267
FXUS65 KBOU 010548
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1148 PM MDT SAT MAY 31 2025
.KEY MESSAGES.
- SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS CONTINUE THROUGH
SUNDAY (MAINLY OVER THE HIGHER TERRAIN).
- WARMER WEATHER MAKES A RETURN THROUGH THE WEEKEND, WITH HIGHS
BACK INTO THE LOW 80S FOR MOST OF THE PLAINS.
- WETTER PATTERN RETURNS EARLY NEXT WEEK (MON-WED), ALONG WITH A
RETURN TO BELOW NORMAL TEMPERATURES. SNOWMELT PLUS RAINFALL WILL
LEAD TO HIGH FLOWS ON MOUNTAIN STREAMS.
DISCUSSION /THROUGH SATURDAY/
ISSUED AT 251 PM MDT SAT MAY 31 2025
WEAK CONVECTION HAS BEGUN OVER THE MOUNTAINS AND SHOULD INCREASE
THROUGH THE LATE AFTERNOON. THERE'S STILL POTENTIAL FOR A FEW
CELLS TO MOVE SOUTHEAST OFF THE MOUNTAINS, THOUGH THE ENVIRONMENT
AT LOWER ELEVATIONS IS LESS FAVORABLE THAN YESTERDAY. THE CURRENT
FORECAST SEEMS TO HAVE A DECENT HANDLE ON THIS, THOUGH WE DID
INCREASE THE CLOUD COVER OVERNIGHT FOR LINGERING MID LEVEL CLOUDS.
SUNDAY'S ENVIRONMENT ISN'T MUCH DIFFERENT, ALTHOUGH A DENVER
CYCLONE BOUNDARY COULD HELP GET A BIT MORE STORM ACTIVITY GOING
SOUTH OF DENVER IN THE MID TO LATE AFTERNOON. TEMPERATURES WILL BE
4 TO 8 DEGREES WARMER. DENVER WILL LIKELY BE NEAR 90, BUT PROBABLY
JUST SHORT OF THAT MARK.
THE MODEL HANDLING OF THE MONDAY/TUESDAY SYSTEM IS NOT THAT BAD,
THOUGH THE RESULTANT QPF STILL VARIES. ONE MODEL TREND IS TO MOVE
THE SYNOPTIC SCALE LIFT STEADILY EASTWARD AND BRING AN END TO THE
SIGNIFICANT PRECIPITATION EARLIER ON THURSDAY. SOME MODEL RUNS HAD
SLOWED THE DEPARTURE OVER THE PLAINS RESULTING IN LARGER RAIN
AMOUNTS. NOW THE CONSENSUS IS THAT THE RAIN IN THE MOUNTAINS WILL
MOSTLY BE MONDAY AFTERNOON AND MONDAY NIGHT, AND ON THE PLAINS 4
TO 6 HOURS LATER. THIS REDUCES THE FORECAST RAIN AMOUNTS A BIT.
MOST MODELS ARE STILL IN THE 0.5 TO 1.5 INCH RANGE FOR THE
MOUNTAINS, AND 0.75 TO 2 INCHES FOR THE PLAINS. THE NBM IS IN THE
MIDDLE OF THESE RANGES OVERALL AND SEEMS ADEQUATE. THERE ARE SOME
RUNS WITH LIGHTER AMOUNTS, AND A FEW OUTLIERS THAT HAVE TWICE
THAT. IT SEEMS UNREALISTIC TO HAVE THAT MUCH OVER A LARGE AREA,
BUT THERE IS POTENTIAL FOR EMBEDDED THUNDERSTORMS OR A MESOSCALE
FOCUS THAT LASTS A FEW HOURS. THE MOST LIKELY CHANCE FOR INTENSE
RAIN WOULD BE WITH CONVECTION MONDAY AFTERNOON AND EVENING. SEE
BELOW FOR HYDRO IMPACTS.
THERE'S PRETTY GOOD AGREEMENT ON KEEPING A COOL MOIST ENVIRONMENT
WITH ANOTHER SHORTWAVE LATE WEDNESDAY. AMOUNTS SHOULD BE MUCH
LIGHTER OVERALL, BUT POPS WILL STILL BE HIGH AND THERE COULD BE
SOME LOCALIZED HEAVY SHOWERS. THERE'S A DRYING AND WARMING TREND
AFTER THAT, WITH THURSDAY AS THE TRANSITION DAY. NBM GUIDANCE IS
ON THE WARM EDGE OF THE ENVELOPE, BUT THIS IS PROBABLY OK, WITH
TEMPERATURES BACK AROUND 80 IN DENVER FRIDAY AND SATURDAY. WITH
DRYING ALOFT BUT PROBABLY LESS AND THE SURFACE, THIS LOOKS LIKE A
FAIRLY TYPICAL JUNE PATTERN AND THERE COULD BE SOME THREAT OF ALL
KINDS OF SEVERE WEATHER AND BURN AREA FLOODING BY THE END OF THE
WEEK, THOUGH THERE'S NOTHING THAT LOOKS LIKE A PARTICULAR THREAT.
JUST A FAIRLY NORMAL EARLY JUNE PATTERN.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1138 PM MDT SAT MAY 31 2025
VFR THROUGH THE TAF PERIOD. WINDS ARE GRADUALLY TURNING BACK TO
TYPICAL DRAINAGE FLOW AND SHOULD CONTINUE OVERNIGHT. A FAIRLY
TYPICAL LATE SPRING DIURNAL PATTERN IS LIKELY AGAIN FOR SUNDAY,
WITH WINDS EVENTUALLY TURNING TOWARDS SOME SORT OF LIGHT E/ENE
COMPONENT DURING THE DAY.
SOME HIGH-BASED CONVECTION IS EXPECTED BY TOMORROW AFTERNOON,
WITH MOST GUIDANCE GETTING A FEW STORMS NEAR THE TERMINALS BY
ABOUT 21-22Z. MAIN IMPACT WOULD LIKELY BE A COUPLE OF HOURS OF
VARIABLE/GUSTY WINDS, WITH STRONGER STORMS PRODUCING A FEW GUSTS
NEAR 35KT. ANY CONVECTIVE ACTIVITY SHOULD QUICKLY DIMINISH BY
ABOUT 03Z WITH DRAINAGE FLOW RETURNING.
HYDROLOGY
ISSUED AT 251 PM MDT SAT MAY 31 2025
FORECAST TEMPERATURES, SNOWMELT, AND RAINFALL WILL BE ENOUGH TO
CAUSE RISES ON STREAMS IN THE MOUNTAINS, AND MINOR FLOODING COULD
RESULT LATE MONDAY AND TUESDAY IN AREAS THAT GET HEAVIER
RAINFALL. IN AREAS EAST OF THE MOUNTAINS AND BURN AREAS, THE
THREAT IS LOWER, BUT THERE COULD BE ENOUGH RAINFALL TO CAUSE
LOCALIZED MINOR FLOODING.
LARGER RIVERS SHOULD BE ABLE TO HANDLE THE MOST LIKELY RAIN AND
SNOWMELT, THOUGH THEY WILL BE RUNNING HIGH. THERE IS A SMALL
CHANCE OF RAIN THAT IS HEAVIER THAN EXPECTED ON A SCALE OF A
COUNTY OR TWO, THAT COULD PRODUCE FLOODING ON ONE OF THE LARGER
RIVERS. AT THIS TIME, THIS APPEARS TO BE A LOW PROBABILITY (10
PERCENT OR LESS).
BOU WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...GIMMESTAD
AVIATION...HIRIS
HYDROLOGY...GIMMESTAD
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