Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 202102

Area Forecast Discussion
National Weather Service Pocatello ID
202 PM MST Fri Jan 20 2017

.SHORT TERM...Tonight through Sunday night. A deep upper low off
the WA/OR coast will send the first wave of energy thru the Pac NW
tonight. Snow will spread across the fcst area overnight...but the
wave quickly loses strength as it departs from the main system. As
a result...snow amounts will be on the light side most areas. The
exception will be the northern Magic Valley where the strong SW
flow will encounter higher terrain. This area may see around 4
inches...while the rest of the Magic Valley should see 2 to 3
inches. Will not go with an advisory on this system due to the
expected lack of other hazards. The mtns can expect 2 to 4 inches
...while the Snake River Plain should see around an inch. Snow
diminishes to scattered showers by Sat aftn. Snow diminishes Sat
night in all but the eastern highlands.

Another wave is ejected Sunday from the Pac storm system off the
coast. This will increase pops quickly across the fcst area Sun
aftn. Precip from this system is expected to continue thru the
night into Mon. This system looks like it will produce 3 to 6
inches in the valleys and central mtns...and 6 to 10 inches in the
eastern highlands. In addition, fairly windy conditions are
expected Sunda, Will hold off on a watch for the eastern highlands
until the Sat system is moving out.  Hedges

.LONG TERM...Monday through Friday. It appears we are still looking
at some higher precipitation amounts Monday and Monday night as the
next storm of significance moves in. HOWEVER, details have changed
once again. The models still favor a good chunk of the southeast
highlands and the I-15 corridor for heavier snowfall. The difference
is the GFS and ECMWF now want to bring the closed circulation over
the central mountains vs farther south. This pulls more snow back
toward the northwest and also frontal/convergence band passage until
Tuesday now. We trended back to the northwest a bit with amounts and
snow chances because of this and kept a bit more in the forecast
Tuesday especially across the Snake Plain and points east. We have a
feeling given the pattern we are in right now, we may see some
fluctuations each time the models run back east until we get toward
the end of the weekend. After that, the trend continues to drier.
ward drier, although it may not be totally dry. There are some
indications that we could see occasional very light snow as we are
close enough to the deepening low east of the Rockies. This is also
pattern where we should see some pockets of fog, stratus and
flurries. Also look for inversions and quicker warming at
mid/upper slopes toward the end of next week. Keyes


.AVIATION...It appears all sites except KSUN are VFR this afternoon.
There are still some patches of stratus and fog around. This is
what`s affecting KSUN and it may not go away as the southerly wind
has kicked in. Expect MVFR weather along with some light snow there
and anywhere else we are seeing stratus linger this afternoon. As we
go into tonight and Saturday morning, we will see snow spreading in
from the southwest. As this occurs, we will see a gradual decline
ahead of the main push of moisture. As that hits each terminal, we
are forecasting MVFR/IFR conditions although we might be a bit
optimistic. Based on current timing, we should see it at KBYI and
KSUN around midnight. KPIH and KIDA between 3-5am, and KDIJ last
around 6-8am. That could easily change. Conditions should gradually
improve from west to east behind this area of snow, as it should
last very long. Keyes



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