Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 120409

Area Forecast Discussion
National Weather Service Pocatello ID
909 PM MST Wed Jan 11 2017

.UPDATE...Complex storm system continues to wind down over most of
the region with a few trouble spots remaining. Winds remain gusty
through the Arco Desert late this evening but HRRR and RAP
continue to show rapid decrease over the next few hours. Light
snow and pockets of blowing snow continue over the Upper Snake
Highland region, and will continue Winter Storm Warning overnight
as currently headlined. Light snows have dissipated per radar and
observations and area webcams across the southeast corner of the
state, therefore have dropped the headlines for those regions a
few hours early. Cold temperatures have caused a couple river
gages to indicate icing, but discussions with law enforcement
indicate no issues on area main stem rivers so those data points
have been QCd to remove erroneous data. Have tweaked overnight
grids to continue to highlight decreasing trend in precipitation
and winds. DMH


.PREV DISCUSSION... /issued 208 PM MST Wed Jan 11 2017/

SHORT TERM...The long awaited for end to this storm system is close
at hand. Snow has been decreasing over the Central Mountains this
afternoon and some scattered showers still remain in the Snake Plain
and South Central Highlands. Additional significant accumulation of
snow from these are not expected. The winter storm warnings and
advisories will be cancelled for all but the Eastern Highlands from
Island Park south to Bear Lake. For the Upper Snake Highlands, some
1 to 5 inch snow amounts are expected through Thursday morning.
Further south in the Caribou Highlands, only 1 to 3 inches
additional snow is expected. Runoff from rain on snow and periods of
elevated snow levels, plus strong gusty winds the past two days is
still causing some flooding problems roughly south of a Burley to
Pocatello line to the Utah border. There are some flooding issues
near Hailey and Challis as well. Runoff can last for several hours
after the rain ends. Freezing temperatures tonight and the next
several days will help with this, but could also cause some local
issues with ponding water icing up. The Flood Warnings have been
continued into Thursday, we`ll see how things progress. There is
another secondary circulation system digging south along the coast
that will cause all of the precipitation over this area to move
south of the state by Thursday afternoon. High temperatures Friday
and Saturday will fall back into the teens and lower twenties.
Overnight lows will be in the single digits to a little below zero
by Friday morning. RS

LONG TERM...Saturday Night through next Wednesday.
Expect high pressure to bring dry weather Saturday night through
Monday night as a break from the wet weather continues early in the
long term period.   That trend will end Tuesday night through
Wednesday as models are in pretty good agreement in pushing another
extended wet period into southeast Idaho and continuing through the
end of the week.   Snow levels should start out at valley floors
Tuesday night into Wednesday but expect warm air intrusions beyond
Wednesday.  Temperatures remain cold through Monday with a warming
trend setting up Wednesday as the moisture moves into Idaho.

Main issue will be winds and ceilings at sites.  Cold front has
moved through all sites and 15 to 25 know sustained winds expected
at BYI, PIH and IDA through early evening before diminishing. Expect
MVFR stratus ceilings at DIJ, PIH and IDA in the colder air but kept
out fog as think winds will stay up enough through most of the night
to prevent widespread fog.  Expect stratus to linger at those three
sites through much of Thursday morning.

A Flood Advisory continues for the Draper Preserve along the Big
Wood River Hailey due to effects of a recent avalanche diverting
river flow. Additional slides remain possible due to heavy snowfall
in the last 24 hours. After collaborating with city officials in
Hailey, the advisory will continue. Fortunately, flooding has
receded from the Della Vista neighborhood.

A Flood Advisory remains in place today for an ice jam along the
Challis Bridge Recreation Site as there has been no change in the

Significant flooding has been reported and is ongoing across Cassia
County as many county roads remain closed due to flooding. Highway
81 is under water in a few places west of Burley, however no road
closures along the highway have been reported as of late this
morning. The Raft River bottoms including the city of Malta have
been particularly impacted, as water has entered many homes on the
west side of Highway 81 in Malta. In addition, water was reported
running down city streets last night. The City of Oakley has also
been impacted by flooding Birch Creek has been diverted, causing its
flow to flood city streets. As a result, several basements have been
flooded. Elsewhere, water has been reported over roads in Heyburn,
resulting in the closure of some roads near the Snake River. Water
has also been reported over some roads near Preston, however
closures have not been instituted at this time. As a result, an
Aerial Flood Warning Continues. The counties of Lincoln, Bingham and
Bonneville have been removed from the Warning as no impactful
flooding has been reported.

Additional precipitation amounts through tonight across the above-
mentioned areas will be light, and should not contribute to
additional flooding. Temperatures will fall below freezing tonight
and will remain below freezing through at least the weekend,
resulting in a gradual end to snow melt runoff. However, the return
of cold temperatures will increase the risk of additional ice jam
flood potential along streams, creeks and rivers. AD/RS


Winter Storm Warning until 4 AM MST Thursday for IDZ019.


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