Area Forecast Discussion
Issued by NWS Pocatello, ID

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656
FXUS65 KPIH 220235 AAA
AFDPIH

Area Forecast Discussion...UPDATED
National Weather Service Pocatello ID
835 PM MDT SUN AUG 21 2016

.UPDATE...A quick update this evening to tweak temperatures up a
bit overnight and also add smoke to a few areas. With dry and hot
conditions today, along with some wind, we saw several new and
existing fires develop and send out smoke. The most noticeable
places were the central mountains due to the Pioneer and others,
plus around Bear Lake from the fire west of the lake itself in the
Wasatch Range. We did flirt with Red Flag conditions today as
winds were a bit higher than expected but it still looks like
Monday could be a bigger day with more wind coming our way. Keyes

&&

.PREV DISCUSSION... /issued 206 PM MDT SUN AUG 21 2016/

SHORT TERM...Tonight through Tuesday. Weak shortwave catches
northeast corner of forecast area this evening but little moisture
to work with so only a few clouds expected. Stronger upper low
transitioning through southern Canada will drag a dry cold front
across the region Monday. There is still some uncertainty about
how much moisture will work north of the Utah border but do not
expect much and therefore have kept precip chances quite limited
with only isolated mention in a few places along the state line.
Bigger concern is resulting winds behind passage of the front. 700
mb flow in the 30kt range and sunny skies should mix most of that
down to the surface. Have nudged winds up especially through the
Snake River Plain and higher elevation regions, and have issued a
Lake Wind Advisory for Monday afternoon/evening. Upper low
continues east through southern Canada through Tuesday.
Temperatures drop several degrees for Tuesday, but winds may
remain breezy during the day. DMH

LONG TERM...Tuesday Night through Sunday...Broad upper level
trough will develop and linger over the region as an anchoring low
forms over western NV late in the week. This upper low in NV
transitions to an open shortwave Friday night and swings east-
northeast through the northern Great Basin on Saturday. Expect
development of isolated convective showers over the central
mountains and along the MT border Wednesday afternoon and evening
as the trough deepens and upper low forms. Very low potential for
convective showers over elevated terrain on Thursday and Friday,
followed by a larger threat of convective showers for Saturday and
Sunday as two upper level shortwaves move over the area.
Temperatures will cool 6 to 10 degrees on Wednesday and remain
mild through the remainder of the week. DSH

AVIATION...Widespread VFR with breezy southwest winds in the Snake
Plain during daylight hours. DSH

FIRE WEATHER...Timing of cold front passage continues to be
during the day Monday. Surface gradient and mid level flow strong
enough to support windy conditions with gusts over 30 mph many
locations. Have upgraded fire weather watch to red flag warning
and included zones 425 and 413 in the mix. Believe the strongest
winds in 413 will occur in northern half of zone. Cold front
remains dry with little moisture to work with across the region
so have kept any potential precip mention limited to small areas
along the Utah border. Upper low crosses southern Canada into
Tuesday with flow remaining westerly in base of trough. Could
remain breezy to windy into Tuesday as well with guidance
indicating potential for wind gusts near or above red flag
thresholds again. Humidities will remain low so conditions could
be close enough for another headline across the region.
Reinforcing shortwave drops south into East Idaho wednesday
afternoon and a round of convection looks to occur
afternoon/evening. Uncertain how much moisture will be available
to work with but isolated dry thunderstorms not out of the
question so far. Expect a broad trough to remain in place over the
region Friday into the weekend with return of deeper moisture
Friday/Saturday. DMH

&&

.PIH Watches/Warnings/Advisories...
Red Flag Warning from noon to 9 PM MDT Monday for IDZ410-411-413-
422-425-475-476.

Lake Wind Advisory from noon to 9 PM MDT Monday for IDZ021.

&&

$$



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