531
FXUS65 KGJT 301121
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
521 AM MDT Wed Sep 30 2026

.KEY MESSAGES...

- Scattered to widespread precipitation showers and storms
  continue through Wednesday evening.

- Flooding concerns are increased for rain-soaked terrain,
  especially within and adjacent to the southern San Juans.

- A Flood Watch is in effect for southeast Utah and southwest
  Colorado through 6AM Wednesday. The Flood Watch has been
  extended for the San Juan Mountains and part of the San Juan
  River Basin through 6AM Thursday.

&&

.DISCUSSION...
Issued at 1030 PM MDT Tue Sep 29 2026

ACTIVE WEATHER WITH FLOODING POTENTIAL THROUGH LATE WEDNESDAY:

A vertically stacked closed low is currently located over
central Arizona, resulting in southwest upper level flow over
southwest Colorado with easterly wraparound flow at the surface
as seen earlier with storm motion. Radar looks quite benign at
the moment as we remain in the deformation area but that will
change overnight as the low moves eastward, allowing
precipitation to wraparound the low across the San Juans. Most
precipitation chances will remain south of I-70 through the day
on Wednesday. While precipitation has been mostly stratiform
under this stratus cloud shield today, we are seeing some
convection firing closer to the low and on the edges of the
moisture gradient. If we get enough breaks in the cloud cover,
more robust convection could develop resulting in heavier
rainfall rates. However, if the cloud cover remains prevalent,
this could limit the convective potential resulting in a more
steady light to moderate precipitation with pockets of locally
heavy rainfall. Regardless, Southwest Colorado has already
received well over an inch of rainfall in many locations over
the last 48 hours so they remain saturated even with rainfall
over the past week or two. As a result, the Flood Watch will
continue for the San Juan Mountains and San Juan River Basin
through 6 am Thursday morning. Periods of prolonged or heavy
rainfall increase concerns for flooding and flash flooding,
especially in these saturated areas. Rivers may rise out of
their banks even after rainfall has ended over an area, so be
sure to monitor the forecast and have a way to receive weather
alerts. Most shower and storm activity will decrease in coverage
Wednesday evening as the low moves east and drier air moves in
behind it from the northwest.

DRY AND WARMER THURSDAY THROUGH THE WEEKEND:

High pressure moves into our region on Thursday as the low
pressure system moves to our east. This pattern shift will
bring dry and warmer weather through at least the weekend. High
temperatures are forecast to climb from near normal on Thursday
to 5 to 10 degrees above normal this weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 518 AM MDT Wed Sep 30 2026

Light precipitation continues to spread across southern and
central portions of the area. Lower clouds are moving in with
the rainfall with MVFR currently impacting KTEX and KDRO. This
will continue for much of the forecast with these conditions
lifting up toward KGUC to KMTJ through the morning. Farther
north from KASE to KEGE VFR/ILS appear more likely until showers
move by sunrise. Slow improvement comes after sunset on
Wednesday though the wet conditions may lead to additional
stratus and fog formation by sunrise on Thursday.

&&

.HYDROLOGY...
Issued at 1030 PM MDT Tue Sep 29 2026

Tropical moisture continues to fuel a shield of precipitation
drifting north across New Mexico. As the closed low lifts
towards the Four Corners tonight, another round of showers and
thunderstorms redevelops. Embedded thunderstorms and additional
rain expected through Wednesday evening maintain our concerns
for flash flooding and rises on local rivers until precipitation
finally exits the Western Slope Wednesday night.

RFC guidance maintains a second peak at several sites, peaking
around midnight due to Wednesday`s precipitation. Fortunately,
water levels are not anticipated to exceed previous high water
marks. That being said, localized flooding and flash flooding
continue to pose a threat to our southwestern Colorado
communities until remnant moisture from Hurricane Polo and the
closed low completely exit our region.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Flood Watch until 6 AM MDT early this morning for COZ017-
     020>022.
     Flood Watch through late tonight for COZ018-019-023.
UT...Flood Watch until 6 AM MDT early this morning for UTZ022-028-
     029.

&&

$$

DISCUSSION...MDA/TGJT
AVIATION...TGJT
HYDROLOGY...ERW