025
FXUS65 KBOU 230523
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1123 PM MDT TUE OCT 22 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. CHANCE (30-40%) OF THE
SEASON'S FIRST SNOW INTO THE I-25 CORRIDOR AND PLAINS.
UPDATE
ISSUED AT 936 PM MDT TUE OCT 22 2024
SATELLITE PICTURES ARE SHOWING SOME UPPER LEVEL CLOUDINESS
IN THE WEST-NORTHWESTERLY FLOW ALOFT OVER THE NORTHERN HALF OF THE
CWA THIS EVENING. UPSTREAM RADARS ARE SHOWING A WEAK COLD FRONT
PUSHING SOUTH-SOUTHWESTERLY NOW OVER SOUTHEASTERN WYOMING HEADING
OUR WAY. IT SHOULD BE THROUGH MOST OF THE PLAINS BY 12Z WEDNESDAY
MORNING. WILL MAKE A FEW MINOR ADJUSTMENTS TO THE SKY, WIND AND
TEMPERATURES GRIDS BASED ON REALITY.
SHORT TERM /THROUGH WEDNESDAY/
ISSUED AT 230 PM MDT TUE OCT 22 2024
WATER VAPOR IMAGERY SHOWS DRY AIR OVER COLORADO WITH AN EAST-WEST
ORIENTED JET STREAM FROM OREGON THROUGH WYOMING. COLORADO WILL
CONTINUE TO BE UNDER SUBSIDENT FLOW UNDER THE RIGHT EXIT REGION OF
THE JET. THIS EVENING AND TONIGHT WILL BE RELATIVELY MILD WITH A
FEW HIGH CLOUDS COMING ACROSS.
AT THE SURFACE, THERE IS A COLD FRONT CURRENTLY IN WYOMING THAT HAS
PASSED THROUGH BUFFALO AND GILLETTE ON ITS WAY THROUGH CASPER AND
DOUGLAS SOON. THIS FRONT WILL MOVE SOUTHWARD TONIGHT AND WILL
PENETRATE THROUGH THE EASTERN PLAINS OF COLORADO BETWEEN MIDNIGHT
(AT THE WY/CO BORDER) AND 6AM (AT THE PALMER DIVIDE). THIS FRONT
WILL BRING SLIGHTLY COOLER AIR BUT LOWS WILL STILL BE ABOVE NORMAL
BY A FEW DEGREES. SOME AREAS IN THE SOUTH PLATTE RIVER VALLEY BY
GREELEY COULD SEE SOME FROST AGAIN DURING THE MORNING. WITH WINDS
UNLIKELY TO BE CALM DUE TO THE FRONTAL PASSAGE, THE FROST WILL
LIKELY BE LIMITED IN COVERAGE AND NO HIGHLIGHTS ARE NEEDED.
WEDNESDAY MORNING WILL HAVE COOL TEMPERATURES DUE TO THE POST-
FRONTAL AIRMASS BEING IN PLACE. BY THE AFTERNOON, SOUTHERLY WINDS
WILL DEVELOP ACROSS THE PLAINS AS LEE CYCLOGENESIS FORMS OVER
WYOMING. WITH SUNNY SKIES, TEMPERATURES WILL WARM ABOVE NORMAL WITH
HIGHS REACHING THE UPPER 60S TO LOW 70S ACROSS THE PLAINS.
LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/
ISSUED AT 230 PM MDT TUE OCT 22 2024
AN UPPER LEVEL RIDGE WILL SHIFT EAST OF THE AREA WEDNESDAY NIGHT,
AS A FAST MOVING SHORTWAVE RACES EAST ACROSS IDAHO AND NORTHERN
GREAT BASIN. FLOW ALOFT WILL BEGIN TO INCREASE, WITH AN INCREASING
DOWNSLOPE COMPONENT AND THUS SHALLOW INVERSIONS TO START THE DAY
THURSDAY. THURSDAY'S MAIN CONCERN SURROUNDS THE TIMING OF THE
SHORTWAVE, AS THAT HAS IMPLICATIONS ON TEMPERATURE FORECASTS AND
THUS FIRE WEATHER CONCERNS. THERE WILL ALMOST CERTAINLY BE GUSTY
WINDS (TO ~40 MPH) IN THE WAKE OF THE SHORTWAVE AND DEVELOPMENT
OF LARGE SCALE SUBSIDENCE. AT THIS TIME, THERE IS REASONABLE
AGREEMENT THAT THE COLD ADVECTION ARRIVES BY LATE MORNING, AND
THEN STRENGTHENS THROUGH THE AFTERNOON DURING WHAT NORMALLY WOULD
BE PEAK HEATING. THAT SHOULD LIMIT DAYTIME MAXES A BIT, BUT
TEMPERATURES WILL STILL BE SEVERAL DEGREES ABOVE NORMAL. ANY
MOISTURE ADVECTION WITH THE SHORTWAVE APPEARS MARGINAL AND MOSTLY
TO OUR NORTH. THUS, WE THINK AT LEAST ELEVATED IF NOT CRITICAL
FIRE WEATHER CONDITIONS WILL DEVELOP IN THE LOWER FOOTHILLS AND
PLAINS WHERE HUMIDITIES WILL BE LOWEST (15-22%). IT SHOULD BE
NOTED THAT SOME MODELS HAVE A SLIGHTLY EARLIER ARRIVAL OF THE
FRONT AND THUS COOLER TEMPERATURES AND MORE MOISTURE RESULTING IN
HIGHER RH, BUT WE MAY NEED A FIRE WEATHER HIGHLIGHT IN THE COMING
SHIFTS DEPENDING ON THE SPEED OF THE SHORTWAVE. THERE IS JUST
ENOUGH MID LEVEL MOISTURE ALONG THE NORTHERN BORDER AREA FOR A
FEW PASSING SNOW SHOWERS IN THE NORTHERN MOUNTAINS, BUT LITTLE IF
ANY ACCUMULATION.
FRIDAY WILL BE A FEW DEGREES COOLER ON THE PLAINS IN THE WAKE OF
THURSDAY'S SHORTWAVE AND COLD FRONT, BUT MOUNTAIN AREAS WILL TREND
WARMER WITH THE ONSET OF WARM ADVECTION ALOFT AND MORE SUNSHINE.
A SIGNIFICANT WARMING TREND WILL OCCUR THROUGH THE WEEKEND, WITH
MUCH ABOVE NORMAL TEMPERATURES REESTABLISHING THEMSELVES IN WARM
WEST/SOUTHWEST FLOW ALOFT. THERE IS GOOD AGREEMENT IN THE
ENSEMBLES THAT HIGHS WILL APPROACH 80F ON THE PLAINS BY SUNDAY,
WITH SOME MEMBERS REACHING RECORD HIGHS (83F IN DENVER, FOR
EXAMPLE). WITH THAT WARMTH, WE'LL AGAIN SEE FIRE WEATHER CONCERNS
INCREASE DEPENDING ON HOW STRONG THE FLOW ALOFT IS. THAT WOULD
LIKELY LAST INTO MONDAY IN PREFRONTAL WARMTH, BUT SOME UNCERTAINTY
STARTS TO CREEP INTO THE FORECAST WITH TIMING OF THE NEXT PATTERN
CHANGE.
AT LEAST THERE'S GOOD AGREEMENT IN THE ENSEMBLES THAT WE WILL SEE
A PATTERN CHANGE SOMETIME EARLY NEXT WEEK. MOST LIKELY THIS
OCCURS BY TUESDAY PER ENS (AND WEDNESDAY PER GEFS), WITH ARRIVAL
OF MUCH COOLER TEMPERATURES AND A CHANCE OF RAIN OR SNOW IN THE
LOWER ELEVATIONS. MOST ENS MEMBERS MAINTAIN SOME SNOW IN THE
FORECAST, WHILE THE GEFS WAS DECIDEDLY DRIER WITH ONLY A HANDFUL
OF MEMBERS SHOWING ANY SNOW, OR RAIN FOR THAT MATTER. EVEN THE
VAST MAJORITY OF ENS MEMBERS ARE QUITE LIGHT WITH REGARD TO QPF,
SO NOT EXPECTING MUCH CHANCE OF SIGNIFICANT PRECIPITATION. THE
MOUNTAINS COULD STILL SEE A FEW INCHES IN THIS TYPE OF PATTERN,
HOWEVER.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1116 PM MDT TUE OCT 22 2024
A WEAK FRONT WAS MOVING INTO DIA WHICH WILL ALLOW FOR A NE WIND
FOR A FEW HOURS. WINDS MAY BECOME LIGHT SE BY 09Z AND THEN
SSW BY 12Z. LATE WED MORNING WINDS WILL BECOME SE AND REMAIN
THAT DIRECTION THRU THE AFTN. BY EARLY WED EVENING WINDS
WILL BECOME MORE SSW. AT THIS TIME, VFR CONDITIONS ARE EXPECTED
THRU THE PERIOD. THERE COULD BE SOME STRATUS TOWARDS SUNRISE TO
THE NORTH AND NORTHEAST OF DIA, HOWEVER, FOR NOW WILL KEEP IT OUT
OF THE 06Z TAF.
BOU WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE.......RJK
SHORT TERM...DANIELSON
LONG TERM....BARJENBRUCH
AVIATION...RPK
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