Wildfire in Utah, October 29, 2023

Area Forecast Discussion
National Weather Service Salt Lake City UT
402 AM MDT Sun Oct 29 2023

.SYNOPSIS...Anomalously cold temperatures remain in place
through the early week period behind a reinforcing cold front. A
building ridge of high pressure will result in gradually warming
temperatures by midweek.

&&

.SHORT TERM (Through 12Z/6AM Tuesday)...Cold temperatures have
now overspread all of Utah and SW Wyoming as temperatures more
reminiscent of late November rather than late October are in
place. When combined with the wind chill, apparent temperatures
will be as cold as 20 degrees across the Wasatch Front through
mid-morning. Elsewhere, apparent temperatures to as cold as the
single digits across SW Utah to near 30 in St. George are forecast.
A tight northerly pressure gradient is in place across the
region, with a ~16mb pressure difference in place between NW Utah
and SE Utah. The strong pressure gradient combined with a tight
low-level thermal gradient in SW Utah continues to support locally
windy conditions across SW Utah early this morning, with the
strongest winds observed near the southern end of the Black Ridge
Canyon and immediately downstream of the Beaver Dam range. Peak
gusts thus far have topped out around 50 mph near Leeds and near
60 mph immediately SW of the Beaver Dam range. Models suggest
winds of a similar magnitude will continue through the morning
before easing up a bit by afternoon as the thermal gradient
relaxes. With a somewhat weaker, but still strong pressure
gradient in place, NE gusts in the 40-45 mph range are well-
advertised in the model wind gust distribution in the same wind-
prone locations discussed above through the Sunday evening hours.

The pressure and thermal gradient is expected to quickly relax
overnight, allowing for boundary layer decoupling over Lower
Washington county, and when combined with the late November-like
airmass in place, we continue to forecast low temperatures around
32F for Lower Washington County around sunrise Monday morning.
Cold conditions will remain in place through the day Monday with
temperatures recovering only ~5F across the area when compared to
Sunday.

A few flurries or light snow showers remain in place this morning
for orographically favored areas such as the northern slopes of
the Uintas and west-east oriented terrain features across central
Utah as well. With dry advection underway today, this activity
along with associated cloud cover will gradually diminish through
the day today. Additional snowfall amounts are forecast to be
light, generally <1" across these areas today.

.LONG TERM (After 12Z/6AM Tuesday)...The long term begins in a
transition period between a cold northerly flow regime on the heels
of an exiting trough and warmer westerly flow from a ridge building
across the west. The jet stream will be positioned to our north, and
as a result temperatures will gradually warm above average for this
time of year. Conditions will also remain dry. By the end of the
period, guidance remains on board with the passage of a trough to
our north. However, the depth and timing of the trough remain
uncertain, but precipitation chances will remain confined to
northern Utah/SW Wyoming. A more substantial trough is possible by
the end of the weekend. This trough could bring more precipitation
to the entire CWA.

Tuesday morning will be the coldest window throughout the long term
period with freezing temperatures statewide, aside from Lower
Washington County where temperatures will be a couple degrees above
freezing. Highs Tuesday afternoon will be a few degrees below normal
before a climb to near normal/above normal temperatures for the rest
of the week/weekend. Dry air will remain in place with few clouds
allowing for dramatic diurnal temperature swings on the order of 20-
30 degrees.

The next chance for precipitation arrives by Thursday/Friday as a
trough grazes us to the north. The most likely outcome from this
will be a weak cold front dropping temperatures a degree or two.
Only ~30% of ensemble members have precipitation for northern Utah,
with the highest chances near the Utah/Idaho border.
Southern/Central Utah will remain dry. By the end of the weekend 30%
of ensemble members bring a deeper trough into the Great Basin that
would bring more widespread precipitation. The remaining 70% of
members maintain some sort of dry ridging pattern.

&&

.AVIATION...KSLC...VFR conditions will prevail throughout the period
for the KSLC terminal. Expect clear skies with light northerly
winds.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will prevail
throughout the period for the area. Skies will be mostly clear with
light northerly winds across the central and northern zones with
slightly gusty northerly winds across the south.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Wind Advisory until noon MDT today for UTZ123.

     Freeze Warning until 10 AM MDT Monday for UTZ123-124.

WY...None.
&&

ADeSmet/Mahan

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

Preliminary Local Storm Report
National Weather Service Salt Lake City UT
859 AM MDT Sun Oct 29 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0857 AM     Snow             Stansbury Park          40.64N 112.31W
10/29/2023  M0.5 inch        Tooele             UT   NWS Employee

0800 AM     Snow             1 NNW Park City         40.68N 111.50W
10/29/2023  M0.2 inch        Summit             UT   Cocorahs

            Cocorahs station UT-SM-12 Park City 1.4 NNW.

0700 AM     Snow             1 WNW Mantua Res        41.50N 111.94W
10/29/2023  M0.0 inch        Box Elder          UT   Cocorahs

            Cocorahs station UT-BE-19 Mantua 0.6 WNW.

&&