830
FXUS65 KBOU 151938
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
138 PM MDT WED OCT 15 2025
KEY MESSAGES
- ISOLATED AFTERNOON THUNDERSTORMS WEDNESDAY, MAINLY SOUTH OF
I-76. LOCALIZED GUSTS 55-70 MPH NEAR STRONGEST STORMS.
- PATCHY FROST EXPECTED FOR PORTIONS OF THE PLAINS THURSDAY
NIGHT/FRIDAY MORNING, WITH MORE WIDESPREAD FREEZE ANTICIPATED
SATURDAY NIGHT FOR THE RURAL PLAINS.
- COOLER AND BREEZY MOST DAYS THROUGH THIS WEEKEND. NEXT POTENTIAL
FOR MORE WIDESPREAD PRECIPITATION ARRIVES MONDAY.
DISCUSSION /THROUGH WEDNESDAY/
ISSUED AT 1254 PM MDT WED OCT 15 2025
AFTER A MORNING OF DENSE FOG FOR MANY LOCATIONS ALONG AND NORTH OF
I-76, THE STRATUS HAS FINALLY ERODED, NOT WITHOUT LEAVING A SWATH
OF NOTABLY COOLER AIR IN THESE AREAS. IN THE MEANTIME, HEALTHY
SOUTHERLY FLOW CONTINUES TO OVERSPREAD THE SOUTHERN HALF OF OUR
FORECAST AREA, WITH CLEAR SKIES AND THE DOWNSLOPE PATTERN OFF THE
PALMER DIVIDE BOOSTING TEMPERATURES TO AROUND 80F IN THE WARMEST
LOCATIONS. THIS SURFACE WARMING WILL ALLOW FOR MODEST INSTABILITY
TO DEVELOP THIS AFTERNOON (MLCAPE 300-700 J/KG ACROSS THE EASTERN
PLAINS). WATER VAPOR IMAGERY ALREADY DEPICTS SOME ELEVATED
CONVECTION TO OUR EAST EMBEDDED WITHIN A MOIST WARM ADVECTION
LAYER ALOFT, AND CONVECTION SHOULD DEVELOP OVER/NEAR THE PALMER
DIVIDE BY MID TO LATE AFTERNOON AS WE TAP INTO THIS ELEVATED
MOISTURE. STEERING FLOW WILL REMAIN ROBUST, THUS KEEPING STORMS
MOVING VERY QUICKLY, BUT SIMULTANEOUSLY INCREASING THE OUTFLOW
WIND POTENTIAL WITH ANY STORMS THAT DO DEVELOP. A SEVERE STORM
CAN'T BE RULED OUT LATE AFTERNOON OR EARLY EVENING, PRIMARILY FROM
THE WIND THREAT (THE STRONGEST STORMS COULD PRODUCE LOCALIZED
GUSTS UP TO 70 MPH) AND FAVORING LINCOLN/WASHINGTON COUNTIES, BUT
CONFIDENCE ISN'T OVERLY HIGH. FOR THE LOWER ELEVATIONS,
THUNDERSTORM ACTIVITY SHOULD REMAIN CONFINED TO LOCATIONS SOUTH OF
I-76. RADAR SHOWS A WELL-DEFINED DCVZ BOUNDARY CURRENTLY SOUTH OF
DENVER INTERNATIONAL AIRPORT AND, WHILE SOME NORTHWARD MIGRATION
OF THIS BOUNDARY CAN BE EXPECTED THROUGHOUT THE AFTERNOON, IT
SEEMS UNLIKELY TO CROSS THAT I-76 CORRIDOR.
COME THIS EVENING, MOST AREAS WILL STAND A CHANCE (20-50%) OF
SEEING SOME PRE-FRONTAL SHOWERS AS THE TROUGH AXIS AND JET MAX
APPROACH. THE BULK OF THE SHOWER ACTIVITY WILL BE FOCUSED OVER OUR
NORTHERN MOUNTAINS, WHERE LIGHT SNOW COULD ACCUMULATE TO AROUND 1"
ABOVE 9,500 FT BY THURSDAY MORNING (MAINLY FOR THE PARK AND
MEDICINE BOW RANGES). EXPECT COOLER TEMPERATURES THURSDAY
FOLLOWING THE ASSOCIATED MORNING COLD FRONT, WITH THE CHANGE BEING
MOST PRONOUNCED IN OUR MOUNTAINS (15 TO 20 DEGREES COOLER THAN
TODAY). SHOWERS WILL GENERALLY SUBSIDE BY THE AFTERNOON, SAVE FOR
PERHAPS OUR FAR NORTHEAST CORNER. WITH CLEARING SKIES AND OUR
POST-FRONTAL AIRMASS IN PLACE, PATCHY FROST WILL RETURN TO
PORTIONS OF THE PLAINS, PARTICULARLY AROUND THE SOUTH PLATTE RIVER
VALLEY AND IN LINCOLN COUNTY, PROMPTING THE ISSUANCE OF A FROST
ADVISORY FOR THESE LOCATIONS. SEASONAL CONDITIONS ARE IN STORE
FOR FRIDAY UNDER WEAK FLOW ALOFT AS THE TROUGH SHEARS OFF, WITH
HIGHS IN THE 60'S FOR THE PLAINS AND URBAN CORRIDOR, AND 40'S TO
50'S FOR OUR MOUNTAIN COMMUNITIES.
SATURDAY'S WEATHER WILL BE INFLUENCED BY AN AMPLIFYING TROUGH
DIPPING DOWN FROM THE NORTHERN PLAINS. BRUSHING US TO THE
NORTHEAST, IT WILL USHER IN SLIGHTLY COOLER TEMPERATURES ONCE
MORE, INCLUDING OVERNIGHT WHEN LOWS LOOK TO FALL BELOW FREEZING
FOR MUCH OF THE PLAINS. ADDITIONALLY, BREEZY CONDITIONS WILL
BECOME INCREASINGLY WIDESPREAD. THE SHORTWAVE WOULD ALSO SUPPORT
AT LEAST A CHANCE (~30%) FOR SOME LIGHT SNOW SHOWERS IN OUR
NORTHERN MOUNTAINS DURING THE DAY.
HIGHLY TRANSIENT RIDGING WILL FOLLOW SUIT FOR SUNDAY, BRINGING
ABOUT 10 DEGREES OF WARMING AND KEEPING ALL AREAS DRY. EYES THEN
TURN TO MONDAY, WITH ENSEMBLES HIGHLIGHTING ANOTHER DEVELOPING
TROUGH OVER THE PACNW APPROACHING THE CENTRAL ROCKIES. THIS
FEATURE WILL GIVE WAY TO OUR NEXT OPPORTUNITY FOR MORE WIDESPREAD
PRECIPITATION, ALTHOUGH UNCERTAINTY IN THE TRACK REMAINS
PARTICULARLY NOTABLE AND COULD SIGNIFICANTLY IMPACT PRECIPITATION
CHANCES. NONETHELESS, THE AIRMASS SHOULD BE COLDER, SUPPORTING
SNOW FOR MOST OF OUR HIGHER ELEVATIONS AND, IF THE COLDEST
SOLUTIONS WERE TO VERIFY, PERHAPS INTRODUCE SOME WINTRY
PRECIPITATION TO THE LOWER ELEVATIONS MONDAY NIGHT INTO TUESDAY.
PLENTY OF TIME FOR THOSE DETAILS TO CHANGE STILL, OF COURSE.
FINALLY, WILL NEED TO MONITOR THE SPATIAL EXTENT OF ANY LINGERING
DRIER AIRMASS ON MONDAY, WHICH IF REMAINING FAR ENOUGH NORTH, MAY
RESULT IN LOCALLY CRITICAL FIRE WEATHER CONDITIONS FOR PORTIONS
OF OUR SOUTHERN PLAINS MONDAY AS WINDS STRENGTHEN.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1140 AM MDT WED OCT 15 2025
FOG AND LOW CLOUDS HAVE BEEN SLOW TO BURN OFF THIS MORNING, BUT
ANY LINGERING LOW CLOUDS/FOG WILL STAY NORTH OF DEN. RADAR SHOWING
THE DENVER CYCLONE/CONVERGENT LINE TO THE SOUTH OF DEN. THIS WILL
RESULT IN NORTH TO NORTHEAST WINDS UNTIL IT LIFTS NORTHWARD
(AROUND 21 TO 22Z). AFTER THIS, SOUTHERLY WINDS TO 30 KNOTS WILL
BE POSSIBLE. THESE SOUTHERLY WINDS WILL BE GUSTY AT TIMES AND
PERSIST THROUGH THE NIGHT. WILL CONTINUE WITH THE PROB30 FOR
THUNDERSTORMS (22-04Z). CONFIDENCE IN THE MODELS (REGARDING
THUNDERSTORMS) IS VERY LOW WITH THEM PERFORMING POORLY THIS
MORNING WITH THE CONVECTION OFF TO THE SOUTHEAST OF DENVER.
FOR THURSDAY MORNING, CAN'T RULE OUT ANOTHER ROUND OF LOW CLOUDS
AND FOG WITH NORTHERLY WINDS PER THE NAM MODEL. HOWEVER, THE OTHER
MODELS KEEP A SOUTHERLY FLOW OVER THE DENVER AREA THROUGH THE
NIGHT AND INTO THURSDAY MORNING WITH LOWER PRESSURE OFF TO THE
NORTHEAST. WILL GO WITH THIS SCENARIO FOR THE FORECAST. WINDS THEN
SLOWLY TURN CLOCKWISE THROUGH THURSDAY WITH NORTH TO NORTHWEST
WINDS EXPECTED TOWARDS 00Z FRIDAY.
BOU WATCHES/WARNINGS/ADVISORIES
FROST ADVISORY FROM 2 AM TO 8 AM MDT FRIDAY FOR COZ042-043-046.
DISCUSSION...BRQ
AVIATION...12
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