Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 182019
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
219 PM MDT THU AUG 18 2016

.SHORT TERM...Tonight through Sunday. Tstms developing this aftn
over the mtns in response to a weak upper trof over southeast ID.
Some of these tstms may produce gusty winds...but not much
rainfall. Tstms will diminish this eve as the upper trof moves out
of the area and the airmass stabilizes. A push of Canadian air
will push into MT this eve... then spill over the Divide by Fri
morning. This will result in brisk northeast winds on Fri...
especially in the upper Snake River Plain. The American Falls
Reservoir is particularly sensitive to northeast winds...so a lake
wind advisory has been issued for Fri. The cooler northwest flow
aloft continues thru Sat...but the Great Basin upper high builds
back up by Sun. This will push temps back up again.

.LONG TERM...Monday through Thursday. The upper high over the
Great Basin is pushed back down on Mon as a broad upper trof
dominates the Pac NW. The northwesterly flow keeps the monsoon
moisture to the south...so dry conditions are expected to continue
thru Thursday. Hedges

&&

.AVIATION...Expect Vicinity thunderstorms this afternoon into
early evening for all taf sites with a moist and unstable
atmosphere. KSUN and KIDA have best chance of seeing thunderstorms
on station. Expect gusty winds of around 30 mph in and around
thunderstorms. Tomorrow morning a dry cold front will bring gusty
Northeast winds across the TAF sites...particularly KIDA...KPIH and
to a lesser extent KBYI and KSUN. Wyatt

&&

.FIRE WEATHER...Instability and moisture will allow for isolated to
scattered thunderstorms this afternoon into early evening. A red
flag is in effect for lightning for all areas except the Southern
Sawtooths consisting of Western Lemhi and Custer counties and our
Southwest areas consisting of Cassia County and the Eastern Magic
valley where isolated thunderstorm coverage is expected instead.
Thunderstorms are already occurring over the Southern Central
mountains and Southern Pahsimeroi mountains. Thunderstorm outflows
of around 30 mph can be expected in addition to lightning. Look for
a dry cold front to sweep across the area tomorrow morning. Look for
Northeast winds to move across the area with gusts of 30 to 40 mph
especially for the Upper Snake river plain.  The minimum relative
humidity will likely stay above 15 percent except for the Upper
Snake river plain where downslope winds will keep this area drier. A
red flag warning may be needed for tomorrow for the Upper Snake
river plain. Look for temperatures to drop today over yesterday and
drop even more on Friday. Temperatures will rebound Saturday into
Sunday as high pressure ridging builds back into the area. Monday
look for winds to start to increase ahead of the next system that
will graze our Northern areas on Tuesday. Tuesday look for moderate
winds and low relative humidity across the area. A red flag warning
will likely be needed Tuesday especially for our Northern areas.
Wyatt

&&

.PIH Watches/Warnings/Advisories...
Red Flag Warning until midnight MDT tonight for IDZ410-411-413-
422-476.

Lake Wind Advisory from 9 AM to 9 PM MDT Friday for IDZ021.

&&

$$



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