Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 160846

Area Forecast Discussion
National Weather Service Pocatello ID
246 AM MDT Mon Apr 16 2018

.SHORT TERM...Today through Wednesday night.
Cold front moving through eastern Idaho this morning with the
potential for showers, increasing winds and cooling temperatures
today. Snow levels will begin at around 6500 to 7 thousand feet
this morning then gradually drop to valley floors by this evening.
Mountain locations may see 2 to 6 inches of snow through tonight
with the heaviest amounts above 7 thousand feet. Expect 20 to 30
mph winds today in the Snake Plain and again on Tuesday.
Temperatures will turn sharply colder today behind the cold front
and fall into the 30s in the mountains and into the 40s in the
Snake River Plain. Tuesday will remain cold and windy with snow
showers mainly in the mountains but accumulations will be light.
Will have dry conditions Wednesday under high pressure with a
warming trend beginning but temperatures still well below normal.

.LONG TERM...Thursday through next Monday. The 00z GFS and 12z ECMWF
were in good agreement through Sunday morning before departing ways.
Initially, the models both depicted a closed upper low migrating
east through SRN Nevada and Utah Thursday and Thursday night
resulting in a chance mention of precip across SRN Idaho. By Friday
the low was working east through SRN Colorado as a transient ridge
of high pressure was building across WRN Idaho resulting in dry and
warm conditions. Both models showed the ridge giving way to a
progressive upper trough sweeping east along the Canadian border
which resulted in warmer temperatures and a slight chance mention of
showers across the CNTRL and NE mountains Saturday and to a lesser
extent Sunday. On Monday, the models were having difficulty trying
to resolve the speed and track of the next upstream disturbance and
thus have generally defaulted to the GFS solution here which
maintained a slight chance mention of showers across the north until
we can get this one sorted out. Statistical guidance was showing
afternoon highs pushing into the lower 70`s by the weekend and I had
no problem chasing that solution. Huston

.AVIATION...A broad upper low positioned over the NW coast was
moving onshore early this morning as associated moisture lifted
north across WRN and CNTRL Idaho ahead of the low. Numerical models
show the low lifting gradually NE across Washington today as the
associated plume of moisture spreads a little further east into the
forecast area. A disturbance ejecting from the low late this
afternoon and evening should help to drive the moisture further east
through the remainder of SE Idaho overnight. Model time-sections
were showing low VFR CIGS in showers this afternoon at KBYI, KPIH,
and KIDA with improving CIGS overnight. KSUN may see temporary MVFR
CIGS in showers this morning followed by improving CIGS this
afternoon and especially overnight. And finally, KDIJ will likely
see deteriorating CIGS later this afternoon with MVFR conditions
developing by early evening with temporary IFR CIGS in snow showers
overnight. Huston


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