421
FXUS65 KGJT 252325
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
525 PM MDT Fri Sep 25 2026

.KEY MESSAGES...

- Periods of moderate to occasionally heavy rain and
  thunderstorms will impact western Colorado and eastern Utah
  today.

- Warmer and drier conditions return for the weekend.

- Another push of moisture will arrive by Monday, bringing
  widespread moderate to heavy precipitation through midweek.

&&

.UPDATE...
Issued at 233 PM MDT Fri Sep 25 2026

A hydrology section has been added to the discussion below ahead
of the next surge of moisture expected to occur by Monday. A
hydrologic outlook will also be active from 6AM Monday until
6AM Wednesday.

&&

.DISCUSSION...
Issued at 1108 AM MDT Fri Sep 25 2026

MORE PRECIPITATION CHANCES TODAY BEFORE A DRIER WEEKEND:

A trough will be kicked out over the Desert Southwest and into the
Four Corners area today. This will introduce scattered shower and
storm chances across western Colorado and portions of eastern Utah.
Recent HiRes guidance depicts the bulk of storm activity to be along
and south of I-70. Periods of moderate to occasionally heavy
rainfall can be expected out of the stronger cells. Locations that
saw the sun this morning may see a quicker transition into
convective mode than those who started the morning with light
stratiform rainfall. All that being said, some isolated stronger
storms are possible as instability remains fairly moderate. With
that, some locations could see small hail and gusty outflow winds.
This activity will quiet down by the overnight period as flat
ridging moves back into the area. This will indicate a drier
weekend, with daytime highs warming by a few degrees.

NEXT WEEK`S MOISTURE:

By Monday, the forecast becomes a bit more challenging. Another
trough arrives to the PacNW coast, albeit stronger than the last
one. This will work to push the ridging east of the Rockies and
backing the upper flow to the southwest over the Great Basin.
Moisture from a pair of tropical systems, including Polo, will be
drawn into the southwest flow aloft ahead of the trough. PWATs will
again return to upwards of 200% of normal, particularly in southwest
Colorado and southeast Utah. This indicates the start of another wet
period through at least midweek. It is important to note that some
discrepancies exist between models, with the GFS consistently
showing a drier solution, whereas the Euro continues to be more
bullish with the moisture. Additionally, both the GFS and Euro have
different placements when it comes to the location of the low
pressure system. Cluster solutions also continue to be inconsistent
on how to handle the moisture in addition to the upstream trough, so
confidence remains low on a final solution. Bottom line is that the
start of next week looks to be wetter, but whether this will be a
significant/anomalous event for the Four Corners area is yet to be
determined. Stay tuned for how this forecast begins to develop.

In addition to this moisture, daytime highs will also drop by a few
degrees come Monday, which also means overnight lows will do the
same. If you`re catching what I`m putting down, that would indicate
snowflakes returning to the forecast for some our highest peaks and
passes. At this point, these chances look most confined to the San
Juans and central Divide mountains.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 525 PM MDT Fri Sep 25 2026

Shower and thunderstorm activity will decrease through the
remainder of the evening though a few TAF sites may still be
briefly impacted by gusty outflow winds. Will be monitoring the
possibility of stratus and/or fog developing with clearing
skies and lingering low level moisture. Confidence not
high...otherwise VFR should prevail over the next 24 hours.

&&

.HYDROLOGY...
Issued at 233 PM MDT Fri Sep 25 2026

In the wake of today`s precipitation, our attention will turn to the
Eastern Pacific. Tropical moisture is anticipated to spread across
the Desert Southwest early next week, drawing moisture from a pair of
Hurricanes; Odalys and Polo. The forecast becomes
increasingly complex due to a closed low currently forecast to
drive across the Southwest CONUS as Hurricane Polo approaches
the Baja California Peninsula. Strong southerly winds ahead of
the low are expected to pull tropical moisture towards eastern
Utah and western Colorado as early as Monday morning. The
challenge and uncertainty in our precipitation forecast increase
as the week progresses and the low traverses our southern
States. Excessive rainfall is most probable over AZ and NM,
attm, but the northerly extent poses a threat to our southern
San Juan river basins. Current forecasts suggests 1 to 3 inches
of rain over Monday morning through Wednesday. At face value,
rivers and tributaries will see a bump up due to said moisture.
However, localized heavier amounts could result in minor
flooding across the southern San Juan foothills and communities
further downstream.

Rivers have responded rapidly to recent rainfall due to saturated
soils and increased runoff potential. Thus, prolonged periods of
additional rainfall over these regions would trigger a similar
response. The current precipitation forecast suggests larger peaks in
several creeks and rivers than what has been observed over the
previous 7 days. However, high end probabilistic rainfall amounts
(i.e. above 90th percentile) may lead to rivers exceeding action
stage to minor flooding. Most probable basins to see significant
rises include; the Rio Blanco, San Juan, Piedra, Los Pinos/Vallecito
Creek, and the Animas River Basins.

Convective storms and periods of heavy rainfall fed from said
tropical moisture could result in localized flooding impacts across
the CWA, however, confidence decreases rapidly north of the San
Juans. Please continue to monitor the forecast as these systems
evolve. Especially for those who reside and/or plan to recreate in
the southwest quadrant of the forecast area.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

UPDATE...BS
DISCUSSION...BS
AVIATION...TGJT
HYDROLOGY...ERW