214
FXUS65 KGJT 220009
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
609 PM MDT WED OCT 21 2026
KEY MESSAGES
- WIDESPREAD RAIN IS EXPECTED TOMORROW THROUGH EARLY FRIDAY.
- STRONG TO SEVERE STORMS WILL BE POSSIBLE NEAR THE FOUR
CORNERS...FAVORING SOUTHEAST UTAH...ON WEDNESDAY AND THURSDAY.
- THE POTENTIAL FOR FLOODING INCREASES THURSDAY AND FRIDAY,
ESPECIALLY FOR PORTIONS OF SOUTHEAST UTAH AND SOUTHWEST
COLORADO.
- RAINFALL AMOUNTS IN THE SOUTHERN MOUNTAINS RANGE FROM 1-3
INCHES WITH HIGHER AMOUNTS OF 2-4" OR MORE POSSIBLE IN THE
SAN JUANS AND SOUTHERN FOOTHILLS.
DISCUSSION
ISSUED AT 159 PM MDT WED OCT 21 2026
HAZARDOUS WEATHER POSSIBLE THROUGH FRIDAY:
REMNANT MOISTURE FROM A TROPICAL CYCLONE FORMERLY KNOWN AS
TRUDY IS MOVING NORTHEASTWARD ACROSS EASTERN UTAH AND WESTERN
COLORADO. A PLETHORA OF WEATHER HAZARDS ARE POSSIBLE WITH THIS
SYSTEM INCLUDING FLOODING, FLASH FLOODING, STRONG TO SEVERE
THUNDERSTORMS, AND SNOW ABOVE 12,000-13,000 FEET. AS A RESULT, A
FLOOD WATCH IS IN EFFECT FOR PARTS OF SOUTHEAST UTAH AND
SOUTHWEST COLORADO THROUGH 12 PM FRIDAY.
THIS AFTERNOON:
AN INITIAL PUSH OF CONVECTION HAS DEVELOPED OVER THE FOUR
CORNERS REGION AND WILL POSE A LOCALIZED THREAT FOR HEAVY
RAINFALL AND FLASH FLOODING IF STRONGER STORMS DEVELOP,
ESPECIALLY IF STORMS BEGIN TO TRAIN OVER THE SAME AREAS.
ISOLATED SEVERE STORMS CAPABLE OF PRODUCING LARGE HAIL, DAMAGING
WIND, AND BRIEF TORNADOES CANNOT BE RULED OUT DUE TO THE
PRESENCE OF MODEST INSTABILITY AND STRONG SHEAR. HOWEVER, THE
HIGHEST POTENTIAL FOR SEVERE WEATHER WILL REMAIN OFF TO OUR
SOUTHWEST STRONG DOWNSTREAM BLOCKING RIDGE WILL FAVOR THE
TROUGH OVER THE WEST TO LINGER UPSTREAM OF US THROUGH EARLY
TUESDAY. THIS WILL KEEP US IN STRONG SOUTHWEST FLOW ALOFT AND A
GENERALLY WARMER AND MOIST ENVIRONMENT. AS MENTIONED EARLIER THE
HIGHLY ANOMALOUS TROPICAL PLUME WILL BE ADVECTING NORTH OF THE
AREA TONIGHT BUT STILL REMAIN ABOVE NORMAL UNTIL THE TROUGH
PASSES AND WE BEGIN TO DRY OUT AFTER MIDWEEK. WINDS WILL REMAIN
BREEZY IN THE LEADING EDGE OF THE TROUGH WITH GUSTS OF 25 TO 35
MPH...WITH A FEW HIGHER GUSTS POSSIBLE IN THE 4 CORNERS REGION
TOMORROW AFTERNOON. HIGHER GUST OVER THE TERRAIN CAN BE EXPECTED
AS WELL. THE PARENT LOW IN THIS TROUGH IS OVER THE OREGON THIS
EVENING AND MODEL CONSENSUS HAS IT DIGGING THROUGH THE
INTERMOUNTAIN WEST TO THE 4 CORNERS REGION BY TUESDAY EVENING.
THIS WILL KEEP BROAD ASCENT OVER OUR AREA SUPPORTED BY THE JET
ALOFT WHICH WILL KEEP WORKING ON THE MOISTURE TO PRODUCE SHOWERS
THROUGH TUESDAY MORNING. THE BEST CHANCES WILL BE OVER THE
WESTERN 2/3 OF THE CWA AND THE SAN JUANS WITH LESS COVERAGE OVER
THE CENTRAL DIVIDE. ASCENT INCREASES SIGNIFICANTLY THROUGH THE
DAY TUESDAY AS THE UPPER LOW DIGS THROUGH THE LOWER GREAT BASIN.
THIS WILL OOZE A COLD FRONT THROUGH THE AREA UNDER THE STRONG
QG SIGNAL IN NORTHWEST INTO CENTRAL ARIZONA. STAY WEATHER AWARE
IF YOU HAVE OUTDOOR ACTIVITIES PLANNED! IF YOU EXPERIENCE ANY
OF THE HAZARDS NOTED ABOVE, PLEASE REPORT THEM TO NWS GRAND
JUNCTION.
TONIGHT - THURSDAY NIGHT:
WITH AN ANOMALOUSLY MOIST TROPICAL AIRMASS OVERHEAD, WIDESPREAD
RAINFALL TAKES HOLD OF THE FORECAST AREA WEDNESDAY NIGHT.
PLEASE SEE THE HYDROLOGY SECTION BELOW FOR MORE INFORMATION
CONCERNING THE THREAT FOR FLOODING FROM THIS PERIOD OF MODERATE
TO WIDESPREAD RAINFALL.
ANOTHER ROUND OF STRONG TO SEVERE STORMS CANNOT BE RULED OUT ON
THURSDAY AFTERNOON/EVENING WITH MARGINAL INSTABILITY AND STRONG
WIND SHEAR PRESENT. HOWEVER, WIDESPREAD CLOUD COVER ADDS A
LAYER OF UNCERTAINTY TO THE FORECAST AND MAY INHIBIT SURFACE
HEATING. IF STRONGER STORMS DEVELOP, ISOLATED DAMAGING WIND,
LARGE HAIL, BRIEF TORNADOES ARE POSSIBLE. WE HAVE LOW CONFIDENCE
IN THIS ASPECT OF THE FORECAST.
FRIDAY:
MODELS HAVE CONTINUED TO KEY IN ON A DRY SLOT QUICKLY
EVACUATING THE TROPICAL MOISTURE FROM THE REGION ON FRIDAY
MORNING. EVEN AFTER IT STOPS RAINING, THE RISK FOR FLOODING WILL
REMAIN ELEVATED ON FRIDAY MORNING AS WATER CONTINUES TO WORK
THROUGH THE SYSTEM. DO NOT LET YOUR GUARD DOWN RIGHT AWAY! WE'LL
HAVE A BETTER IDEA OF HOW LONG FLOODING MAY CONTINUE TO CAUSE
ISSUES AFTER WE GET A BETTER SENSE OF HOW MUCH RAINFALL IS
RECEIVED ON THURSDAY.
LOOKING AHEAD:
CHANCES FOR LIGHT PRECIPITATION (VALLEY RAIN, MOUNTAIN SNOW
ABOVE 10,000 FEET) CONTINUE THROUGH THE WEEKEND AS A LOW
PRESSURE SYSTEM, CURRENTLY SPINNING OFF THE CALIFORNIA COAST,
TRAVERSES THE INTERMOUNTAIN WEST. PLENTY OF UNCERTAINTY REMAINS
IN HOW THIS LOW WILL EVOLVE AS IT MOVES INLAND, BUT ENSEMBLE
GUIDANCE TENDS TO SHOW A WEAKENING SYSTEM BY THE TIME IT REACHES
OUR FORECAST AREA. REGARDLESS, THIS SYSTEM WILL PROVIDE ENOUGH
FORCING FOR SCATTERED TO WIDESPREAD PRECIPITATION AS IT MOVES
THROUGH, ALONGSIDE A BRIEF REDUCTION IN TEMPERATURES.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 546 PM MDT WED OCT 21 2026
EXPECT WIDESPREAD LIGHT RAIN AND MODERATE RAIN SHOWERS ACROSS HE
REGION THROUGH THE TAF PERIOD. CURRENTLY SCATTERED EMBEDDED
THUNDERSTORMS ARE LIMITED TO THE SOUTHERN AREAS OF SOUTHEASTERN
UTAH AND SOUTHWESTERN COLORADO, BUT WILL SPREAD NORTH TO ALONG
AND WEST OF THE LINE FROM KVEL TO KCPW AFTER 12Z. WINDS WILL BE
GENERALLY LIGHT ACROSS THE REGION THROUGH THE TAF PERIOD, BUT EXPECT
OUTFLOW GUSTS TO 40 KTS ASSOCIATED WITH THUNDERSTORMS OVERNIGHT
INCREASING TO OVER 50 KTS AFTER 12Z. CONDITIONS WILL BE MOSTLY
MVFR TO IFR WITH THE SHOWERS AND THUNDERSTORMS, BELOW ILS
BREAKPOINTS FOR MOST MOUNTAIN TAF SITES FOR THE NEXT 24 HOURS.
HYDROLOGY
ISSUED AT 257 PM MDT WED OCT 21 2026
HYDROLOGIC CONCERNS REMAIN ELEVATED THROUGH FRIDAY DUE TO THE
INFLUX OF HIGHLY ANOMALOUS TROPICAL MOISTURE ACROSS THE 4
CORNERS AREA INTO THE CENTRAL ROCKIES. POTENTIAL HAZARDS
INCLUDE LOCALIZED FLASH FLOODING FROM THUNDERSTORMS PRODUCING
HEAVY RAINFALL RATES AND RIVER FLOODING DUE TO A PROLONGED
PERIOD OF WIDESPREAD MODERATE TO HEAVY RAINFALL.
SOUTHEAST UTAH AND THE LOWER VALLEYS ALONG THE CO/NM BORDER
WILL BE UNDER THE HIGHEST THREAT OF STRONG TO SEVERE
THUNDERSTORMS CAPABLE OF PRODUCING FLASH FLOODING ACROSS DESERT
FLOORS AND DRY WASHES THE THROUGH TOMORROW EVENING.
THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL LEADING TO
FLOODING ACROSS PORTIONS OF THE SAN JUANS AND ADJACENT SOUTHERLY
VALLEYS WHERE PRECIPITATION TOTALS OF 2 TO 4 INCHES WILL BE
POSSIBLE. THE BULK OF THIS PRECIPITATION WILL FALL OVERNIGHT
THROUGH EARLY FRIDAY MORNING. HIGHER PRECIPITATION TOTALS OVER
PORTIONS OF THE SOUTHERN SAN JUANS OF 4 TO 5 INCHES ARE
DEFINITELY POSSIBLE. AN ADDITIONAL CONCERN OF RAIN ON SNOW
LEADING TO ADDITIONAL RUNOFF MAKING IT INTO THE WATERWAYS. SNOW
LEVELS ARE FORECAST ABOVE 12-13 KFT THROUGHOUT THE DAY THURSDAY,
WHICH WILL LIKELY RESULT IN MELTING OF SOME OF THE EXISTING
EARLY-SEASON SNOW PACK. THE COMBINED RUNOFF FROM RAIN AND RAIN-
ON-SNOW WILL RESULT IN A RAPID RISE IN MANY OF OUR CREEKS,
STREAMS AND RIVERS. MODELED RESPONSES SUGGEST SEVERAL RIVERS
REACHING BANKFULL OR HIGHER AT RIVER FORECAST POINTS ACROSS
SOUTHWEST COLORADO AND SOUTHEAST UTAH. THE HIGHEST CONFIDENCE IN
MINOR FLOODING AND RELATED IMPACTS ALONG THE SAN JUAN RIVER,
PIEDRA, ANIMAS, LA PLATA RIVERS AND ABOVE VALLECITO RESERVOIR.
HOWEVER, OTHER CREEKS AND TRIBUTARIES WITHIN THE FOUR CORNERS
REGION REMAIN SUSCEPTIBLE. ALL RIVER RESPONSES ARE HEAVILY
DEPENDENT ON WHERE THE HEAVIEST PRECIPITATION FALLS, SO PLEASE
CONTINUE TO MONITOR THE FORECAST AS THE WEEK UNFOLDS.
GJT WATCHES/WARNINGS/ADVISORIES
CO...FLOOD WATCH THROUGH FRIDAY MORNING FOR COZ019-021>023.
UT...FLOOD WATCH THROUGH FRIDAY MORNING FOR UTZ022-027>029.
DISCUSSION...KAA
AVIATION...DB
HYDROLOGY...ERW
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