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Area forecast discussion 
National Weather Service Cheyenne Wyoming 
247 am MDT Monday Oct 13 2008 


Short term...Columbus day through Tuesday night. 
Satellite imagery this morning shows the extremely amplified upper 
level trough continuing to be located from eastern Montana 
southwest to Southern California. The strongest jet energy is on 
the east side of the trough now and will cause the trough to begin 
moving northeast of the forecast area today. A slightly weaker jet 
streak on the western side of the trough will create sufficient 
vorticity in the base of the trough over Arizona and southern Utah 
to shear off a closed low feature that will much more slowly eject 
east-northeast across Colorado by late Tuesday. This weak feature 
is not expected to create precipitation for southeast Wyoming as 
it moves east of the area Tuesday night. 


Surface high pressure will remain in place today along with fairly 
light northwest flow. Cloud cover will gradually decrease through 
the day...and temperatures will warm slightly while remaining 
around 12 to 20 degrees below normal across southeast Wyoming and 
the Nebraska Panhandle. 


Temperatures Tuesday will warm slightly again...but will still be 
around 10 degrees below normal. The southern end of a weak cold 
front will move southeast across the area early Tuesday 
night...but no precipitation is expected with this frontal 
passage. 


Long term...Wednesday through Sunday 
dry conditions will prevail throughout the extended period. A weak 
short wave will move across the County Warning Area late Wednesday morning into early 
afternoon...with another wave moving across the forecast area Thursday 
morning. Both these waves will only produce some clouds over the 
area. Brisk winds will occur at the surface Thursday morning in the 
vicinity of the short wave. An upper ridge will move across the County Warning Area 
Friday...while the airmass remains dry. On Sat...SW flow will 
develop aloft Sat...but the upper flow will become zonal on sun as a 
high amplitude ridge develops over the western U.S. High 
temperatures will be around normal for Wednesday...then 4 to 7 degrees 
above normal for Thursday through Sunday. 


&& 


Aviation... 
localized MVFR conditions due to low stratus cloud will occur 
through around 14z this morning...followed by VFR conditions 
through the rest of the period as dry low levels of the atmosphere 
will be expected with the surface high pressure. Patchy fog will 
be possible across Carbon and Albany counties tonight...although 
confidence is limited as to how much additional moisture will 
enter the boundary layer from snow-melt today. 


&& 


Cys watches/warnings/advisories... 
Wyoming...none. 
NE...none. 


&& 


$$ 


Short term/aviation...CArpenter 
long term...kmd