942
FXUS65 KGJT 140540
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1140 PM MDT Sun Sep 13 2026

.KEY MESSAGES...

- There is a chance for strong storms over the next few days,
  capable of producing hail, gusty winds, and heavy rainfall.

- Moderate to heavy rainfall could lead to localized flash
  flooding, rockfalls, and mudslides at times this week.

- Temperatures return to near-normal through the week.

&&

.DISCUSSION...
Issued at 1015 PM MDT Sun Sep 13 2026

FLASH FLOODING POSSIBLE MONDAY:

We`re still seeing isolated convection ongoing across the
region early tonight, and CAM`s are in unison indicating
stratiform-type rainfall developing across portions of the CWA
throughout the remainder of the night. Some of this, as seen in
northeastern Utah and creeping into northwestern Colorado, is
being driven by a cold front. Without daytime heating to further
support the active weather, nighttime impacts should be
minimal, but don`t be surprised if we get a stronger cell or two
over the next few hours. Otherwise, the front looks to cool the
area back to near-normal for the next week.

These overnight storms and cooling associated with the passing
cold front may marginally stabilize the atmosphere. To add to
the stabilization, CAM`s are in good agreement about broken
cloud cover within the southeast quadrant of the CWA Monday
morning. However, some guidance`s cloud cover looks marginally
less dense than it has over the past couple days, and the
northwestern half of the CWA is still on track to see relatively
clear skies in the morning. Plus, we are still slated to sit
underneath a favorable region of the upper-level jet streak. So,
while it may be struggle for some areas to garner significant
instability, there is evidence that there will be a handful of
powerful storms capable of localized heavy rainfall, gusty
winds, and some hail. Most hail will be sub-severe, but we`ve
seen a couple supercells capable of large hail over the past 48
hours, so don`t rule out a severe storm or two.

CAM`s are hinting at the best area for strong storm development
to come on the edge of the densest cloud cover where
destabilization will be easier to achieve and moisture will be
potent. This corridor looks to span from southeastern Utah
towards the Grand Mesa, though the exact location will vary
depending on said morning cloud cover. As the event unfolds
Monday and active weather transits eastwards, the expectation is
for storms to stratiform out given the likely more stable
environment over the San Juans and central Colorado mountains.
Even so, embedded stronger cells will be possible. For those
stronger cells, localized heavy rainfall will raise concerns of
flash flooding, especially over vulnerable areas and burn scars.
In the scenario that storms struggle to organize or cloud cover
spans a greater area than anticipated, stratiform rainfall will
be favored region-wide. As mentioned before, embedded stronger
cells could and likely will still develop, which means a flash
flooding threat will exist regardless of storm mode. As always,
be weather aware Monday (and beyond) and stay up-to-date with
additional information as it becomes available.

ACTIVE WEATHER EXPECTED THROUGH THE END OF THE WEEK:

The CWA remains in southwest flow aloft as the first low tracks
over the Midwest and another low drops into the PacNW. This
will ultimately keep moisture in place through at least the mid-
week, so expect the chances for showers and storms to continue.
On Wednesday the models are hinting that a subtle shortwave
moves in from the southwest. If this were to happen it would
certainly be a focus for showers and storms especially given the
persistent moisture pool. On Friday, moisture begins to
diminish as the low moves eastwards through the western US.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1140 PM MDT Sun Sep 13 2026

Showers and embedded thunderstorms will continue to lift across
much of western Colorado through sunrise with minimal impacts
expected. This activity will linger through tomorrow evening
with the best focus south of highway 40 with the highest
probability along and south of highway 50 tomorrow. IlS break
points may be met in these areas with a low probability MVFR if
the right shower moves over an airfield. However VFR remains the
prevailing condition in this forecast for the next 24 hours.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

DISCUSSION...BW
AVIATION...TGJT