Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 162203
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
403 PM MDT Sat Mar 16 2024

.SYNOPSIS...Easterly downslope winds are expected to linger into
Sunday morning, with the strongest winds gradually becoming closer
to the canyons of Weber and Davis counties for this last phase of
the event. Meanwhile, a closed low will continue to bring
accumulating snow to the central and southern Utah mountains
into tonight.

&&

.SHORT TERM (THROUGH 12Z MONDAY)...A Rex Block remains in place over
the western CONUS with a cutoff low centered over Lake Mead and high
pressure across the PacNW and northern Rockies. This general pattern
is not expected to change significantly through the short term
forecast period. Over Utah, this will continue to result in a mean
easterly flow, while moisture and associated precipitation continue
to rotate around the low and impact central and southern Utah.

Surface winds remain fairly gusty along portions of the Wasatch
Front, especially near canyons. These winds should increase again
tonight, given a continued easterly surface pressure gradient and 30-
40kt H7 cross-barrier flow. Probabilistic guidance from the 12z HREF
shows an 80-90% chance of exceeding the 45 mph Advisory criteria
along the northern Wasatch Front once again tonight. A Wind Advisory
thus remains in effect through tomorrow morning. A few gusts in the
most favored downslope areas (i.e. near Park Lane in Farmington)
will probably exceed 60 mph, but this will be very isolated. The
winds are expected to finally wind down tomorrow afternoon as H7
flow decreases, followed by a relaxation of the surface pressure
gradient.

Precipitation across central and southern Utah has started to turn
more showery this afternoon rather than having a more banded nature,
owing in part to weaker H7 convergence. Snow levels will be
generally higher through early evening, around 6-6.5kft. However,
heavier showers will continue to have the potential to bring snow
levels lower (to 5-5.5kft), especially as temperatures cool
overnight. Models suggest one more round of steadier precipitation
hitting the east-central valleys and the central mountains tonight
for around 3-4 hours, otherwise precipitation will be spotty for the
most part. Tomorrow during the day, the focus will be more across
far southeast Utah as a weak embedded disturbance rotates around the
low. Overall, additional snow accumulations are expected to be
generally light except for an additional 2-6 inches locally on the
east slopes of the central and southern mountains. Will let the
going winter weather highlights continue on through 00z, then
determine if they are fine to expire.

.LONG TERM (After 12Z Monday)...A Rex Block will be in place for the
western U.S. as a ridge will be positioned over the PacNW and a
nearly stationary closed low will be in the southwest. Mostly clear
and dry conditions will continue throughout southwest Wyoming and
northern Utah, while more clouds and isolated to scattered showers
are likely for portions of southern Utah. Largely unchanged synoptic
conditions will last through Tuesday. Precipitation throughout
southern Utah will be light, with generally less than 0.1" of water
Monday through Tuesday. Snow levels will be around 6500 feet.
Temperatures will be around 5-10F warmer than normal for southwest
Wyoming and northern Utah. Temperatures will be near normal
throughout southern Utah.

There is good model and ensemble agreement that the low will exit to
the east Wednesday. There is more disagreement on a trough that will
track in from the west. Dry and warmer than normal conditions will
likely last through Wednesday, with isolated showers primarily in
the northern mountains.

It is more likely that an incoming trough will bring isolated to
scattered showers Thursday. Around 30% of ensemble members, mainly
EPS, bring precipitation with a trough to the west. The probability
stays similar Friday, with more EPS members bringing precipitation.
Most members from other ensembles keep ridging through Friday.
Confidence will be better from Thursday into the weekend as guidance
gets in better agreement on details with the aforementioned trough.

&&

.AVIATION...KSLC...Another forecast with tricky winds due to
atypical easterly flow overhead. Guidance suggests easterly winds
(and occasional gusts) will persist while daytime heating keeps low
levels mixed. With loss of heating, anticipate winds to become
increasingly variable late evening into the overnight. A similar
progression is expected Sunday with fairly variable winds
anticipated to pick up a more easterly component by early afternoon
as mixing increases. Otherwise, VFR conditions persist, with a bit
of mid/upper cloud cover expected to filter through overnight.

.REST OF UTAH AND SOUTHWEST WYOMING...A cutoff low in the Desert
Southwest will continue to influence much of the region in one way
or another. At EVW, more persistent easterly winds (and daytime
gusts) continue, and at ENV winds expected to remain more northerly.
At OGD/LGU, easterly winds/gusts expected to mix in during the
daytime, with more variability with loss of heating/mixing. PVU
looks to hang more diurnal to variable at times, with HCR generally
variable. Otherwise, VFR conditions expected at northern terminals.
At southern terminals, closer proximity to the low will result in
continued scattered precipitation and increased cloud cover.
Generally should see VFR to MVFR conds persist, but periods of IFR
possible (~10-20% chance) at BCE/CDC, primarily during times of
precip.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Wind Advisory until noon MDT Sunday for UTZ104.

     Winter Storm Warning until 6 PM MDT this evening for UTZ117-125-
     127-129.

     Winter Weather Advisory until 6 PM MDT this evening for UTZ128.

WY...None.

&&

$$

Cheng/Wilson/Warthen

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http://weather.gov/saltlakecity


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