Area Forecast Discussion
Issued by NWS Pocatello, ID

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478
FXUS65 KPIH 281936
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
136 PM MDT Sun May 28 2017

.SHORT TERM...Today through Tue night.  Upper level ridge firmly
in place over the northern Rockies and Intermountain Region
through Monday night. Forecast models indicating moisture and
instability sliding down the downwind side of the ridge over MT
and clipping the NE corner of ID. Definite difference between the
models on how far west this moisture is able to penetrate into
ID. This afternoon seeing development of very weak and short-
lived showers over the Upper Snake Highlands which will end
quickly in the early evening hours. For Monday and Tuesday, it
looks like this trend will continue with development of weak
afternoon showers, but question still remains on whether showers
will spread into eastern portions of the Central Mountains of ID.
Will begin to see a transition with the upper ridge shifting east
as an upper level trof swings through the base of a large upper
low in the Gulf of AK. Main forecast issue in the short term is
snowmelt and flooding associated with warmer temperatures.
Temperatures continue with a strong warming trend today, up 2 to 7
degrees for Mon, then another 1 to 5 from Mon to Tue. DSH

.LONG TERM...Wednesday through Sunday. GFS ensembles indicate upper
ridge will gradually shift to the east as we come more under the
influence of an upper trough. Main changes to long-term periods was
a slight bump in PoPs as GFS/ECMWF trending a bit upwards in
moisture distribution, particularly on Thursday coincident with a
modest upper wave. There is notable disagreement between GFS/ECMWF
as this upper wave exits the area. By Friday evening, the ECMWF
drops an upper low off the WA coast while the GFS maintains a weak
upper ridge. ECMWF thus proposes a wetter solution for next weekend.
Touched up the PoPs with a model consensus, but mainly kept the
focus over the mountains. Hinsberger

.AVIATION...Dominant upper ridge will lead to widespread VFR
conditions. Some instability will make showers possible over the
Eastern Highlands, and may impact KDIJ this afternoon. Dry
conditions and light winds will prevail elsewhere.  Hinsberger

&&

.PIH WATCHES/WARNINGS/ADVISORIES...None.

&&

$$



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