590
FXUS65 KGJT 161805
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1205 PM MDT THU JUL 16 2026
KEY MESSAGES
- EXPECT TERRAIN-BASED SHOWERS AND THUNDERSTORMS EACH AFTERNOON
THIS WEEK, FAVORING THE SAN JUANS, BUT SPREADING NORTH BY THE
WEEKEND.
- LOCALIZED HEAVY RAINFALL WILL HAVE THE ABILITY TO PRODUCE
FLASH FLOODING AND DEBRIS FLOWS IN VULNERABLE TERRAIN,
INCLUDING AREAS NEAR AND DOWNSTREAM OF BURN SCARS.
- DAYTIME HIGHS COOL THROUGHOUT THE WEEK, RETURNING TO NEAR-
NORMAL FOR MOST AREAS BY FRIDAY.
DISCUSSION
ISSUED AT 1041 PM MDT WED JUL 15 2026
DAILY SHOWERS AND THUNDERSTORMS:
PERSISTENT HIGH PRESSURE ALOFT KEEPS A PLUME OF MOISTURE OVER
MUCH OF THE WEST THROUGH AT LEAST THIS WEEKEND, POTENTIALLY
BEYOND. GUIDANCE KEEPS THE MOST MOISTURE RICH PART OF THIS PLUME
(IN TERMS OF PWAT ANOMALIES) TO OUR WEST, BUT ENSEMBLES PLACE
PWATS OF 130- 200% OF NORMAL OVER OUR FORECAST AREA THIS WEEK.
THE ECMWF ENS AND GFS ENS HAVE CONSISTENTLY SHOWN DIFFERENCES IN
THE MAGNITUDE OF THE ANOMALIES, WITH ECMWF ENS FAVORING A MUCH
MORE MOIST SETUP WITH MAX PWATS CLOSER TO 200% AT TIMES. THIS
MOISTURE BRINGS DAILY CHANCES OF SHOWERS AND THUNDERSTORMS IN
THE AFTERNOON AND EVENING.
PRECIPITATION WILL CONTINUE TO FAVOR THE HIGHER TERRAIN ALONG
AND SOUTH OF I-70 ON THURSDAY, WITH SOME STORMS EXPECTED TO MOVE
INTO THE VALLEYS AS DEW POINTS CONTINUE TO RISE. OVER THE NEXT
FEW DAYS, PRECIPITATION COVERAGE WILL INCREASE AND SPREAD INTO
NORTHEAST UTAH AND NORTHWEST COLORADO.
WHILE MOISTURE IS A RELIEF FOR DROUGHT CONDITIONS, IT ALSO
CREATES A RISK OF FLASH FLOODING AND DEBRIS FLOWS, INCLUDING
OVER THE BURNS SCARS OF THE GOLD MOUNTAIN, FERRIS, AND BABYLON
FIRES. THE HYDROLOGY SECTION BELOW DISCUSSES THIS RISK IN
GREATER DETAIL. THESE STORMS CAN DEVELOP QUICKLY, SO BE SURE TO
MONITOR THE FORECAST AND HAVE A WAY TO RECEIVE WEATHER ALERTS,
ESPECIALLY IF YOU ARE VISITING OR RESIDE BELOW TERRAIN THAT IS
VULNERABLE TO FLASH FLOODING, INCLUDING DOWNSTREAM OF ACTIVE
FIRES.
DECLINING TEMPERATURES:
TEMPERATURES WILL GRADUALLY DECREASE FOR THE REMAINDER OF THE
WEEK THANKS TO INCREASED CLOUD COVER DURING PEAK HEATING.
GUIDANCE CONTINUES TO FAVOR ANOTHER DROP IN TEMPERATURES NEXT
WEEK, POTENTIALLY LEADING TO BELOW-NORMAL TEMPERATURES.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1146 AM MDT THU JUL 16 2026
SHOWERS AND THUNDERSTORMS ARE BEGINNING TO POP OVER THE UINTA
MOUNTAINS IN NORTHEASTERN UTAH, AND ALONG THE DIVIDE AND OVER
THE SOUTHERN MOUNTAINS IN COLORADO. EXPECT THESE STORMS TO
BECOME WIDELY SCATTERED OVER THE HIGHER TERRAIN ALONG AND SOUTH
OF THE I-70 CORRIDOR THROUGH THE AFTERNOON IMPACTING THE
MOUNTAIN TAF SITES WITH BRIEF MVFR AND STRONG WINDS GUSTING TO
40 KTS. LOOK FOR THIS CONVECTION TO DECREASE AFTER 00Z ENDING
BY ABOUT 04Z. OTHERWISE, VFR CONDITIONS AND LIGHT WINDS WILL
PREVAIL ACROSS THE REGION.
HYDROLOGY
ISSUED AT 1235 PM MDT WED JUL 15 2026
AN ANOMALOUS PLUME OF MOISTURE CONTINUES TO ROTATE INTO UTAH
AND WESTERN COLORADO THIS AFTERNOON, AS AN ELONGATED AREA OF
HIGH PRESSURE SHIFTS INTO THE SOUTHWESTERN CONUS. FOR TODAY,
STEERING WINDS OVERHEAD ARE NORTHERLY, PROVIDING A UNIQUE STORM
MOTION FOR THE GJT FORECAST AREA. IN ADDITION, OUR SOUTHERN
ZONES AND MOST OF EASTERN UTAH CONTAIN HIGHER AMOUNTS OF
MOISTURE, SO AS STORMS GENERALLY BUILD AND SHIFT SOUTH, THEY'RE
MOVING INTO JUICIER ENVIRONMENTS.
EVEN THOUGH THIS SOURCE OF MOISTURE IS A GREAT RELIEF TO THE
DROUGHT STRICKEN WEST, EXCESSIVE RAINFALL RETURNS THE CONCERNS
OF FLASH FLOODING AND DEBRIS FLOWS OVER RECENT (OR EVEN ON
GOING) BURN SCARS. 18Z'S SOUNDING ALSO SHOWS WEAK FLOW
THROUGHOUT THE ATMOSPHERIC COLUMN, WHICH WILL RESULT IN SLOW
MOVING THUNDERSTORMS THIS AFTERNOON. THE COMBINATION OF
INCREASED MOISTURE AND SLOW STORM MOTION FURTHER ELEVATES THE
CONCERN FOR EXCESSIVE RAINFALL IN LOCALIZED AREAS. THE SAN
JUAN'S ARE A BULLSEYE IN PRECIPITATION FORECASTS OVER THE NEXT
SEVERAL DAYS, MAINTAINING FLOOD THREATS REDEVELOPING EACH
AFTERNOON. DUE TO THE PROLONGED PERIOD OF ANOMALOUSLY HIGH
MOISTURE, OVER AREAS WITH SENSITIVE BURN SCARS, WE WANT TO
EMPHASIZE THE POTENTIAL FOR FLASH FLOODING AND DEBRIS FLOWS IN
THIS REGIME. WE'RE EXPECTING AN UPTICK IN MOISTURE CONTENT
ACROSS THE ENTIRE REGION ON THURSDAY, WHICH FAVORS A HIGHER
LIKELIHOOD OF WETTING RAIN WITH BURSTS OF HEAVY RAIN IN
LOCALIZED STORMS.
FOR 2026 FIRES, WE HAVE YET TO TEST THEIR SUSCEPTIBILITY TO
HANDLE RAINFALL. THEREFORE, WE WANT TO INCREASE OUR MESSAGING OF
THE POTENTIAL HAZARDS AT PLAY DOWNSTREAM NEARBY FIRES. KEEP AN
EYE ON OUR FORECASTS THROUGH THE END OF THE WEEK AND STAY TUNED
FOR UPDATED HYDRO ALERTS IF VISITING OR IF YOU RESIDE BELOW
VULNERABLE TERRAIN TO FLASH FLOODING AND/OR DEBRIS FLOWS. STORMS
ACROSS THE WEST DEVELOP QUICKLY, LEAVING LITTLE ROOM FOR LEAD
TIME IN FLASHY TERRAIN.
GJT WATCHES/WARNINGS/ADVISORIES
CO...NONE.
UT...NONE.
DISCUSSION...TGJT
AVIATION...DB
HYDROLOGY...ERW
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