503
FXUS65 KBOU 180553
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1153 PM MDT THU OCT 17 2024
KEY MESSAGES
- MUCH COOLER TEMPERATURES ON FRIDAY AND SATURDAY.
- LIKELY TO WIDESPREAD PRECIPITATION FRIDAY NIGHT INTO SATURDAY
MORNING, WITH SNOW IN THE MOUNTAINS.
- SCATTERED TO LIKELY PRECIPITATION SATURDAY AFTERNOON INTO
SUNDAY...WITH SNOW IN THE MOUNTAINS.
- A FEW INCHES OF SNOW EXPECTED IN MOST OF THE MOUNTAINS, WITH
HEAVIER TOTALS SOUTH OF I-70.
- DRY AND WARMER FOR ALL THE FORECAST AREA MONDAY THROUGH
THURSDAY.
UPDATE
ISSUED AT 755 PM MDT THU OCT 17 2024
FORECAST IS PRETTY MUCH ON TARGET FOR TONIGHT, BUT WE DID MAKE
SOME ADJUSTMENTS MAINLY FOR TEMPERATURES TOMORROW. ONE AREA OF
LIFT HAS ROTATED EAST ACROSS THE PLAINS, WITH A NOTABLE DRY SLOT
ACROSS THE FRONT RANGE THIS EVENING. MORE PRECIPITATION WAS
ORGANIZING IN BETTER LIFT TO THE WEST IN NORTHWEST COLORADO AND
EASTERN UTAH, BUT THE MAJORITY OF THIS WILL ONLY REACH THE PARK
AND NORTHERN GORE RANGES TONIGHT.
A COLD FRONT WAS ALREADY PUSHING SOUTH THROUGH MUCH OF EASTERN
WYOMING. TEMPERATURES WERE MUCH COOLER BEHIND IT WITH READINGS
ONLY IN THE UPPER 30S AND LOWER 40S AS FAR SOUTH AS CASPER! WHILE
THE SURGE APPEARS TO BE WEAKENING, IT WILL PROBABLY AT LEAST PUSH
SOUTH TO AROUND DENVER LATE TONIGHT BEFORE PERHAPS BRIEFLY
STALLING, OR AT LEAST SLOWING. HOWEVER, WITH CONTINUED SHOWERS
NORTH OF THE FRONT THAT TYPICALLY REINFORCES THE COOL AIR, AND AT
A MINIMUM STRENGTHENS THE BAROCLINICITY SOMEWHERE ACROSS THE
PALMER DIVIDE FOR TOMORROW (WITH AREAS OF STRATUS TO THE NORTH AND
A DEEPER/WARMER MIXED LAYER FARTHER SOUTH). ESSENTIALLY THAT WILL
KEEP DENVER AND POINTS NORTH AND EAST LOCKED IN THE MUCH COOLER
AIRMASS. THUS, WE'VE LOWERED TEMPERATURES SEVERAL DEGREES, AND AT
THIS POINT EXPECT ANYWHERE FROM DENVER NORTHWARD TO ONLY BE IN THE
50S FOR HIGHS.
SHORT TERM /THROUGH FRIDAY/
ISSUED AT 216 PM MDT THU OCT 17 2024
SHOWERS CONTINUE TO GRADUALLY INCREASE, WITH THE MAIN AREA OF
SHOWERS AND A FEW THUNDERSTORMS JUST APPROACHING THE CONTINENTAL
DIVIDE IN NORTHERN COLORADO. THE AREA OF LIFT PRODUCING THESE
SHOWERS WILL MOVE GRADUALLY EAST OVERNIGHT, WITH A BREAK IN THE
FORCING OVER THE MOUNTAINS LATE TONIGHT AND MUCH OF OUR AREA
DURING THE DAY TOMORROW. THERE'S STILL SOME MOISTURE, BUT NOT A
LOT OF LIFT OR INSTABILITY. THE EXCEPTION MIGHT BE NORTHERN BORDER
AREAS IN THE MOUNTAINS, WHICH WILL PROBABLY HAVE SOME LIGHT
OROGRAPHIC SNOW ANYWAY. SO AFTER THE CURRENT SHOWER CLUMP MOVES
EAST, WE'LL HAVE SCATTERED LIGHT SHOWERS FORECAST OVER THE
MOUNTAINS AND JUST A SLIGHT CHANCE OF SHOWERS ON THE PLAINS
THROUGH FRIDAY MORNING.
THERE'S SOME DISAGREEMENT BETWEEN THE MODELS ON WHEN THE DEEP COOL
AIR MOVES SOUTH ACROSS THE PLAINS ON FRIDAY AFTER AN INITIAL
NORTHERLY WIND SHIFT IN THE MORNING. THE NAM HAS GOTTEN REALLY
AGGRESSIVE WITH THIS, BRINGING THE REAL FRONT AND LOW CLOUDS INTO
DENVER BY 18Z AND KEEPING METRO AREA HIGHS AROUND 50. OTHER MODELS
ARE A FEW HOURS SLOWER AND ALLOW US TO WARM UP THROUGH MIDDAY,
INTO THE 60S. NOT SURE WE WANT TO BUY INTO THE SPEED OF THE NAM
DESPITE THE USUAL MODEL BIAS OF "FASTER IS BETTER", BUT WE DID
ADJUST THE FORECAST TO SHOW MORE COOLING, INTO THE 40S IN THE LATE
AFTERNOON. IN ADDITION TO GRADUALLY INCREASING LIFT FROM THE WEST
AND A LITTLE DESTABILIZATION FROM DAYTIME HEATING, THE FRONT
SHOULD PROVIDE A NICE SURFACE TO OVERRUN FOR INCREASING SHOWERS BY
MID TO LATE AFTERNOON. THERE'S NOT MUCH COOLING ALOFT YET, SO THE
SNOW LEVEL WILL REMAIN AROUND 8 TO 9 THOUSAND FEET, WITH GENERALLY
LIGHT ACCUMULATIONS IN THE HIGHER MOUNTAINS. BACKCOUNTRY AREAS
NEAR THE NORTHERN BORDER COULD SEE MORE THAN THAT IF THEY HAVE
PERSISTENT SNOW THROUGH THE PERIOD.
LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/
ISSUED AT 216 PM MDT THU OCT 17 2024
MODELS SHOW A DECENT UPPER CLOSED LOW A BIT SOUTH OF THE FOUR
CORNERS FROM FRIDAY NIGHT THROUGH SATURDAY NIGHT, MOVING VERY
LITTLE. ON SUNDAY INTO SUNDAY NIGHT IT MOVES SLOWLY NORTHEASTWARD
RIGHT ACROSS THE CWA AND WEAKENS SOMEWHAT. IT IS PROGGED TO BE
CENTERED RIGHT OVER THE NORTHEAST CORNER OF COLORADO BY 12Z MONDAY
MORNING. THE SYNOPTIC SCALE ENERGY ON THE QG OMEGA FIELDS IS NOT
GREAT, BUT IT IS DECENT ENOUGH FRIDAY EVENING FOR MUCH OF THE CWA.
AFTER THAT, IT IS PRETTY WEAK SATURDAY THROUGH SUNDAY EVENING.
THE UPPER TROUGH BRINGS A COOLER AIRMASS INTO THE CWA STARTING
FRIDAY AND IT STICKS AROUND THROUGH THE WEEKEND, WITH SOME
MODERATING TEMPERATURES ON SUNDAY. THE UPSLOPE BEHIND THE FRONT FOR
THE PLAINS IS PROGGED MUCH OF FRIDAY NIGHT INTO SATURDAY MORNING,
BUT THAT'S IT.
FOR MOISTURE, THE BEST QPF OCCURS FRIDAY EVENING. BY SATURDAY,
THERE IS PRECIPITATION PROGGED MAINLY FOR JUST THE SOUTHERN HALF
OF THE CWA, AND AMOUNTS ARE LIMITED. THERE IS A BIT OF CAPE AROUND
SATURDAY AFTERNOON AND EVENING FOR THE WESTERN THIRD AND
SOUTHEASTERN PORTION OF THE CWA. THEN THERE IS SOME FOR MUCH OF
THE CWA SUNDAY AFTERNOON AND EVENING. CRITICAL FIRE WEATHER CONDITIONS WILL OCCUR THIS AFTERNOON FOR PARTS
OF THE EASTERN PLAINS WHERE SOUTHWEST WINDS PRODUCE WIND GUSTS UP TO
35-40 MPH. RELATIVE HUMIDITY VALUES DROP BETWEEN 14-18% THROUGH THIS
EVENING. THUS THE RED FLAG WARNING WILL REMAIN IN EFFECT FOR THESE
AREAS STARTING 10 AM TO 6 PM MDT. MAJORITY OF SCATTERED SHOWERS
WILL REMAIN OVER THE HIGHER TERRAIN PRODUCING GUSTY WINDS AND
LITTLE RAINFALL. THERE IS POTENTIAL FOR SCATTERED SHOWERS TO ENTER
THE EASTERN PLAINS THIS EVENING AND RELATIVE HUMIDITY VALUES
SHOULD RECOVER 65-85% OVERNIGHT EASING FIRE WEATHER CONCERNS.
FOR SNOWFALL IN THE MOUNTAINS, THE HIGHEST AMOUNTS LOOK TO BE ALONG
THE DIVIDE FROM BOULDER COUNTY DOWN INTO PARK COUNTY. AREAS ABOVE
10,000 FEET MAY EVENTUAL NEED AN ADVISORY, AT LEAST FOR ZONE 34. WE'LL
SEE.
FOR TEMPERATURES, THE COOLEST DAY WILL BE SATURDAY. THROUGH THE
17TH OF OCTOBER 2024 SO FAR, WE HAVE YET TO HAVE EVEN ONE DAY WITH A
BELOW NORMAL AVERAGE DAILY TEMPERATURE HERE IN DENVER. THAT SHOULD
HAPPEN ON SATURDAY, HOWEVER IT IS NOT EXPECTED TO BE SIGNIFICANTLY
BELOW NORMAL. SUNDAY WARMS BACK UP.
FOR THE LATER DAYS, MONDAY THROUGH THURSDAY, MODELS HAVE UPPER
RIDGING TO DOMINATE ALL FOUR DAYS, WITH ABOVE NORMAL TEMPERATURES
ONCE AGAIN. AFTERNOON HIGHS SHOULD BE IN THE UPPER 60S TO MID 70S
OVER THE PLAINS ALL FOUR DAYS. NO PRECIPITATION IS EXPECTED FOR THE
CWA.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1139 PM MDT THU OCT 17 2024
AS THE FRONT ARRIVES TO TAF SITES, LOWER CLOUD DECKS NEAR 10K ARE
POSSIBLE. VFR CONDITIONS SHOULD CONTINUE THROUGH THE TAF PERIOD
BUT THERE IS POTENTIAL FOR LOWER STRATUS DEVELOPING STARTING
13Z-19Z FOR ALL SITES. AS SHOWERS BEGIN TO DEVELOP THIS AFTERNOON,
CLOUD COVERAGE SHIFTS FROM SCT TO BKN AND WIND SPEEDS INCREASE
BETWEEN 10-13KTS. WINDS SHOULD REMAIN NORTH THROUGH THE EVENING.
BY LATE EVENING, THERE IS POTENTIAL FOR IMC WHERE CLOUD DECKS
LOWER NEAR 8-6K FEET. WHILE A FEW SHOWERS MAY LINGER, IT IS
POSSIBLE FOR FOG IF SHOWERS DECREASE IN COVERAGE INTO SATURDAY
MORNING.
FIRE WEATHER
ISSUED AT 755 PM MDT THU OCT 17 2024
IT WILL BE DRY AND BREEZY FRIDAY OVER PORTIONS OF THE PALMER
DIVIDE BEFORE THE COLD FRONT ARRIVES, LIKELY IN THE MIDDLE OF THE
DAY, THEN COOLER WITH SHOWERS DEVELOPING.
BOU WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...BARJENBRUCH
SHORT TERM.....GIMMESTAD
LONG TERM......RJK
AVIATION...AD
FIRE WEATHER...GIMMESTAD
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