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fxus66 klox 081140 
afdlox 


Southwest California area forecast discussion 
National Weather Service Los Angeles/Oxnard California 
330 am PST Thursday Jan 8 2009 


Short term... 
marine clouds forming near the sea/land interface and pushing weakly 
onshore across the beaches. Patchy dense fog is also occurring with 
these clouds. Gradients are offshore both to the north and east and 
this will limit cloud penetration to just the vicinity of the beaches. 
Later in the day a weak cold front will wash out overhead. The front 
looks even weaker that it was forecast and have removed all probability of precipitation and 
most of the clouds previously associated with the front. What the 
front will do is kick things into motion for a large possibly 
dangerous wind event. As the front passes overhead a brief burst of 
north winds will set up over the sba mountains and will set up small 
sundowner. Across the central coast local NE winds will keep the low 
clouds away...lows across the central coast will be very erratic 
with breezy areas stay 10 or more degrees warmer than the wind 
sheltered areas. An eddy will drive some low clouds across the l.A. 
And vta coasts...although developing NE flow will erode most of the 
Ventura County clouds before sunrise. 


Friday will be sunny...save for some early morning low clouds across 
the la coast. Friday will be a little odd as the winds will increase 
during the day instead of peaking middle morning and then subsiding 
with the diurnal pressure pattern. In this case the peak cold air 
advection will drive the winds despite the pressure pattern. This 
cold air advection will also keep temperatures on the cool side in fact 
Friday will be the coldest day of the week. 


Very strong wind event will start in earnest Friday night and last 
into Sunday morning with a brief diurnal lull Saturday afternoon. 
Strong 1039 mb high will sit across Nevada and upper high will sit to 
the west-northwest of San Francisco the anti cyclonic flow around this high 
will bring good northeast upper flow support to Ventura and l.A. 
Counties during this time. Weak cold air advection will continue 
also. Peak winds should occur in the Ventura coastal valley areas in 
the Santa Monica Mountains. The Laguna Peak wind sensor should see 
some very high readings middle Saturday morning. Coastal temperatures will 
rise some as the there will not be enough cold air advection to 
overwhelm the compressional heating. Winds will still be strong 
Sunday morning but all wind parameters are a little bit lower and 
the winds will be 5 to 10 miles per hour less than saturdays very high values. 
Low temperatures will be above normal in the windy areas but with 
the clear skies and dry air lows will be below normal in the wind 
free areas. 


Unless something otherworldly happens to the forecast look for a 
high wind watch this afternoon. 


Fire weather danger will be heightened during this wind event as the 
strength and duration of the winds could well be enough to 
overwhelm the higher fuel moistures. 


Long term... 


GFS and ec both agree on a fairly static long range pattern for the 
extended period with a long wave trough menacing the East Coast while 
a long wave ridge will keep the west warmer than normal and dry. The 
high stays fairly well entrenched over Utah through the period and 
there will be offshore winds each morning. The winds will be weaker 
each day. Offshore winds will keep temperatures above normal but heights will 
slowly lower during the period which combined with the lessening 
offshore flow will allow for some cooling each day. 


&& 


Aviation... 


08/01130z 


Latest satellite/surface observation indicate generally clear skies across 
the area...except for some patchy stratus/fog near the coast. The 
patches of stratus/fog are producing IFR/LIFR conds at coastal 
taf sites this morning. Expect these IFR/LIFR conds to burn off 
by 18z...with VFR conds for all taf sites through this evening. 
Overnight tonight...a slightly deeper marine layer is expected 
which may bring some IFR ceilings/visibilities into koxr/klax/klgb. Expect 
northerly flow tonight to keep slow/sba County taf stratus-free 
tonight. Strengthening northerly winds tonight may produce some 
turbulence across the mountains. 


Klax...moderate confidence in 12z taf. Current LIFR conds should 
continue through early morning hours...then begin to lift an hour 
or two after sunrise...then VFR conds by this afternoon. Low to 
moderate confidence in return of marine layer this evening. No 
wind issues expected. 


Kbur...high confidence in 12z taf. VFR conds expected through the 
taf period with no wind issues. 


&& 


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


&& 


$$ 


Public...rorke 
aviation...Thompson 


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