Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 180838
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
238 AM MDT THU AUG 18 2016

.DISCUSSION...

A low pressure system will move along the Idaho/Utah border today.
Expect scattered showers and thunderstorms to develop today.
Expect initial development across the eastern highlands and the
southern half of the central mountains this afternoon. Expect
storms to move southeast with some storms drifting into the Snake
Plain. Gusty winds from these storms is likely once again this
afternoon. A cold front will move through the area Friday morning.
This will bring a chance for some isolated showers and
thunderstorms to the central mountains and eastern highlands. Also
expect much cooler temperatures for Friday. High pressure will
develop over the area and remain in control for the rest of the
forecast. This should produce dry weather for the weekend into
next week. Expect warm temperatures to return for Sunday and
beyond.

Valle

&&

.AVIATION...Continued unstable atmosphere with plenty of moisture
for -TSRA most areas. Least likely area would be the KBYI area,
while KDIJ most likely. Outside of thunderstorm wind...wind
shear...and lightning hazard, expect cig and vsby to remain VFR,
wind light outside of -TSRA. Messick

&&

.FIRE WEATHER...Based on lightning patterns of last night, continued
precipitable water above 0.75 for many locations, and even more
instability, have issued Red Flag Warning for lightning in all but
the two southwestern zones that will have more of an isolated
thunderstorm condition. This is the last serious day of thunderstorm
activity. A trough sweeping through on Fri will bring much cooler
and more stable air into eastern and central Idaho, along with some
thunderstorm activity, but mainly limited to the ID-WY border. The
main forecast problem will be the downslope winds in the northern
end of the Idaho Falls BLM District combining with lowered humidity
in the very dry air that will likely be below 15 percent for
portions of Fremont and Clark Counties. With the current Red Flag
out, will allow oncoming shifts to coordinate and take one last look
at the humidity. The northerly wind continues into Sat with a ridge
of high pressure remaining to the west of Idaho. High temperatures
will be down strongly both Fri and Sat, with some warming in the
nearly clear skies allowing temperatures by Sun to be near seasonal
normal. The next chance for thunderstorms occurs Tue timeframe when
a weak trough flattens the ridge, but threat is really low as the
upper level flow stays mainly from the west and nearly no chance of
entraining some moist unstable air from the Gulf of California.

Messick

&&

.PIH Watches/Warnings/Advisories...
Red Flag Warning from noon today to midnight MDT tonight for
IDZ410-411-413-422-476.

&&

$$



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