Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 191443

Area Forecast Discussion
National Weather Service Pocatello ID
843 AM MDT Thu Apr 19 2018

.UPDATE...Minor adjustments to the forecast today. Chance showers
still expected mainly in central mountains this afternoon,
working south into the southern highlands tonight. QPF amounts
expected to remain very light so snow amounts even at higher
elevations should be minimal. DMH


.PREV DISCUSSION... /issued 319 AM MDT Thu Apr 19 2018/

SHORT TERM...Today through Sat Night. Spring snow storm moving
through NV and UT today and tonight, throwing a little bit of
wrap-around moisture into southern Idaho. However, amounts in
excess of an inch are staying above 9000 ft elevation, and would
expect much of it to melt shortly after reaching the ground, with
even Galena reaching 51 deg F this afternoon. On the north side of
the low, not much in the way of wind. The low is slow to move, and
on Fri the southeast corner could still be cloudy with a slight
chance of precipitation, but meanwhile at the opposite end of the
forecast area, not a cloud to be seen in the central Idaho
mountains. Sat has clear skies pretty much everywhere, with
temperatures 8 to 12 deg F above normal. So some 70-plus deg
readings possible for Snake River plain dwellers? Yes! Sat may be
breezy to windy in the Snake River plain and eastern Magic Valley
with a strong west to east wind aloft, so it may be just under
wind advisory conditions. Messick

LONG TERM...Saturday through next Thursday night. Warm and Breezy
conditions expected Saturday across the region, with some chop
expected on area Waterways as a result. Some locations across the
southern Snake Plain may experience their first 70 degree day of the
year. On Sunday, a Low Pressure Trough is forecast to quickly dig
into the PacNW and cross Idaho Sunday night into Monday. Forecast
guidance continues to become more closely clustered together in
terms of Precipitation timing and location, and thus confidence has
increased to continue to boost forecast Precipitation potential.
These Showers are expected to develop across SE Idaho Sunday
Evening, and overspreading nearly all areas into Monday, with the
best chances across the Sawtooths/Pashimeroi eastward along the
Montana border, with lesser chances across the Utah border. Enough
Cold air is forecast to be in place to allow for a changeover to
Snow Sunday night into Monday for passes such as Galena, Willow
Creek, Monida and Targhee, possibly resulting in some Winter driving
conditions. A drying and warming trend is then anticipated to
commence for Tuesday. Forecast guidance then diverges significantly
by Wednesday, and forecast guidance decreases as well. Overall
forecast trend is for an increase in Showers from Wednesday into
Thursday night with seasonable Temperatures. AD/Messick

AVIATION...VFR conditions expected through the period under
extensive cloud cover and perhaps some VCSH, particularly at KSUN.
Gusty NE winds on the order of at least 15 knots expected to develop
for BYI, IDA and PIH after 18Z, with Winds expected to back Westerly
by the end of the forecast period (12Z Fri) with little change in
speed expected. AD/Messick

HYDROLOGY...The Snake River at Lorenzo has gone above flood
stage, with many stations down river from the main storage dams
along the ID-WY border are seeing flow managed for maximum
tolerable release. So many locations are at action stage. The
river should be avoided, especially by families with small
children with very strong flows continuing. Messick



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