Hydrologic Outlook
Hydrologic Outlook
COC007-033-051-053-067-083-091-111-113-UTC019-037-301200-
Hydrologic Outlook
National Weather Service Grand Junction CO
221 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 increasing 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.
$$
ERW
