466
FXUS65 KGJT 062353
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
553 PM MDT Sun Sep 6 2026

.KEY MESSAGES...

- Expect showers and thunderstorms this evening into Monday.
  Stronger storms may be capable of producing flash flooding.

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

&&

.DISCUSSION...
Issued at 200 PM MDT Sun Sep 6 2026

The current  weather pattern is dominated by low pressure over the
Pacific Northwest and high pressure over the Texas Panhandle
keeping eastern Utah and Western Colorado under a southwesterly
flow. A plume of moisture is being drawn up over the region in this
flow aloft off the Pacific and Hurricane Marie. Though pwats look
impressive at an inch to an inch and a half with this plume, the 18Z
sounding shows warm air advection aloft and cool air advection in
the lower levels. This, along with the right exit region of a weak
jetstreak moving in overhead associated with a shortwave passing to
the north are stifling convection so far today. Hence, the fair
weather cumulus with no real vertical extent. A shift of only about
two degrees in the profile which should occur with surface heating
by late this afternoon, will change the dynamics to a more
convective pattern. Not looking at large CAPE`s and strong
thunderstorms, but more of a thin cape promoting efficient rain. The
weak jetstreak passes through the evening and overnight bringing the
right entrance region into play to support nocturnal convection, but
with heating shut down, the cooler lower levels will limit this
activity. By Monday, the drier air in the trough to the west moves
into the region to end most shower activity. Beyond Monday, high
pressure builds across the southern states and a longwave trough
develops along the Canadian Border to put eastern Utah and Western
Colorado under a dry zonal flow aloft for the rest of the week
limiting the afternoon convective activity.

Currently isolated showers are moving to the northeast across
southeastern Utah and southwestern Colorado with more widespread
showers to the west in Salt Lake`s area. Cloud cover is limiting
heating and lightning has yet to be observed. Look for these showers
to continue to slide east into the region going into the evening and
overnight. Should the clouds limit heating, then expect light
showers across the region through the evening and overnight with low
risks for flash flooding. But it`s treading a fine line, and if
heating or the weak upper-level support be enough to trigger
thunderstorms, then expect heavier rain with increased risk for
flash flooding possible. Stay tuned for forecast updates and have a
way to receive any warning we may issue tonight if you are in an
area prone to flash flooding, particularly near recent fire
scars.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 542 PM MDT Sun Sep 6 2026

Moisture and clouds are increasing from the southwest this
evening. Showers are moving in over eastern Utah and northwest
Colorado impacting KVEL and KHDN. Light showers and possible
thunderstorms are developing south of I-70. Activity will shift
east through the night with clearing by 12z. Gusty southwest
winds of 20-30 knots will impact TAF sites during the evening
and again tomorrow afternoon. VFR conditions will prevail and
ceilings will remain above breakpoints.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

DISCUSSION...DB
AVIATION...RJ/TGJT