Area Forecast Discussion
Issued by NWS Pocatello, ID

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000
FXUS65 KPIH 230955
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
255 AM MST Wed Jan 23 2019

.SHORT TERM...Through Saturday morning. Low pressure disturbance
is observed on Stiletto, various observational suites and
confirmed in model data moving ashore across western Washington
and Oregon as of 2AM MST. Moisture surging ahead of the
disturbance has manifest itself in the form of Snow, which is well
underway across the Montana and Wyoming border regions, but
mainly from Palisades on north at this hour. Expectation is for
Snow to expand south through the morning to include all of the
Eastern Highland Mountains and Valleys between the Interstate
corridor and Wyoming, and eventually for the high terrain areas
south of I-86 by late morning. Portions of the Sawtooths and
surrounding Mountains will experience Snow as well. Higher
uncertainly lies across the Interstate corridor and Snake Plain as
typically in these NW flow events, the above-mentioned valleys
see little Precipitation. However, some higher resolution models
indicate a little more in the way of Snow for the Snake Plain, but
should still see amounts under 1". Am currently not carrying
quite that much in the forecast, so may need to monitor trends for
possible updates. The benches of Pocatello will likely be in the
1-3 inch range, with amounts ranging up to near 12" for Pine Creek
Pass. Plenty of wind will be felt as well, which will lead to
blowing and drifting. After collaboration with Salt Lake, added
the Bear River Range and Bear River valley zones to the Winter
Weather Advisory as well.

Snow and wind will quickly wind down this evening with just a few
light snow showers left across the eastern highlands by Thursday
morning.

A second disturbance is then indicated to offer a resurgence in
snow shower activity beginning Friday afternoon for the Island
Park area south to Palisades and West to near Monida, with this
quickly winding down Friday evening.

Temperatures are forecast to be near climatological averages for
this time of year through the short term period. AD/DMH



.LONG TERM...Saturday through Wednesday. Extended range remains
dominated by deep trough over central and eastern states, with ridge
along/near Pacific coast and northerly flow into East Idaho. Two
main features during this period. The stronger feature still
expected late Sunday into Monday with precipitation primarily
focused along eastern highlands. Could see an uptick in winds with
this system, but at this time not significant enough to signal a
threat for widespread blowing snow. Wednesday into Thursday could
see another system drop into Montana from Canada. GEFS means favor a
wetter solution than both the operational GFS and ECMWF would
indicate. Opted to keep a trend toward the wetter blends with weak
precip chances higher elevations. DMH


&&

.AVIATION...Shortwave pushing through PacNW states this evening
producing weak precipitation across the northeast corner of the
region this morning, and expected to spread further south mainly
along the WY border through the day. KDIJ still expected to be the
terminal with greatest threat for precipitation today given
northwest flow and upslope into that region. However can`t
completely rule out precipitation other terminals, though KBYI
would be the least likely to see any snowfall out of this event.
Will continue trend of MVFR/VFR ceilings dropping to localized IFR
in heavier snow for KDIJ with VCSH mention most other terminals.
Breezy winds also likely this afternoon especially Snake Plain
terminals with sustained SW 15-25kts. Threat dissipates this
evening for both snow and wind, though snow could linger longer at
KDIJ. Clearing aloft might be favorable for stratus formation
overnight as indicated with guidance and model soundings, so will
likely lean in that direction after 03Z for at least KIDA and
KPIH. DMH


&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 11 PM MST this evening for
IDZ062>066.

Winter Weather Advisory until 11 PM MST this evening for IDZ060-
061.

&&

$$


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