616
FXUS65 KGJT 211753
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1153 AM MDT TUE JUL 21 2026
KEY MESSAGES
- SHOWERS AND STORMS WILL CONTINUE THIS WEEK EACH AFTERNOON AND
EVENING, WITH COVERAGE BECOMING MORE WIDESPREAD BY TUESDAY
AND WEDNESDAY.
- PRIMARY THREATS INCLUDE HEAVY RAINFALL, LIGHTNING, AND
OUTFLOW WINDS UP TO 30-40 MPH. SMALL HAIL CANNOT BE RULED OUT
IN STRONGER STORMS.
- STORMS HAVE THE ABILITY TO PRODUCE FLASH FLOODING AND DEBRIS
FLOWS IN VULNERABLE TERRAIN, INCLUDING AREAS NEAR AND
DOWNSTREAM OF BURN SCARS.
DISCUSSION
ISSUED AT 1148 AM MDT TUE JUL 21 2026
STORMS THIS AFTERNOON/EVENING:
LITTLE CHANGE IN THE SYNOPTIC PATTERN IS EXPECTED TODAY WITH
HIGH PRESSURE PARKED TO OUR NORTHEAST LEADING SOUTHEAST FLOW
ALOFT. HOWEVER, A FEW MESOSCALE DEVELOPMENTS WILL PROVE PIVOTAL
TO THE FORECAST. MONSOONAL MOISTURE WILL CONTINUE TO TRICKLE IN
BENEATH THE HIGH THIS AFTERNOON. WEAK SHORTWAVE ENERGY IS
EXPECTED ENGAGE THE EXISTING MOISTURE POOL AND PRODUCE ANOTHER
ROUND OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING.
YESTERDAY'S STORMS PRODUCED RAINFALL RATES OF 2-3 INCHES PER
HOUR IN PLACES, ENOUGH FOR NUMEROUS FLASH FLOOD WARNINGS ON
SUSCEPTIBLE BURN SCARS AND FLOOD- PRONE TERRAIN. THIS GAVE US
HIGH ENOUGH CONFIDENCE TO ISSUE A FLASH FLOOD WARNING TODAY FOR
PORTIONS OF SOUTHEAST UTAH AND WESTERN COLORADO WITH ADDITIONAL
DYNAMIC FORCING FROM THE SHORTWAVES. PLEASE SEE THE HYDROLOGY
SECTION BELOW FOR MORE INFORMATION.
PLEASE CONTINUE TO MONITOR THE FORECAST AND ADJUST YOUR PLANS
AS NEEDED. STORMS CAN DEVELOP RAPIDLY, BRINGING SUDDEN HAZARDS.
MIDWEEK OUTLOOK:
BY MIDWEEK, THE HIGH-PRESSURE SYSTEM WILL SHIFT SLIGHTLY TO THE
EAST, ALLOWING A WEAK LOW PRESSURE SYSTEM TO SET UP OVER THE
FOUR CORNERS REGION. WHILE STORMS HAVE RECENTLY BEEN TAKING AN
UNUSUAL EAST-TO-WEST PATH, THE NEW PATTERN WILL LIKELY STEER
THEM UP FROM THE SOUTH AND PERHAPS THE WEST BY LATE WEEK. THIS
WILL ALSO INCREASE CLOUD COVER ACROSS THE REGION WHICH WILL
LOWER OUR CONFIDENCE IN STORM STRENGTH, BUT INCREASE THE
COVERAGE OF SHOWERS AND STORMS ACROSS THE REGION. WE WILL BE
MONITORING THIS ASPECT OF THE FORECAST CLOSELY. IF THERE IS
ENOUGH CLEARING TONIGHT, A FLASH FLOOD WATCH MAY BE WARRANTED
AGAIN TOMORROW.
DAYTIME HIGHS WILL COOL A HANDFUL OF DEGREES TOMORROW AND
RETURN TO SEASONABLE OR SLIGHTLY BELOW NORMAL THROUGH FRIDAY.
LOOKING AHEAD:
HIGH PRESSURE BUILDS BACK IN BY THE END OF THE WEEK BRINGING
WARMER TEMPERATURES WITH SOUTHWEST FLOW ALOFT. THE AMOUNT OF
MOISTURE AVAILABLE VARIES GREATLY BETWEEN MODELS BY THIS POINT
IN THE FORECAST, SO FORECAST CONFIDENCE DECREASES. HOWEVER,
THERE IS NO REAL PUSH OF DRY AIR ACROSS THE REGION, SO WE
ANTICIPATE ENOUGH MOISTURE FOR AFTERNOON SHOWERS AND STORMS
FAVORING THE MOUNTAINS EACH DAY THROUGH EARLY NEXT WEEK. THE
STRENGTH, COVERAGE, AND HAZARDS ASSOCIATED WITH THIS CONVECTION
REMAIN UNCERTAIN AT THIS TIME.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1148 AM MDT TUE JUL 21 2026
PLENTY OF MOISTURE AND INSTABILITY WILL BE IN PLACE FOR ANOTHER
ACTIVE AFTERNOON AND EVENING. EXPECT SHOWERS AND THUNDERSTORMS
TO IMPACT MOST TAF SITES WITH THE THREAT OF A PASSING
THUNDERSTORM WELL INTO THE EARLY MORNING HOURS OF WEDNESDAY. VFR
IS PREVAILING IN TAF SITES WITH ILS POSSIBLE IN THE TEMPO AND
PROB30 GROUPS AT SOME SITES. CONFIDENCE NOT HIGH ENOUGH FOR MVFR
OR BELOW, BUT IF A HEAVY RAIN SHOWER MOVES OVER THE AIRFIELD
THIS IS VERY POSSIBLE OVER THE NEXT 24 TO 36 HOURS.
HYDROLOGY
ISSUED AT 1148 AM MDT TUE JUL 21 2026
A RICH PLUME OF MONSOONAL MOISTURE HAS BECOME ESTABLISHED
ACROSS PORTIONS OF EASTERN UTAH AND WESTERN COLORADO. SCATTERED
THUNDERSTORMS CAPABLE OF PRODUCING HEAVY RAIN ARE EXPECTED TO
CONTINUE THIS AFTERNOON INTO LATE EVENING HOURS. RAINFALL RATES
OF 2- 3 INCHES PER HOUR WILL BE POSSIBLE WITH THE STRONGER
STORMS. THESE RATES COULD LEAD TO FLASH FLOODING AND DEBRIS
FLOWS ESPECIALLY OVER STEEP TERRAIN AND RECENT BURN SCARS. ALSO,
RAIN OVER THE PAST SEVERAL DAYS HAS LEAD TO SATURATED SOILS,
WHICH INCREASE THE CHANCES FOR EXCESSIVE RUNOFF.
SOUTHEAST TO EAST UTAH, AND NOSING INTO SOUTHWEST COLORADO,
SHOW HIGHER LEVELS OF SURFACE BASED CAPE THIS AFTERNOON, WHICH
WILL SUPPORT DEEPER CONVECTION TO DEVELOP. THESE AREAS ARE MORE
LIKELY TO OBSERVE STRONGER THUNDERSTORMS, RICH WITH THE
ATMOSPHERIC MOISTURE. FOR THAT REASON, WE HAVE HOISTED A FLASH
FLOOD WATCH FOR SAID AREAS. IN ADDITION, CAM GUIDANCE
ILLUSTRATES ANOTHER ROUND OF EVENING CONVECTION DRIVING ACROSS
WESTERN COLORADO. DUE TO EXCESSIVE RAINFALL OBSERVED WITHIN THE
LAST 24 TO 72 HOURS, SATURATED SOILS OVER ALREADY SUSCEPTIBLE
TERRAIN TO FLASH FLOODING TRIGGERED AN EXPANSION OF THE WATCH
AREA TO INCLUDE THE GRAND MESA, PORTIONS OF THE I-70 CORRIDOR
AND ACROSS THE ROAN CLIFFS.
AS A REMINDER: KEEP AN EYE ON OUR FORECASTS THROUGH THE END OF
THE WEEK AND STAY TUNED FOR UPDATED HYDROLOGY ALERTS IF VISITING
OR IF YOU RESIDE BELOW TERRAIN VULNERABLE TO FLASH FLOODING
AND/OR DEBRIS FLOWS. DRY CREEKS AND ARROYOS CAN FILL QUICKLY AND
WITHOUT WARNING FROM STORMS MILES AWAY.
GJT WATCHES/WARNINGS/ADVISORIES
CO...FLOOD WATCH THROUGH LATE TONIGHT FOR COZ003-007-009-017-020-
021.
UT...FLOOD WATCH THROUGH LATE TONIGHT FOR UTZ022-025-027>029.
DISCUSSION...KAA/TGJT
AVIATION...TGJT
HYDROLOGY...ERW/TGJT
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