683
FXUS65 KGJT 231129
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
529 AM 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 1039 PM MDT TUE SEP 22 2026
THE H500 HAND ANALYSIS MAP AT 23/00Z HAS A COMPLEX PATTERN
DOWNSTREAM WITH AN COMPACT OMEGA BLOCK OVER THE GREAT LAKES
REGION ON TOP OF THE LARGER SUBTROP HIGH STILL CENTERED OVER THE
WESTERN GULF STATES. DOWNSTREAM OF US THERE IS A SPLITTING
TROUGH EXTENDING FROM THE N.ROCKIES TO SOCAL/BAJA. WE ARE
SQUEEZED BETWEEN THE TROUGH AND HIGH WHICH HAS ALLOWING FOR A
DEEP FETCH OF SUBTROPICAL MOISTURE TO INVADE OUR CWA OVER THE
PAST 24 HOURS WITH THE KGJT RAOB PWAT GAINING A THIRD OF AN INCH
OVER THE PAST 24 HOURS. THIS OF COURSE HAS FED THE UPTICK IN
CONVECTIVE COVERAGE TODAY WITH A MIX OF MODERATE/HEAVY RAINFALL
STORMS AND GUSTY OUTFLOW WINDS OVER 50 MPH. THE INTERACTION
BETWEEN THE UPSTREAM TROUGH AND LARGE HIGH WILL PLAY A ROLE IN
THE HEAVY RAIN THREAT OVER A PORTION OF OUR CWA OVER THE NEXT
FEW DAYS. THE NORTHERN SPLIT IN THE UPSTREAM TROUGH LOOKS TO
HAVE ENOUGH INFLUENCE TO KEEP A FETCH OF DRIER AIR FLOWING INTO
OUR FAR WESTERN AND NORTHERN CWA THROUGH TOMORROW EVENING. WHILE
TO THE SOUTH MOISTURE WILL BE STREAMING IN UNABATED EAST OF THE
4 CORNERS INTO OUR SOUTHERN AND CENTRAL MOUNTAINS TONIGHT
THROUGH TOMORROW MORNING. PWATS IN THIS AREA LOOK TO BE 150-200
PERCENT OF NORMAL EQUATING TO THE 99THE PERCENTILE WITH A 10
YEAR RETURN INTERVAL FOR EARLY FALL. SO THE JUICE IS THERE AND
WILL BE IN THE AREA THROUGH THURSDAY BEFORE FLUSHING TO THE EAST
ON FRIDAY. SOUTHERLY FLOW INTO THE TERRAIN WILL CREATE ON
AVENUE OF LIFT FOR SQUEEZING THIS MOISTURE OUT. A LARGE
ANTICYCLONIC JET IN THE FASTER FLOW ALOFT WILL BE ANOTHER WHICH
WILL BE JOINED BY ANOTHER SPEED MAX ARRIVING WEDNESDAY NIGHT
INTO THURSDAY. THIS SECONDARY JET WILL BE FORCED BY A STRONGER
WAVE/CLOSED MID LEVEL SYSTEM ALLOWED TO LIFT NORTHWARD AROUND
THE SUBTROP HIGH BY A WEAKENING DOWNSTREAM TROUGH. THIS FORCING
SHOULD HELP PROVIDE STRONGER LIFT TO HELP RELEASE INSTABILITY
AND PRODUCE EFFICIENT RAIN PROCESSES EARLY THURSDAY THROUGH THE
AFTERNOON. THIS SYSTEM WILL ALSO HELP PULL MOISTURE BACK
WESTWARD AND SPREAD PRECIPITATION/CLOUD COVER FARTHER NORTH AND
WEST ON THURSDAY. WITH MOISTURE AND LIFT IN PLACE THERE ARE HIGH
PROBABLE CHANCES OF RAINFALL(AND SNOW ON SOME PEAKS?) ACROSS SW
COLORADO TONIGHT THRU MUCH OF THURSDAY. THE MISSING INGREDIENT
IS INSTABILITY TO HELP DRIVE HEAVIER RAINFALL RATES AND
THUNDERSTORMS. THIS SHOULD HAPPEN ON THE PERIPHERY OF THE CLOUD
COVER AND DEEPER MOISTURE TODAY BUT UNDER THE RAIN SHIELD TO THE
SOUTH THIS ISN'T AS CLEAR. SOUNDING SHOW MODERATE LAPSE RATES
AND ANY CAPE IN A LONG SKINNY PROFILE. SO SOME ENHANCEMENT FROM
LITTLE PIECES ENERGY AND MAYBE OROGRAPHICS WILL HELP BUT THE
STRONGER STORMS REMAIN ON THE EDGE WHERE MORE SUNSHINE IS LIKELY
TO OCCUR. AS THE SYSTEM LIFT THROUGH ON THURSDAY THERE COULD BE
ENOUGH MIXING TO BRING SOME PEAKS OF SUNSHINE AND HELP PRODUCE
SOME STRONGER STORMS DOWN SOUTH BEHIND THE LIFTING RAIN SHIELD.
FRIDAY WITH THE BETTER MOISTURE MOVING EAST AND MORE POSSIBILITY
OF SUNSHINE SHOULD LEAD TO MORE SCATTERED THUNDERSTORMS. WHEN
ALL IS SAID AND DONE THE MOST PROBABLE OUTCOME FOR THE HEAVIEST
PRECIPITATION REMAINS OVER THE SOUTHERN SAN JUANS AND ADJACENT
VALLEYS AND WHERE POPS WILL BE THE HIGHEST FOR THIS EVENT. QPF
AMOUNTS HAVE COME DOWN SLIGHTLY FROM PREVIOUS FORECAST BUT STILL
WIDESPREAD 1-2 INCHES IN THIS AREA HAVE AT LEAST A 70 PERCENT
CHANCE OF PROBABILITY. THEREFORE THE FLOOD WATCH IN PLACE LOOKS
ON TRACK. SO WE WILL BE WATCHING FOR THE THREAT OF FLASH
FLOODING IN SMALLER BASINS AND AS IN THE LAST EVENT SOME OF THE
MAIN STEM RIVERS IN SOUTHERN COLORADO ARE LIKELY TO SEE A JUMP
IN STAGES AS THIS PRECIPITATION RUNS OFF. WE SHOULD SEE A DRYING
TREND FOR THE WEEKEND WITH ANOTHER PUSH OF MOISTURE COMING BACK
LATE SUNDAY TO START THE NEW WEEK ON THE WETTER SIDE.
TEMPERATURES WILL BE SEASONABLE TO COOL DEPENDING ON CLOUD COVER
AND PRECIPITATION OVERHEAD THE NEXT FEW DAYS WITH A WARMER
WEEKEND ON TAP.
AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 523 AM MDT WED SEP 23 2026
SCATTERED TO BROKEN SKIES, OCCASIONALLY OVERCAST, WILL BE THE
RULE AGAIN TODAY. ANOTHER ROUND OF SHOWERS AND A FEW EMBEDDED
THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON AND LIKELY
CONTINUING INTO THE OVERNIGHT HOURS. THE BEST CHANCES FOR PRECIP
REMAIN OVER THE CENTRAL MOUNTAINS AND SAN JUANS MAKING KTEX AND
KDRO SEEING THE HIGHEST PROBABILITIES FOR FLIGHT RESTRICTIONS.
SOME MVFR MAY BE POSSIBLE AT THOSE SITES DUE TO LOWER CIGS AND
VISIBILITIES. REMAINING TAF SITES SHOULD STAY VFR THROUGH BRIEF
MVFR CAN'T BE RULED OUT FOR KASE, KEGE, KMTJ AND KGUC IF A
STRONGER SHOWER OR STORM MOVES OVERHEAD.
HYDROLOGY
ISSUED AT 1039 PM MDT TUE SEP 22 2026
WIDESPREAD MODERATE TO HEAVY RAINFALL IS EXPECTED WEDNESDAY AND
THURSDAY, FOCUSED ACROSS THE SOUTHERN SAN JUANS AND ADJACENT
VALLEYS. A FLOOD WATCH HAS BEEN ISSUED FOR WEDNESDAY MORNING
THROUGH THURSDAY NIGHT FOR THIS AREA WHICH REMAINS SOMEWHAT SATURATED
FROM THE HEAVIER PRECIPITATION LAST WEEK. THE FORECAST CONTINUES
TO INDICATE 1 TO 2 INCHES OF ADDITIONAL PRECIPITATION DURING
THE WEDNESDAY AND THURSDAY TIMEFRAME. 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 FROM NOON MDT TODAY THROUGH LATE THURSDAY NIGHT
FOR COZ019-022-023.
UT...NONE.
DISCUSSION...TGJT
AVIATION...TGJT
HYDROLOGY...MDA
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