Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 240920

Area Forecast Discussion
National Weather Service Pocatello ID
320 AM MDT WED AUG 24 2016

.SHORT TERM...Today through Friday. A storm will drop south and
east into the Northern Rockies and Great Basin through tomorrow.
Besides bringing cooler weather our way, this will bring back a
chance of showers and isolated thunderstorms to portions of
eastern Idaho. The best chance through tonight will be north of a
Stanley-Blackfoot-Wayan line. The models are showing a better
chance of storms across the Upper Plain likely due to outflows and
also a back-door cold front. It does appear that despite the front
moving farther southwest through the area, the chance of
precipitation quickly shuts off but that is something to watch.
Sometimes the models don`t handle these scenarios very well. A
similar scenario sets up tomorrow although the chance looks a
little less overall. By Friday, only isolated coverage is expected
from around Copper Basin to Monida and Island Park, as well as
along the Wyoming border south to around Driggs. We will see an
overall wind shift to a north or northwest direction today and
north to northeast overnight with the front. Winds be strongest
overnight actually and Thursday morning as the gradient tightens
up a bit. At this point, we are just shy of a Lake Wind Advisory
for American Falls Reservoir for a northeast wind pattern. Going
back to temperatures, we should stay rather steady with 70s/near
80 in the lower valleys with 50s and 60s in the mountains. It will
be chilly in some areas at night. Keyes

.LONG TERM...Friday Night through next Wednesday. We eventually
switch back to a warmer southwest flow over the weekend and early
next week. The potential for any more showers and storms will be
determined on how the storm offshore evolves and when it moves
inland. The GFS holds it back to the west and we end up pretty dry
and warmer. The ECMWF brings it to our door by next week and
therefore a chance of precipitation. The previous idea was to keep
it pretty dry except for a 10-15% chance of mountain storms. We
saw nothing that would push the forecast one way or the other, so
it was left as it was. Keyes


.AVIATION...Expect VFR conditions at most TAF sites although we
will likely have to contend with some variations in visibilty at
KDIJ and perhaps KIDA due to nearby fires. The models do show the
potential for -SHRA/-TSRA at KDIJ and KIDA as well later this
afternoon and evening, lingering at KDIJ all night. It`s possible
that storm could get close enough to KSUN as well. Winds will
gradually shift to north/northwest this afternoon and northeast
overnight as a cold front moves in from the north. Expect 10-20
kts winds at times from this afternoon through Thursday morning.
KSUN may end up with a decent south wind today, switching briefly
to northwest this evening. It remains to be seen if it will stay
northwest or go variable as sometimes can happen in a northeast
gradient pattern.  Keyes


.FIRE WEATHER...Low pressure disturbance is moving south from
Montana today. N-NE surface winds already showing up in the Arco
Desert this morning and will gradually take over the Salmon-Challis
Forest area and all of the Middle and Upper Snake Plain by this
evening. For the Caribou Highlands, general winds over the ridge
tops will become northerly tonight as well, but lower slopes will be
more easterly or drainage driven. The risk of isolated thunderstorms
this afternoon is further south to about a Sun Valley to Idaho Falls
line and possibly as far south as Blackfoot this evening. Rainfall
amounts are only trace to 0.03 inches. Thursday, the disturbance
slides south and east with a slight chance of afternoon thunderstorms
mainly over the Central mountains and eastern highlands. some
clearing of skies in the afternoon will help westerly surface winds
to return particularly in the Middle Snake River Valley. There may
be a few lingering showers near Island Park on Friday, otherwise
northwest to west winds bring dry conditions and temperatures
warming into the weekend. Upper 80s expected in the Snake Plain
again by Monday. RS


.PIH Watches/Warnings/Advisories...

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