Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 240842

Area Forecast Discussion
National Weather Service Pocatello ID
242 AM MDT Thu May 24 2018

.SHORT TERM...Today through Saturday...Patchy early morning fog is
noted along the Continental Divide, Monida Pass, in the Valleys
of the Central Mountains and are possible in Upper Snake Plain.
Temperatures today will quickly rise toward the 80 degree mark in
the lower Snake Plain with otherwise 70 degree weather and mostly
rain free conditions expected. Showers and a chance for
thunderstorms will lie in the Central Mountains this afternoon and
early evening with little accumulations expected overall. Around
1/4 inch is possible in select locations however. Friday continues
to look generally dry with warm temperatures exceeding 80 degrees
across the Snake Plain and mountain valleys. Drying conditions
are also expected for Friday with RH values dropping to 20 to 25
percent or so. By Friday evening into Saturday, the influence of
our next upper low will begin to take hold with increases in
precipitation expected. Showers are expected in the west initially
which will gradually spread eastward through the weekend.
Forecast models are rather consistent tracking this low south of
Idaho with isolated to scattered showers and thunderstorms in our
area. NP/JH

.LONG TERM...Sunday through next Thursday. Long-term models
maintain an upper low over the Great Basin just to our south
through Monday. Both GFS and ECMWF show the low filling and
lifting northeastward through eastern Idaho. Showers and isolated
afternoon/evening thunderstorms still remain likely across the
region. GFS is favoring a heavy band of precip aligned from Island
Park to Twin Falls just north of the 500mb low on Monday. ECMWF
has a less organized precip pattern for that timeframe, but does
have a bullseye of 0.37 inches along I-15 between Dubois and
Downey. While the GFS pattern becomes more amplified Tuesday and
Wednesday, the ECMWF shows a progressive upper trough approaching
the PAC NW early Tuesday. GFS becomes nearly 24 hours slower in
bringing in the next upper trough. Both models continue to show
unsettled weather continuing through next week, though the GFS
shows promise of drier weather after the upper trough passes
Thursday afternoon. Hinsberger


.FIRE WEATHER...Mountain showers and afternoon thunderstorms are in
the forecast once again today. Friday looks to be a bit drier, but
we`re not completely without the threat of some isolated afternoon
thunderstorms, particularly over the Central Mountains. We resume a
wet weather pattern Saturday and Sunday with another upper low
dropping into UT/NV. Showers and wet thunderstorms should keep
humidity rather high. A chance of showers continues through most of
next week with isolated thunderstorms in the afternoon/evening.


.AVIATION...Little change expected in the morning TAF package with
isolated thunderstorms expected over the mountains this
afternoon/early evening. KSUN and KDIJ have the best potential for
any precip. VFR conditions will prevail, though brief heavy
downpours would result in lowered visibility. Hinsberger


.HYDROLOGY...Yesterdays rain indeed created an increase in area
rivers, streams and creeks which have lead to the issuance of a
Flood Advisory at the Teton River at St. Anthony and a Flood
Watch for the Henry`s Fork River near Rexburg. A Flood Advisory on
the Big Wood at Hailey continues until further notice. Additional
area rivers are increasing and are nearing or exceeding their
action stages, including the Teton River at Driggs, Snake River at
Menan, Snake River at Blackfoot and the Big Lost River at Howell
Ranch, all of which may require watches, warnings or advisories.
The Snake River near Idaho Falls is forecast to reach action stage
this weekend and will bear monitoring. Additional rainfall
amounts in the near term will be light and should not be a cause
for concern. Conditions are expected to generally be dry Friday
with another period of rain showers Sunday, Monday and Tuesday.



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