The latest significant Pacific storm is moving inland across California
and headed for Wyoming. The morning water vapor satellite imagery clearly
depicts the stream of very moist air mass originating near Hawaii which
will provide copious amounts of rain and mountain snows inland across
California northeastward into Western Wyoming.

Water Vapor Satellite Imagery Monday Morning

Model forecast precipitation through Wednesday focus on the large totals in
Califonia and also in the mountains of Western Wyoming.

Model forecast precipitation from Monday morning through Wednesday evening.

Snow levels will rise with the warmer air mass, with precipitation becoming mixed
snow/rain in Star Valley and likely mostly rain tonight and into Tuesday prior
to the arrival of colder air.

Following are the current statements and warning from Riverton Forecast Office. 

National Weather Service Riverton WY
315 AM MST Mon Feb 20 2017




Star Valley-
Including the cities of Afton, Alpine, Star Valley Ranch,
and Thayne
357 AM MST Mon Feb 20 2017

Periods of snow are expected to develop across Star Valley this
morning. Snow is expected to mix with or change to rain this
afternoon into the evening. The precipitation is expected to
change back to all snow Tuesday afternoon and evening as a cold
front sweeps across western Wyoming. Rainfall amounts between a
half and one inch are expected with this storm, with a few inches
of wet snow possible. The rainfall along with some melting snow
could result in localized flooding or ponding of water.

...A strong Pacific storm will bring heavy snow to the western
mountains from this Afternoon through Tuesday night...

.A strong Pacific storm will bring heavy snow to the western
mountains from Monday afternoon through Tuesday evening. Also,
strong west to southwest winds will cause significant blowing and
drifting snow. The western valleys will see a mix of rain and
snow.


Teton and Gros Ventre Mountains-Salt River and Wyoming Ranges-
315 AM MST Mon Feb 20 2017

...Winter Storm Warning in effect from noon today to 5 am MST
Wednesday...

The National Weather Service in Riverton has issued a Winter
Storm Warning for snow and blowing snow, which is in effect from
noon today to 5 AM MST Wednesday. The Winter Storm Watch is no
longer in effect.

* Timing...Snow and strong winds are expected to move into the
  western mountains of Wyoming Monday afternoon. Snow and wind are
  expected to continue through Tuesday night.

* Snowfall Accumulation...12 to 24 inches are expected, with
  localized amounts up to 30 inches in the Teton mountains.

* Wind and Visibility...West to southwest winds of 25 to 35 mph
  with gusts to 60 mph...especially in open areas or mountain
  summits. Visibility frequently below a quarter mile in heavy
  snow and blowing snow.

* Main Impact...Travel will become very difficult with the wind
  and snow producing slick, snow-packed roads along with high
  drifts over mountain passes. Please monitor JHAVALANCHE.ORG if
  your plans include travel into the backcountry. Also, the
  severely reduced visibility will be very disorientating for
  those recreating in the backcountry.