867
FXUS65 KSLC 290409
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
1009 PM MDT Tue Jul 28 2026

.KEY MESSAGES...

- Monsoon moisture will increase and spread northward for
  Wednesday, bringing a heightened threat of flash flooding,
  before building high pressure brings a drying trend Thursday
  through the weekend.

- There is a high chance that temperatures will become extremely
  hot by the weekend as the ridge continues to build, bring the
  potential for an increase in heat related illness.

&&

.DISCUSSION...A broad ridge is centered over the central United
States this evening, allowing for a southerly flow to develop over
Utah and southwest Wyoming. The airmass over the area has remained
relatively moist, with satellite derived PW values in the 0.8 to
1.0 range across much of the area, highest over southern Utah.
Earlier showers and storms over southern Utah are decreasing in
coverage at this time. However, a series of weak shortwaves moving
north across Utah overnight will allow for some showers to
continue into the morning.

The southerly flow will allow moisture over the area to increase
and spread northward through tomorrow afternoon, with PW values of
an inch or more expected to spread over the vast majority of the
forecast area. Combined with the supplemental instability from the
shortwaves, this will bring another round of showers and
thunderstorms, and any storms that develop will be capable of
producing heavy rain that could lead to flash flooding. The
showers and associated cloud cover area expected to keep high
temperatures near to just below seasonal normals during the day.

Beginning Thursday, the broad ridge is expected to re-orient
itself over the west, with the center moving directly over Utah
for the weekend. This will add a westerly component to the flow
aloft that will draw a drier airmass into the area, decreasing the
threat of convection. As the ridge strengthens, temperatures will
become increasingly hot, peaking on Saturday with 700mb
temperatures expected to be in the lower 20s Celsius across the
entire area. This will result very hot temperatures that will
increase the risk of heat related illness, particularly for valley
locations. Some uncertainty remains with regard to how high the
HeatRisk will get on Friday, with Thursday nights lows potentially
getting low enough to keep the HeatRisk in the orange (moderate)
range for much of northern Utah during the day. For Saturday and
Sunday, confidence is higher than usual in the potential for very
hot maximum temperatures, but there remains a good amount of
spread in the ensembles with regard to low temperatures and
therefore how much overnight relief the area, northern Utah
in particular, will see. Therefore, have decided to hold off on
an Extreme Heat Watch at this time due to uncertainty about the
length of time of the event.

By early next week, the ridge is expected to weaken a bit and
shift south as a Pacific Northwest trough moves over the top of
it. This would provide some relief from the heat, at least for
northern portions of the area, though there remains a good amount
of spread in the guidance with regard to how much the trough will
act to weaken the ridge and therefore how much of a drop in
temperatures there might be. It does seem likely, however, that
the very hot weather will continue for at least southeast Utah.

&&

.AVIATION...KSLC...The SLC terminal will see VFR conditions
through the night with winds expected to prevail out of the south
by 06Z. There is a 20-30 percent chance that showers overnight
will bring a period of gusty and/or erratic winds to the terminal,
most likely between 09Z and 12Z.

REST OF UTAH AND SOUTHWEST WYOMING...The airspace will see
prevailing VFR conditions through the overnight hours. Scattered
showers with a few thunderstorms will continue overnight, with the
best threat shifting from southern Utah late this evening to
northern Utah during the early morning. Any storms that develop
will have the potential to produce periods of gusty and erratic
winds.

&&

.FIRE WEATHER...Moisture will increase over the area through
Wednesday afternoon. This will bring the continued potential of
showers and thunderstorms with a good chance of wetting rainfall.
However, these storms will also be accompanied by light and
periods of gusty and erratic winds.

Building high pressure will bring a sharp drying trend Thursday
through the weekend with extremely hot temperatures developing,
particularly Saturday and Sunday. Minimum relative humidity values
will likely fall into the single digits for many locations during
this time. Winds are expected to remain generally light through
Saturday, with west to southwest winds expected to pick up Sunday
as the ridge weakens with a Pacific Northwest trough grazing the
area. Winds are most likely to remain below critical values, but
there is a low chance of pockets of critical fire weather
conditions early next week.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&

$$

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

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