060
FXUS65 KBOU 252121
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
321 PM MDT MON AUG 25 2025
KEY MESSAGES
- CONTINUED ACTIVE PATTERN THROUGH THE NEXT SEVERAL DAYS, WITH
BELOW NORMAL TEMPERATURES LIKELY.
- THE MAJORITY OF DAYS WILL HAVE WIDESPREAD COVERAGE OF SHOWERS
AND STORMS ACROSS THE HIGHER TERRAIN AND SCATTERED COVERAGE
ACROSS THE LOWER ELEVATIONS.
- LOCALLY HEAVY RAINFALL POSSIBLE, INCLUDING SOME POTENTIAL FOR
BURN AREA FLASH FLOODING WITH ANY STORMS OVER THE NEXT FEW DAYS.
DISCUSSION /THROUGH MONDAY/
ISSUED AT 226 PM MDT MON AUG 25 2025
A WAVE OF SHOWERS AND STORMS IS MOVING ACROSS THE FOOTHILLS AND
ONTO THE I-25 CORRIDOR THIS AFTERNOON. WITH AMPLE MOISTURE FOR
COLORADO STANDARDS AND LONG, SKINNY CAPE PROFILES, THE SHOWERS
AND STORMS ARE PRODUCING EFFICIENT RAINFALL. WITH SLOW MOVING
STORMS, THIS MAY PROVIDE A FLASH FLOODING THREAT ESPECIALLY OVER
THE BURN AREAS. HOWEVER, SINCE IT WAS CLOUDY ALMOST THE ENTIRE DAY
AND LOW LEVEL TEMPERATURES DID NOT WARM UP VERY MUCH, THE
INSTABILITY IS QUITE LIMITED. MIXED-LAYER CAPE IS AROUND 500 J/KG
FOR MUCH OF THE AREA AND NO SEVERE STORMS ARE EXPECTED. IN
ADDITION, THE LACK OF VERY INTENSE UPDRAFTS/STORMS IS LIMITING THE
FLASH FLOODING THREAT AS WELL. OVERALL, THERE IS OPTIMISM THAT
THERE WILL BE GREAT COVERAGE OF SHOWERS AND STORMS WITHOUT THE
FLOODING RAINFALL.
TUESDAY WILL BEGIN IN A SIMILAR WAY TO TODAY. THERE WILL BE PATCHY
FOG ACROSS THE SOUTH PLATTER RIVER VALLEY AND SOME FOG COULD
DEVELOP OVER THE DENVER METRO. A SHORTWAVE TROUGH WILL ARRIVE MUCH
LATER IN THE AFTERNOON THAN MONDAY WHICH MEANS SHOWERS AND STORMS
WILL BE SLOWER TO DEVELOP. THE HIGHER TERRAIN WILL SEE STORMS
BEGIN IN THE EARLY AFTERNOON WITH 70-80 PERCENT COVERAGE. ACROSS
THE I-25 CORRIDOR AND EASTERN PLAINS, CONDITIONS WILL BE SOMEWHAT
STABLE. WHILE MODELS LIKE THE HRRR PRODUCE STRONG STORMS, THERE IS
SKEPTICISM DUE TO THE STABILITY AND A SOLUTION MORE LIKE THE NAM
NEST IS FAVORED. THAT IS, SHOWERS AND STORMS WEAKENING
SUBSTANTIALLY AS THEY HEAD OVER LOWER ELEVATIONS.
WEDNESDAY AND THURSDAY APPEAR TO BE WET WITH MORE INTENSE STORMS
THAN MONDAY AND TUESDAY. EACH DAY WILL HAVE A SHORTWAVE TROUGH
THAT WILL BE PROVIDING FORCING AS WELL AS DEEPENING A SURFACE LOW
PRESSURE SYSTEM OVER SOUTHEAST COLORADO. THIS WILL INCREASE THE
EASTERLY, UPSLOPE FLOW AND WILL KEEP THE HIGH MOISTURE VALUES IN
PLACE. IT REMAINS TO BE SEEN IF TEMPERATURES WILL ACTUALLY WARM UP
AS THE MODELS SUGGEST BUT IF TEMPERATURE DO REACH THE 80S ACROSS
THE PLAINS EACH DAY, THERE COULD BE STRONG TO SEVERE STORMS. WHAT
IS MORE LIKELY IS THESE STORMS WILL PRODUCE HEAVY RAINFALL WHICH
COULD LEAD TO FLASH FLOODING. POPS ARE GENERALLY IN THE 60-80%
RANGE FOR EACH DAY.
THERE WILL BE A SLIGHT DECREASE IN PRECIPITABLE WATER ON FRIDAY
AND SATURDAY WHICH WILL LEAD TO LESS COVERAGE OF STORMS.
SCATTERED SHOWERS AND STORMS ARE STILL EXPECTED WITH A FLASH FLOOD
THREAT.
THE WET PATTERN MAY END ON SUNDAY OR MONDAY AS DRIER AIR MOVES IN
WITH SUBSIDENT FLOW. A RIDGE ALOFT APPEARS IT MAY DEVELOP INTO
EARLY NEXT WEEK WITH WARMER AND DRIER WEATHER.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1157 AM MDT MON AUG 25 2025
CEILINGS IN THE 3-4 KFT RANGE WILL PERSIST THROUGH AROUND 21Z AND
PERHAPS FURTHER INTO THE AFTERNOON AT ALL TERMINALS. SHOWERS AND
STORMS HAVE FORMED OVER THE HIGHER TERRAIN BUT WITH SUCH STABLE
CONDITIONS, IT IS UNCERTAIN HOW THEY WILL HOLD TOGETHER OVER THE
PLAINS. THERE WAS CONSIDERATION FOR CHANGING THE TEMPO TO A PROB30
SINCE THERE IS LESS CONFIDENCE THAT STORMS WILL IMPACT THE
TERMINALS BUT WITH ACARS SOUNDINGS SHOW ENOUGH INSTABILITY, THE
TEMPOS WERE KEPT. THE PRIMARY CONCERN FROM THE STORMS WILL BE
HEAVY RAINFALL WHICH COULD LOWER VISIBILITY AND CEILINGS.
TONIGHT, THE HIGH HUMIDITY WILL STICK AROUND AND THE THREAT FOR
FOG WILL EXIST AGAIN. AT THE MOMENT, MODELS KEEP THE FOG JUST OFF
THE TERMINALS OF DEN AND BJC SO VCFG WAS ADDED TO FORECAST. IF FOG
WERE TO MOVE OVER A TERMINAL, VISIBILITY DOWN TO 1/4SM WILL BE
POSSIBLE 10-15Z.
ANOTHER ROUND OF SHOWERS AND STORMS IS POSSIBLE TUESDAY AFTERNOON.
THERE WILL BE A STRONG CAP TOMORROW, SO THE CHANCE OF IMPACTS AT
THE TERMINALS IS AROUND 30 PERCENT SO A PROB30 WAS ADDED TO THE
FORECAST.
HYDROLOGY
ISSUED AT 226 PM MDT MON AUG 25 2025
PRECIPITABLE WATER VALUES WILL BE WELL ABOVE NORMAL TODAY AND
TUESDAY. STORMS THAT DEVELOP WILL BE SLOW MOVING AND WILL HAVE
EFFICIENT RAINFALL PROCESSES. THIS WILL LEAD TO A THREAT OF FLASH
FLOODING ESPECIALLY OVER THE BURN AREAS. HOWEVER, THERE WILL BE
LIMITED INSTABILITY EACH DAY SO THERE IS HOPE THAT STORMS WILL NOT
BE INTENSE ENOUGH TO PRODUCE MUCH FLOODING.
SIMILAR MOISTURE AND RAINFALL PROCESSES ARE EXPECTED WEDNESDAY AND
THURSDAY. HOWEVER, THERE WILL BE BETTER FORCING AND HIGHER
INSTABILITY VALUES EACH DAY. THEREFORE, THE THREAT OF FLASH
FLOODING WILL INCREASE AND A FLOOD WATCH FOR FLASH FLOODING MAY BE
NEEDED.
BOU WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...DANIELSON
AVIATION...DANIELSON
HYDROLOGY...DANIELSON
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