Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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879
FXUS65 KSLC 282254
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
354 PM MST Mon Nov 28 2016

.SYNOPSIS...A cold Pacific storm system will cross the region
today. A trailing cold northerly flow will follow through
midweek, with another storm system possible late in the week.

&&

.SHORT TERM (Through 00Z Thursday)...Moist, northwesterly flow has
developed across northern Utah as a shortwave crosses the area
this afternoon. As the trough digs further south, expect the flow
to switch to northerly later this evening.

Fairly widespread snow showers are occurring in this unstable,
deeply moist northwesterly flow. Heaviest rates are currently
impacting the Bountiful to Sandy Bench areas and adjacent upslope
mountain areas.

The biggest question for northern Utah this evening into tonight
will be the potential for the development of a lake band or lake
enhanced snow showers. Given the combination of the potential for
dry air to entrain on the low to mid-levels this evening into
tonight and a somewhat marginal lake temperature and 700mb
temperature difference, think the best chance is for a period of
lake enhanced snow showers that may begin to impact western Salt
Lake County this evening and then gradually shift to the Tooele
Valley as the flow becomes more northerly through the evening.

Winter weather advisories continue for the northern valleys and
mountain valleys through the evening. Winter storm warnings remain
in effect for the mountains of Utah until tomorrow morning. Both
look to be on track.

As for southern Utah, a band of heavy snow with occasional
embedded thundersnow continues to move across south central Utah.
High snowfall rates can be expected with this band. Snow showers
are expected to continue along the I-15 corridor in western Utah
and winter driving conditions can be expected through the evening.
Going winter weather advisories for the southwest/west central
Utah valleys are on track as well.

As the trough pulls away from the area on Tuesday, a period of
shortwave ridging can be expected Wednesday. Mid-level warm air
advection may bring the threat of light snow to the northern
Wasatch Mountains by Wednesday evening.

.LONG TERM...(After 00Z Thursday)...The next short wave trof to impact
the CWA will be approaching from the northwest at the start of the
long term period. The EC continues to indicate this trof will slide
past mainly to our east while the GFS is a little farther west but
there won`t be all that much difference in the sensible weather that
results.

Both models are initially similar sending a cold front n to s thru
the CWA starting in the pre dawn hours Thu exiting the CWA Thu
eve. This will not be all that wet a system but any precip should
fall as snow.

Expect sub surface temps to chill down after todays snow and the
colder airmass that will be in place thru tomorrow so even some
light accumulation Thu morning could stick to colder roads and
have an impact on travel.

Snow becomes more showery and orographic Thu aftn into Thu night
in the cold nly flow that develops with a few mtn snow showers
lasting thru Fri.

Upstream ridging brings an end to any precip Fri night but a warm
front on the nw flow Sat morning will bring clouds to the north.
The EC keeps a lower amplitude ridge in place thru the weekend
with clouds and a chance of precip over the north. The ridge in the
GFS is sharper and keeps the CWA dry thru Sun. Have leaned towards a
compromise between these solutions keeping a very low pop across the
far north.

Both med range models then drop a large pool of cold air into the
western states starting Mon with a strong wnw flow over UT. The
frontal boundary sags swd into the CWA on Mon with even colder
temps and a threat of snow over the north. This threat continues
past day 7 and spreads across more of the CWA.

&&

.AVIATION...The SLC terminal will see IFR conditions in snow through
the evening with brief periods of LIFR in the heavier snow showers.
Lake enhanced snow will develop by 23z, lasting through the evening
hours and shifting west. Accumulation on untreated surfaces may see
1 to 3 inches. MVFR cigs will persist into the morning hours.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Winter Storm Warning until 5 AM MST Tuesday for UTZ007>010-517-
     518.

     Winter Weather Advisory until 11 PM MST this evening for
     UTZ002>004-006-015-016.

WY...None.
&&

$$

Kruse/Wilensky/Dewey

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



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