low level north winds will develop and 
strengthen to around 10 knots after 22/15z and prevail for several 
hours. 


Kbur...very likely scattered low clouds will clear early. There is a 
chance visibility will become 5sm haze after 22/11z and through the 
remainder of the period. 


Virtually certain - 95-100% 
very likely - 80-95% 
likely - 60-80% 
chance - 30-60% 
very unlikely - 20% or less 


&& 


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


&& 


$$ 


Public...boldt/Hall 
aviation...30 
synopsis...meier 


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