988
FXUS65 KBOU 011749
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1149 AM MDT SUN JUN 1 2025
.KEY MESSAGES.
- A FEW MORE SHOWERS AND STORMS TODAY, WITH WARMER WEATHER. HIGHS
IN THE MID/UPPER 80S ACROSS THE PLAINS.
- STILL ON TRACK FOR A WIDESPREAD RAINFALL EVENT MONDAY AFTERNOON
INTO TUESDAY, ALONG WITH A RETURN TO BELOW NORMAL TEMPERATURES.
- SNOWMELT PLUS RAINFALL WILL LEAD TO HIGH FLOWS ON MOUNTAIN
STREAMS.
UPDATE
ISSUED AT 406 AM MDT SUN JUN 1 2025
TODAY IS EXPECTED TO BE THE WARMEST DAY OF THE WEEK, AS OUR CWA
SITS NEAR THE AXIS OF THE UPPER LEVEL RIDGE. TEMPERATURES SHOULD
EASILY REACH THE MID 80S ACROSS THE PLAINS, WITH SOME NEAR 90F
READINGS POSSIBLE DEPENDING ON HOW QUICKLY CONVECTIVE CLOUD COVER
DEVELOPS THIS AFTERNOON. SHOWERS AND STORMS WILL BE ISOLATED TO
SCATTERED ACROSS MAINLY THE HIGHER ELEVATIONS, WITH A FEW MAKING
THE TREK DOWN INTO THE I-25 CORRIDOR. GUSTY WINDS WOULD BE THE
MAIN THREAT WITH ANY STORMS TODAY WITH DCAPE VALUES CLOSER TO
1200-1400 J/KG THIS AFTERNOON.
MEANWHILE, WE CONTINUE TO SEE A TREND AWAY FROM THE MORE
SIGNIFICANT RAINFALL ADVERTISED BY GUIDANCE MONDAY NIGHT INTO
TUESDAY. MOST OVERNIGHT MODEL RUNS HAVE CONTINUED TO PULL AWAY
FROM A CLEAN INTERACTION BETWEEN THE SOUTHERN CUTOFF AND THE
LARGER SCALE TROUGH AXIS OVER THE NORTHERN ROCKIES. AS A RESULT...
THE SURFACE LOW ENDS UP WEAKER AND FURTHER SOUTHEAST, AND SYNOPTIC
SCALE LIFT IS QUICKER TO EXIT THE REGION. THERE STILL LOOKS TO BE
A FAVORABLE WINDOW FOR SOME MEANINGFUL RAINFALL MONDAY AFTERNOON
INTO MONDAY NIGHT... FIRST FROM THE ADVANCING SURFACE COLD FRONT
AS IT ENCOUNTERS A FAIRLY WARM/UNSTABLE AIRMASS, AND THEN IN THE
POST-FRONTAL/UPSLOPE REGIME WHERE WE STILL HAVE SOME QG ASCENT.
SOME OVERNIGHT CAMS WERE SURPRISINGLY DRY ACROSS THE CWA, BUT THE
LARGE SCALE SIGNAL FROM ENSEMBLE AND AIFS GUIDANCE WOULD STILL
FAVOR A CORRIDOR OF >0.50" OF RAINFALL ACROSS MUCH OF OUR EASTERN
PLAINS. THE MORE NOTABLE DRYING TREND IS FURTHER NORTHWEST ACROSS
MIDDLE/NORTH PARK AND THE SURROUNDING MOUNTAINS.
FINALLY, IT IS WORTH NOTHING THAT THERE IS AT LEAST A CONDITIONAL
SEVERE WEATHER THREAT MONDAY AFTERNOON ACROSS MOST OF LOWER
ELEVATIONS. WITH SURFACE DEW POINTS REMAINING IN THE UPPER 40S TO
MID 50S, MLCAPE SHOULD INCREASE TO 1000-1500 J/KG. WHILE DEEP
LAYER SHEAR IS MODEST, AT LEAST A FEW MULTICELL CLUSTERS OR
PERHAPS A SPLITTING SUPERCELL OR TWO (GIVEN RELATIVELY STRAIGHT
LINE HODOGRAPHS) WOULD BE POSSIBLE, ESPECIALLY CLOSER TO THE
NEBRASKA BORDER WHERE THE BETTER PARAMETER SPACE AND FORCING LIE
DURING THE AFTERNOON.
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 /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1149 AM MDT SUN JUN 1 2025
MAIN CONCERN WILL BE FOR GUSTY AND VARIABLE OUTFLOW WINDS FROM
PASSING SHOWERS/ISOLATED STORMS. SURFACE ANALYSIS SHOWS THAT DCAPE
HAS INCREASED TO >1300 J/KG AND WILL LIKELY PEAK OUT NEAR 1500
J/KG. CUMULUS IS ALREADY GROWING IN/NEAR THE MOUNTAINS, AND
EXPECT THEM TO GROW INTO SHOWERS/STORMS AND PUSH INTO THE
VICINITY OF THE TAF SITES 21Z-01Z. GUSTY OUTFLOW WINDS WILL BE THE
MAIN THREAT AS THEY WILL BE RELATIVELY HIGH BASED, AND ENOUGH
THREAT TO PUSH US INTO TEMPO FOR VRB WINDS G35-40KTS, AND
POTENTIAL (20-30% CHANCE) FOR 45KT GUSTS GIVEN EXPECTED DCAPE.
ACTIVITY SHOULD BE EAST OF METRO TAF SITES BY/BEFORE 01Z. THEN
FAIRLY NORMAL DIURNAL WIND PATTERNS WILL PREVAIL THROUGH TONIGHT.
STORM CHANCES WILL INCREASE FURTHER MONDAY AFTERNOON, WITH TEMPO
TSRA EXPECTED AFTER 21/22Z. VFR CONDITIONS WILL PERSIST FOR THIS
PERIOD.
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.
UPDATE...HIRIS
DISCUSSION...GIMMESTAD
AVIATION...BARJENBRUCH
HYDROLOGY...GIMMESTAD
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page