Weather Service Report

FXUS65 KPIH 212018

Area Forecast Discussion
National Weather Service Pocatello ID
118 PM MST Tue Nov 21 2017

.SHORT TERM...Tonight through Friday afternoon. A ridge of high 
pressure will continue to build over Idaho through Wednesday. This 
has raised snow levels close to 9000 feet elevation. Horton Peak at 
8800 feet just north of Galena Summit was reporting a temperature of 
38F at noon today. Some rain has fallen in the mountains, probably 
absorbed by the high elevation snow pack. Certainly no snow 
accumulation concerns. Precipitation shifts a little further north 
with the building ridge on Wednesday, roughly a Challis to Island 
Park line by afternoon. Thanks Giving Day starts off with some 
partly cloudy skies, then increasing clouds in the afternoon ahead 
of a cold front that will make the Snake Plain close to Friday 
morning. Snow levels drop to about 6000 feet elevation Friday 
afternoon with this passing disturbance. Some breezy winds expected, 
but well below advisory levels. The precipitation is short lived, 
late Thursday night and Friday morning and not enough for 
significant travel concerns. RS 

.LONG TERM...Friday night through next Tuesday. Mean upper ridge 
will be situated over the Intermountain West on Saturday, then shift 
to the east. Moisture feeding into the ridge will support some 
slight chance-chance PoPs over the Central Mountains and the Island 
Park area. Precipitation chances increase and spread through the 
rest of east Idaho on Sunday night/Monday with the approach of a 
strong cold front. This will also impact winds across the area as 
the front passes. Current guidance is keeping winds just shy of 
advisory levels. Synoptically, the GFS is slightly more progressive 
than the ECMWF with regard to the upper trough, but models overall 
are in general agreement through early next week. GFS and ECMWF show 
an improving trend throughout the day Tuesday. Hinsberger

.AVIATION...Low-level moisture represented by forecast BUFKIT 
soundings this afternoon for KPIH, KIDA, and KDIJ. Teton Valley 
webcams and KDIJ observations indicate the presence of patchy dense 
fog, which I've left in a TEMPO group for the first hour of the TAF. 
Gradual improvement is anticipated through the afternoon and into 
this evening. Models suggest a period of rain tonight, keying in on 
upslope-favored areas in a westerly flow. Best chances will be at 
KSUN and KDIJ tonight into tomorrow morning. Perhaps a bit more 
prolonged at KDIJ, which would support the lower ceilings. 




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