Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 232049

Area Forecast Discussion
National Weather Service Pocatello ID
149 PM MST Thu Nov 23 2017

.SHORT TERM...Moist subtropical air continues to stream into
southern Idaho this afternoon, just ahead of a disturbance
expected to cross this area tonight. Cotton Ridge RAWS site in
western Cassia county already reported 0.03 inches of rain this
afternoon. Snow levels this afternoon are quite high, at or above
9000 feet elevation. Surface temperatures are also unseasonably
high. At 1:00 PM Pocatello reported a high temperature so far
today of 65F, the old record for this date was 58F set in 2011;
Burley reported 65F, the old record was 60F set in 1995; and
Challis reported 64F, the old record was 62F set in 1933. These
are highs so far today and not final temperatures for the day. A
surface front will cross this area Friday morning, followed by
colder air and breezy winds 15 to 30 mph in the Snake Plain Friday
afternoon. Snow levels by afternoon will range from about 5800
feet near Challis to about 7200 feet near Burley. Snow
accumulation in the mountains will be limited to 1 to 3 inches and
most of that above 8000 feet. This disturbance moves east of the
state by FRiday evening. The high pressure ridge gains some
amplitude by Saturday and a minor disturbance will track further
north from about Challis to Salmon with little impact. RS

.LONG TERM...Sunday night through next Thursday. GFS is trending
towards a deeper Pacific trough, and is more in tune with the ECMWF.
GFS is still slightly more progressive, but in better congruence
with the ECMWF. This will impact the timing of the lowering of the
snow levels until late Monday morning, so the "back-to-work" commute
should see minimal impacts. The Monday afternoon/evening commute,
however, may continue to see snow--particularly along and east of I-
15. Total snow amounts int he Central Mountains still looks to be
around 6 to 8 inches, 4 to 6 inches in the Eastern Highlands, and
half inch or less in the Snake Plain. MOS guidance has cut wind
speeds on Monday just below advisory levels, but I anticipate this
forecast will fluctuate as we head into the weekend. Things quiet
down again on Tuesday and Wednesday, but a shot of moisture may
stream across the region Wednesday night into Thursday as an upper
trough swings in from British Columbia. A split flow will be in play
associated with this trough, and the GFS favors the greater energy
from the northern stream and the ECMWF, the southern stream.

.AVIATION...Active period with a stream of moisture advancing across
the area ahead of a fast-moving cold front. Ceiling impacts will be
generally MVFR, but IFR is expected at KIDA in the morning hours.
Winds will also be brisk starting this afternoon, and increasing as
the front approaches. BUFKIT soundings show the potential for LLWS
at KSUN during the overnight hours. Hinsberger



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