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FXUS65 KBOU 211733
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1133 AM MDT MON SEP 21 2026
KEY MESSAGES
- COOLER CONDITIONS CONTINUE MONDAY, WITH MORE LIMITED SHOWER AND
THUNDERSTORM COVERAGE.
- GRADUAL WARMING RETURNS TUESDAY, WITH GENERALLY ISOLATED
PRECIPITATION CHANCES EACH DAY.
DISCUSSION /THROUGH SUNDAY/
ISSUED AT 1215 AM MDT MON SEP 21 2026
CURRENT RADAR IMAGERY SHOWS A FEW STRONG THUNDERSTORMS LINGERING
OVER ELBERT AND LINCOLN COUNTIES AS WELL AS A COUPLE OF WEAK SHOWERS
OVER THE NORTHERN COLORADO PLAINS. ANY STORM THAT IS ABLE TO
STRENGTHEN OVER THE NEXT HOUR OR TWO WILL BE ABLE TO PRODUCE LARGE
HAIL AND TORRENTIAL RAINFALL. HOWEVER, WE BELIEVE THE SEVERE
THUNDERSTORM THREAT TO BE NEARING ITS END FOR THE NIGHT AS
MESOANALYSIS SHOWS AN OVERWORKED ATMOSPHERE AND DECREASING CAPE.
AREAS OF PATCHY FOG WILL LIKELY DEVELOP DUE TO THE LOW LEVEL
MOISTURE LEFT OVER FROM TODAY'S CONVECTION AND SMALL DEWPOINT
DEPRESSIONS.
MONDAY AFTERNOON LOOKS TO BE FAIRLY QUIET AS A WEAK RIDGE BUILDS
OVER COLORADO AND SUBSIDENCE GIVES WAY TO MOSTLY SUNNY SKIES.
TEMPERATURES WILL REMAIN SLIGHTLY COOLER THAN NORMAL, WITH AFTERNOON
HIGHS MAINLY IN THE LOW 70S AT LOW ELEVATIONS, AND 50S-60S FOR THE
MOUNTAINS. MODEL GUIDANCE SUGGESTS A WEAK SHORTWAVE GRAZING
SOUTHEAST COLORADO MONDAY NIGHT AS WELL AS AN INCREASE IN WIND
SPEEDS AT THE 700MB LEVEL. GIVEN THE SLIGHTLY ABOVE NORMAL MOISTURE
ALREADY IN THE ENVIRONMENT, FEW SPRINKLES OVER THE PLAINS CANNOT BE
RULED OUT LATE MONDAY NIGHT INTO TUESDAY MORNING.
THE UPPER LEVEL RIDGE TRACKS EAST AND FLOW ALOFT TURNS SOUTHWESTERLY
ON TUESDAY. AT LEAST A FEW ISOLATED SHOWERS SEEM POSSIBLE OVER THE
HIGH TERRAIN DUE TO THE SLIGHT UPTICK IN MONSOONAL MOISTURE, WITH
THE PLAINS REMAINING DRY. ONE POINT OF UNCERTAINTY FOR TUESDAY IS
THAT MODEL GUIDANCE SUGGESTS BREEZY SOUTHERLY WINDS OVER EASTERN
COLORADO/WESTERN KANSAS WHICH COULD LEAD TO A RICHER ATMOSPHERE
FOR STORM DEVELOPMENT, ALTHOUGH INSTABILITY SHOULD REMAIN FAIRLY
LIMITED.
A DISTURBANCE WILL TRACK NORTH FROM NEW MEXICO ONTO COLORADO ON
WEDNESDAY, WHICH WILL BRING A BETTER CHANCE FOR SHOWERS AND
STORMS OVER THE EASTERN COLORADO PLAINS IN THE LATE AFTERNOON AND
EVENING. THE MOUNTAINS WILL SEE AN INCREASE IN SHOWER ACTIVITY
WEDNESDAY AFTERNOON AS WELL, BUT IT REMAINS UNCLEAR WHETHER ANY
SHOWERS FROM THE FOOTHILLS WOULD SURVIVE AND MAKE THEIR WAY ONTO
THE DENVER METRO OR IF LOW LEVEL MOISTURE WILL BE TRANSPORTED WEST
ENOUGH. MOISTURE WILL GENERALLY REMAIN ABOVE NORMAL THROUGH THE
ENTIRE FORECAST PERIOD, AND MODELS HAVE BEEN CONSISTENT IN
BRINGING PRECIPITABLE WATER VALUES THAT ARE AT LEAST 150% OF
NORMAL TO THE REGION WEDNESDAY THROUGH FRIDAY. HOWEVER, GIVEN THE
COOLER TEMPERATURES EXPECTED TO BE IN PLACE, LIFTING MECHANISMS
WILL BE NEEDED FOR MEANINGFUL RAINFALL TO COME TO FRUITION.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1129 AM MDT MON SEP 21 2026
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE TAF PERIOD.
DAY CLOUD PHASE SATELLITE SHOWS A SMALL PATCH OF CUMULUS NEAR
DEN/APA, WITH CLOUD BASES SOMEWHERE BETWEEN 2-4KFT AGL. WHILE A
FEW-SCT DECK MAY CONTINUE FOR A COUPLE MORE HOURS, GUIDANCE
GENERALLY LIFTS/DRIES OUT ANY REMAINING BOUNDARY LAYER MOISTURE.
WINDS SHOULD REMAIN LIGHT TODAY WITH A PREVAILING DIRECTION OUT OF
THE EAST.
WINDS SHOULD SLOWLY TURN CLOCKWISE THIS AFTERNOON AND EVENING
BEFORE SETTLING ON DRAINAGE OVERNIGHT TONIGHT... BEFORE WEAKENING
AND BECOMING MORE VARIABLE TUESDAY MORNING. DEPENDING ON HOW MUCH
SURFACE MOISTURE/INSTABILITY IS AVAILABLE IN THE AFTERNOON, THERE
COULD BE A FEW SHOWERS OR THUNDERSTORMS NEAR THE TERMINALS BY
MID/LATE AFTERNOON TUESDAY. INSTABILITY LOOKS WEAK ENOUGH TO ONLY
CARRY A PROB30 FOR SHRA AT THIS TIME.
BOU WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...AA
AVIATION...HIRIS
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