346 
FXUS65 KPIH 252042
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
242 PM MDT Mon Oct 25 2021

.SHORT TERM...Today through Wednesday. Moisture continues to
stream into our area with an Atmospheric River event. Already 1 to
3 inches of precipitation has fallen in our northwest areas.  
Currently, moisture is mainly along a slow moving cold front 
boundary that is over the Snake Plain. There is lingering light 
moisture mainly over the southern Central mountains behind this 
cold front. Expect this cold front boundary to move slowly east 
through the afternoon into tomorrow morning. Valley areas for the 
Snake Plain, Southeastern, and Eastern Highlands will get 0.75 
inch to 1.25 inches with mountains receiving 1 to 2 inches of 
precipitation. Expect snow levels around 8500 to 9000 feet across 
the Eastern Highlands along the Wyoming border ahead of this cold 
front. Snow levels will drop to around 4500 to 5000 feet in the 
Central mountains and 5000 to 6000 feet in the Eastern Highlands 
by Tuesday morning. Overnight into Tuesday morning, look for an 
lingering 1 to 3 inches of snow for the Central mountains and 2 to
4 inches of snow above 7000 feet for the Southeastern and Eastern
Highlands with higher amounts of 4 to 8 inches (possibly higher) 
above 8000 feet for the same area, Southeastern and Eastern 
Highlands. Rain will be steady, light to moderate. Flooding is 
not expected. However, some low-lying areas with bad drainage, 
and areas that have burn scars may see some localized flooding.

By Tuesday afternoon Northwest flow aloft sets up. Expect light 
snow of 1 to 4 inches for mainly the northern Central mountains 
and the Upper Snake Highlands (Island Park area) with snow levels 
around 5500 to 6000 feet. Some snow will extend more south along 
the Wyoming border, but little is expected. Early Tuesday morning 
behind the cold front expect moderate winds gusting 25 to 40 mph,
very close to wind advisory levels. Winds will back off some 
before getting near to the same levels by Tuesday afternoon.

Wednesday, northwest flow aloft continues. A wave moves through 
the northwest flow allowing for moderate winds, likely wind 
advisory levels with gusts of 35 to 50 mph. Also, look for light 
snow mainly for the Upper Central Mountains and the Upper Snake 
Highlands (Island Park) with snow levels around 5000 to 6000 feet.
Wyatt

&&

.LONG TERM...Thursday through next Monday. High pressure briefly 
holds Thursday. We could still see a few showers across the central 
mountains and around Island Park. The next low moving across the 
northern US and southern Canada will impact us as early as Friday, 
but more likely holding off until Saturday and beyond. The GFS and 
ECMWF keep the main low well into Canada, and we are impacted by a 
"wave" extending to the south of it. With a much deeper low in those 
models, we remain northerly/northwest flow on the backside of that 
storm through the weekend, with showers possible...especially across 
the eastern and southeast highlands. This is also shown in the Blend 
of Models and current forecast, along with much cooler temperatures 
once again. Of note, the cluster forecasts either have a ridge right 
back over the top of us by Sunday, or much weaker influence from the 
low...a fairly even split. 
Keyes

&&

.AVIATION...Rain and high elevation snow continues to shift south 
and east across eastern Idaho this afternoon. Where precipitation is 
heavier, MVFR/IFR weather is reported. Winds are also decreasing 
over much of the area. We will see most of this shifting into 
Wyoming and Utah tonight. Lingering rain and snow is expected for 
areas along and east of I-15, impacting PIH, IDA and DIJ. A 
convergence band is also forecast to form over the Upper Snake Plain 
and eastern highlands, impacting DIJ after 12z Tuesday. At the 
moment, this band MAY stay north of IDA. This band potentially will 
be all snow and produce MVFR/IFR ceilings and visibility. During the 
day tomorrow, showers are still possible along the Wyoming border 
and also resurging into the central mountains. That would at least 
give SUN and DIJ VCSH conditions. Winds will also return from west 
and southwest late tonight and Tuesday for the Snake Plain, Magic 
Valley and higher elevations. Winds at BYI, PIH and IDA will peak 
tomorrow at 15-25kts...possibly a but higher before factoring in 
gusts. Expect VFR weather at all TAF sites, unless showers end up 
impacting DIJ or SUN directly...where at least MVFR weather could 
occur. 
Keyes

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$