957
FXUS65 KSLC 211128
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
528 AM MDT Fri Aug 21 2026

.KEY MESSAGES, Issued 1018 PM MDT Thu Aug 20 2026...


- Hot temperatures will persist over the valleys of northern Utah
  Friday, with low temperatures in the mid to upper 70s providing
  little overnight recovery.

- Monsoonal moisture will surge into Utah and southwest Wyoming
  Friday and Saturday, persisting through at least early next
  week. This will bring an increased threat of showers and
  thunderstorms capable of producing heavy rain that could lead to
  flash flooding.

&&

.DISCUSSION, Issued 1018 PM MDT Thu Aug 20 2026...
High pressure is centering itself over the Four
Corners region this evening, with a southerly flow developing over
Utah and southwest Wyoming. Despite some drying over the past
couple of days, satellite derived PW values are still
predominately in the 0.7 to 0.8 inch range, more than enough for
development of showers and thunderstorms over the higher terrain
this afternoon, with convective activity continuing over southern
Utah, including a few strong thunderstorms Short range guidance is
indicating that shortwave energy moving in from Arizona should
keep some showers and thunderstorms going through the first part
of the overnight hours, with coverage diminishing as sunrise
approaches.

Temperatures were quite hot across the valleys of northern Utah
this afternoon, with most valleys seeing temperatures around 100F.
Lows in the lower to mid 70s will not provide much in the way of
relief, with highs in this area tomorrow expected to be similar to
today. Going Heat Advisory covers this threat well.

The southerly flow that is developing will allow monsoon moisture
to spread into central and southern Utah during the day Friday and
into northern portions of the area Friday evening into Saturday
morning. As a result, coverage of convection will be more
widespread tomorrow afternoon, but given the lack of additional
forcing mechanisms initially, should be focused over the higher
terrain at first. Seeing evidence that some more shortwave energy
from Arizona will eject northward during the late afternoon,
impacting northern Utah during the evening, potentially bringing
additional convection to the valleys of northern Utah.

Once the moisture is in place, there is little change in the
pattern expected through early next week as confidence is high
that the ridge will continue to park itself over the Four Corners.
This will bring high temperatures near seasonal normals by the
start of the upcoming week, with a daily threat of showers and
thunderstorms that could produce heavy rain capable of flash
flooding, particularly during the afternoon and early evening. As
the middle of next week approaches, confidence in the pattern
decreases noticeably, with a good portion of guidance showing a
drying trend from the west as the ridge retrogrades over Arizona.



&&

.AVIATION...

KSLC...VFR conditions will persist for the KSLC terminal through the
period. Dry conditions during the day will transition to scattered
convection late in the afternoon through the early evening becoming
more isolated showers overnight. Winds will be light and diurnally
driven except during instances of gusty and erratic outflow winds
from thunderstorms.

REST OF UTAH AND SOUTHWEST WYOMING...Mostly VFR conditions will
persist for the entire airspace throughout the day. Isolated to
scattered convection will develop across the airspace during the
afternoon and early evening with brief impacts to terminals. Gusty
and erratic winds will be possible with nearby storms. Otherwise,
winds will remain relatively light and diurnally driven.

&&

.FIRE WEATHER, Issued 242 AM MDT Fri Aug 21 2026...
High pressure centered over the Four Corners will peak
temperatures today with a gradual cooling trend through the
weekend. It is also drawing up moisture into the area that will
remain in place through early next week. Some dying showers remain
across southwestern Utah this morning. This will remain the
pattern through the weekend: showers and storms developing during
the day with some storms lingering into the overnight. Where
exactly these storms linger will be determined by where the
heavier precipitation develops during the day.

The highest chance of precipitation will be in the mountains with
significantly lower precipitation, particularly wetting rain,
chances across the lower terrain where min RH will still be low in
the upper teens to low 20s. Storms remain through early next week
along with increasing southwesterly winds as low pressure grazes
the area to the north.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Heat Advisory until 7 AM MDT Saturday for UTZ101>106.

     Heat Advisory until 7 AM MDT this morning for UTZ115-116.

WY...None.
&&

$$

PUBLIC...Traphagan
AVIATION...Mahan
FIRE WEATHER...Mahan

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