Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 131124
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
424 AM MST Fri Jan 13 2017

.SYNOPSIS...A low pressure system moving south along the
California coast will continue to spread moisture into the region
through tonight. A drying trend will follow into the weekend
before an active pattern redevelops by the middle of the week.

&&

.SHORT TERM (Through 06z Sunday...The upper level low spinning
down the coast of Baja of California this morning per water
vapor satellite continues to entrain dry air into it while
kicking moisture from the Desert Southwest through the Central
Rockies. The baroclinic leaf feature noted on IR satellite
overnight from Nevada/Arizona/Utah and into Colorado continues to
shear off to the east, as the deformation zone stretches the
atmosphere over northeast Nevada and northwest Utah. Temperatures
overnight have fluctuated very little and persisting snow and
rain showers have continued across far southern Utah. The winter
weather headlines will remain through late morning as conditions
deteriorate.

As the upper low migrates farther south today, and then
more eastward Saturday, the flow aloft is very light. Rising
heights from the west with drier air and relative high pressure
will continue to build in today. The active winter weather
pattern over the last week or so will come to an end for a few
days.

Temperatures in valley locations, especially those in
far northeastern Utah and southwest Wyoming should stay quite
cold as somewhat warmer air is advected in from southerly flow
aloft. Capping these valley locations as warm air overrides the
cold air in valleys should play a part in low visibility and
inversion conditions setting up. With high pressure moving in
from the west over the weekend, expect valley locations will only
settle in harder with inversion conditions as well. Otherwise,
the weekend looks to remain dry for most of Utah and southwest
Wyoming.

.LONG TERM (After 06z Sunday)...Models are in good agreement with
the track of the upper-level low to our south for the weekend,
sliding it across far western TX and the TX Panhandle by Sunday.
Wrap-around showers are expected to extend across the Four Corners
area and into southern Utah, though precip should be light and
mostly confined to the higher terrain as isentropic lift exits to
the east.

Elsewhere in Utah, quieter weather is expected by Sunday as colder
and drier northerly flow sets up over the area. Temperatures are
expected to drop to around 5-10 degrees below normal readings. The
NAM model does try to initiate a shallow saturated layer at the
surface across the West Deserts and northern UT valleys, resulting
in scattered light snow showers. The Canadian model hints at this as
well. This solution does not make much sense, however, given the
drier upstream air mass, so have kept the forecast dry for these
areas.

Brief ridging Monday/Tuesday will likely set up weak temperature
inversions in northern valleys, which could cause some haze to
develop. This will be short-lived, however, as the active pattern
roars back to life across the Eastern Pacific. Yet another
atmospheric river will move into the Pacific Northwest, reaching our
area around midweek. This initial push will feature westerly flow,
which is not as favorable as recent atmospheric river events for
moisture traveling inland to our area due to upstream mountain
ranges. That said, a longwave trough does push inland by later in
the week, buckling the flow aloft to southwesterly and likely
allowing more moisture to reach our area. Thus, current thinking is
midweek will feature increasing clouds, dissipating inversions, and
light precip limited mostly to the higher terrain. By late week,
there is a potential for area-wide precipitation and potentially
colder air to push snow levels back to valley floors. Then, right on
the heels of that storm, Models suggest yet another wet and cold
trough into next weekend. Bottom line, after a brief break early
next week, an active weather pattern will continue for the
foreseeable future.

&&

.AVIATION...Ceilings at the KSLC terminal will continue to improve
during the TAF period. VFR conditions expected, with brief periods
of low stratus and MVFR cig/vis possible through 18z. Expecting
northerly winds to persist through the TAF period as well.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Winter Storm Warning until 11 AM MST this morning for UTZ010.

     Winter Weather Advisory until 11 AM MST this morning for UTZ011-
     012-014-015-517-518.

WY...None.
&&

$$

SHORT TERM/AVIATION...Dewey
LONG TERM...Van Cleave

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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