698
FXUS65 KSLC 170459 CCA
AFDSLC

Area Forecast Discussion...CORRECTED
National Weather Service Salt Lake City UT
1059 PM MDT Sat May 16 2026

.KEY MESSAGES...

- Areas of critical fire weather conditions will continue across
  far southern Utah through Sunday afternoon.

- A quite unseasonably cold storm system will result in
  temperatures 10-20F below normal for Sunday and Monday along
  with accumulating mountain and mountain valley snow, significant
  for the Western Uinta mountains and in southwest Wyoming.

- Freeze conditions will impact many Utah valleys outside of the
  Wasatch Front Monday and Tuesday mornings. Some areas that might
  see a hard freeze include the Cache Valley, Wasatch Back, west
  central Utah, southwest Utah, and the Sanpete Valley.

&&

.DISCUSSION...An upper trough with several embedded shortwave
features is in place over the western CONUS this evening. Across
Utah, a cold front has moved through most of the area and is now
located across far southern Utah. Convection was in place near this
boundary through much of the afternoon, but has trended weaker and
will continue to decrease in coverage late this evening and
overnight.

Another embedded trough dropping into the Great Basin for Sunday
will push a stronger reinforcing cold front into the area. This will
be accompanied by much cooler air and more widespread precipitation.
Frontogenesis is expected to occur across central and southern
Utah which should focus heavier precipitation Sunday
afternoon/evening. This is also expected to bring even stronger
prefrontal winds to far southern Utah compared to today, and
combined with low humidities will result in another round of
critical fire weather conditions along the AZ border.

The shortwave trough is then expected to pinch off into a closed low
as it tracks across Utah Sunday evening through Monday morning.
Moisture wrapping around this low with associated TROWAL feature
will maintain precipitation through Monday, but becoming more
confined to northeast Utah and southwest Wyoming from Monday
afternoon onward. Precipitation amounts with this storm will
likely be most significant across the Uintas and southwest Wyoming
(with somewhat lesser amount across the central/southern
mountains) given the frontogenesis and favorable upslope flow with
the wraparound moisture. Models are quite aggressive with
precipitation amounts across the Uintas and southwest Wyoming,
with in excess of 1 inch in portions of southwest Wyoming and in
excess of 2 inches in the high Uintas. However, would not discount
this given the TROWAL. Additionally, the ECMWF Extreme Forecast
Index does show a good signal for anomalous precipitation in this
area.

With the cooler air spreading into the area behind the cold front,
temperatures will fall well below climatological normals, with max
temperatures failing to reach 60F across most northern Utah valleys
on Sunday and across many northern, central and southwest valleys on
Monday. This colder air will also bring snow levels down to near
5500-6000 ft, especially Sunday night into Monday morning. As such,
accumulating snow can be expected in the mountains and mountain
valleys and in southwest Wyoming. Greatest amounts and potential
impacts will be over the Uintas and southwest Wyoming, coincident
with the greatest QPF. Winter Weather Advisories are in effect for
these areas. While the forecast is showing storm totals reaching
warning criteria, given surface temperatures and sun angles this
time of year, actual impacts will be moderated, so will not plan on
upgrading at this time.

Freezing temperatures are still in the forecast for many valley
areas especially Sunday night/Monday morning and Monday
night/Tuesday morning. However, have some concerns about
precipitation and sky cover limiting radiative cooling for the first
night, especially in valleys below the snow level.

The airmass is expected to trend warmer and drier Tuesday into late
week. However, a cyclonic flow is progged to remain in place on
Tuesday, which could maintain a few showers across northeast Utah
and southwest Wyoming. Model spread also increases for late week, as
some models are trying to bring a storm of some sort back into the
area by Thursday. Since high pressure will remain over the Pacific,
the door does stay open for more storms to work their way into the
area, but will have to wait for models to come to a better consensus
before focusing on any details.

&&

.AVIATION...KSLC...VFR conditions will persist for the KSLC terminal
through the period. Northerly winds will continue across the
terminal overnight and through tomorrow. There is a 30% chance of
afternoon showers tomorrow with intermittent mountain obscuration.
Widespread light rain will develop tomorrow evening near the
terminal.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will persist
for the entire airspace through the night and tomorrow morning. A
cold front will keep winds out of the north for the northern
terminals with gusty southerly winds across the southern terminals.
Scattered showers develop tomorrow afternoon across the northern
half of the airspace with increasing southerly winds across the
southern half. Brief mountain obscuration will occur tomorrow
afternoon for the northern half.

&&

.FIRE WEATHER...A stronger storm system will cross the area
Sunday afternoon through Monday, bringing much colder temperatures
and accumulating snow to the higher terrain of Utah. Winds will
remain elevated over southern Utah, and while relative humidities
will be increasing, they will remain critically low over far
southern Utah, where a Red Flag Warning will remain in effect
tomorrow. Behind the exiting system, conditions will trend drier
and warmer for the remainder of the upcoming week.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Winter Weather Advisory from noon Sunday to midnight MDT
     Monday night for UTZ112.

     Red Flag Warning until 9 PM MDT Sunday for UTZ497-498.

WY...Winter Weather Advisory from noon Sunday to midnight MDT Monday
     night for WYZ021.

&&

$$

Cheng/Mahan

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