661 
fxus65 kbou 062025 
afdbou 


Area forecast discussion 
National Weather Service Denver Colorado 
225 PM MDT Monday Oct 6 2008 


Short term...enough moisture for some shallow convection west of 
the Front Range this afternoon...but capped by warmer dry air above 
600 mb. Gusty winds on the plains mainly from mixing. The winds and 
the clouds should go away this evening. This will leave US with 
clear skies and a dry airmass. With strong low level stability I 
expect that drainage winds will be light. Plains temperatures will 
generally be in the 30s with the colder areas experiencing frost. 
Low lying spots and especially Weld County and the Platte valley 
downstream from there. Temperatures below freezing should be rare. 
Mountain valleys will likely have their coldest night yet with some 
spots in the teens...but mainly 20s. Lots of sunshine for a big 
diurnal swing on Tuesday. Current forecast is in the middle of 
guidance and looks pretty good...trimmed mountain highs back ever so 
slightly. 


Long term...mild and dry conditions will continue to prevail 
Tuesday night through Thursday under a westerly flow aloft. Models 
have been consistently showing this over the past few days. Airmass 
will be dry and stable under this pattern...resulting in few if any 
clouds. Highs will be slightly above normal with readings in the 
lower 70s. 


The big question continues to be how the system digging south over 
the western U.S. Thursday night and Friday evolves through out the 
weekend. Models continue to show vastly different scenerios for 
Friday and through this weekend. There is a good amount of cold air 
with this system for this time of year...so this storm will likely 
have a good swath of snow where ever it tracks. General trend is to 
have a trough dig and rapidly strengthen over the western U.S. With 
it centered somewhere over Nevada or Utah by 12z Saturday. After 
this models really diverge. The 12z European model (ecmwf) takes the low from Nevada 
and kicks it northeast through Wyoming and into eastern 
Montana...which would leave our area relatively dry and mild. The 
12z GFS brings the closed low from Utah into southern Colorado and 
then ejects northeast across eastern Colorado...western Nebraska and 
western Kansas. This track would be very favorable for cold and 
heavy snow across most of the forecast area. 


Right now will continue to trend temperatures cooler for this 
weekend. Should see cool air enter the state by Saturday as the low 
progresses eastward. Will keep probability of precipitation in the 20-30 percent because of 
all the uncertainty with the track and strength of this system. Main 
highlight is that there will be a strong Fall storm moving across 
parts of the western U.S. Late this week and this weekend with 
potentially dangerous winter conditions. 


&& 


Aviation...VFR conditions will continue through Tuesday. Gusty 
north winds will decrease and shift to normal southerly drainage 
winds between 01z and 03z. 


&& 


Bou watches/warnings/advisories...none. 


$$ 


Gimmestad/meier