Winter Storm and Heavy Snow in Idaho, February 22 to 24, 2017

Area Forecast Discussion
National Weather Service Pocatello ID
224 PM MST Wed Feb 22 2017

.SHORT TERM...Tonight through Friday. Strong shortwave driving
across Nevada this afternoon per satellite imagery. Good moisture
north of circulation with cooling cloud tops in area of increasing
divergence aloft in southern ID. Models greatly increase the
amount of divergence aloft through the remainder of the evening,
then rotate region north into Snake Plain and weakening it through
the rest of tonight. Surface low still expected to rapidly deepen
near the state line this evening, but model consensus
considerably weaker on exact positioning of surface features
overnight. this is problematic because while divergence aloft will
drive much of the upward motion, snowfall overnight will likely
be enhanced by orographics driven by the lower level features.
Regardless, there is quite a bit of model consensus that a strong
band of snow fall will develop over the southern highlands then
develop/swing northeast into the Caribou highlands overnight.
Snowfall max extend into the Snake Plain as well. Consensus puts
several inches of snow fall along I-84/I-86 corridors along with
the southern highlands but there is much less agreement on whether
significant snow will develop much farther north than Pocatello.
First shortwave drives east during the day Thursday but inverted
700mb and surface trough remain draped over region Thursday
through early Friday with flow favorable for orographically
enhanced snowfall to continue. Current estimates maintain snow
amounts sufficient to provide significant impact on travel through
the region mainly across the southern portions of the forecast
area. There is much lower confidence on significant snows reaching
as far north as Idaho Falls, but given divergence of model
solutions cannot quite rule out yet. Have maintained previously
issued advisory headline, but also added the Pocatello region.
Have also upgraded IDZ022 to winter storm warning to support
higher snow amounts above 6000 ft. If system develops as expected,
more regions could be upgraded to warnings as well. DMH

.LONG TERM...Saturday through Wednesday. Saturday will start off
mild but quickly become snowy with a series of shortwaves passing
through the region over the weekend. Snow accumulations are expected
to be light overall, with anywhere from 1 to 4 inches expected
across the mountains and along the Continental Divide. Snake
Plain regions may see a light dusting as well. Temperatures both
days will be in the mid 20s to low 30s for highs with areas below
0 for minimum temperatures in the Central Mountains and Bear Lake
regions. Late Sunday into Monday will bring a widespread wet
period with an anticipated closed low approaching from the
southwest. Snow is expected Monday morning through early Tuesday
across the region. Winds are expected to increase Tuesday into
Wednesday in response to a passing shortwave behind the main low.
Additionally, light snow is possible across Southeast Idaho with
low confidence in occurrence either day. NP/DMH

&&

.AVIATION...VFR conditions expected until the late evening/overnight
hours due to approaching trough. Ceilings will then lower to MVFR
through tomorrow with snow or a mix or rain and snow at BYI, PIH and
SUN. IDA and DIJ are not expected to be impacted by SN until
tomorrow morning. Winds are not forecast to be of impact today
either. NP/DMH

&&

.HYDROLOGY...Moderate precipitation amounts and mild low to mid elevation
temperatures the past several days have maintained and worsened low
land flooding threat across the region. Minidoka, Lincoln, Oneida,
Franklin, Southwest Bingham, and Southwest Caribou counties have, in
particular, seen increased low land flooding where flood warnings
are in effect.  Some minor low land flooding has continued for
Western Caribou, Eastern Bingham, Western Jefferson and Madison
counties where flood advisories remain in effect. Some rises have
been seen in area creeks as well as some small responses to rivers.
Goose creek from the Utah line to the Oakley reservoir has continued
to have significant flooding where a flood warning is also in
effect. The Raft river continues to have minor low land flooding
from Utah to the Snake River where a flood advisory is in effect.
Have also continued the flood warning for the Portneuf River at
Pocatello. The river is at minor flood stage currently and cresting
below moderate stage tomorrow afternoon before dropping below flood
stage on Saturday.

A cool down today through most of the weekend will aide to the slow
down of some flooding particularly for Northern areas, though it may
take some time to see the full effect. Though cooler temperatures
are expected to move into the area today into tonight, several
inches of snow is in the forecast mainly for our Southern areas
extending Northward into the Southern Snake river plain and Eastern
Magic valley. Snow will start this evening and continue through
early Friday. Temperatures will gradually start to rise Saturday and
daytime temperatures will approach the low to mid 30s for our
Northern areas and low 40s for our Southern areas Monday which will
aide to melting.
Wyatt

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 11 AM MST Friday for IDZ017-021-
023>025.

Winter Storm Warning until 11 AM MST Friday for IDZ022.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE POCATELLO ID
1125 AM MST WED FEB 22 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....

0800 AM     HEAVY SNOW       33 WNW ARCO             43.75N 113.93W
02/22/2017  E16.8 INCH       CUSTER             ID   MESONET

            BEAR CANYON SNOTEL 7903 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       12 NNW KETCHUM          43.77N 114.42W
02/22/2017  E9.9 INCH        BLAINE             ID   MESONET

            CHOCOLATE GULCH SNOTEL 6440 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       11 NE SPENCER           44.43N 112.00W
02/22/2017  E15.4 INCH       CLARK              ID   MESONET

            CRAB CREEK SNOTEL 6686 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       16 WSW KETCHUM          43.60N 114.67W
02/22/2017  E14.4 INCH       BLAINE             ID   MESONET

            DOLLARHIDE SUMMIT SNOTEL 8421 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       20 NE PRESTON           42.37N 111.57W
02/22/2017  E6.5 INCH        FRANKLIN           ID   MESONET

            EMIGRANT SUMMIT SNOTEL 7390 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       20 ENE HAILEY           43.62N 113.93W
02/22/2017  E13.5 INCH       BLAINE             ID   MESONET

            GARFIELD R.S. SNOTEL 6560 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       20 NW KETCHUM           43.88N 114.67W
02/22/2017  E12.1 INCH       BLAINE             ID   MESONET

            GALENA SNOTEL 7440 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       22 NW KETCHUM           43.87N 114.72W
02/22/2017  E14.5 INCH       BLAINE             ID   MESONET

            GALENA SUMMIT SNOTEL 8782 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       30 NNW ARCO             44.02N 113.47W
02/22/2017  E24.2 INCH       CUSTER             ID   MESONET

            HILTS CREEK SNOTEL 8001 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       11 ENE HAILEY           43.72N 114.17W
02/22/2017  E11.0 INCH       BLAINE             ID   MESONET

            HYNDMAN SNOTEL 7440 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       1 W ISLAND PARK         44.42N 111.38W
02/22/2017  E6.0 INCH        FREMONT            ID   MESONET

            ISLAND PARK SNOTEL 6293 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       10 NW KETCHUM           43.82N 114.27W
02/22/2017  E17.2 INCH       BLAINE             ID   MESONET

            LOST WOOD DIVIDE SNOTEL 7903 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       37 NE MACKAY            44.43N 113.32W
02/22/2017  E28.0 INCH       LEMHI              ID   MESONET

            MEADOW LAKE SNOTEL 9150 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       28 NE STANLEY           44.47N 114.48W
02/22/2017  E16.1 INCH       CUSTER             ID   MESONET

            MILL CREEK SUMMIT SNOTEL 8870 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       32 NE MACKAY            44.42N 113.40W
02/22/2017  E11.8 INCH       LEMHI              ID   MESONET

            MOONSHINE SNOTEL 7440 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       24 N CHALLIS            44.85N 114.27W
02/22/2017  E12.9 INCH       LEMHI              ID   MESONET

            MORGAN CREEK SNOTEL 7600 MSL. 72-HOUR TOTAL.

0800 AM     SNOW             14 NW PRESTON           42.27N 112.13W
02/22/2017  E3.1 INCH        FRANKLIN           ID   MESONET

            OXFORD SPRINGS SNOTEL 6740 MSL. 72-HOUR TOTAL.

0800 AM     SNOW             38 E IDAHO FALLS        43.57N 111.22W
02/22/2017  E5.9 INCH        BONNEVILLE         ID   MESONET

            PINE CREEK PASS SNOTEL 6720 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       10 SSE LAVA HOT SPRINGS 42.52N 111.95W
02/22/2017  E9.1 INCH        BANNOCK            ID   MESONET

            SEDWICK PEAK SNOTEL 7897 MSL. 72-HOUR TOTAL.

0800 AM     SNOW             14 N MONTPELIER         42.57N 111.30W
02/22/2017  E3.7 INCH        BEAR LAKE          ID   MESONET

            SLUG CREEK DIVIDE SNOTEL 7225 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       17 SW MACKAY            43.73N 113.83W
02/22/2017  E40.2 INCH       CUSTER             ID   MESONET

            SMILEY MOUNTAIN SNOTEL 9520 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       2 NE WAYAN              42.95N 111.37W
02/22/2017  E6.0 INCH        CARIBOU            ID   MESONET

            SOMSEN RANCH SNOTEL 6801 MSL. 72-HOUR TOTAL.

0800 AM     SNOW             32 E BLACKFOOT          43.22N 111.68W
02/22/2017  E5.4 INCH        BINGHAM            ID   MESONET

            SHEEP MOUNTAIN SNOTEL 6571 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       50 NW ARCO              43.87N 114.22W
02/22/2017  E10.4 INCH       CUSTER             ID   MESONET

            STICKNEY MILL SNOTEL 7431 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       21 ENE HAILEY           43.63N 113.97W
02/22/2017  E14.3 INCH       BLAINE             ID   MESONET

            SWEDE PEAK SNOTEL 7641 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       22 NW KETCHUM           43.80N 114.85W
02/22/2017  E19.9 INCH       BLAINE             ID   MESONET

            VIENNA MINE SNOTEL 8963 MSL. 72-HOUR TOTAL.

0800 AM     SNOW             7 S POCATELLO           42.75N 112.48W
02/22/2017  E3.7 INCH        BANNOCK            ID   MESONET

            WILDHORSE DIVIDE SNOTEL 6490 MSL. 72-HOUR TOTAL.

0800 AM     HEAVY SNOW       8 NW ISLAND PARK        44.53N 111.42W
02/22/2017  E26.1 INCH       FREMONT            ID   MESONET

            WHITE ELEPHANT SNOTEL 7713 MSL. 72-HOUR TOTAL.

&&

NWS POCATELLO