048
FXUS65 KGJT 120555
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1155 PM MDT Fri Sep 11 2026

.KEY MESSAGES...

- Warm and windy conditions prevail through Saturday with an
  increase in afternoon shower and thunderstorm activity
  Sunday.

- Daytime highs remain 5 to 10 degrees above normal through
  Sunday before a shift to cooler temperatures next week.

- Cool, wet and unsettled weather is expected through much of
  next week as moisture continues to feed into the area.

&&

.DISCUSSION...
Issued at 1038 PM MDT Fri Sep 11 2026

WINDY AND WARM WITH ISOLATED STORMS THIS WEEKEND:

Modest moisture has settled in over the region, promoting
sparse, weak showers and thunderstorms over Colorado`s west
slope. This comes amidst warm zonal upper-level flow set up
across the majority of the western CONUS. Decent mixing
underneath the strong flow paired with a modest pressure
gradient has supported and will continue to support gusty
afternoon winds. In addition, with low- levels on the drier
side, showers will also contribute to windy conditions should
gusty outflow winds develop. Over the next 48 hours as moisture
continues to creep upwards, look for storms to increase in
coverage, particularly over the high terrain. Impacts should
remain relatively isolated Saturday, but we could see storm
coverage become more scattered on Sunday as the next strong push
of moisture begins to move in.

COOLER AND WETTER PATTERN MONDAY AND BEYOND:

As we begin the work week, a powerful trough will push into the
PacNW, pushing flow across the southwestern CONUS to
southwesterly. This pulls subtropical moisture further inland
towards us. As such, by Monday, look for the strong plume of
moisture to be centered over the CWA. PWAT anomalies are
anticipated to be near or exceed 200% of normal on Monday,
pushing or breaking records for this time of year. The ECMWF Ens
is more bullish on the moisture, but even the GFS Ens is
indicating PWAT`s should be a sure-thing to exceed the 75th
percentile. Either way, this pool of moisture surging through
the region will be enough to prompt our next round of widespread
showers and thunderstorms.

With mid-level moisture already in place and only strengthening
over the coming days, cloud cover should generally be ample,
including in the morning. This will dampen storm potential,
potentially enough to push storm mode more in a stratiform
direction. However, dynamic forcing looks to be on the more
favorable side with this system, perhaps the most impressive
that we`ve seen in weeks. For one, by Monday we are expected to
fall underneath the right entrance region of a powerful jet. In
addition to jet placement, overnight Sunday into Monday morning
look for cold front pass through. Both factors will go towards
supporting discrete storm development. With this, at the very
least we should expect to see embedded stronger storms in
stratiform rainfall, if not widespread discrete storm
development. Wherever discrete storms do develop (whether they
be isolated or widespread in nature), localized heavy rainfall
will also be likely, especially in areas where the low-level
atmosphere is able to significantly moisten up over the weekend.
As far as QPF goes, the NBM is heavily favoring southwestern-
facing slopes of the San Juans, Grand Mesa, and West Elk
Mountains. In these locations, the NBM probability of exceeding
a half inch of rain Monday is over 75%, though this could be an
overestimate if rain stratiforms out. Northeastern-facing slopes
are expected to see lower rain totals, though with a quarter
inch of precipitation still likely according to the NBM (>50%
chance), hydrologic concerns would still be on the table. That
being said, with a few days left to go until the event, it is
key to understand that there are too many uncertain factors left
to be figured out before we can speculate on the likeliest
scenario. Stay tuned for future updates, especially once we
receive hi-res model guidance.

Though the combination of highly anomalous moisture and
reasonably strong forcing is most potent on Monday, active
weather looks to stay relatively strong throughout the work
week. The pool of moisture looks to lock in over the West Slope,
and the jet continues to stretch across the Intermountain West.
Without a clear frontal boundary or shortwave accompanying the
mid-to-late week pattern, impacts could become even more
conditional on morning cloud cover, but that is a problem that
we cannot resolve at this point in time. Ensembles are in step
with each other that moisture dissipates on Friday, but even
then there is no indication that we will see PWAT`s fall below
normal, so look for a weakening in storms, but not a complete
dissipation.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1151 PM MDT Fri Sep 11 2026

Overnight winds will generally be light and terrain driven with
isolated showers and storms moving through the region from west
to east. Precipitation chances will continue through the TAF
period, most notably at the mountain terminals Saturday
afternoon. Gusty winds up to 25-30 knots are also possible
Saturday afternoon.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...None.
UT...None.

&&

$$

DISCUSSION...BW
AVIATION...TGJT