Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 252045

Area Forecast Discussion
National Weather Service Pocatello ID
145 PM MST Sat Feb 25 2017

.SHORT TERM...Tonight through Tuesday. The latest satellite imagery
was showing a weak trough shifting SE through Montana. Numerical
models support some mention of light snowfall across the CNTRL and
ERN mountains tonight as a result. Looking further upstream, the
next storm system was digging rapidly south along the WRN Canadian
coast. Numerical models show the leading edge of snowfall associated
with this system extending into the CNTRL mountains as early as
Sunday afternoon. As the storm swings through Oregon and into the
Great Basin Sunday night/Monday increasing coverage and intensity of
snowfall will spread across the remainder of SE Idaho. Snow totals
with this first system fall well within advisory criteria for both
the CNTRL and ERN mountains with lesser amounts elsewhere. We will
continue with the special weather statement for now and probably
follow suite with an Advisory either tonight or tomorrow. A second
disturbance follows close behind late Monday night/Tuesday with
another round of light snowfall, generally sub-advisory in nature.
We will see some instability Monday afternoon but well behind the
cold frontal passage that would have occurred Monday morning so I am
not inclined at this point to add any mention of thunder to the
forecast. Breezy winds are expected both Monday and Tuesday with the
passing systems. Huston

.LONG TERM...Tuesday night through next Saturday. High pressure is
generally in control of the weather pattern next week. A passing
upper trough may provide a chance for snow showers across the
Eastern Highlands late Tuesday/early Wednesday. Forecasting
uncertainty exists in the Upper Snake Highlands Wednesday through
Friday with a lingering weak trough over the Idaho/Wyoming border.
This trough appears deeper in the GFS and is therefore forecasting
higher amounts of precipitation over this region, while other models
are less enthusiastic about potentials. The location of heavier
showers may set up over Yellowstone National Park with lesser precip
amounts on the Idaho side. For now, a mild ongoing chance for snow
showers will exist in the official forecast with a low confidence.
By early Saturday, all traces of the precipitation are gone from the
models as high pressure builds and clear skies are briefly expected
before the next system moves in from the west. This next system
brings in quite windy conditions and may potentially be a heavy snow
maker for the weekend. Since it is a week away, and the timing of
global models are not quite in agreement with each other right now
the forecast for now is calling for a chance of snow with the caveat
that this forecast is likely to increase in precip potentials in the
coming days. NP/MH

.AVIATION...Expect VFR conditions through Sunday morning at all
sites other than DIJ where I have some MVFR ceilings overnight and
light snow showers.  Next system appears to be slowing down and
expect the worst conditions at TAF sites with potential snow and
lowered ceilings mainly Sunday night into Monday. GK

.HYDROLOGY...Cooler temperatures have helped reduce impacts of
local snow melt flooding. A few areas continue with
warning/advisories at request of Emergency Managers. Huston


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