568
FXUS65 KGJT 291923
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
123 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 /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1140 AM MDT TUE SEP 29 2026
ABUNDANT MOISTURE WILL LEAD TO CONTINUED CLOUD COVER AND
SCATTERED SHOWERS OVER THE REGION THIS AFTERNOON. SHOWERS WILL
BECOME WIDESPREAD THIS EVENING SOUTH OF I-70 WITH LESSER
COVERAGE OVER NORTHERN SITES. TERRAIN OBSCURATION WILL ALSO BE
WIDESPREAD LEADING TO AREAS OF ILS TO MVFR VISIBILITY IN
ADJACENT VALLEYS AND ASSOCIATED TAF SITES. LOWER CLOUDS
LINGERING BEHIND THE MOISTURE COULD ALSO LEAD TO MVFR/IFR
CONDITIONS AS STRATUS AND/OR FOG DEVELOPS.
HYDROLOGY
ISSUED AT 153 PM MDT MON SEP 28 2026
THE BULK OF TROPICAL MOISTURE WILL BE STREAMING ACROSS EASTERN
UTAH AND WESTERN COLORADO TODAY. INTEGRATED WATER VAPOR
TRANSPORT (IVT) MAXIMIZES THIS EVENING ACROSS THE SAN JUANS, SO
ANTICIPATE PRECIPITATION AMOUNTS TO WANE AS OUR MOISTURE FETCH
DECLINES, TOO. RIVER RESPONSES WILL BE HIGHLY DEPENDENT ON
PRECIPITATION TOTALS, AND PEAK FLOWS WILL LAG BEHIND PERIODS OF
MODERATE RAINFALL. FORECAST GUIDANCE SHOWS PEAK ARRIVAL TIMES
BETWEEN MIDNIGHT TONIGHT TO TUESDAY MORNING, DEPENDING ON RIVER
SEGMENTS AND PROXIMITY TO THE WATERSHED'S HEADWATERS.
THE NAVAJO RIVER, RIO BLANCO AND SAN JUAN RIVER ARE FORECAST TO
INCH TOWARDS BANKFULL CONDITIONS AND NEAR ACTION STAGE BY EARLY
TUESDAY MORNING, WITH 2 TO 2.5" OF PRECIPITATION EXPECTED IN
THEIR UPPER BASINS. HOWEVER, IF LOCALLY HIGHER AMOUNTS ARE
OBSERVED (I.E. EXCEEDING THE 90TH PERCENTILE FORECASTS OF 4.5 TO
5.5 INCHES) THEN MINOR FLOODING IS POSSIBLE. ELSEWHERE, RIVERS
AND CREEKS WILL ALSO SEE A NOTABLE RISE, BUT PROBABILITIES OF
EXCEEDING FLOOD STAGE ARE LOWER. NONETHELESS, A SIGNIFICANT RISE
IN SEVERAL STREAMS, RIVERS AND CREEKS IS EXPECTED IN RESPONSE
TO TODAY'S TROPICAL SURGE, AND MINOR FLOOD POSES A THREAT,
NAMELY ACROSS OUR SOUTHERN COUNTIES.
THE NORTHERN EXTENT OF MOISTURE MAINTAINS SOME AMBIGUITY AS THE
SYSTEMS MERGE OVER THE NEXT 48 HOURS. HOWEVER, AFTER A BRIEF
LULL ON TUESDAY, WRAP AROUND MOISTURE ON THE NORTHERN PERIPHERY
OF THE LOW COULD SUPPORT ANOTHER WAVE OF PRECIPITATION ACROSS
THE SOUTHERN HALF OF THE CWA ON WEDNESDAY. AS A RESULT, RIVER
FORECASTS REVEAL A SECONDARY PEAK WEDNESDAY EVENING, ALBEIT,
LESS THAN ITS PREDECESSOR.
A FLOOD WATCH REMAINS IN EFFECT ACROSS SOUTHEAST UTAH AND
SOUTHWEST COLORADO, WHERE THE HIGHER PRECIPITATION TOTALS ARE
FAVORED. HOWEVER, KEEP AN EYE ON EVOLVING CONDITIONS AND
CONDITIONS UPSTREAM. FLOODING CONTINUES TO BE A CONCERN,
ESPECIALLY WITH RIVERS RISING OVERNIGHT.
GJT WATCHES/WARNINGS/ADVISORIES
CO...FLOOD WATCH THROUGH LATE TONIGHT FOR COZ017-020>022.
UT...FLOOD WATCH THROUGH LATE TONIGHT FOR UTZ022-028-029.
DISCUSSION...GF/TGJT
AVIATION...TGJT
HYDROLOGY...ERW
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