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fxus65 krev 231043 
afdrev 


Area forecast discussion 
National Weather Service Reno Nevada 
243 am PST Monday Nov 23 2009 


Short term... 


Upper level ridge near the West Coast will build inland over the 
Great Basin through Wednesday. Light winds and low sun angle will 
keep inversion conditions over valleys each day...with maximum temperatures 
in the Tahoe basin likely to equal or even slightly exceed temperatures 
in some of the lower valleys. 


Areas of cirrus will move across the region today through Tuesday...then 
virtually no cloud coverage is expected until Thanksgiving day. 
Patchy fog around Truckee is probable for next couple of 
nights/mornings...although coverage and duration will likely be 
greater this morning compared to tonight and Tuesday night when 
more easterly low level flow with further low level drying is 
expected. Mjd 


Long term...Thanksgiving through Sunday... 


Amplified blocking pattern over North America middle week should begin 
to break down on Thursday. However models inconsistently handle the 
track of energy entering the West Coast as it tries to dislodge the 
ridge. 


Warm and dry forecast for Thanksgiving day...with increasing chances 
of showers and gusty winds Thursday night into Friday. 00z European model (ecmwf) 
remains slower and has trended farther north with the system than 
the GFS solution. Have left the forecast alone...but thinking 
Thursday night will be dry with showers affecting the northern areas 
Friday. 


For the end of the Holiday weekend...ridge should rebuild somewhere 
between 120w and 130w as a deep low moves into the Gulf of Alaska. 
Ensemble spread is very high in the Gulf of Alaska and North 
Pacific...as models struggle with energy ejecting from the parent 
low in the Bering Sea. 


This factors into the placement of a downstream trough somewhere 
over the Great Basin or High Plains. Main issues are temperatures 
and chance for snow showers Saturday into Sunday. Kept the current 
forecast going...especially with temperatures as the low level flow 
should remain from the north-northeast keeping the Nevada valleys 
cool under strong inversions. Chance of showers will depend on the 
track of the cold pool dropping south out of Canada...current models 
push the cold pool well east of the area. Brong 


&& 


Aviation... 


High pressure will remain over the west through Thanksgiving...with 
light winds and dry conditions. Only concern is IFR/LIFR conditions 
due to fog Truckee 08z-18z the next few days. 


No significant impacts for travel to start of Thanksgiving weekend. 
System forecast to move into the West Coast Thursday night into 
Friday...should bring an increase in winds a chance for rain/snow 
showers north of tvl-nfl. Brong 


&& 




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


$$ 


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