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Area Forecast Discussion
Issued by NWS Salt Lake City, UT
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FXUS65 KSLC 220839
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
239 AM MDT Mon Apr 22 2024

.SYNOPSIS...A dry front will bring slightly less warm temperatures
over northern Utah and southwest Wyoming today as central and
southern Utah temperatures stay quite unseasonably warm. 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 Wednesday)...High pressure has
flattened over Utah and southwest Wyoming this morning as a weak
storm system grazes northern Utah. This trough has brought a dry
cold front into northern portions of the forecast area, which is
currently near a KNFL-KPVU-KEEO line. Seeing some high clouds
along and north of this boundary, with clear skies for much of
central and southern Utah.

The front is expected to stall shortly if it has not already, so
associated cooling will be primarily limited to the northern third
of the forecast area, where maxes today will be 5F or more cooler
than what was observed yesterday for most locations. Over central
and southern Utah, temperatures will be similar to yesterday but
some breezy west to southwest winds can be expected this afternoon
ahead of the front.

By Tuesday, the ridge over the area should begin to amplify again,
allowing temperatures to quickly return to values 10-15F above
seasonal normals Tuesday. Guidance is continuing to indicate some
shortwave energy flowing into the ridge, bringing the potential
for some showers and thunderstorms to light up in the vicinity of
the boundary Tuesday afternoon as it lifts northward. All
indications are that coverage would be widely scattered at best,
with limited associated precipitation. As this is Utah, cannot
rule out the possibility of gusty winds with any storms that
develop.

.LONG TERM (After 12Z/6AM Wednesday)...Southwesterly flow will increase
across the area on Wednesday ahead of an upper trough that will mark
the start of a pattern change. With good mixing and H7 temperatures
between +6-8C, afternoon max temperatures on Wednesday are likely to
be the warmest of this week across most areas, and around 10-15
degrees above climatological normals. The NBM has a 50% chance of
SLC reaching 80F. Otherwise, remnant moisture may fire up a few
showers, mainly across northwest Utah Wednesday afternoon and
evening, aided by large-scale lift owing to upper diffluence ahead
of the approaching storm system.

Global deterministic models are in relatively good agreement with
the approaching storm featuring as a closed low as it moves onto the
SoCal coast early Thursday morning, then gradually opening up as it
tracks across northern AZ and southern UT through the day Thursday.
However, there remains some spread in the ensembles, with varying
degrees of amplitude and timing noted. Regardless, precipitation is
likely to fill in from the northwest behind the trough axis Thursday
under H7 cold advection. However, the airmass will not cool very
significantly, and snow levels are expected to remain above 8.5-9kft.

This trough then opens up the door for trailing features to phase
into a mean longwave trough pattern which will then dominate the
western CONUS through the weekend. The second main storm system
within this wave train is progged to arrive on Friday. Deterministic
models hint at it trying to close off, which would slow its
progression and as a result, continue to impact the forecast area
with fairly widespread precipitation through at least Saturday.
Cooler temperatures are expected with this second feature, with
temperatures trending below climatological normals by Friday.
Additionally, snow levels are progged to fall to around 7.5-8kft on
Friday, and potentially to 7-7.5kft on Saturday.

However, spread increases amongst deterministic models and their
respective ensemble members as to how quickly the storm exits the
area. Cluster analysis of ensemble members show varying positions of
the trough axis, with the top two clusters, both encompassing 33% of
members, either showing the trough well into CO/NM, or directly
overhead on Sunday afternoon. Of the remaining two clusters, cluster
3 has the trough axis still just upstream of Utah, while cluster 4
shows a low-amplitude ridge over Utah. So not a whole lot of help
there, and will have to maintain some PoPs and below normal
temperatures into Sunday.

&&

.AVIATION...KSLC...The SLC terminal will see VFR conditions
throughout the day with some high clouds. Northwest winds will
prevail throughout the day, with a 40 percent chance that winds
will become light and variable or light southeasterly at times
during the early morning.

.REST OF UTAH AND SOUTHWEST WYOMING...The airspace will see VFR
conditions throughout the day, with some high clouds over northern
Utah and some cumulus buildups during the afternoon for the higher
terrain north of I-70. Winds will be generally light and terrain
driven for the Wasatch Front valleys and northwest Utah, with
occasionally breezy west to southwest winds anticipated elsewhere.

&&

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

$$

SHORT TERM/AVIATION...Traphagan
LONG TERM...Cheng

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