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Area forecast discussion 
National Weather Service Cheyenne Wyoming 
844 PM MST Monday Nov 23 2009 


Update... 
a drying and stabilizing air mass has dissipated any hint of 
wrap-around moisture across southeast zones this evening. Satellite pictures 
depict only a few cloud fragments remaining across southeast 
Wyoming and the westernmost row of counties in Nebraska. So...have 
reduced cloud-cover across all areas of the County Warning Area overnight. Removed 
precipitation chances across the southeast...but did keep small chances 
going across just the higher peaks of the Snowy Range through 
midnight. Otherwise...conditions will remain dry through the 
remainder of the overnight. Hahn 


&& 


Previous discussion... /issued 152 PM MST Monday Nov 23 2009/ 


Short term...tonight through Wednesday...current kcys radar loop 
shows isolated snow showers/flurries over the mountains of southern 
Wyoming and along i25 north of Cheyenne with Douglas reporting a 
half mile visibility and moderate snow in the last half hour. 
Expect his activity to remain isolated into late this afternoon 
before dissipating around sunset as the cold front and intensifying 
surface low over Kansas continue to push east of the region tonight. 
Expect temperatures to remain below normal tonight with clearing skies 
and good radiational cooling. Winds will slowly dissipate by 
midnight as the pressure gradient decreases across the region. 


The upper level trough currently over the area is expected to push 
east of the area into the Great Plains and Great Lakes region by 
Tuesday resulting in cool northwest flow over southeast Wyoming 
and the Nebraska Panhandle...with highs in the upper 30s to 
upper 40s east of the Laramie range...and upper 20s to middle 30s 
across Carbon and Albany counties. Models in good agreement for 
Wednesday...showing the next cold front moving into the High 
Plains. This front will be drier...since its expected to move into 
the area from the north and has very little moisture with it. 
However...models show a strong 120 knots jet pushing across eastern 
Wyoming early Wednesday and some low level lift...so can not rule out a 
band of light snow or flurries along the front over the northern 
Nebraska Panhandle and eastern Wyoming Tuesday night into early 
Wednesday morning. After the front pushes across the area...expect 
winds to increase from the north between 25 to 35 miles per hour with gusts 
possibly around 50 miles per hour Wednesday along and east of the Laramie 
range with Wind Advisory conditions possible over the Panhandle. 
Otherwise...cooler than normal temperatures will continue into Wednesday 
with highs 3 to 7 degrees cooler compared to Tuesday. 


Long term...Wednesday night through Sunday...dry and mild 
conditions expected for Thanksgiving day through Friday as an 
upper ridge shifts across the region. Some breeziness over an 
close to the mountains as some surface troffing creates some decent 
pressure gradient but no high winds foreseen. Over the weekend 
into early next week next upper system should affect the area. 
Models differ on handling of this system...mainly with how much 
energy GOES where...which would affect details over the County Warning Area. 
Current extended forecast looks to be in decent shape and cannot see 
good reason to alter at this time. Will maintain cooling trend 
over the weekend as next front due Friday night with some light 
precipitation possible mainly overt the mountains and far north sections of the 
County Warning Area. Otherwise no big surges of very cold air seen headed this way 
with generally progressive pattern keeping Arctic air bottled well 
north. 


&& 


Aviation...current observations show improving conditions this 
afternoon as the cold front...which pushed across the area 
yesterday evening and last night...continues to move southeast into 
Kansas and central Nebraska. Snow has diminished to isolated snow 
showers...mainly in the mountains and along i25. 
However...northwest winds will remain gusty into this evening with 
sustained winds between 15 to 25 kts and gusts around 35 
kts...becoming west and diminishing to 10 to 20 kts late in the 
evening. Expect brief periods of IFR conditions in moderate snow 
showers late this afternoon...with activity dissipating around 
sunset. 


&& 


Fire weather...no fire weather concerns through Thursday with cool 
temperatures and high humidities expected. 


&& 


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


&& 


$$ 


Short term/aviation...tjt 
long term...re