617
FXUS65 KSLC 161026
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
426 AM MDT Wed Apr 16 2025

.SYNOPSIS...Isolated high-based afternoon convection is possible
across central and northern Utah Wednesday with microburst
potential. A cold front will bring widespread valley rain and
mountain snow Thursday to all of Utah and SW Wyoming with cooler
temperatures and unsettled conditions persisting through Saturday.

&&

.SHORT TERM (Through 12Z Saturday)...A closed low off the
California coast is drawing in moisture to the area and providing
some weak ascent that will help to produce some isolated high
based showers and convection across central and northern Utah/SW
Wyoming Wednesday afternoon. Low levels remain pretty dry with
soundings depicting an inverted V signature which highlights to
potential for some microburst and gusty outflow winds in the
vicinity of these showers.

A deepening trough is currently moving into northern Idaho/Montana
and will continue to dive south, arriving in northern Utah
Thursday night. As the cold front associated with this trough
moves into northern Utah it will interact with the moisture from
the closed low to help produce widespread precipitation along the
front. This front will quickly race into central and southern Utah
by Thursday evening. The airmass behind the front is much colder
and quite a bit drier. This drier airmass will limit the duration
of the widespread precipitation to only a few hours as the cold
front moves across the area. The trend over the last several
model runs has the heaviest precipitation further south where the
closed low eventually phases with the trough. Guidance is now showing
the heaviest precipitation to be to our east and south, but there
is still some room for this area to shift as guidance is still
reflecting some inconsistencies regarding the timing and exact
track of this closed low.

The post-frontal environment will have some remaining low level
moisture along with temperatures 10-15 degrees below average.
This moisture will interact with weak broad synoptic scale ascent
associated with the deepening closed low across the four corners
and produce some showers, particularly during the afternoon and in
the mountains on Friday. Steep lapse rates will create conditions
favorable for graupel and isolated lightning as well as snow
levels briefly dropping to valley floors. Speaking of snow, totals
across most of the mountains of central and northern Utah will be
between 4-12" with higher totals closer to 15" possible across
the higher terrain of south central Utah.

This low will continue its trek to the east with precipitation
coming to an end by Saturday morning. Temperatures Saturday
morning will be near or below freezing for most locations outside
of lower Washington county. This would be a pretty late freeze for
areas like Zion, so if the cold trend continues it may necessitate
a freeze warning.

.LONG TERM (After 12Z/6AM Saturday)...The cold upper trough will be
exiting the region at the beginning of the long term period. Roughly
half of the ensemble solutions, heavily influenced by the Canadian
members, are deeper and slower with the evolution of the upper
trough, and keep cool and unstable conditions across the eastern
half of the forecast area during the day Saturday, while the
majority of the GEFS and EC ensemble members are more progressive in
lifting this trough out of the region by Saturday morning. As such
have maintained 20-30% PoPs during the day Saturday east of I-15 and
south of I-80 with any lingering precip likely minimal.

As the upper trough lifts away from the region, temperatures will
begin to rebound Saturday assuming the more progressive solution
supported by the majority of the ensemble members plays out, before
climbing near to slightly above climo by Sunday.

A longwave trough will reside across western Canada late in the
weekend through at least the first half of next week, with a general
cyclonic flow around the southern periphery of this trough across
the Pacific Northwest, northern Rockies and northern Great Basin. As
a result northern Utah/southwest Wyoming will remain susceptible to
embedded shortwaves passing through this mean flow, with a chance of
precip each day mainly across the higher terrain as temperatures
remain near climo. Southern Utah will remain far enough removed from
the upper forcing and moisture to maintain a dry forecast next week
with temperatures running a little above climo.

&&

.AVIATION...KSLC...Predominant VFR conditions are expected at KSLC
through this evening. Southerly drainage winds will switch to
northwesterly around 18Z. There is a 20-30% chance of showers
around the terminal after 22Z with gusty outflow winds in excess of
30 kts the main concern. The chance of lightning late this afternoon
and evening is less than 10%. A cold front will cross the terminal
late tonight, after 10Z, and will be followed by showers and a
slight chance of thunderstorms toward Thursday morning.

.REST OF UTAH AND SOUTHWEST WYOMING...Predominant VFR conditions
can be expected through this evening at all TAF sites. There is a 20-
30% chance of showers this afternoon and evening affecting northern
Utah and southwest Wyoming TAF sites, with gusty winds in excess of
30 kts the main concern. An isolated lightning strike is possible
with this activity near these terminals. After 06Z a cold front will
cross northern Utah and southwest Wyoming turning winds
northwesterly. This front will be accompanied by showers and a few
thunderstorms affecting northern Utah and far southwest Wyoming late
tonight.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Winter Storm Watch from Thursday morning through Friday evening
     for UTZ125.

WY...None.
&&

$$

SHORT TERM...Mahan
LONG TERM...Seaman
AVIATION...Seaman

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