Area Forecast Discussion
Issued by NWS Pocatello, ID

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102
FXUS65 KPIH 130908
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
208 AM MST Fri Jan 13 2017

.SHORT TERM...Today through Sunday...Areas of patchy fog are showing
up in Pocatello and across Cassia and Bear Lake counties overnight.
Skies are quite clear and moisture is plenty high so have added
freezing fog to much of the southeast Idaho, with the exception of
those areas where winds will be too strong. Even for those areas
where fog is in the forecast, the winds will be the deciding
factor as to whether or not fog develops; if they are too high it
will deplete the fog production, although speeds are expected to
be decreasing and relatively light this morning. Expect fog
development overnight tonight and tomorrow morning again for much
of these same areas including most of the Snake River Plain,
Challis, Clayton, Ketchum, Preston and the valleys of the
Highlands and Bear Lake region.

The remainder of the forecast in the near term focuses on the cold
morning temperatures with temperatures in the negative 20 to
negative 30 range in the valleys of the Central Mountains. These
conditions will be identical or colder tomorrow morning with wind
chill values about negative 30 to negative 35. The Snake River
Plain and Upper Snake Highlands will see temperatures ranging from
10 above near Burley to 20 below from Mud Lake to Island Park.
Warmer temperatures are forecast along the Utah border of above 10
above. Daytime highs are not expected to reach above the freezing
mark through the weekend and may drop a few degrees Sunday as
well. NP/Keyes

&&

.LONG TERM...Sunday Night through next Friday. Dry conditions will
continue until Tuesday. We will some stratus and fog in some valley
locations, especially where temperatures really drop and/or we get
continued snowmelt and sublimation. A weak wave passes overhead
Sunday night, which MAY hold fog at bay. The flip side is that could
also create some flurries under the stratus deck. Inversions will
keep temperatures down in the valleys, however temperatures really
crank up in the mountains. We are talking highs above the inversion
approaching freezing on Monday with not much cooling down Tuesday
morning. This is really going to be an issue in the central
mountains and south-central highlands. Our attention to Tuesday
through late next week. Plenty of pacific moisture is poised to hit
Idaho once again. With warmer air returning, we will be dealing with
up and down temperatures especially at lower elevations. We will be
dealing again with changing from rain to snow and back by Wednesday.
This will leave us with heavy and potentially wet snow for the
mountains and rain on snow at times down low. Both will not offer
any relief from the last storm across eastern Idaho.  Keyes

&&

.AVIATION...There are some pockets of dense freezing fog and low
clouds this morning.  We are not seeing a whole affecting airports
especially our TAF sites, except for KPIH which is actually a
product of the nearby plant.  Whatever the method, conditions will
easily drop to LIFR/VLIFR when this happens. Otherwise, look for VFR
weather today. For tonight, we may end seeing a bit more potential
for freezing fog/stratus to develop. Inversions will strength which
will trap more moisture from any snowmelt. Again, ceilings and
visibility could easily drop below IFR in these situations. Keyes

&&

.HYDROLOGY...
Ice jam concerns from freezing temperatures remains a concern for
today and over the weekend, especially on local streams feeding
larger rivers. This could lead to additional flood/sheet flooding
concerns. The forecast does not call for additional rain and/or
snow until next Tuesday or Wednesday therefore we are not expected
additional concerns in this regard. An Areal Flood Warning will
remains in effect at this time for portions or all of Cassia,
Minidoka, Blaine, Power and Oneida counties as flooding continues
in these areas.

A Flood Warning remains in effect for Antelope Creek at
Darlington due to an ice jam on this creek along with runoff from
recent rain and mild temperatures. This has resulted in some
homes being flooded in Darlington.

The Flood Advisory for the Challis River Bridge south of Challis
will continue at the request of the BLM and local law enforcement.
Citizens are urged to avoid this area.

.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$



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