St. George, Utah 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

708
FXUS65 KSLC 121037
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
437 AM MDT Tue Aug 12 2025

.SYNOPSIS...High pressure overhead will lead to hot and dry
conditions Tuesday and Wednesday. This ridge slides further east
towards the end of the week with moisture increasing resulting in
scattered thunderstorms Thursday and Friday with near normal
temperatures. Drier air starts to move in late in the weekend into
early next week.

&&

.SHORT TERM (Through 12Z/6AM Thursday)...High pressure centered
over Utah on Tuesday will keep conditions hot and dry with
relatively light winds. High temperatures on Tuesday will be in
the low to mid 90s across most valley locations with highs near
108F across lower Washington county.

This ridge shifts further east and becomes oriented over the Four
Corners region by Wednesday with temperatures peaking in the upper
90s to low 100s across most valleys and staying near 108F for
lower Washington County. This will be some of the hottest
temperatures of the summer with overnight lows remaining warm. The
position of high pressure over the Four Corners is a more
favorable orientation for moisture to advect into the CWA.
Conditions will remain relatively dry on Wednesday as only some
mid and upper level moisture stream in, but some high-based
terrain driven convection will be possible across the southern
Utah mountains with dry lightning possible.

.LONG TERM (After 12Z/6AM Thursday)...The beginning of the long
term period will feature a trough situated along the Sierra/western
Great Basin, with an upper ridge centered across the
central/southern High Plains. This will induce a general
southwesterly flow aloft across the forecast area through the latter
portion of the week and into the upcoming weekend. Unlike recent
southwesterly flow events which spread very dry air across the
forecast area, this round will feature a modest influx of
predominantly mid level moisture, which will support an increasing
chance for showers and thunderstorms Thursday through Friday. The
majority of ensemble members from both the GEFS and EPS suggest this
moisture lingers into the weekend, maintaining a chance for showers
and thunderstorms through Saturday. With this increase in moisture,
temperatures will trend cooler through the latter portion of the
week, returning to near climo by Friday.

Given the very dry airmass currently in place across the region
region as a whole, and the lack of a better defined low level surge
of higher dew points (model forecasts keep dew points in the 30s
through Thursday with PW values generally around 0.5"), the most
likely scenario Thursday afternoon/evening is a round of high based,
predominantly dry convection accompanied by dry lightning and strong
microburst winds, but little in the way of measurable rainfall. By
Friday, with the column moistening from the top down, the chance for
wetting rainfall (0.10" or more) and perhaps isolated heavy rainfall
will increase with afternoon/evening convection.

The consensus through the weekend and into early next week is for
the airmass to trend drier as the region comes under the influence
of large scale subsidence associated with an amplifying ridge across
the central and southern Rockies. There is some spread in model
guidance with respect to how quickly this drying trend manifests
itself, but the overall downward trend in NBM PoPs from scattered
coverage of terrain driven convection Saturday, to more isolated
coverage Sunday into Monday seems to handle this well. This
amplifying ridge looks to become the dominant weather feature across
the region throughout next week.

&&

.AVIATION...KSLC...VFR conditions will prevail through the TAF
period with a typical diurnal wind pattern. Southeasterly drainage
winds will transition to northwesterly around 18Z with the passage
of the lake breeze.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will prevail
across the region today through tonight at all TAF sites. Winds will
remain light, and will be driven primarily by local terrain flows.

&&

.FIRE WEATHER...With high pressure overhead today expect hot and dry conditions
with relatively light winds and low relative humidity. As this
high becomes more oriented over the four corners region by midweek
moisture will increase with temperatures gradually cooling toward
the end of the week. Low levels will remain dry on Wednesday, but
some high based terrain driven convection across the southern
Utah mountains will be possible with the threat of dry lightning
increasing. Conditions will become wetter by Thursday and Friday
with thunderstorm chances spreading across most of the area and
winds, outside of convection, remaining relatively weak.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...Fire Weather Watch from Wednesday afternoon through Wednesday
     evening for WYZ277.

&&

$$

SHORT TERM...
LONG TERM...
AVIATION...
FIRE WEATHER...

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