260
FXUS65 KSLC 142136
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
336 PM MDT Tue May 14 2024

.SYNOPSIS...More isolated diurnal convection on Wednesday across
the terrain of eastern Utah and near Lake Powell followed by a
warming and drying trend through Friday. Another trough grazing by
to the north this weekend will bring a slight cool down and a
return of isolated diurnal convection.

&&

.SHORT TERM (Through 12Z/6AM Thursday)...Current radar this
afternoon has isolated convection across far northeastern Utah/SW
Wyoming near Bear Lake with more widespread high-based convection
across southern Utah. The main threat with this convection will be
winds, but so far the highest winds have stayed below 40 mph. This
convection will quickly diminish after sunset.

The shortwave responsible for the spotty convection today will be
shifting east tomorrow which will leave areas along and west of
I-15 dry tomorrow with isolated diurnal convection focused across
the terrain of eastern Utah and near the Lake Powell region.
Similar convective mode tomorrow with high based storms capable of
producing strong erratic wind gusts, small hail, and frequent
lightning. Temperatures tomorrow will trend down a few degrees
compared to today as the "cool" front fully pushes out of the
region. High pressure will begin to build in from the west
starting tomorrow which will help to dry out the CWA later in the
week.

.LONG TERM (After 12Z/6AM Thursday)...Thursday remains at least the
one day in the long term period where forecast confidence is fairly
high. Guidance remains in good agreement that ridging will extend in
from the west, resulting in dry and mild conditions across the
forecast region. To the latter point, afternoon highs are expected
to run about 5 to 10 degrees above climatological normal for mid May.

Friday forecast confidence begins to dip slightly, but ridging is
largely expected to remain the dominant influence for much of the
day. As such, most of the day remains dry, and temperatures bump
upwards several degrees for afternoon highs. That said, through the
day Friday a stronger jet/trough will begin pushing inland from the
PacNW. Most guidance sources keep this feature far enough north to
preclude impacts aside from some increasingly gusty winds across the
northern half of the region Friday afternoon, but ~33% ensemble
members (heavily GEFS weighted) have enough amplitude to nudge a
boundary into northern Utah and southwest Wyoming later Friday
evening. If this pans out, would expect potential for some scattered
convection accordingly, as well as some cooler post-frontal
temperatures.

This trough will continue to serve as a source of uncertainty moving
into the weekend. Around 40% of ensemble members include either a
slower progression of the trough`s boundary (or lingering impacts
from an earlier frontal passage), with around 60% of ensemble
members maintaining or building a stronger ridge atop much of the
area. As is typical, the stronger trough would increase odds of
cooler and slightly more unsettled weather, and the stronger ridge
would lean towards continued warm and dry conditions. All that said,
given what is likely to be a fairly low amplitude to the trough,
most of this uncertainty is noted to be further north in the
forecast region. For example, the NBM 75th/25th percentile high
temperatures at KSLC show a fairly large spread (82/72), but at KSGU
the spread narrows a good bit (96/92).

Sunday onward through the remainder of the forecast period
uncertainty remains high, though it seems guidance is starting to
offer at least some consensus as to how the pattern eventually
evolves, but with differences on timing and strength of synoptic
features. In general, it appears a stronger shortwave will begin
digging through the northern stream and amplify a trough through the
PacNW, with potential for a southern stream cutoff low to eventually
phase and help either maintain or deepen the northern stream trough
as it begins to shift east. On Sunday, around 35% of ensemble
members support some sort of trough dipping in, with 15% showing a
stronger higher amplitude trough. By Monday, trough membership
increases to around 70%, with around 40% of total ensemble members
showing a a bit higher amplitude to the trough. Tuesday increases
further with around 75% of ensemble members depicting some sort of
trough. Once again opted to maintain NBM guidance with this forecast
package, which largely includes a gradual cooldown and somewhat
unsettled conditions. Until some of the aforementioned uncertainty
gets ironed out though, will likely continue to see some moderate
fluctuations to exact day-to-day forecast values.

&&

.AVIATION...KSLC...VFR conditions will continue through the TAF
period with generally clear skies. Expect northwest winds to turn
southeast between 4-6Z for the overnight period, though there is a
30% chance that winds will remain light northerly overnight.

.Rest of Utah and Southwest Wyoming...Scattered storms over far
northeast Utah in vicinity of KLGU and over southern Utah from KMLF
to KHVE with isolated MVFR/IFR vsbys should dissipate early this
evening. Otherwise, VFR conditions with generally northerly flow are
expected this evening and overnight. Showers/thunderstorms tomorrow
afternoon will be limited again to mostly areas east of I-15, with
cumulus buildups over higher terrain in general.

&&

.FIRE WEATHER...A storm system shifting east on Wednesday will
leave mostly dry conditions for areas along and west of I-15. Some
isolated convection will be possible across the Uintas down
through the Grand Staircase and Lake Powell, but chance of wetting
remain remains low (~15-20%) so expect high based storms capable
of producing gusty winds. High pressure builds in for Thursday and
Friday with drying conditions and rising temperatures along with
light winds. Another storm system approaches from the north by
this weekend, but looks to graze Utah. This will mainly result in
increased southwesterly winds during the day and isolated
convection.

&&

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

$$

SHORT TERM...Mahan
LONG TERM...Warthen
AVIATION...Van Cleave
FIRE WEATHER...Mahan

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http://weather.gov/saltlakecity