491
FXUS65 KSLC 302150
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
350 PM MDT Tue Apr 30 2024

.SYNOPSIS...A cold front will cross the region tonight, bringing
additional cooling for Wednesday. Gradual warming is then
expected late week into the weekend.

&&

.SHORT TERM (Through 12Z/6AM Thursday)...
Little impactful weather expected through the short term, with
temperatures running about 3-6 degrees below normal today,
trending cooler to about 5-10 degrees below normal on Wednesday.
The main highlight is the potential (60-75% chance) for sub-
freezing temperatures in Eastern Box Elder and Utah Valleys
Wednesday night into early Thursday morning, as the growing season
begins in those zones Wednesday, May 1st.

A stalled frontal boundary remains in place across central Utah,
weakening in place while also starting lift back northward ahead
of the next approaching shortwave. That shortwave trough can be
seen on WV image moving on the Oregon coast this afternoon, and
will continue to track east-southeastward grazing across northern
Utah Wednesday.

Ahead of this trough, the surface cold front will be force back
southward across the state on Wednesday, making it through central
Utah by midday and southern Utah by Wednesday evening. Moisture
and forcing with this system are both limited, and thus expect
just some isolated to widely scattered showers to develop along
the boundary, mainly over central Utah where the interaction with
the pre-existing boundary provides just a bit more forcing. The
main sensible weather impact for most will be a cooler
northwesterly wind which will push temperatures roughly another 5
degrees cooler from today into Wednesday.

Also, this front has a bit more southward push than the last
couple, and will actually make through southern Utah, thus finally
knocking the temperatures down a few degrees even in St. George
going into Thursday. In addition, late Wednesday night, the
northerly gradient behind the cold front will be enough to support
some breezy conditions through the typical Washington County gap
areas, although largely expect winds to remain below advisory
levels (gusts mainly less than 45 mph).

As far as the Freeze Watch goes, potential for sub-freezing
temperatures in Eastern Box Elder and Utah Counties is around
60-75% percent. One potential limiting factor for optimal cooling
below freezing remains how quickly clouds clear out behind the
Wednesday frontal passage, and whether any upstream cloud cover
ahead of the next wave starts to move in. There appears to be a
window for clearer skies to accelerate radiational cooling early
Thursday morning. Given the current probabilities and potential
cloud cover starting with a Freeze Watch, and will monitor for
needing to upgrade to a Warning with future forecast updates.

.LONG TERM (After 12Z/6AM Thursday)...
The local area will remain beneath a broad cyclonic flow through
the end of the week, with progressive short wave energy largely
staying north of the region through that time. Caveats to this are
Wednesday/Friday when model consensus points towards two short
waves amplifying just enough to clip the northern quarter of the
region. Scattered showers at most, areal coverage greatest over
the northern mountains, and a check back on temps the primary
changes to sensible weather with each.

A transitory ridge will build across the area Saturday in advance of
a deeper trough progged to translate onto the pac coast by midday.
Backing flow with increasingly gusty winds and a marked increase in
temps (from 5 below Fri to 10 above climo Sat) will bring the
weekend on a positive note, though increasingly cooler/unsettled
conditions will end it. Still a lot of uncertainty regarding
amplitude/timing/strength of this trough with passage into the early
week period, but guidance is leaning towards another round of
bullish precip and high mountain snow. More details to come in
time...


&&

.AVIATION...

KSLC...Light and variable winds in place are expected to
prevail from a light northwest through 03z prior to returning to the
south per norm. A dry boundary will cross the terminal tonight
between 07-09z switching winds back to the north. Increasingly gusty
northerly winds expected after sun up Wednesday morning. VFR
conditions will prevail.

.REST OF UTAH AND SOUTHWEST WYOMING...Breezy southwesterly winds
within VFR conditions expected across southern/eastern Utah and
southwest Wyoming through this evening...otherwise light winds will
prevail. A dry boundary will move north-south across the area
between 06z-18z driving increasingly gusty north winds within VFR
conditions Wednesday.


&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Freeze Watch from late Wednesday night through Thursday morning
     for UTZ103-106.

WY...None.
&&

$$

SHORT TERM...Church
LONG TERM...Merrill
AVIATION...Merrill

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