Area Forecast Discussion
Issued by NWS Pocatello, ID

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000
FXUS65 KPIH 232014
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
214 PM MDT Sun Sep 23 2018

.DISCUSSION...Shortwave trough and cold front marching through SE
Idaho today. Winds are breezy but not significantly strong and
humidities holding up nicely under cooler temperatures and keeping
fire weather concerns limited. Have already seen weak convection
build over Central Mountains this afternoon with a small amount of
lightning associated. Winds have a chance to pick up briefly later
this afternoon and early evening once leading mid deck cloud
shield shifts east and some clearing helps mix stronger winds
aloft to the surface. Convection should remain limited to northern
zones in region of best mid level instability and favored jet
dynamics. Strongest impact of this system remains the coldest
temperatures filtering into the region tonight, and then lingering
Monday night. Frost remains very viable many areas tonight, but
believe temps will remain above freezing most areas. Have expanded
Frost Advisory into Teton Valley for both Frost Advisory tonight
and Freeze Watch Monday night. There is a chance a few locations
could see a season-ending hard freeze Monday night, but a
widespread hard freeze is currently not expected.

Remainder of the forecast remains largely unchanged. Cool
northwest flow gradually gives way to upper ridge through Friday.
Guidance becomes more diverse headed into the weekend as models
are still struggling with opening Pacific feature merging with
northern stream shortwave dropping out of Canadian Rockies. Upper
low appears to eject NE into SE Idaho by Saturday night,
introducing potential for showers across the region into Sunday.
The next Pacific trough looks to rapidly amplify along or just off
the coast Sunday into Monday, but details are sketchy. Kept
forecast trended toward model/ensemble blends. DMH


&&

.AVIATION...Mid and high clouds are streaming across the state along
a surface cold front. Terminals should stay dry and VFR throughout
the period, but will experience gusty winds this afternoon and
evening. Clouds should clear out by midnight tonight. Hinsberger


&&

.FIRE WEATHER...A cold front is pushing through southeast Idaho this
afternoon, bringing some mid and upper level clouds. Some showers
are expected over the Central Mountains and perhaps the Island Park
area this afternoon and evening. There may even be an isolated
thunderstorm in the mix today. The main impact will be winds as
winds along the front could bring gusts to 25 to 30 mph. However,
humidity values are much improved over yesterday. This will mitigate
critical fire weather concerns. It will be less breezy, cooler, and
less cloudy tomorrow as high pressure builds back into the area. We
should be in a prolonged period of dry and stable conditions thanks
to a developing high-amplitude blocking pattern setting up in the
East Pacific. The blocking ridge will shift to the west next
weekend, allowing some weather systems to drop in from the north.
Hinsberger


&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 2 AM to 9 AM MDT Monday for IDZ051>054-065.

Freeze Watch from late Monday night through Tuesday morning for
IDZ051>054-065.

&&

$$


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