Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 152048

Area Forecast Discussion
National Weather Service Pocatello ID
148 PM MST Thu Feb 15 2018

.SHORT TERM...Tonight through Sunday.

Most of the snow has ended for the day. Still might see some
residual snow showers this evening, but should be isolated with
little to no accumulation. Another weak system will arrive on
Friday. The bulk of the snow with this system will pass through
Montana but we will still likely see light snow across portions of
the high country, mainly along the Wyoming border. areas around
Island Park potentially could pick up 2 to 5 inches of snow as this
system passes by. Otherwise, most locations across the eastern
highlands will be in the 1 to 3 inch range. Expect breezy conditions
to develop in the afternoon and early evening, possibly approaching
wind advisory levels across the Snake Plain.

There will be a brief reprieve Friday night before the next system
arrives Saturday. This is a much stronger system associated with an
upper level low and consequently signifies a pattern change. This
will be a long duration event, that will persist into early next
week. Looking primarily at high country snow with gusty winds
through the weekend. Snow levels will climb during the day on
Saturday to around 5000 feet, perhaps a little higher in some
places. Then, a cold front will arrive Saturday night and bring snow
levels back to the surface. Because of strong winds, the Snake Plain
and Magic Valley will be largely downsloped once again. The more
significant snows arrive Saturday afternoon and persist into
Saturday evening across the central Idaho mountains into the upper
Snake highlands. Then, as the front moves through the region, the
focus shifts into the southern highlands. Latest model runs show
this front slowing down across the southern highlands late Saturday
night through the day on Sunday which may allow heavier snow to move
across the frontal zone. 2 day totals for this event run from 6 to
12 inches from Galena Summit through Stanley to Banner Summit. 6 to
12 inches is likely across the eastern and southern highlands above
6000 feet. Localized amounts up to 2 feet are possible in these
areas. Once again, this is a 2 day total. With the breezy conditions
likely through the weekend, blowing snow could be problematic.
Potentially could see advisories and/or warnings issued for the high
country this weekend.


.LONG TERM...Sun night through next Thu night. Storm that started in
the near term forecast will linger into Sun night, especially for
the ID-WY border region. The rest of the time has weak troughing in
the upper levels carving out a position in central and western
Montana, with very weak impulses moving through the mean
northwesterly flow over the Gem State. This means slight chances of
precipitation, mainly in the central Idaho mountains and the ID-MT
and northern ID-WY border regions. The lack of strong shortwaves
moving through this flow is also indicated by little to no
difference from the operational 500mb forecasts and the 500mb 5-wave
forecast; both have this same trough through central MT, southern
ID, and northern NV. This nearly continuous northwest flow does mean
a large change in temperature. Afternoon highs are 8 to 15 deg F
below normal for the time of year, with morning lows about the same
range and below normal as well. The next significant shortwave does
not approach until the last period, next Thu night, where it gets
into the northern zones first. Wind continues very strong Sun night
and Mon, windy for Tue, then breezy the rest of the period.


.AVIATION...Weak winter storm of last night is clearing out and
skies should improve during the evening. Only threat of overnight
stratus appears to be KIDA and KDIJ, where the snow was more
significant in accumulation and winds are weakest. CIGs return Fri
afternoon/evening with next approaching storm, starting out in the
mid-levels. Messick



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