925
FXUS65 KGJT 060408
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1008 PM MDT Sat Sep 5 2026

.KEY MESSAGES...

- Precipitation chances increase through Monday. Stronger storms
  may be capable of producing flash flooding.

- Daily showers generally over the high terrain expected Tuesday
  through the end of the week.

&&

.DISCUSSION...
Issued at 1006 PM MDT Sat Sep 5 2026

Southwesterly flow ahead of a deep trough along the west coast
is set up overhead. Amidst this flow, a pool of substantial
moisture is nudging into southern Utah per water vapor imagery.
According to ensembles, we should expect this pool to continue
seeping into the Intermountain West over the coming 48 hours,
bringing impacts to our CWA. Per the 00Z GJT sounding, low-
levels are still very dry, and model guidance suggests that even
as we see the plume of moisture begin drifting from the west
Sunday, it will take some time for near- surface conditions to
saturate enough to support significant rainfall. With this, look
for Sunday`s storm coverage to be generally isolated for most
of the region aside from northeastern Utah where the stream of
moisture will be the strongest.

Overnight Sunday into Monday morning, the moisture plume
centers itself over the CWA. With stabilization from nighttime
cooling and without any significant upper-level dynamics or
forcing mechanisms, look for precipitation to be steady and
relatively light throughout the night. Where things get more
interesting is after sunrise on Monday. Though the bulk of the
moisture will have come and gone, wetter low-levels will remain,
supporting more storm development. The caveat to these storms
is the denser cloud cover that is anticipated to be in place
during the morning hours, dampening destabilization. What this
means for us is that storm mode is trending in a more stratiform
direction instead of discrete cells capable of heavier
localized rainfall. Some early CAM guidance suggests that a few
pockets of 300+ J/kg of CAPE may manifest in spite of the
morning cloud cover, but this likely would result in little more
than a few stronger cells embedded within stratiform rainfall.
Though this supports a broader areal coverage of wetting rains
without amplifying the hydrologic threat, we have seen in
recent days that even stratiform rains are capable of producing
flash flooding, partially due to the more saturated nature of
soils region-wide. So don`t go discounting the flash flood
threat come Monday even should stratiform storms dominate. This
is especially true for vulnerable areas and recent burn scars.

Beyond Monday, the trough to our west breaks down and transits
eastwards, producing more zonal flow across much of the CONUS.
This elongates the Southern Plains high, pushing the high
westwards towards us and re-establishing in the southwestern
CONUS. Exactly how far west the high will get shoved is a point
of uncertainty, one which potentially holds significant
ramifications on mid-to-late-week storm potential. Moisture
from the Pacific is expected to get drawn around the high into
the southwestern US. Regardless of the high`s position, we are
unlikely to be in a favorable position to receive the brunt of
this moisture, but the exact trajectory of the pool will still
have notable impacts on the resulting precipitation over the
West Slope. At the very least, daily showers along the high
terrain are expected throughout the week. As it stands,
uncertainty is too high to speculate on the details, so stay
tuned over the coming days for additional information.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 521 PM MDT Sat Sep 5 2026

A few stray showers or thunderstorms are possible through this
evening, though impacts are not expected for any terminals.
Otherwise, few to scattered clouds persist throughout the night
alongside light, terrain-driven winds. Moisture arrives from the
west tomorrow. Some showers and thunderstorms may pass over VEL,
with a lower chance of storms at CNY and TEX. For drier parts of
the region, some gusts up to 20 kts may be observed. VFR
conditions prevail throughout the TAF period nonetheless.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

DISCUSSION...BW
AVIATION...TGJT