419
FXUS65 KBOU 282005
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
205 PM MDT MON JUL 28 2025
KEY MESSAGES
- COOLER, WETTER AND MORE ACTIVE PATTERN LIKELY TUESDAY THROUGH
FRIDAY, PARTICULARLY EAST OF THE CONTINENTAL DIVIDE.
- AFTERNOON SHOWERS AND THUNDERSTORMS EACH AFTERNOON (20-80%
CHANCE) WITH MAIN THREATS LIGHTNING, STRONG/GUSTY WINDS, AND
LOCALIZED FLASH FLOODING.
DISCUSSION /THROUGH MONDAY/
ISSUED AT 205 PM MDT MON JUL 28 2025
THE RIDGE AT 500MB REMAINS CENTERED OVER THE CENTRAL PLAINS
TOMORROW WITH A TROUGH OFF THE U.S. WEST COAST. TONIGHT A SHALLOW
COOL FRONT WILL MOVE SOUTH ACROSS THE AREA, EAST OF THE DIVIDE.
THE FRONTAL BOUNDARY WILL SHAPE OUR WEATHER FOR MUCH OF THE WEEK
AS IT STALLS SOMEWHERE ALONG THE OKLAHOMA BORDER FOR MUCH OF THE
WEEK, ALLOWING LOW-LEVEL MOISTURE AND NOT-SO-HOT AIR TO WORK
WESTWARD THROUGHOUT MUCH OF THE PERIOD. STARTING TOMORROW,
EASTERLY WINDS ACROSS THE PLAINS WILL ADVECT SURFACE DEWPOINTS IN
THE MID 60S (NORTHEAST PLAINS) TO UPPER 50S ALONG THE I-25
CORRIDOR. NOT SURPRISINGLY THIS SHOULD RESULT IN PW VALUES UP TO
AN INCH EAST OF THE DIVIDE, AND 1.25" ACROSS THE NORTHEAST CORNER
OF COLORADO. AFTERNOON THUNDERSTORMS WILL BE MUCH MORE WIDESPREAD
THAN THE PAST SEVERAL DAYS, AND THERE SHOULD BE PLENTY OF
INSTABILITY AROUND TO GET STORMS GOING, WITH AROUND 1000 J/KG
SBCAPE EAST OF THE DIVIDE, AND UP TO 1400 J/KG SBCAPE ACROSS THE
NORTHEAST CORNER. HOWEVER, EFFECTIVE BULK SHEAR WILL BE 15-20 KTS
GIVEN THE POSITION OF THE RIDGE; THUS LIGHTNING, STRONG/GUSTY
WINDS, AND HEAVY RAIN WILL BE THE MAIN THREATS THROUGHOUT THE
AFTERNOON. POPS WILL BE HIGH BUT IT WILL STILL BE HIT OR MISS
GIVEN THE WEAK SHEAR AND EXPECTED STRONG COLD POOLS. WE EXPECT
STORMS TO FORM ACROSS THE MOUNTAINS AROUND NOON AND DRIFT EAST-
NORTHEAST THROUGHOUT THE AFTERNOON, WITH MOVEMENT AND DEVELOPMENT
TIED TO GUSTFRONTS. THE BEST CHANCE FOR TSRA ACROSS THE NORTHEAST
CORNER WILL BE IN THE LATE EVENING WHEN GUST FRONTS FINALLY MAKE
IT EASTWARD. THE WEST SLOPE UNFORTUNATELY DOES NOT HAVE ANYWHERE
NEAR AS MUCH PW OR LOW-LEVEL MOISTURE, SO JUST ISOLATED
THUNDERSTORMS ARE POSSIBLE (20-40%) ON TUESDAY. A FINAL NOTE ON
TUESDAY'S FORECAST IS ON THE SMOKE FROM WILDFIRES IN UTAH AND
ARIZONA. THE HRRR SMOKE BRINGS QUITE A BIT OF SMOKE ALOFT INTO OUR
AREA TUESDAY AFTERNOON AND EVENING. THE NORTHERN QUARTER OF
COLORADO WILL SEE THE MOST SMOKE TOMORROW AFTERNOON/EVENING, BUT
IN GENERAL THE NEARS-SURFACE SMOKE LEVELS SHOULDN'T GET TOO HIGH.
YOU WILL DEFINITELY NOTICE THE HAZY SKIES AND ORANGE SUNSET
TOMORROW. WE'VE INCLUDING AREAS OF SMOKE IN THE WX GRIDS. HIGHS
WILL ALSO BE COOLER THAN TODAY WITH 80S EXPECTED ACROSS THE PLAINS
AND MOUNTAIN VALLEYS, AND CLOSE TO 90 ACROSS THE NORTHEAST
PLAINS.
WEDNESDAY WILL BE MORE OF THE SAME WITH CONTINUED HIGH PW VALUES OF
AN INCH OR MORE EAST OF THE DIVIDE. THERE IS A MUCH BETTER UPSLOPE
COMPONENT OUT OF THE EAST WEDNESDAY AFTERNOON WHICH WILL NO DOUBT
INCREASE THUNDERSTORM COVERAGE STARTING IN THE MOUNTAINS MIDDAY THEN
MIGRATING EAST. SURFACE DEWPOINTS SHOULD BE IN THE UPPER 50S ACROSS
THE PLAINS. FLOW ALOFT IS STILL WEAK SO LIGHTNING, STRONG WINDS,
AND HEAVY RAIN WILL BE THE MAIN THREATS. GIVEN THESE INGREDIENTS,
WPC HAS PUT OUR AREA IN A SLIGHT RISK OF EXCESSIVE RAINFALL. WARM
CLOUD DEPTHS STILL LOOK PRETTY SHALLOW, OTHERWISE WE'D BE MUCH MORE
CONCERNED ABOUT A WIDESPREAD FLOODING THREAT. AS IT STANDS, A FEW
LOCALIZED AREAS COULD EXCEED AN INCH AND SEE SOME FLASH FLOODING,
BUT IN GENERAL WIDESPREAD PRECIPITATION AMOUNTS SHOULD BE MUCH LESS
THAN THAT. PRECIPITATION AMOUNTS WILL BE LIGHT ACROSS THE WEST SLOPE
ONCE AGAIN GIVEN MUCH LESS MOISTURE. HIGH TEMPERATURES SHOULD
REMAIN IN THE LOW TO MID 80S WITH EXTENSIVE CLOUD COVER AND RAIN-
COOLED OUTFLOWS. THE MOUNTAIN VALLEYS SHOULD SEE UPPER 70S TO LOW
80S.
THURSDAY AND FRIDAY LOOK TO BE MUCH OF THE SAME. AMPLE MOISTURE
AROUND FOR AFTERNOON THUNDERSTORMS BOTH DAYS. THE HEAVY RAIN THREAT
LOOKS A LITTLE LESS BOTH AFTERNOONS WITH MORE SOUTHEAST FLOW ACROSS
THE PLAINS AND THE LIKELY DEVELOPMENT OF A DENVER CYCLONE, WHICH
WILL TEND TO FOCUS STORMS AND HEAVY RAIN ACROSS THE EAST SIDE OF
METRO DENVER AND GREELEY, AND POINTS EAST. INTERESTINGLY ON FRIDAY
SIGNIFICANTLY MORE SHEAR WILL BE IN PLACE BECAUSE A WEAK TROUGH
MOVES ACROSS WYOMING EARLIER ON FRIDAY, WITH STRONGER NORTHWEST
WINDS ON THE BACKSIDE OF THAT WEAK TROUGH. WITH 1000-1600 J/KG
SBCAPE POSSIBLE ON FRIDAY AFTERNOON THERE COULD BE SOME BORDERLINE
SEVERE WEATHER IF THE SHEAR INCREASES BY THE AFTERNOON HOURS.
BOTH DAYS WILL HAVE AMPLE CLOUD COVER IN THE AFTERNOON AND WITH
700 MB TEMPS REMAINING "COOL" FOR LATE JULY AROUND +12 TO +14,
HIGH TEMPERATURES SHOULD CONTINUE TO BE BELOW NORMAL WITH HIGHS IN
THE 80S ACROSS THE PLAINS AND I-25 URBAN CORRIDOR, AND 70S TO LOW
80S FOR THE MOUNTAIN VALLEYS.
THIS WEEKEND LOOKS DRIER AND WARMER THAN THE WORKWEEK, WITH THE
RIDGE CENTERED OVER COLORADO. STILL A CHANCE OF WEAK AFTERNOON
SHOWERS/THUNDERSTORMS BUT IT LOOKS MORE LIKELY THAT 90S WILL RETURN
TO THE PLAINS AND I-25 URBAN CORRIDOR, WITH THE NBM SHOWING 50-70%
CHANCE OF 90 DEGF+ ON SATURDAY AND 70-85% ON SUNDAY FOR ELEVATIONS
BELOW 6,000 FT.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1130 AM MDT MON JUL 28 2025
VFR TODAY WITH HOT TEMPERATURES AND VIRGA EXPECTED NEAR ALL THE
TERMINALS AFTER MID AFTERNOON. IT IS UNLIKELY TS OR -RA OCCUR,
BUT THERE IS A DECENT CHANCE OF STRONG AND GUSTY WINDS OCCURRING
BECAUSE OF VIRGA. WE DIDN'T INCLUDE ANYTHING IN THE TAF YET
BECAUSE IT WOULD BE HAD TO PIN DOWN TIMING AND DEFINITELY
DIRECTION. THE OPTION WAS INCLUDE TEMPO FOR VRB20G35KT BUT OVERALL
FELT THE CHANCES WERE LOW ENOUGH TO NOT INCLUDE IN THE 18Z TAF.
NE WINDS 8-13KT SHOULD BE THE NORM INTO THE EVENING HOURS IF VIRGA
DOESN'T RESULT IN ERRATIC AND GUSTY WINDS. TONIGHT A COLD FRONT
WILL MOVE ACROSS THE TERMINALS AFTER 06/07Z WITH A WIND SHIFT TO
THE NORTH. THERE IS A 10-15% CHANCE OF STRATUS PER THE LATEST NBM,
BUT GIVEN IT'S NOT THAT MOIST IN A DEEP LAYER FOR NOW WILL JUST
HANDLE WITH FEW020 AT DEN AND SCT020 AT APA AND BJC. WE'LL MONITOR
CLOSELY THE POTENTIAL FOR MVFR CONDITIONS WITH THE FRONT.
POST FRONTAL AIRMASS ON TUESDAY WILL HAVE PLENTY OF MOISTURE FOR
AFTERNOON -TSRA AFTER 20Z. UNTIL THEN, WINDS SHOULD BE EAST
10-14KT DURING THE AFTERNOON HOURS.
BOU WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...SCHLATTER
AVIATION...SCHLATTER
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