317 
fxus65 kbou 071056 
afdbou 


Area forecast discussion 
National Weather Service Denver Colorado 
350 am MST Sat Nov 7 2009 


Short term...no changes to the forecast package were needed. Dry 
and moderate west-southwesterly flow aloft will continue over the 
state through tonight. At the surface...pressure gradients will be 
weak...resulting in typical diurnal wind fields. Temperatures at 
lower and middle levels will not be as warm as the past couple 
days...so highs across the plains will only be in the middle and upper 
60s. Still quite nice for the first weekend of November. Zero probability of precipitation 
across the forecast area and only occasional middle-high level 
cloudiness through Sunday morning. 


Long term...west-southwest flow aloft will be over the area on sun with some 
increase in middle level moisture by afternoon in the mountains which could lead to 
some isolated showers over the higher terrain. Over northestern Colorado a fnt will 
move across the area and bring a 5-6 degree c drop in 700-850 temperatures 
as weak upslope flow develops. Thus should see 10-12 degree drop in 
highs over northestern Colorado. For Sun night into Monday a weak upper level 
trough will move across the area with minimal qg ascent. NAM and 
GFS show varying amounts of moisture with this feature as the GFS is 
wetter and the NAM drier. For now will continue with chance probability of precipitation in the 
mountains with a slight chance of showers over lower elevations. 850-700 mb 
temperatures are forecast to drop another 2-3 degrees c on Monday with highs 
mainly in the 50s for the plains. 


By Tuesday and Wednesday southwesterly flow aloft will be over the area with dry 
conditions on Tuesday. On Wednesday the GFS shows some increase in middle level 
moisture in the mountains by afternoon so will leave in low probability of precipitation but continue 
dry forecast over the plains. 850-700 mb temperatures will begin to rise once 
again which should allow for highs both days to be above seasonal 
normals over northestern Colorado. 


For Thursday and Friday there is virtually no agreement between the European model (ecmwf) 
and GFS on the 00z runs. The GFS shows an upper level trough 
shearing apart as it moves across the area Thursday into Thursday night while 
at the same time the European model (ecmwf) has the main upper level trough still 
hanging back over Nevada and California. At this point its 
certainly not clear which if any solution is correct so will not 
alter previous forecast. 


&& 


Aviation...no aviation impacts anticipated through tonight. Only 
intermittent middle and high level clouds are expected and the winds 
should remain out of the south to southeast 


&& 


Bou watches/warnings/advisories...none. 


$$ 


Kdrby/rpk