Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 252014

Area Forecast Discussion
National Weather Service Pocatello ID
214 PM MDT Sun Jun 25 2017

.SHORT TERM...Tonight through Tuesday night. Focus remains on
breakdown of upper ridge Monday with nose of upper jet pushing
toward East Idaho and moisture working around apex of ridge per
sat imagery. Timing of thunderstorm development likely between
noon and 3pm, especially western edges of forecast area.
Convection shifts east into the evening with passage of frontal
boundary, and could see continuation overnight as favorable jet
dynamics remain in place with shortwave axis still to the west.
Have added gusty wind wording to thunder, with best potential over
central mtns. Repeat possible for Tuesday into Tuesday night as
second shortwave axis and upper jet arrive. Moisture a little less
favorable but still enough to warrant convection. Both days have
PW values over .50 so storms will have potential to drop wetting
rains. Tuesday also breezy/cooler behind frontal passage with
favorable westerly surface gradient. DMH

.LONG TERM...Wednesday through Sunday. Convection could linger in
eastern portions of the region through the day Wednesday with
reinforcing shortwave dropping through MT/northern ID. Otherwise
dry northwest flow expected to be in place with temps near
normals. Weak ridge axis strengthens and shifts over Idaho
Saturday, but medium range models a little divergent this far out.
ECMWF wants to shift another amplified Pacific trough inland by
Sunday, and is more amplified with the ridge ahead of this
feature. GFS slower with the next trough, and quite a bit less
amplified with the ridge. If ECMWF bears out, next chance for
convection across the region could be Sunday. In the meantime,
kept the weekend warmer and continued dry. DMH


.AVIATION...Continued VFR conditions will occur through Monday.
Did put vicinity thunderstorms at SUN Monday afternoon however. Not
expecting widespread thunderstorm activity though overnight Monday
may see vicinity at most sites.  Expect much windier conditions
Tuesday with the best chance for thunderstorms at DIJ.


.FIRE WEATHER...Upper level trof approaches Monday and with that
will have very hot temperatures with many locations approaching 6
Haines index.   Almost all thunderstorm activity should be in zones
422, 475, and 476 Monday afternoon through midnight Monday night.
Activity Tuesday will spread east into much of 410, 411, and 413.
Winds will also be a factor Tuesday with 20 to 35 mph gusts expected
mainly in zones 425 and 410.   Many areas will be under 15 percent
minimum humidity Monday in the hot conditions but should rise above
15 percent Tuesday.   Expect about a 10 degree drop in high
temperatures Tuesday behind the cold front with the cooler
conditions continuing through Friday. GK



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