191 
fxus65 kbyz 062031 
afdbyz 


Area forecast discussion 
National Weather Service Billings Montana 
231 PM MDT Sat Sep 6 2008 


Short term...valid for sun and Monday... 


Cool and unsettled weather to continue tonight through Sunday 
with northwest flow aloft remaining over the forecast area. Jet 
maximum pushing across southern Montana this evening which will force 
energy in northern stream to push across SC/southeast Montana. Short wave 
energy combined with entrance region of the jet and some warm air 
advection at the middle levels...will continue to bring scattered 
showers going overnight. A stronger short wave will move into the 
area on Sunday. Jet couplet over the area by 18z Sunday along 
with strong qg forcing. Have increased probability of precipitation Sunday afternoon to 
likely from Billings west with the strong dynamics pushing 
through as well as upslope flow increasing with surface high 
pressure over the eastern zones. Jet orientation will pull colder 
air into the area. Models showing cold 500mb pocket of air to 
move through in the afternoon. This will bring a potential for 
snow to elevations above 7000 feet during the day. Expecting snow 
accumulations over the mountains to stay below warning/advisory 
criteria as dendritic layer is fairly high and main lift below 
favorable Crystal growth zones. Upper lift will be exiting the 
area by evening with precipitation decreasing Sunday night. Dry 
weather returning Monday and Monday night as short wave ridging 
builds over the region. 


Lowered temperatures for Sunday with cloud cover and expected 
rainfall. Temperatures will once again range from 15 to 20 
degrees below seasonal normals. Temperatures warming on Monday as 
ridge builds in but will still be 5 to 10 degrees below normal. 
Richmond 


Long term...valid for Tuesday...Wed...Thu...Fri...Sat... 


Models in overall good agreement for the extended forecast. 
Mostly dry and warmer conditions anticipated for Tuesday in 
southwest flow ahead of next system dropping southeast toward the 
region. Downslope flow should push temperatures to near 80 
degrees. Will not rule out the risk for an isolated storm in the 
Southwest Mountains with weak upper level energy riding this 
southwest flow aloft. A strong short wave trough will push quickly 
across the area for Wednesday. This will push a strong cold front 
across the region early in the day...cooling temperatures once 
again. Will keep precipitation chances around 30 percent or 
so for Wednesday...despite stronger upper support...as system is 
working against a downslope flow. Have added an isolated storm 
potential with some weak instability advertised. This system moves 
quickly east of the area Wednesday night with building upper 
heights and warm air advection for late in the week. Have trended 
temperatures up slightly for late in the week...but warmup could be 
much quicker. Temperatures likely approaching 80...especially by 
Friday. Frieders 




&& 


Aviation... 


Showers will be scattered across the area into the early evening 
hours...before decreasing. Mostly VFR conditions will be 
noted...with only isolated MVFR/IFR conditions with a heavier 
shower. Showers will increase again by Sunday morning for mainly 
areas along and southwest of a Billings/Sheridan line as the next 
system approaches. Expect mountain obscurations persisting into 
Sunday. Frieders 


&& 


Preliminary point temp/pops... 


Sun Monday Tuesday Wednesday Thursday Friday Sat 
----------------------------------------------------------- 
bil 045/058 042/067 047/080 051/068 046/072 047/078 051/076 
37/west 40/u 00/u 13/T 20/u 00/u 00/b 
lvm 040/057 037/070 041/080 043/065 038/069 039/077 042/077 
56/west 20/u 01/b 23/T 20/u 00/u 00/b 
hdn 042/062 040/071 046/081 048/069 043/075 044/082 047/080 
35/west 40/b 00/u 13/T 20/u 00/u 00/b 
mls 041/061 040/069 046/079 050/068 045/073 047/079 050/075 
32/west 20/b 00/u 03/T 20/u 00/u 00/b 
4bq 042/060 040/067 043/078 049/069 044/073 045/079 048/079 
33/west 20/b 00/u 13/T 20/b 00/u 00/b 
bhk 036/058 035/065 041/076 047/069 042/073 043/080 046/079 
32/west 20/b 00/u 03/T 20/b 00/u 00/b 
shr 039/055 036/064 039/080 043/067 039/071 041/078 044/073 
57/west 40/b 00/u 12/T 30/u 00/u 00/b 


&& 


Byz watches/warnings/advisories... 
Montana...none. 
Wyoming...none. 


&& 


$$ 
Weather.Gov/Billings