943
FXUS65 KGJT 271855
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1255 PM MDT Sun Sep 27 2026

.KEY MESSAGES...

- Warmer and drier conditions continue today.

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

- Chances of prolonged rainfall increases flooding concerns in
  southeast Utah and southwest Colorado, especially in areas
  that have recently received rain. A Flood Watch is in effect
  from 6am Monday through 6am Wednesday for southern portions of
  the forecast area. &&

.DISCUSSION...
Issued at 1253 PM MDT Sun Sep 27 2026

NORMAL TEMPERATURES WITH A FEW ISOLATED SHOWERS TODAY:

High temperatures will be near normal today despite warm
southwesterly flow thanks to substantial afternoon cloud cover.
This cloud cover is associated with moisture from Tropical Storm
Odalys and Hurricane Polo, which is just beginning to advect into
our region. This increased moisture brings chances of a few isolated
showers and thunderstorms late this afternoon, mostly over the
higher terrain. Chances of precipitation increases for the central
and northern Divide this evening. Overnight chances will increase in
the Four Corners region, gradually spreading northward across the
CWA through the morning hours.

WIDESPREAD PRECIPITATION MONDAY AND TUESDAY:

Moisture advection from the tropical storm activity in the Pacific
will bring anomalous moisture to our region through at least
midweek, with precipitable water anomalies peaking around 250% of
normal on Monday. This moisture will be accompanied by synoptic
forcing as a closed upper level low digs southward through
California on Monday, and then across the Southwest on Tuesday and
Wednesday. On Monday energy downstream of the trough axis will move
across our area along with a jet streak aloft, providing lift to
support widespread precipitation. This widespread precipitation will
continue through most of Tuesday  until the trough axis moves across
the Divide. The potential for prolonged periods of rainfall,
including in areas that have recently received substantial rain,
raises flooding concerns particularly in southeast Utah and
southwest Colorado where a Flood Watch is in effect from 6AM Monday
through 6AM Wednesday.
On Wednesday the low and elevated mositure will move east of the
Rocky Mountains, bringing drier weather the the area. However,
lingering moisture may be able to support some additional convection
over the high terrain on Wednesday.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1146 AM MDT Sun Sep 27 2026

Clouds are streaming in from the southwest as moisture
increases. An occasional gust of 15 to 20 kts is also possible
this afternoon but won`t be widespread. Clouds will begin
lowering during the evening and overnight with showers
developing over southern Colorado. VFR conditions will remain in
place through the day. Showers will become more widespread
tomorrow morning with MVFR conditions becoming more likely.

&&

.HYDROLOGY...
Issued at 1253 PM MDT Sun Sep 27 2026

Strong southwesterly winds ahead of a closed low centered over
California will pull tropical moisture from Tropical Storm Odalys
and Hurricane Polo towards eastern Utah and western Colorado, with
atmospheric moisture peaking in our area on Monday. The northerly
extent of the expected excessive rainfall poses a threat to our
southern San Juan river basins. Current forecasts suggest 1 to 4
inches of rain Monday morning through early Wednesday. At face
value, rivers and tributaries will see a rise due to the forecast
rainfall. However, localized heavier amounts could result in
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 recently observed.
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. Confidence has increased enough for a Flood Watch to be
issued for southern portions of the forecast area valid from 6am
Monday through 6am Wednesday. Continue to monitor the latest
forecasts especially for those who reside and/or plan to recreate in
the Watch areas.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Flood Watch from Monday morning through late Tuesday night for
     COZ017>023.
UT...Flood Watch from Monday morning through late Tuesday night for
     UTZ022-028-029.

&&

$$

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