Lake Powell, Utah Weather Forecast Discussion

542
FXUS65 KGJT 260514
AFDGJT
Area Forecast Discussion
National Weather Service Grand Junction CO
1114 PM MDT Thu Sep 25 2025
.KEY MESSAGES...
- Chances for precipitation increase tomorrow through Monday,
  with Sunday being the most widespread coverage.
- Some storms may be capable of producing strong winds as well
  as heavy rainfall, which could impact the recent burn scars.
- With freezing levels around 11-13 kft this weekend there could
  be snowfall on the mountains with little if any impacts to
  the roadways.
&&
.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 117 PM MDT Thu Sep 25 2025
Dry air has taken over with little clouds to speak of across the
area. The next feature to watch is a closed low pressure over
Southern California. Southwesterly flow out ahead of the low will
advect steep lapse rates and moisture into the forecast area tonight
that may be enough for high based showers and or virga. Very little
rain is expected with these showers. Tomorrow the low pressure moves
over the CA/AZ state line so do not expect much forcing from that
system, but with the moisture advection it should result in
some instability with peak heating. With the minimal forcing
showers are expected to develop over and favor the high terrain
in the afternoon. The western and southern portions of the area
have the highest chances for showers. There is quite a bit of
dry air to overcome once this moisture arrives to so it is
uncertain what the rainfall rates will be, and if the showers
will survive moving over the valleys. The stronger cells may be
able to produce moderate to heavy rainfall, which could impact
the recent burn scars. Temperatures today and tomorrow look to
end up slightly above normal.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 117 PM MDT Thu Sep 25 2025
Models continue in good agreement with the cutoff low over SoCal
Saturday starting to track northeastward becoming an open wave
Sunday as it tracks across eastern Utah and Western Colorado, but
discrepancies are creeping into the deterministic solutions on
timing of the system moving across the region with the European
model lagging the GFS by 18 hours and the Canadian in between. The
ensembles show better agreement more in line with the European
model. This is to be expected with cutoff lows as the models
struggle to predict their ejection out of SoCal, especially in the
transition season. There is also good agreement with a deep low
descending out of the gulf of Alaska to shift the synoptic pattern a
half wavelength east for the coming week with troughing over the
Western States and ridging over the Plains States extending up into
the Great Lakes by mid week. As this forecast is dependent on a
cutoff low ejection across the region, there is not a lot of
confidence in the model solutions, especially on timing, but the
most likely outcome is subtropical moisture wrapping around the low
to the southwest pushing clouds and showers with embedded scattered
thunderstorms up into the southern and central mountains Saturday.
Sunday looks to be the wettest day with widespread showers and
scattered thunderstorms across the higher terrain with some storms
moving off the terrain into the valleys. Of course, this will depend
on the timing of the open wave tracking overhead. If it is delayed,
then convection will stay mostly south of I-70 through the day with
widely scattered showers and thunderstorms moving north more Sunday
evening and overnight. We shall see; stay tuned. With the long wave
trough over the Western States through the coming week allowing
shortwaves to move through daily, the forecast is for unsettled
weather daily through mid week amounting to isolated to scattered
showers and thunderstorms mostly over the higher terrain with the
shortwaves passing to the north mostly along and north of I-70.
&&
.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1113 PM MDT Thu Sep 25 2025
Moisture wrapping into the 4 Corners region will lead to some
shower activity there overnight and high cloudiness elsewhere.
This moisture lifts farther into the region on Friday and will
lead and bring a larger coverage of shower and thunderstorm
activity through the afternoon. However KTEX looks to be the
most likely airfield to be impacted and attm the only terminal
to carry a PROB30. Overall winds be light except near showers
and storms where gusts could excess 30 mph.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
SHORT TERM...KJS
LONG TERM...DB
AVIATION...TGJT

NWS GJT Office Area Forecast Discussion