Winter Storm and High Wind in Utah, February 6 to 8, 2020

Area Forecast Discussion
National Weather Service Salt Lake City UT
1011 PM MST Wed Feb 5 2020

.SYNOPSIS...
High pressure aloft locked in over the eastern Pacific will leave
Utah under a north to northwest flow aloft through the end of the
week. A couple of weak weather disturbances embedded in this flow
aloft will bring snow, along with some rain, back to northern and
central Utah through Friday.

&&

.SHORT TERM (THROUGH 12Z SATURDAY)...
A moist anticyclonic north-northwest flow will continue to fuel
areas of light/moderate snow across northern/western Utah tonight
through Thursday morning. Snow largely driven by warm advection
could become enhanced again across northern Utah/southwest
Wyoming as a weak embedded shortwave moves south-southeast
through western Wyoming late tonight/early Thursday.

The precip-type will become an issue beginning late Thursday
morning as the air mass becomes increasingly well mixed and
modestly warmer temperatures aloft move into the state. A mix of
rain and snow could develop during the afternoon, though areas
with extensive snow cover may struggle to turn over and could stay
in snow throughout the day. Mountain locations will remain in snow
through Thursday night and will likely see significant accumulations
along mainly the Wasatch range and the northern portion of the
central mountains. Trailing embedded shortwaves moving southeast
along the continental divide will likely keep some precip going
across far northern Utah/southwest Wyoming into Friday.

Strong winds will become an issue across southwest Wyoming and
through the eastern Utah valleys beginning Thursday and continuing
in Friday. Strong westerly winds aloft aloft and an increasing
mixed air mass across Wyoming will make for very strong winds late
in the week. Across the western Uinta Basin and San Rafael Swell
the very strong winds aloft and downsloping off the higher terrain
to the west will create favorable conditions for high winds by
Thursday afternoon and continuing into Friday.

A fairly strong upper trough advancing into the Pacific Northwest
late Friday night will produce a downstream warmer/drier air mass
Friday night. Lingering light precip across the far northern
mountains should end during the evening with generally mild temps
ahead of the next storm for Saturday morning.

.LONG TERM (AFTER 12Z SATURDAY)...
A weakly developed ridge over the region beginning 00Z Saturday
will quickly get flattened by a trough moving southeast from
southwest Canada. The EC and GFS ensembles are pretty much in
agreement with the timing of reaching northern Utah between 18Z
Saturday and 00Z Sunday, but the EC is farther west. In either
case, a decent 700mb baroclinic zone moves across northern Utah by
00Z Sunday and southern Utah by 12Z Sunday. Although much colder
air will filter in behind this baroclinic zone, the winds at 700mb
are not very convergent so minimal lift will occur with this
boundary, resulting in only light precipitation, a rapid
changeover from rain to snow in the valleys.

While the north is expected to dry out for Sunday, the south,
especially the southwest will remain under the trough axis that
extends out towards the closed low that the EC has over the central
California coast and the GFS has over Death Valley from 00Z Monday
through 12Z Monday. Light precip possible over the southwest through
this time.

Both EC and GFS ensemble means show that the closed low will begin
to open up and move across Arizona across on Tuesday as another cold
trough moves southward from southwest Canada. The timing between the
models is different, but the idea is similar. A cold pattern with
cyclonic flow aloft will mean unstable conditions will likely occur
most of the CWA Wednesday. Temperatures will probably be 5-10
degrees or more below normal and even Saint George will have the
opportunity to have some snow.

&&

.AVIATION...
Expect ceilings to range between 4K and 2K at SLC terminal in
intermittent light snow through 18Z Thursday. The most likely time
for the ceilings to be below 3K and visby below 3SM will be
between 10 and 16Z, but it could occur at other times as well.
Accumulation on untreated surfaces is expected to range from 1 to
3 inches by 17Z Thursday.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Winter Weather Advisory until 4 PM MST Friday for UTZ001>005-
     007>010.

     Winter Storm Warning until 4 PM MST Friday for UTZ006.

     High Wind Warning from 9 AM Thursday to 4 PM MST Friday for
     UTZ011>013.

WY...Winter Weather Advisory until 4 PM MST Friday for WYZ021.

     High Wind Warning from 9 AM Thursday to 4 PM MST Friday for
     WYZ021.

&&

CONGER/STRUTHWOLF/10

For more information from NOAA's National Weather Service visit...
http://weather.gov/saltlakecity

For frequently asked questions about the Area Forecast Discussion
visit...
http://weather.gov/saltlakecity/general/afd_faqs.php

Hazardous Weather Outlook
National Weather Service Salt Lake City UT
234 PM MST Wed Feb 5 2020

UTZ001>016-019>021-517-518-WYZ021-061400-
Cache Valley/Utah Portion-Northern Wasatch Front-
Salt Lake and Tooele Valleys-Southern Wasatch Front-
Great Salt Lake Desert and Mountains-Wasatch Mountain Valleys-
Wasatch Mountains I-80 North-Wasatch Mountains South of I-80-
Western Uinta Mountains-Wasatch Plateau/Book Cliffs-
Western Uinta Basin-Castle Country-San Rafael Swell-
Sanpete/Sevier Valleys-West Central Utah-Southwest Utah-
Utahs Dixie and Zion National Park-South Central Utah-
Glen Canyon Recreation Area/Lake Powell-Central Mountains-
Southern Mountains-Southwest Wyoming-
234 PM MST Wed Feb 5 2020

This Hazardous Weather Outlook is for the western two thirds of
Utah and southwest Wyoming.

.DAY ONE...This Afternoon and Tonight

Periods of light snow across northern Utah today will increase in
coverage and intensity this evening and overnight, with
accumulating snow expected.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Accumulating snow will continue in the valleys of northern Utah
Thursday morning, with some impacts expected for the morning
commute. Snow will transition to rain or a rain/snow mix in some
valleys Thursday afternoon.

The northern Utah mountains and some higher valleys will have the
potential to see significant snowfall through Friday.

Strong gusty winds in the higher elevations of Utah and southwest
Wyoming, western Uinta Basin, and Castle Country Thursday through
Friday will lead to areas of blowing snow.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
conditions according to standard operating procedures.

For more information from NOAA/s National Weather Service visit...
http://weather.gov/saltlakecity

For information on potential road travel impacts visit...
http://www.udottraffic.utah.gov/roadweatherforecast.aspx