365 
fxus65 kpih 202131 
afdpih 


Area forecast discussion 
National Weather Service Pocatello Idaho 
228 PM MST Friday Nov 20 2009 


Short term...a strong Pacific system is pushing inland now. 
Currently we have strong southerly winds across the area. Ridge-tops 
in the south central Highland mountains are receiving gusts of just 
under 50 miles per hour with several gap areas receiving gusts just above 40 
miles per hour. Expect the high winds to continue this afternoon into the 
evening. Expect sustain winds of 25 to 30 miles per hour with gusts near 50 miles per hour 
at ridge tops...gaps and downslope areas. These strong winds will 
occur mainly in south central and Caribou Highlands and adjacent 
areas in the lower Snake River Plain. A Wind Advisory is in effect 
for zones 21...22 and 23 primarily for higher elevations...gaps and 
downslope areas from 2 PM to 11 PM today. Ridge tops across all 
southeast Idaho will receive strong winds. A cold front will begin 
pushing through tonight after midnight. Snow showers will begin in 
the western central mountains and push eastward overnight into early 
morning. With good cold air behind the front...the snow levels will 
drop overnight into early morning. Snow amounts of 3 to 6 inches are 
possible in the central mountains...upper snake Highlands and 
eastern Highlands with higher amounts along ridge tops. Models are 
indicating the possibility of a convergence event setting up along 
the eastern upper Snake River Plain early afternoon with the 
possibility of 2 to 4 inches of snow. Very little accumulation is 
expected in the lower Snake River Plain. Saturday afternoon strong 
winds are again expected in the lower as well as upper Snake River 
Plain behind the front. Models are currently indicating winds right 
at the lower end of a Wind Advisory late Saturday afternoon into 
early Saturday evening. Wyatt 


Expect brief ridging Saturday night before the next strong Pacific 
system begins to impact the western central mountains middle to late 
Sunday morning. The models have pushed this back several hours 
from previous runs. This will be a potent system as well. This 
system will have strong westerly winds but not as strong as 
Friday night's southerly winds. This system has the potential to 
bring more snow with 4 to 8 inches possible in the central and 
eastern Highland mountains with higher amounts at ridge tops. If 
model runs continue to be consistent expect a winter advisory to 
be issued. Snow accumulation across southeast Idaho looks possible 
for this system as well. The Snake River Plain could receive 1 to 
3 inches of snow. 




Long term...GFS guidance has returned to matching the lately more 
consistent European model (ecmwf) and thus have been using GFS guidance for 
temperatures. Progressive pattern takes a break during the upcoming 
Thanksgiving Holiday to make it the warmest day of the week. Ridge 
that develops on Wednesday-Thursday begins its breakdown as early as Friday...but 
more likely Friday night. Expect clear and very cold overnight during 
that time...but temperatures pushing warming than normal for 
afternoon highs. A storm wrapping up Monday is the only significant 
precipitation...the other storms mostly clouds and only slight 
chances. Messick 


&& 


Aviation...wind had just started to gust at the Snake River 
airports. Wind appears to cease gusting for the early evening. 
Kbyi is struggling with this right now. Wind speed increases again 
the front approaches. Expect front with some light precipitation 
from 21/09z to 21/15z. Gusty wind should keep temperatures up and 
thus expect mostly rain at kbyi...but could see snow at kida and 
kpih. Snow at ksun should be ending just as the Airport opens...but 
trends have been to slow the approach and it may end up with a shut 
down Airport during the morning hours. Messick 




&& 


Pih watches/warnings/advisories... 
Wind Advisory until 11 PM MST this evening for idz021>023. 


&& 


$$