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Area forecast discussion 
National Weather Service Sacramento California 
345 PM PDT Wednesday Jul 23 2008 


Discussion...smokey and hazy conditions across much of the County Warning Area 
today from continuing wildfires in norcal. Visibilities from the 
central SAC valley northward have fluctuated today between 1-5 miles 
with the poorest visibility around the Redding/redbluff area and in 
the vicinity of the fires. Changed weather forecast grids this 
afternoon to account for areas of smoke in the northwestern portion 
of our County Warning Area persisting over the next few days. Expect visibilities to 
lower again tomorrow morning. 


Broad ridging across the southern United States will remain fairly 
stationary through the weekend and continue to build for the next 
day or so. GFS and European model (ecmwf) models indicate a low pressure system 
nudging into the high pressure over the weekend...but it should ride 
over the ridge without significant changes to our present weather 
pattern. 


Current temperatures are running 3 to 8 degrees warmer than 
yesterday and maximum daily temperatures are expected to be normal or up to 5 
degrees above normal through the week. The warmest days should be 
Thursday through Saturday followed by gradual cooling to normal 
afterwords. Low temperatures tonight...and for the next few nights...will 
be a bit toasty in the foothills where the thermal belt lies coupled 
with daytime heat being trapped by the smokey skies. Jbb 


Extended discussion (sunday through wednesday)... ridge of high 
pressure over the area through Monday with 850 mb temperatures in 
the middle 20s. This will keep valley temperatures in the 90s which is 
near normal. An upper level trough off the West Coast may weaken 
the ridge on Tuesday and Wednesday bringing a little cooler 
temperatures and more of an onshore flow. The GFS also shows some 
middle level moisture possibly working its way to the Sierra crest on 
Tuesday or Wednesday but with southwest flow do not expect any 
showers or thunderstorms in our area at this time. Although the 
European model (ecmwf) keeps the ridge in place and builds it even more into northern 
California from the southeast on Wednesday and Thursday for warmer 
temperatures. The current forecast leans more towards the GFS with 
slight cooling on Tuesday and Wednesday but with a dry forecast 
either way. 


&& 




Aviation... 
dry and stable airmass remains over interior northern California 
through tomorrow. Thick smoke from wildfires over Trinity County 
will result in an area of MVFR/IFR conditions over the northern SAC 
valley and Shasta County mountains / foothills through tomorrow. 
Otherwise...generally VFR conditions with local MVFR due to smoke 
with a ridge of high pressure over the area. 


&& 


Sto watches/warnings/advisories... 
none. 
&& 


$$