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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS65 KSLC 132207
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
407 PM MDT Sat Apr 13 2024

.SYNOPSIS...
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Active weather returns to the region late tomorrow as
a storm system pushes across the Great Basin region. Valley rain
and accumulating mountain snowfall is expected with this event,
however, impacts will be limited to the highest elevation routes
(i.e. upper Cottonwoods). Moisture holds on through the first half
of the week, with conditions trending warmer and drier through the
second half of the week.
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&&

.SHORT TERM (Through 12Z/6AM Tuesday)...
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High pressure slowly
shifts out of the region today as an upstream trough progresses
inland. Will see a relative maxima in the overhead winds during
the overnight hours tonight which may allow areas directly on the
lee slopes of mountain ranges to continue to see gusty winds.
Primary area of relative concern with these winds will be in the
Cedar City area where we`ll continue to see gusts to around 35
mph. For areas closer to nearby terrain just south of Cedar City
proper, gusts will occasionally reach the 40-45 mph range. Given
this will be more isolated in nature, have not issued any
headlines.

Stronger wind gusts will expand across the western Utah valley
areas during the morning on Sunday, with peak gusts approaching
30-35 mph. The core of stronger winds overhead will translate
eastward during the day, allowing eastern Utah valleys to get in
on the action during the afternoon.

Mostly clear skies will prevail across much of the forecast area
through the first half of the day tomorrow, however, increasing
overhead moisture will bring an increase in cloud cover as we head
through the mid-to-late afternoon hours. Temperature-wise, will
see a stout decrease in daytime high temperatures as the warmest
air overhead shifts eastward and colder air filters into the
region from the incoming low. High temperatures will be about
10-15 degrees colder than today, meaning mid-to-upper 60s for the
Wasatch Front, Cache, and Uinta Basin, around 60 for the Cedar
City area, and upper 60s for the St George area.

Moisture increases significantly Sunday evening as the low
progresses closer to the forecast area. Should see showers begin
developing over the high terrain late Sunday afternoon/ early
Sunday evening. Forcing increases during the late evening and
overnight hours as the center of the low begins moving into Utah,
allowing for shower activity to increase across the central two-
thirds of the forecast area. At this point in time, snow levels
will begin lowering from around 7,500-8,000ft to around
5,500-6,000ft across southern Utah and 6,000-6,500ft across
northern Utah. Snow levels jump back up by 500-1000ft during the
afternoon as solar heating takes over... however, stronger showers
could force snow levels back down. For the most part, not
expecting any significant impacts to valley areas.

Models have trended toward a much wetter forecast across northern
Utah and slightly drier across southern Utah through the duration
of this event. For example, the SLC area 10th to 90th percentile
forecasts for precipitation range from 0.01-0.62 inches, with a
most likely range (25th to 75th percentile) of 0.08-0.41 inches.
For the higher elevations (e.g. Alta), the overall spread of
precipitation forecasts range from 0.2-1.6 inches of liquid
equivalent, with the most likely amounts ranging from 0.35 to 1.0
inches. Thinking that the reasoning for the high amount of spread
in QPF is due to the convective nature of the showers... which
could also bring high uncertainty in the snowfall forecasts for
this event. In general, expecting the mountainous terrain, (above
7,000ft elevations) from Alta through the Tushars, to see 5 to 10
inches of snowfall. Areas most likely to see the upper end of this
range include Alta, the Tushar Mountains, and the Manti Skyline.
Not expecting much in the way of transportation impacts (outside
of visibility issues) given the warm antecedent conditions
bringing warm road temperatures and strong solar heating for this
time of year. Have not issued any headlines given that impacts are
likely to be limited to the upper Cottonwoods... and all other
seasonal roads remained closed at this time.

.LONG TERM (After 12Z/6AM Tuesday)...An area of low pressure will be
pushing into the plains by Tuesday morning with northwest flow
remaining in place over our CWA. Most of the precipitation will have
ended by Tuesday morning across the CWA, but given that the airmass
left in its wake will still have some decent moisture there could be
snow showers remaining across the terrain of central and northern
Utah through Tuesday afternoon.

Flow transitions to more westerly on Wednesday as a trough moves by
to our north. The proximity of this trough and associated baroclinic
zone will help keep temperatures near normal for northern Utah with
increasing temperatures across southern Utah to ~10 degrees above
climo as they become more influenced by the build ridge across the
southwest. PoPs will remain light across far northern Utah/SW
Wyoming as the trough remains within reach to provide some light
showers, but QPF totals >0.1" are hard to find with this scenario.
Even the NBM 95th percentile struggles to produce more than .1" of
QPF across the terrain of northern Utah.

The pattern will likely (70% chance) trend warmer and drier as the
week progresses and the trough to our north shifts further east.
However, there are still ~30% of members depicting a slower
progression east of the trough. This would keep conditions slightly
cooler with some light pops lingering across far northern Utah and
SW Wyoming through the end of the period. Southern Utah will remain
dry with temperatures ~10 degrees above normal. Otherwise, the long
term period lacks any storm with significant precipitation.
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&&

.AVIATION...
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KSLC...Southeast winds will gust to around 20 knots
through 00Z. Lighter winds will follow through the overnight.
Southeast winds will increase by around 15Z, with gusts around 20
knots much of the day. Clear skies will continue through around 15Z,
with ceilings becoming broken to overcast through the afternoon.
Light rain is likely into Monday.

.REST OF UTAH AND SOUTHWEST WYOMING...Southwest winds, strongest
throughout western Utah, will taper off around 00Z. Winds will be
relatively light overnight, then increase by around 15Z, with
similar speeds and gusts much of the day. Clear to mostly clear
skies will last through around 15Z. Broken to overcast ceilings will
build in from the west for the afternoon and evening. Light valley
rain is likely from after 00Z into Monday.
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&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.

&&

$$

SHORT TERM...Webber
LONG TERM...Mahan
AVIATION...Wilson

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