199 
fxus65 kpih 211018 
afdpih 


Area forecast discussion 
National Weather Service Pocatello Idaho 
318 am MST Sat Nov 21 2009 


Short term...today through Monday. Cold front has pushed through 
much of the area this morning. As a result...winds have dropped 
below advisory level however they remain generally elevated. Gap 
flow has diminished with winds turning more southwesterly but 
gusts to 35 miles per hour remain common in snake plain. Precipitation has 
spread throughout the region but temperatures remain above 
freezing everywhere except the central mountains and the higher 
elevations of the eastern Highlands. Cold air will filter into the 
region today...so expect little diurnal temperature rise today 
before falling off through this afternoon. Precipitation will 
continue through the morning then diminish as the trough quickly 
lifts into Wyoming this afternoon. Precipitation amounts are 
generally expected to be light with only a few inches expected in 
the highest elevations. Winds will remain breezy 
today...especially in the Snake River Plain. Expect winds to be 
just below advisory level today. 


Ridging ahead of the next system will bring a brief break in the 
weather this afternoon and tonight. The next fast moving trough 
arrives Sunday morning. With cold air in place...this system will 
bring snow across the area with the highest quantitative precipitation forecast amounts again 
expected in the central mountains and southeastern Highlands. 
Models indicate at least advisory level snow amounts associated 
with this system...however with its fast moving nature and recent 
model tendency to over-estimate the precipitation will hold off 
issuing any headlines for now. The Snake River Plain will escape 
much of the snowfall however an inch or so is possible. Also of 
concern will be another round of gusty winds ahead of the cold 
front on Saturday night. Hanko 




Long term...Monday night through Saturday...isolated showers will 
linger mainly in the northern mountains Monday night as a high 
pressure ridge begins to build. Model consensus favors a higher 
amplitude high pressure ridge and drying conditions Tuesday through 
Thursday. Current forecast reflects much lower probability of precipitation and less clouds 
during that time period. Diurnal temperature range was also 
increased. The ecm is faster than the GFS with the next disturbance 
around Friday morning and depicts more of a stretched...weak trough. 
Therefore stayed close to climatology with probability of precipitation for Friday and 
Saturday time frame. Receiver station 




&& 


Aviation...Post frontal precipitation just now moving through kida 
and kpih and should be limited to the next couple hours. Cold 
advection at or just above cloud level increasing and snow levels 
estimated only 500 to 1000 feet above the valley floor. Cloud cover 
continues to move up the Magic Valley and could keep MVFR ceilings 
pinned against the east benches as the nam12 suggest until about 
18z. Westerly surface pressure gradient will support breezy 15 to 25 
miles per hour winds through 24z. Ceilings improve to VFR tonight. The second 
of two disturbances moves into southeast Idaho after 22/1500z...cold 
frontal passage at kida and kpih near 22/2100z...and snow levels 
about 4400 feet mean sea level. Receiver station 




&& 


Pih watches/warnings/advisories... 
none. 
&& 


$$