Area Forecast Discussion
Issued by NWS Salt Lake City, UT

Current Version |  Previous Version |  Text Only |  Print | Product List |  Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14
FXUS65 KSLC 162139

Area Forecast Discussion
National Weather Service Salt Lake City UT
339 PM MDT Sun Jun 16 2024

.SYNOPSIS...A strong cold front will cross the region Monday,
bringing a much colder airmass to the area for Tuesday.
Temperatures will quickly moderate midweek, with another period of
very hot temperatures by Sunday.


.SHORT TERM (Through 00Z Wednesday)...The Beehive State is in for
a bit of a roller coaster ride, with the next 7 days including
the threat of freezing conditions in the Wasatch near
100 again by next Sunday across the Wasatch Front. So we`ll be
running the gamut here over the next week.

Afternoon upper air and satellite analysis indicates a longwave
trough is shifting south and east into the Pacific Northwest. This
trough is associated with an anomalously cold airmass...around the
lowest in the EPS climatology for this time of year. The
associated cold front will approach the Utah/Idaho border Monday
morning, blasting through the state and reaching southern Utah by
the first half of Monday night.

While the global models have been relatively dry with the frontal
passage, CAMS nearly universally depict convection during the
afternoon and evening associated with the strongest forcing,
mainly near and north Salt Lake City. Given the dry subcloud
environment, suspect a line of high-based convection with
microbursts mixing down stronger winds will be the predominant
mode during the afternoon and evening. Something to monitor going

Guidance still suggesting winds are likely to remain below wind
advisory criteria in most locations, with gusts to 45 mph or so
for an hour to two hours. It should be noted however that the
latest run of the HRRR has become quite bullish with wind gusts
with the front Monday evening into MOnday night, with widespread
gusts in excess of 60 mph across Washington County and perhaps
downsloping into Castle Country and the western Uinta Basin. HREF
probabilities for the Black Ridge Canyon area are approaching
100% for gusts over 55 mph. It should be noted that the high res
guidance notoriously overforecasts strong winds in this area...but
future shifts will need to monitor for a potential High Wind
Watch. For the SR-10 corridor in Castle Country...without jet
support...winds have a difficult time shifting off the terrain.
This will be another area to monitor for future shifts.

As far as the very cold temperatures, guidance continues to show
high probabilities of freezing temperatures across the Wasatch
Back...and thus have issued a Freeze Watch for Monday night into
Tuesday morning. Patchy frost will be possible across the Wasatch
Back, Cache Valley, Sanpete Valley and Rush Valley.

Highs on Tuesday will be well below average across much of the

.LONG TERM (After 00Z Wednesday), Issued 403 AM MDT... In the
wake of Monday`s frontal passage, a much cooler and more stable
airmass will temporarily reside across the forecast area. Clearing
skies Monday night along with this much colder airmass will allow
min temps to fall near freezing across portions of the Wasatch
Back and potentially the Cache Valley as well, and Freeze
headlines may be needed if this trend holds. Max temperatures
Tuesday afternoon will run nearly 15F below climo across northern
Utah, where highs will struggle to reach the 70F mark across the
northern valleys. Further south temperatures will run closer to
10F below climo, with upper 80s to low 90s across the lower
elevations of southern Utah.

A mean trough axis will remain situated to the west of the forecast
area throughout the middle to latter portion of next week, leaving
the forecast area under a mild and dry southerly flow aloft. Max
temperatures will quickly rebound to near climo Wednesday, then
continue to trend a few degrees warmer each day from Thursday into
next weekend. Additionally, moisture being pulled into the southern
and central Rockies may gradually spread west during the latter
portion of next week, allowing for a small chance for showers and
thunderstorms mainly over the far eastern CWA.


.AVIATION...KSLC...NW winds expected to linger into the evening,
flipping SE between ~05Z-07Z Mon. SE winds then persist, with an
early switch back NW ~13Z-15Z Mon as a cold front gradually sinks
through the region. Tightening gradient will result in increasingly
gusty NW winds throughout the daytime, generally in the 25kt to 35kt
range. Winds will gradually relax late Monday evening into the
overnight hours, with NW direction favored to persist. Precipitation
chances low (around 20%), but best chance noted from ~21z Mon to
~03Z Tue. Given high-based nature, any convection would be capable
of further gusty and erratic outflow winds.

.REST OF UTAH AND SOUTHWEST WYOMING...Winds expected to lighten up
and largely follow a diurnally normal pattern overnight. From Mon
morning on through the afternoon, a cold front will sink southward
through N UT and SW WY terminals, reaching S UT terminals by later
Mon evening. At northern terminals, NW winds become favored
following frontal passage, and gusty conditions set in during the
daytime hours (generally in the 25kt to 35kt range). Additionally, a
low chance (around 20%) of high-based convection is noted at
northern terminals during the afternoon. At southern terminals,
gusty SW prefrontal winds develop during the day, with at least some
potential noted for patchy smoke related haze to advect in from
fires in the SW CONUS. Winds at southern terminals flip N to NW
abruptly later Mon evening following frontal passage.


.FIRE WEATHER...Critical fire weather conditions continue across
southern Utah this afternoon, with multiple sites seeing winds in
excess of 30 mph with humidities at or below 15%. Expect another
night of poor recoveries across southern Utah. A strong cold front
will cross the state Monday into Monday night. Ahead of this
front, expect gusty southerly winds across southern Utah with very
low humidities. The front will bring an abrupt change in wind
direction to the north to northwest...remaining strong and gusty
for several hours behind the front. While temperatures will be
considerably cooler in many locations Tuesday, humidities will not
rebound much across southern Utah. Another round of critical fire
weather conditions is possible Thursday into Friday across
southern Utah as southwest flow increases ahead of the next
system. Mid-level moisture may increase by Friday, spreading west
from the Gulf of Mexico, which may bring lightning to areas that
have been very dry for a considerable period of time across
southern Utah. Something to watch moving forward.


UT...Freeze Watch from Monday evening through Tuesday morning for

     Red Flag Warning until 9 PM MDT Monday for UTZ495-496.

     Red Flag Warning until 3 AM MDT Tuesday for UTZ498.

     Red Flag Warning until midnight MDT Monday night for UTZ497.




For more information from NOAA`s National Weather Service visit...