894 
fxus65 kpih 292024 
afdpih 


Area forecast discussion 
National Weather Service Pocatello Idaho 
224 PM MDT Friday Aug 29 2008 


Discussion...ridge axis continues over eastern Idaho today per 
Sat imagery with clear but smokey skies. Pacific trough making 
steady progress toward Washington coast...and moisture beginning 
to surge northward from Arizona/California. Models remain in good 
agreement that middle level moisture should push into forecast area late 
Saturday ahead of deepening trough. Moisture stays generally 
elevated but could see isolated storms over higher terrain Sat 
afternoon. Baroclinic zone strengthens across western 
Idaho/eastern Oregon into Sunday as models close off trough and 
drop center of low toward Nevada. Result of this is drastically 
slowed progression of system and stall of developing surface 
boundary. Track of upper low and strength/gradual movement of cold 
makes forecast details quite uncertain. Deeper southerly flow over 
forecast area should lead to slightly warmer temperatures for Sunday than a 
more progressive solution...but temperatures will be moderated by increased 
cloud cover and precipitation forecast for the region. Cold front 
passage now appears to be Sunday night through eastern Idaho...and 
unseasonably cool temperatures forecast for Monday as center of upper 
low prognosticated to be near Vegas. Light snows possible at higher 
elevations after Sunday...with no significant accumulations forecast 
at this time. Precipitation tapers off by late Tuesday with temperatures beginning a 
rebound to seasonable levels. However...pacnw remains under broad 
long wave trough. Kept remainder of forecast largely dry and slightly 
cooler than normal given lack of features strong enough to force 
precipitation. Dmh 




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Aviation...VFR conditions will continue through Saturday. Winds 
will increase at the taf sites Saturday afternoon to the 10 to 20 
miles per hour in the Snake River Plain sites as a cold front approaches. 
Gk 






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Fire weather...a Pacific trough will move on shore Saturday and push 
a cold front into Idaho. Expect gusty winds Saturday along the 
front in high elevations. With low humidities red flag warnings 
have been issued for zones 412...476...and 477 where gusts are 
expected to be in the 30 miles per hour range. Think humidities will be 
elevated in zone 475 on the back side of the front so they have been 
kept out of the warning. Do not think gusts in the Snake River 
Plain will reach 30 miles per hour. The upper trough moves overhead by Monday 
with the cold front pushing well east by Sunday. Expect much wetter 
and colder conditions Sunday and Monday as relative humidities 
increase substantially and temperatures drop significantly. 
Gk 




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Pih watches/warnings/advisories... 
red flag warning from 2 PM to 9 PM MDT Saturday for idz412-476- 
477. 


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