017
FXUS65 KBOU 231743
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1143 AM MDT WED OCT 23 2024
KEY MESSAGES
- DRY WITH ABOVE NORMAL TEMPERATURES THROUGH THURSDAY. INCREASING
WINDS AND AT LEAST ELEVATED FIRE WEATHER CONDITIONS THURSDAY DUE
TO A FAST MOVING DISTURBANCE AND COLD FRONT.
- SLIGHTLY COOLER TEMPERATURES LATE THURSDAY INTO FRIDAY, THOUGH
TEMPERATURES WILL STILL REMAIN NEAR OR ABOVE NORMAL.
- PATTERN CHANGE LIKELY EARLY NEXT WEEK. HIGH PROBABILITIES OF
BELOW NORMAL TEMPERATURES BEYOND TUESDAY (>70%), AND A CHANCE
FOR THE FIRST WINTRY WEATHER ACROSS THE PLAINS BY MID-WEEK.
UPDATE
ISSUED AT 953 AM MDT WED OCT 23 2024
NOT MANY CHANGES FOR TODAY. JUST A FEW HIGH CLOUDS PASSING ACROSS
THE NORTHERN 1/5 OF COLORADO, AND INTERMITTENT LENTICULAR CLOUDS
ACROSS THE NORTHERN FRONT RANGE. TEMPERATURES ARE WAY AHEAD OF
THE CAMS THIS MORNING, BUT THAT'S OKAY BECAUSE THE OFFICIAL
FORECAST IS ALSO AHEAD OF THE CAMS. TEMPERATURES CURRENTLY IN THE
50S WILL WARM TO THE MID 70S TODAY ACROSS THE PLAINS AND URBAN
CORRIDOR, AND SOUTH WINDS WILL PICK UP THIS AFTERNOON TOO ACROSS
THE PLAINS. THE MOUNTAIN VALLEYS LOOK GORGEOUS TODAY WITH HIGHS
REACHING THE 60S.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 243 AM MDT WED OCT 23 2024
DRY WESTERLY FLOW ALOFT WILL BE OVER THE AREA TODAY. A WEAK COOL
FRONT THAT AFFECTED THE PLAINS LAST EVENING WILL WASH OUT LATER THIS
MORNING INTO THE AFTN. THIS WILL ALLOW FOR INCREASING SOUTHERLY LOW
LEVEL FLOW ACROSS THE PLAINS THIS AFTN. AFTN HIGHS WILL BE SLIGHTLY
COOLER AS READINGS RANGE FROM THE MID 60'S OVER THE FAR NERN PLAINS
WITH LOWER TO MID 70'S ALONG THE I-25 URBAN CORRIDOR.
FOR TONIGHT, THE FLOW ALOFT WILL BECOME MORE WSW AS A QUICK MOVING
UPPER LEVEL TROUGH APPROACHES FROM THE NW. ANY MOISTURE WITH THIS
FEATURE WILL NOT AFFECT THE NRN MTNS UNTIL AFTER 12Z THU. MEANWHILE
WINDS WILL INCREASE ACROSS THE HIGHER TERRAIN OVERNIGHT AS CROSS-
BARRIER FLOW INCREASES TO 35-40 KTS LATE TONIGHT. THUS MAY SEE SOME
GUSTS FROM 50-60 MPH ACROSS PORTIONS OF THE MTNS AND NRN FOOTHILLS.
LONG TERM /THURSDAY THROUGH TUESDAY/
ISSUED AT 243 AM MDT WED OCT 23 2024
WE'LL START THURSDAY WITH A FAIRLY STRONG SHORTWAVE TRACKING JUST
TO OUR NORTH. THE FLOW ALOFT SHOULD INCREASE QUITE A BIT ON
THURSDAY, AND GUSTY WINDS WILL LIKELY DEVELOP ACROSS MOST OF THE
FORECAST AREA AS WIDESPREAD SUBSIDENCE ENTERS IN THE WAKE OF THE
PASSING SHORTWAVE. HIGH RESOLUTION GUIDANCE HINTS AT SOME MOUNTAIN
WAVE AMPLIFICATION THURSDAY MORNING AS THE STABLE LAYER SINKS,
THOUGH THIS WOULD BE BRIEF BEFORE TRANSITIONING TO THE GRADIENT
WINDS. MEANWHILE, A COLD FRONT IS STILL EXPECTED TO TRACK THROUGH
THE PLAINS DURING THE DAY, WITH GUIDANCE PERHAPS A HAIR QUICKER
WITH THE ARRIVAL OF (SLIGHTLY) COOLER TEMPERATURES BEHIND THE
FRONT. THE EARLIER FRONTAL PASSAGE WOULD LIKELY LIMIT THE EXTENT
OF CRITICAL FIRE WEATHER CONDITIONS... BUT TEMPERATURES WILL STILL
BE ABOVE NORMAL, AND THE POST-FRONTAL AIRMASS IS STILL QUITE
DRY... MEANING THAT WIDESPREAD ELEVATED TO NEAR CRITICAL
CONDITIONS ARE STILL EXPECTED THURSDAY AFTERNOON. DIDN'T FEEL
CONFIDENT ENOUGH FOR ANY FIRE WX HIGHLIGHTS AT THIS TIME, AND
WE'LL SEE IF THE DAY SHIFT HAS MORE CONFIDENCE THAN I DO.
FRIDAY SHOULD BE ON THE COOLER SIDE (THOUGH STILL ABOVE NORMAL
FOR THE METRO), WITH QUIET WEATHER. A WARM AIR ADVECTION REGIME
GRADUALLY DEVELOPS DURING THE DAY, AS A RIDGE BEGINS TO QUICKLY
BUILD TO THE SOUTHWEST OF THE FORECAST AREA. MUCH WARMER
TEMPERATURES ARE FORECAST BY THIS WEEKEND AS THE RIDGE EXPANDS AND
SOUTHWESTERLY FLOW ALOFT INCREASES. SATURDAY SHOULD SEE HIGHS
RETURN TO THE 70S ACROSS THE LOWER ELEVATIONS, WITH UPPER 70S
LIKELY BY SUNDAY. IT WOULDN'T BE SURPRISING IF A COUPLE OF SITES
ENDED UP IN THE LOW 80S IN THIS TYPE OF PATTERN, WHICH IS
SUPPORTED BY A HANDFUL OF ENSEMBLE MEMBERS. WELL ABOVE NORMAL
TEMPERATURES MAY LINGER INTO MONDAY AS WELL.
AS WE GET INTO NEXT WEEK, GUIDANCE CONTINUES TO SUGGEST A RATHER
SIGNIFICANT PATTERN CHANGE FOR THE REGION. DETERMINISTIC AND
ENSEMBLE GUIDANCE SHOWS A BROAD, STRONG TROUGH AXIS PUSHING INTO
THE AREA BY EARLY/MID WEEK, WHICH WOULD USHER IN MUCH COOLER
TEMPERATURES ACROSS THE FORECAST AREA. WHILE THE SPECIFICS CAN'T
BE WORKED OUT JUST YET, A LOOK AT WPC'S CLUSTER ANALYSIS SHOWS
THAT THE MAIN UNCERTAINTY IN THIS PERIOD COMES FROM THE
AMPLITUDE/TIMING OF THE TROUGH, RATHER THAN THE EXISTENCE OF THE
TROUGH ITSELF - LEADING TO A RELATIVELY HIGH CONFIDENCE FORECAST
OF NEAR/BELOW NORMAL TEMPERATURES TUESDAY AND BEYOND. ALTHOUGH
WE'RE A FEW DAYS AWAY FROM GETTING A GOOD HANDLE ON PRECIPITATION
POTENTIAL, IT'S WORTH NOTING THAT TONIGHT'S ECMWF ENSEMBLE HAS
>50% PROBABILITIES OF ACCUMULATING SNOW ACROSS THE METRO BY THE
END OF THE FORECAST PERIOD - SIGNALING THE BEST CHANCE OF WINTRY
WEATHER FOR THE DENVER METRO SO FAR THIS SEASON.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1143 AM MDT WED OCT 23 2024
VFR THROUGH THURSDAY. WINDS WILL PICK UP FROM THE SOUTH-SOUTHEAST
THIS AFTERNOON AT THE TAF SITES, 7-12 KTS OR SO. DRAINAGE FLOW
WILL BE AMPLIFIED AT DEN AND APA BY THE PRESSURE GRADIENT
OVERNIGHT, 12-15KTS LIKELY OUT OF THE SOUTH OR SSW AT DEN AND APA.
BJC SHOULD BE LIGHT OUT OF THE WEST UNTIL A MOUNTAIN WAVE
DEVELOPS AROUND OR A LITTLE AFTER SUNRISE. THERE IS A LITTLE
UNCERTAINTY ABOUT THE STRONG WEST WINDS MAKING IT EAST OF THE
FOOTHILLS BUT WE THINK THEY WILL, HENCE THE STRONG WEST WINDS IN
THE BJC TAF BY 13Z. THERE IS A CHANCE GUSTS EXCEED 40 KTS AT BJC,
BUT REMAINING A LITTLE MORE CONSERVATIVE FOR NOW IN THE TAF.
AT DEN AND APA, THERE WILL BE SEVERAL HOURS OF STRONGER WEST WINDS
BEFORE THE COLD FRONT MOVES THROUGH. FOR NOW, IT LOOKS LIKE 2-3
HOURS OF WEST OR WSW WINDS GUSTING TO AROUND 25KTS, STARTING
AROUND 14Z. THE STRONG COLD FRONT SHOULD MOVE THROUGH DEN AROUND
16Z, WITH NORTH WINDS GUSTING OVER 30 KTS. THE FRONT SHOULD REACH
APA BETWEEN 1630-17Z, BUT THE WINDS SHOULD BE WEAKER, GUSTING TO 25,
MAYBE 30 KTS. EXPECT NORTHERLY WINDS THROUGH 00Z FRIDAY AT APA
AND DEN, WHEN THEY WILL WEAKEN BELOW 15 KTS. BJC SHOULD BE
SHELTERED FROM THE STRONG NORTH WINDS TOMORROW, WHERE MAYBE 10 KTS
OUT OF THE NORTH OR NORTHWEST LOOKS LIKELY.
BOU WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...SCHLATTER
SHORT TERM...RPK
LONG TERM...HIRIS
AVIATION...SCHLATTER
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