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afdpub 


Area forecast discussion 
National Weather Service Pueblo Colorado 
330 PM MST Wednesday Nov 19 2008 


Short term... 
(tonight and tomorrow) 


There are multiple short term concerns. These include 
temperatures...the movement of the cold front across the plains late 
tonight...areas of fog early tomorrow morning...the coverage and 
precipitation type of the corresponding stratiform layer. 


Tonight...the remnants of the ridge will move eastward as the main 
cold frontal boundary currently across southern Wyoming and through 
South Dakota will slide through Colorado...beginning around midnight 
tonight. 


Tomorrow..,.The cold frontal boundary will bring a stratiform layer that 
will drape across southern Colorado tomorrow. With this stratiform 
layer there will be areas of freezing drizzle...and areas of light 
snow. Have expanded pop areas to include the Wet Mountain Valley and 
portions of Teller County. The nam12 shows copious amounts of 
moisture through tomorrow. Daytime temperatures will be up to 20 
degrees cooler than today. Have added areas of fog along the I 25 
corridor...the eastern plains...and in the central San Luis 
valley...where the low level moisture...according to the nam12 has 
increased. The fog looks to dissipate by late morning...and the 
freezing drizzle will change to snow flurries in the afternoon. Low 
cloud cover for southern Colorado will continue into tomorrow 
afternoon...before the front moves southeast tomorrow night. -Jc 


Long term... 
(thursday night through wednesday) 


Shallow upslope continues along the lower east facing slopes of the 
southeast mts Thursday evening as flow stays southeasterly. Stratus...with a 
mix of flurries...fog and freezing drizzle will continue through the 
evening...then moisture quickly Shallows out quickly towards 
midnight with southerly flow off the Raton likely resulting in 
clearing south of the Arkansas River valley. 


Southerly flow intensifies across the plains on Friday as the next 
trough moves across the northern US rockies. 12z GFS is the fastest of the 
models with moving this system across Montana/Wyoming on Friday...clipping it 
by NE Colorado during the day. The increase in winds will erode what 
remains of the low clouds across the plains by early morning...and 
result in better mixing and warmer temperatures. Appears system 
will pass too far to the north to have much affect on precipitation 
chances for southeast Colorado. However it does send another cold front into the 
southeast plains late Friday afternoon and Friday night. GFS would suggest a 
slightly quicker frontal passage than NAM. 


Friday night will be colder across the plains and have dropped 
temperatures back a few degrees. 


Not to leave out the mountains during this period...but front should 
be too shallow to affect this area much. Should be windy conditions 
along with a slight cool down on Friday behind the passing trough to 
the north...but for now have kept probability of precipitation out of the central mts as 
better forcing and deeper moisture stays well to the north. 


Zonal flow returns for Saturday bringing warmer temperatures. Next 
trough drops down in northwest flow on Sunday sending a dry cold front 
through eastern Colorado. Then upper ridge transitions in for next week 
bringing a return of warmer temperatures. -Kt 


&& 


Aviation...VFR conditions expected until 10z. The cold front 
currently moving across southern Wyoming is expected across the 
Palmer Divide between 06z-10z and through all of southeast Colorado and banked up 
across the lower eastern slopes by 12z Thursday. MVFR and IFR ceilings to 
develop across the plains behind frontal passage. Local LIFR conditions for 
areas west of the I-25 corridor with light freezing drizzle and 
freezing fog possible. With the increased moisture in the central 
San Luis valley there will be LIFR conditions due to fog starting 
early tomorrow morning and continuing until middle morning. -Jc 




&& 


Pub watches/warnings/advisories... 
none. 
&& 


$$ 


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