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fxus65 krev 191102 
afdrev 


Area forecast discussion 
National Weather Service Reno Nevada 
302 am PST Wednesday Nov 19 2008 


Short term... 
middle and high clouds currently spreading over the pacnw and northern 
California indicative of the strong West Coast ridge breaking 
down. Twin lows also visible on satellite imagery spinning within 
in the longwave trough over the Gulf of Alaska. The southern low 
currently around 40n 145w will rotate towards the pacnw over the 
next 24 hours and really flatten the upper ridge. Lowering heights 
today will bring around 4 degrees of cooling everywhere. Winds 
will still be generally light today however ridge gusts will begin 
to increase this afternoon as southwest flow aloft increases. 


The upper shortwave moves onshore Thursday pushing a decent 
surface cold front across northern California/Nevada by Thursday afternoon. Latest 
model runs continue to bring the precipitation band just south of the 
Oregon border. Kept with chance probability of precipitation over the far northern zones 
Thursday afternoon as light showers move through. 


A bigger story will be the winds as a significant change in 
airmass settles into the area. Model runs tonight do not look as 
impressive as 24 hours ago with lower 700 mb wind speeds and no tropopause 
fold to duct the winds down to the surface. Breezy conditions are 
expected north of Highway 50 for much of Thursday with gusts up to 
45 miles per hour. There is still potential for higher speeds and a Wind 
Advisory however current thinking is that speeds will remain just 
below advisory criteria. The shortwave quickly exits the region 
Thursday night with clearing skies and cool northeast Post-frontal 
surface flow. Temperatures Friday should be around 10 degrees 
cooler behind the front however they will still be just above 
seasonal normals. Another fast moving upper shortwave moves into 
the pacnw Friday night however it remains far enough north of the 
area to have little impact. Jordan 




Long term...Saturday through Tuesday... 
few changes to extended. Models in better agreement through the 
extended with a moderate amplitude ridge over the area Sat-Mon. 
Temperatures aloft will continue to be above freezing...and have kept temperatures 
in the upper 50s...not much warming from day to day. Would not be 
surprised if temperatures are 5 degrees too cold for western Nevada sun/Monday as surface 
gradient becomes flat or more west. GFS/ec in better agreement with 
the splitting trough heading toward the area for mid-week. Both 
bring precipitation to the area for Tue-Wed...but the splitting nature of 
the system will make it Dicey. While ensemble probability of precipitation are high...will 
just add slight chance for Tuesday-Wednesday mainly Sierra for now. It is 
impossible to pin down any area favored for precipitation with a splitting 
system this far out...and sometimes even 48 hours out. Otherwise... 
temperatures will begin to cool again for midweek as trough nears and temperatures 
cool aloft. Wallmann 


&& 


Aviation... 
VFR conditions through Thursday. Some increase in west-SW winds for 
krno/ktvl/ktrk after 15z Thursday...with peak gusts 30-35 kts. Wallmann 


&& 




Rev watches/warnings/advisories... 
Nevada...none. 
California...none. 
&& 


$$ 


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