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fxus66 khnx 230935 
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Area forecast discussion 
National Weather Service San Joaquin Valley - Hanford California 
135 am PST Monday Nov 23 2009 


Synopsis...mostly cloudy in the San Joaquin Valley, with patchy 
early morning fog, and partial afternoon clearing. Over the higher 
elevations of the southern Sierra and high deserts of Kern County, 
skies will be mostly clear. 


&& 


Discussion... 
high temperatures Sunday across the central and southern San 
Joaquin Valley ranged from 59 /at Arvin...Bakersfield...Delano and 
Porterville Municipal Airport/ to 63 degrees /at Merced Municipal 
Airport/. Edwards AFB was the warm spot in the Hanford warning/ 
forecast area with a high of 67 degrees. Of note...November 21st was 
the last day Fresno has a record high in the 80s...the record high 
will not reach 80 again until February 16th. Bakersfield/S last 
record 80-degree day is December 19th...with the first such day in 
the year on January 2nd. 


Stratus fills much of the central and southern San Joaquin Valley 
this morning...with ceilings between 3300 and 4800 feet. The stratus 
has pushed into the foothills...including the Tehachapi Pass. The 
only part of the Hanford warning/forecast area reporting clear skies 
are Merced and Mariposa counties...and Yosemite National Park. Will 
have to watch these areas...as radiational cooling may drop 
temperatures to the saturation point with some fog development. 


An upper-level ridge will build into California today. This will 
strengthen the inversion and keep the stratus in place for much of 
the day. As a result...Valley High temperatures today could be 
cooler than Sunday/S highs. It is also possible that some overnight 
valley and foothill low temperatures could have occurred before 
midnight with little diurnal changes. 


The ridge axis will be over California Tuesday...then move into the 
Great Basin Wednesday as an upper-level trough approaches the coast. 
The trough will be along the Pacific northwest coast by 00z Friday 
and into California by 12z Friday. 


Although both the GFS and European model (ecmwf) keep middle-level moisture with the 
trough north of the Hanford warning/forecast area...there is a push 
of cold air into the region with the arrival of the trough. The 00z 
GFS forecasts 850-mb temperatures over the central and southern San 
Joaquin Valley to drop by 7 c from 00z Friday to 00z Saturday... 
while the 00z European model (ecmwf) lowers 850-mb temperatures by 5 c. Have lowered 
valley highs a few degrees Friday...and kept cool temperatures over 
the south end Saturday in the lingering low-level cold pool. 


The trough is forecast to move into the Great Basin Saturday...with 
a north to northeast flow aloft over the state. The models have 
backed off on the Great Basin surface high for Saturday...with the 
high now over Idaho. The models still forecast an offshore flow over 
California for the weekend...but not as strong as earlier runs. 


An upper-level ridge is forecast to build into California Sunday and 
next Monday behind the trough. This will again strengthen the 
inversion for possibly more morning San Joaquin Valley fog...but 
will not add any fog to day 7 at this time. 


The forecast is dry through the period...although with the 00z runs 
deeper with the trough over California Friday there might be a 
slight chance for rain and higher elevation snow depending on how 
far south the middle-level moisture pushes. The next few model runs 
should give a better picture on whether any probability of precipitation need to be added to 
the Yosemite region Friday. 


&& 


Aviation... 
low clouds...yet within VFR range...expected today across the San 
Joaquin Valley with areas of MVFR and local IFR conditions along the 
foothills of the Sierra Nevada and the Tehachapi Mountains. These 
conditions will persist through this evening with some improvement 
in the foothills during the afternoon hours. VFR conditions will 
prevail elsewhere across the central California interior through 12z 
Tuesday. 


&& 


Air quality issues... 
none. 


&& 


Hnx watches/warnings/advisories... 
none. 


&& 


$$ 


Public...Sanger 
AVN/fw...Molina 


Weather.Gov/Hanford