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Area Forecast Discussion
Issued by NWS Salt Lake City, UT
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FXUS65 KSLC 210936
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
336 AM MDT Sun Apr 21 2024

.SYNOPSIS...High pressure will bring dry and very mild conditions
to Utah and southwest Wyoming today. A dry front will cool
temperatures slightly over northern Utah and southwest Wyoming
while temperatures stay quite unseasonably warm over southern
Utah. Temperatures will rebound Tuesday into Wednesday before a
cooler and more stormy pattern develops for the latter part of the
week.

&&

.SHORT TERM (Through 12Z/6AM Tuesday)...High pressure is centered
over Utah and southwest Wyoming this morning, resulting in mostly
clear skies and mild temperatures. Under the influence of the
ridge, the warming trend will continue over the area, with maxes
averaging 15F above seasonal normals.

The ridge will tend to flatten and shift east through the day,
however, as a weakly defined Pacific Northwest trough moves
onshore. Already seeing some high clouds approach the Utah/Idaho
border in association with this feature. Anticipating little if
any in the way of precipitation with the system as it grazes
northern Utah tonight into early Monday. It will, however, bring a
frontal boundary through to bring temperatures back to 5-10F
above climo for northern portions of the area on Monday.
Meanwhile, southern Utah temperatures will remain similar to
Sunday, so very much on the mild side.

.LONG TERM (After 12Z/6AM Tuesday)...Ensemble members are in good
agreement with amplifying a ridge of high pressure over the Great
Basin on Tuesday, and then shifting ridge eastward on Wednesday.
With some increase in low and mid level moisture and weak
disturbances gliding along periphery of ridge, current chance
probabilities for light showers over northern Utah, primarily high
terrain, are justified. A moderate southwest flow aloft will
promote continued warm advection with 700MB temperatures warming
to plus 4- 8C by Wednesday evening. Despite some cloudiness, high
temperatures will be on the order of 10 to 15 degrees F above
normal both days.

The forecast becomes considerably more complex for the Thursday
through Saturday period as a Pacific trough deepens and slides
eastward, bringing statewide precipitation and cooler temperatures.

On Thursday, roughly 80 percent of ensemble members indicate an
initial trough passing across extreme southwest Wyoming and Utah,
producing widespread precipitation across bulk of forecast area.
Given somewhat modest precipitation totals (QPF less than .25)and
snow levels around 9K feet, any impacts will be minimal.

Ensemble member solutions diverge for Friday and Saturday, both in
terms of timing of trough and amplitude.  Majority of ensemble
members have trended toward a slower solution, with base of trough
and associated frontal boundary crossing region in the Friday night
through Saturday period.  Given some potential for significant
precipitation (20-40 percent chance of QPF above 1.00) across higher
terrain, with 25th to 75 percentile values ranging from roughly
.50 to 1.50 in higher terrain, and snow levels dropping to 8K
feet, will need to monitor for impacts to surface transportation
across mountain routes.

&&

.AVIATION...KSLC...VFR conditions will prevail through the TAF
period, though some mid and high level cloudiness will spread
into the region during the late evening hours.  A southeast
drainage wind will shift to a northwest lake breeze around 20Z, with
an enhanced drainage wind redeveloping around 03Z.  A weak frontal
boundary dropping across the region should turns winds back to the
northwest around 06Z, but confidence in timing and duration of
northwest winds is low.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will
prevail through the TAF period.  Terrain-driven winds will
shift to a generally southwest flow as the day progresses.  A cold
front dropping south across the region should turns winds back to
the northwest during the late evening and nighttime hours, primarily
along a KEVW to KPVU line and points north and west.

&&

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

$$

SHORT TERM...Traphagan
LONG TERM/AVIATION...Barjenbruch

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