304
FXUS65 KGJT 231909
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
109 PM MDT WED SEP 23 2026
KEY MESSAGES
- PERIODS OF MODERATE TO HEAVY RAIN WILL IMPACT SOUTHERN
COLORADO THE NEXT FEW DAYS WITH DRIER CONDITIONS ACROSS THE
NORTH AND FAR WEST.
- WIDESPREAD RAINFALL AMOUNTS IN EXCESS OF AN INCH TO OVER 2
INCHES IN SOME AREAS COULD LEAD TO FLOODING ACROSS THE
SOUTHERN SAN JUANS AND ADJACENT VALLEYS THROUGH THURSDAY. A
FLOOD WATCH IS IN EFFECT FOR THOSE AREAS.
- WARMER AND DRIER CONDITIONS ARRIVE FOR THE WEEKEND WITH
ANOTHER PUSH OF MOISTURE ARRIVING BY EARLY NEXT WEEK.
DISCUSSION
ISSUED AT 108 PM MDT WED SEP 23 2026
A SPLITTING TROUGH TO OUR WEST AND A RIDGE TO THE EAST IS KEEPING
MOIST SOUTHERLY TO SOUTHWESTERLY FLOW ALOFT OVER MUCH OF WESTERN
COLORADO. OVER EASTERN UTAH, A PUSH OF DRIER AIR IS WORKING IN FROM
THE WEST AS THE TROUGH CONTINUES TO SPLIT INTO A NORTHERN STREAM
TROUGH AND SOUTHERN STREAM CLOSED LOW. ALONG THE EDGE OF THE
BOUNDARY BETWEEN THE MUCH MOISTURE AIRMASS AND THE DRIER ONE TO OUR
WEST, A FEW OROGRAPHICALLY DRIVEN SHOWERS AND THUNDERSTORMS HAVE
DEVELOPED AND WILL CONTINUE THROUGH THIS AFTERNOON AND EVENING. THE
MAIN CONCERNS WITH THESE STORMS WILL BE GUSTY OUTFLOW WINDS IN
EXCESS OF 50 MPH AND FREQUENT LIGHTNING, ALONG WITH HEAVY RAIN. THE
BEST CHANCES FOR HEAVY RAIN AND FLASH FLOODING WILL BE WITH STORMS
CLOSEST TO THE MOISTURE BOUNDARY. MEANWHILE, ACROSS SOUTHWEST
COLORADO, A FLOOD WATCH IS IN EFFECT FOR THE SOUTHWEST VALLEYS AND
SOUTHERN SAN JUANS. THIS AREA HAS ALREADY SEEN HALF AN INCH TO AN
INCH OF PRECIPITATION IN THE LAST 24 HOURS, AND STANDS TO SEE
ANOTHER HALF AN INCH TO AN INCH BY TOMORROW EVENING. AS A RESULT,
THERE'S CONCERNS FOR FLASH FLOODING IN STEEPER, SMALL BASINS, AS
WELL AS POTENTIAL FOR RISES IN MAINSTEM RIVERS IN THIS REGION.
THE BEST OF THE MOISTURE PLUME GETS SHUNTED TO THE EAST BY FRIDAY.
HOWEVER ENOUGH ABOVE NORMAL MOISTURE WILL STICK AROUND TO INTERACT
WITH A PASSING SHORTWAVE FRIDAY AFTERNOON TO BRING ONE LAST ROUND OF
SHOWERS, STORMS, AND HEAVY RAIN TO THE SOUTHERN AND CENTRAL
MOUNTAINS. THROUGH THE END OF THE WORK WEEK, TEMPERATURES REMAIN
NEAR TO A FEW DEGREES BELOW NORMAL, AS WE REMAIN MOIST AND CLOUDY.
TRANSIENT RIDGING AND DRIER WESTERLY TO SOUTHWESTERLY FLOW MOVES IN
FOR THE WEEKEND, WITH TEMPERATURES JUMPING TO NEAR OR A FEW DEGREES
ABOVE NORMAL.
A RETURN OF DEEP TROPICAL TO SUBTROPICAL MOISTURE IS EXPECTED EARLY
NEXT AS TROUGHING ONCE AGAIN SLIDES INTO THE WEST COAST AND RIDGING
DOMINATES OVER THE MIDDLE OF THE COUNTRY. SOMETHING TO WATCH WITH
THIS PATTERN SHIFT IS THE INTERACTION BETWEEN THE WEST COAST TROUGH
AND HURRICANE POLO IN THE TROPICAL EASTERN PACIFIC. SHOULD THE
REMNANT MOISTURE FROM THIS HURRICANE GET SWEPT UP IN THE
SOUTHWESTERLY FLOW ALOFT, THE FOUR CORNERS REGION COULD SEE
POTENTIALLY INTENSE RAINFALL. THE SOUTHWEST COLORADO VALLEYS AND THE
SOUTHERN SAN JUANS COULD BE PARTICULARLY SENSITIVE, THANKS TO THIS
WEEK'S MULTIPLE ROUNDS OF HEAVY PRECIPITATION. THERE'S A LOT THAT
CAN CHANGE ABOUT THE FORECAST BETWEEN NOW AND EARLY NEXT WEEK, BUT
THIS IS A SITUATION TO KEEP AN EYE ON OVER THE COMING DAYS.
REGARDLESS OF WHETHER THE MOISTURE IS TAPPED FROM HURRICANE POLO, OR
JUST FROM MORE TYPICAL SUBTROPICAL PACIFIC SOURCES, THE RETURN OF
SHOWERS AND CLOUD COVER WILL SEE TEMPERATURES DROP BELOW NORMAL ONCE
MORE.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1143 AM MDT WED SEP 23 2026
WIDESPREAD MIDDLE TO HIGH LEVEL CLOUDS WILL PERSIST THROUGH THE
TAF PERIOD. SHOWERS AND EMBEDDED THUNDERSTORMS WILL BE POSSIBLE
THIS AFTERNOON POSSIBLY CONTINUING INTO THE OVERNIGHT HOURS.
SOUTHERN COLORADO WILL SEE THE GREATEST CHANCE OF SHOWERS AND
THUNDERSTORMS. MVFR MAY BE POSSIBLE AT THESE SITES DUE TO LOWER
CIGS AND VISIBILITIES. OTHERWISE VFR IS EXPECTED WITH BRIEF MVFR
CONDITIONS POSSIBLE IN SHOWERS AND STORMS.
HYDROLOGY
ISSUED AT 108 PM MDT WED SEP 23 2026
WIDESPREAD MODERATE TO HEAVY RAINFALL IS EXPECTED TODAY AND
THURSDAY, FOCUSED ACROSS THE SOUTHERN SAN JUANS AND ADJACENT
VALLEYS. A FLOOD WATCH HAS BEEN ISSUED THROUGH THURSDAY NIGHT FOR
THIS AREA, WHICH REMAINS SOMEWHAT SATURATED FROM THE HEAVIER
PRECIPITATION LAST WEEK. THE FORECAST CONTINUES TO INDICATE A TOTAL
OF 1 TO 2 INCHES OF PRECIPITATION THROUGH THURSDAY NIGHT. THIS COULD
RESULT NOT ONLY IN EXCESS RUNOFF OVER THE SMALLER BASINS BUT LEAD TO
RISES IN THE MAIN STEM RIVERS OF SOUTHWEST COLORADO. IF YOU ARE IN
THESE AREAS, YOU SHOULD MONITOR FORECAST UPDATES AND BE ALERT FOR
POSSIBLE FLOOD WARNINGS AND ADVISORIES. THOSE LIVING IN AREAS PRONE
TO FLOODING SHOULD BE PREPARED TO TAKE ACTION SHOULD FLOODING
DEVELOP.
GJT WATCHES/WARNINGS/ADVISORIES
CO...FLOOD WATCH THROUGH LATE THURSDAY NIGHT FOR COZ019-022-023.
UT...NONE.
DISCUSSION...BGB/TGJT
AVIATION...RJ/TGJT
HYDROLOGY...TGJT
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