876
FXUS65 KGJT 292356
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
556 PM MDT Tue Sep 29 2026

.KEY MESSAGES...

- Scattered to widespread precipitation showers and storms
  continue.

- 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 1231 PM MDT Tue Sep 29 2026

ACTIVE WEATHER THROUGH LATE WEDNESDAY EVENING:

The ongoing active weather will continue through late Wednesday
evening as a low pressure system slowly moves across the
Southwest and east of the Rocky Mountains by Thursday morning.
Satellite imagery shows the low is currently centered over
northwestern Arizona, which is supporting a transition from
southwesterly to southeasterly flow over our area by this
evening. Upper level support is limited today while the bulk of
forcing and moisture is to our south, so isolated to scattered
showers and thunderstorms are expected through this evening,
primarily south of I-70. Late this evening moisture and forcing
will increase as the low moves eastward, which will further raise
precipitation chances south of I-70. Precipitation chances will
gradually transition to favor Colorado`s higher terrain through
the day Wednesday. Wednesday`s activity may be more convective,
which increases the possibility for periods of heavy rainfall.
As such, the Flood Watch has been extended for the San Juans and
parts of the San Juan River Basin through 6AM Thursday morning.
The Flood Watch remains in effect through 6AM Wednesday morning
for the remaining areas of southwest Colorado and eastern Utah.
Periods of prolonged or heavy rainfall increase concerns for
flooding and flash flooding, respectively, especially in areas
that have recently received substantial rain. 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.

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 /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 539 PM MDT Tue Sep 29 2026

Broken and overcast cloud cover along with scattered showers
remain over the region. Showers will become more widespread
south of I-70 overnight and continue through the rest of the TAF
period. TAF sites north of I-70 should remain mostly dry but
broken/overcast. There may be some ILS/MVFR conditions within
showers. Location specifics remain uncertain but centered over
southwestern Colorado.

&&

.HYDROLOGY...
Issued at 208 PM MDT Tue Sep 29 2026

Tropical moisture continues to fuel a shield of precipitation
drifting north across New Mexico. While areas north of the Four
Corners have seen a downward tick in shower coverage, HiRes
guidance maintains isolated to scattered showers redeveloping
across the Southwest San Juans this afternoon. As a result,
expect periods of heavy rainfall due to additional showers with
embedded thunderstorms possible. Localized heavy rainfall over
already saturated soils will pose a threat to our steep and
flashy terrain as well as recent burn scars. Storm activity is
primarily favored across the southern tier of the forecast area.

The convective potential wanes after sunset; however, 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 through late tonight for COZ017-020>022.
     Flood Watch through late Wednesday night for COZ018-019-023.
UT...Flood Watch through late tonight for UTZ022-028-029.

&&

$$

DISCUSSION...GF/TGJT
AVIATION...TGJT
HYDROLOGY...ERW