Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 152020

Area Forecast Discussion
National Weather Service Pocatello ID
220 PM MDT Sun Oct 15 2017

.SHORT TERM...Tonight through Wednesday. Shallow ridge with
warming temperatures will be the rule for the early part of the
work week. Look for daytime highs to increase day-over-day by
several degrees, with lower elevation temps expected to reach at
least the mid to upper 60s in many locations. GFS operational
guidance temps slightly higher, but current forecast in the middle
of ensemble spread. Could see temps reach into the lower 70s for
PIH, but despite the warmth, this is still some 5-10 degrees below
records. DMH

.LONG TERM...Wednesday night through Sunday. Upper ridge amplifies
and shifts east toward the Plains by early Thursday. Guidance
paints Thursday as warmest day, and this reflected well in current
forecast with turn to southwest flow aloft ahead of approaching
Pacific trough. As trough axis shifts inland along the coast,
moisture spreads inland with timing Thursday night for the
central mountains. GFS much slower than the ECMWF, holding off all
precip until early Friday. Opted to keep current timing for
Thursday night as models have been shifting solutions around.
Friday should be best chance for precipitation across the region
as upper trough slides across Idaho. Temps appear to be warm
enough to keep precipitation as rain at valley floors, but some
mix likely in places Friday night. Upper ridge builds back into
the region Saturday for west-to-east drying trend. Kept weak pops
across the central mountains through the remainder of the forecast
period as flat flow across the PacNW could keep moisture grazing
the northern portions of the region. DMH


.AVIATION...Dry westerly flow will gradually build over the region
through Monday with surface winds remaining light and terrain-
induced. Low-end chance for fog at IDA and PIH around Sunrise Monday
morning but have left out of TAFs due to low probability of
occurrence. Southerly winds increase above the inversion to near 20
KT between 06-12Z at BYI and PIH, but remain below WS criteria so
have not been included in TAFs at this time. AD/DMH



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