Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 120855

Area Forecast Discussion
National Weather Service Pocatello ID
255 AM MDT Sat Aug 12 2017

.SHORT TERM...Today through Monday. Monsoon moisture associated
with the upper ridge will again set off showers and isolated tstms
mainly over the mtns late this afternoon and evening. Isolated
tstms are possible this eve in the Snake River Plain due to
outflow boundary interaction. Tstms will be capable of producing
gusty outflow winds. On upper trof moves into the Pac
NW with an associated cold front pushing into the central mtns
during the afternoon. Scattered showers/isolated tstms are
expected to develop along the front and become more widespread Sun
night as vertical motions are enhanced by an upper jet core.
Precip amounts look fairly decent over the central mtns by Mon
morn. The front gradually slides southeastward through the fcst
area on Mon. Precip backs off some as the support from the upper
jet exits the area. Cooler temps also expected on Mon.

.LONG TERM...Tuesday through Saturday. The upper trof moves off to
the east on Tue...taking the precip with it. Drier northwest flow
prevails thru the end of the week. Temps steadily warm back up.



.AVIATION...Showers and isold tstms expected over the mtns late
this aftn and eve. Gusty outflow winds are possible near tstms.
Isold tstms are possible by eve in the Snake River Plain due to
outflow boundary interaction. Overall conditions expected to
remain VFR. Hedges


Multiple fire weather concerns over the next week as
a pattern change is expected. First, a Pacific trough is expected to
move into Washington and Oregon by this evening. A cluster of
thunderstorms is expected to develop over these states and march
northeast this evening, possibly clipping Fire Weather Zones 475 and
476 with scattered thunderstorms this evening. Initially, this
activity was forecast to remain north of these areas. At this time,
confidence in scattered coverage not quite high enough to push fire
weather potential into the critical category, but it is elevated and
thunderstorm potential over the Salmon-Challis for this evening and
overnight will continue to be monitored. Elsewhere, isolated showers
and thunderstorms again possible this afternoon and evening. Any
activity will have the potential to produce gusty, erratic outflow
winds possibly up to 50 mph.

On Sunday, the Pacific trough will continue to progress eastward and
will drag a cold front towards SE Idaho. Ahead of the front, the
combination of near critical minimum relative humidity values and
near critical wind gusts will combine to create elevated fire
weather conditions across Fire Weather Zones 422, 475, 476, 410 and
425. Winds are expected to be strongest Sunday afternoon and
evening. Currently, forecast is borderline for critical fire weather
conditions, but will require continued monitoring. The cold front is
expected to reach the Salmon-Challis late Sunday. Isolated to
perhaps widely scattered thunderstorms will develop ahead of the
boundary late Sunday, with confidence a band of wetting rains
increasing in the development of a band of wetting rains behind the
front Sunday night into Monday morning over the Salmon-Challis,
spreading eastward into the Snake Plain during the day. Gusty winds
are possible along and behind the front. Finally, breezy and dry
conditions are expected Tue-Fri with critically low minimum relative
humidity values developing each day and marginally critical wind
gusts, potentially making for an active week. AD/Hedges



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