852
FXUS65 KBOU 211011
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
411 AM MDT MON OCT 21 2024
KEY MESSAGES
- WINTER WEATHER ADVISORY IN EFFECT UNTIL NOON TODAY FOR PORTIONS
OF THE MOUNTAINS ABOVE 9,000'. SLICK DRIVING CONDITIONS ARE
POSSIBLE THIS MORNING FOR MOUNTAIN PASSES AND NEAR THE TUNNEL ON
I-70.
- LIGHT TO MODERATE SNOW WILL OCCUR IN THE MOUNTAINS THIS MORNING
WITH 4-8 INCHES OF ACCUMULATION, MAINLY ON THE WESTERN SLOPE OF
THE FRONT RANGE MOUNTAINS. RAIN SHOWERS WILL BE POSSIBLE ACROSS
THE FOOTHILLS AND I-25 CORRIDOR THIS MORNING.
- WINDY CONDITIONS WITH GUSTS UP TO 40 MPH POSSIBLE THIS AFTERNOON
ACROSS ALL OF OUR FORECAST AREA.
- DRY WITH ABOVE NORMAL TEMPERATURES TUESDAY AND WEDNESDAY. A COLD
FRONT MAY DROP TEMPERATURES BACK TO MORE SEASONAL LEVELS FOR
THURSDAY AND FRIDAY.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 310 AM MDT MON OCT 21 2024
WE ARE STARTING TO SEE SNOW AND RAIN SHOWERS WITH A FEW LIGHTNING
STRIKES (YES, THUNDERSNOW!) DEVELOP OVER THE HIGH COUNTRY EARLY
THIS MORNING AS THE CENTER OF THE UPPER LEVEL LOW PASSES ACROSS
COLORADO. THE LATEST GUIDANCE INDICATES THERE COULD BE SLIGHTLY
HIGHER SNOWFALL ACCUMULATIONS THAN PREVIOUSLY THOUGHT, WITH 4 TO 8
INCHES POSSIBLE FROM EARLY THIS MORNING THROUGH AROUND NOON TODAY
FOR ELEVATIONS ABOVE 9,000', WITH SOME LOCALLY HIGHER AMOUNTS AT
THE HIGHEST ELEVATIONS. WITH SLICK ROADS A CONCERN FOR THE MONDAY
MORNING COMMUTE ACROSS OUR MOUNTAIN PASSES AND EISENHOWER-JOHNSON
TUNNEL, WE HAVE GONE AHEAD AND ISSUED A WINTER WEATHER ADVISORY
FOR ZONES 33 AND 34 TO CONTINUE THROUGH NOON TODAY.
AS THE LOW CONTINUES ITS TREK EAST, THERE SHOULD BE ENOUGH
INSTABILITY ON ITS BACK END TO PRODUCE SOME SHOWERS AND WEAK STORMS
OVER THE FOOTHILLS AND ADJACENT PLAINS. HOWEVER, WITH DOWNSLOPING
WINDS COMING OFF THE MOUNTAINS, PRECIPITATION AMOUNTS WILL LIKELY BE
LIMITED. QPF TOTALS ACROSS THE PLAINS ARE FORECAST TO RANGE FROM .01
TO .05", WITH SOME LOCALLY HIGHER AMOUNTS WITHIN ANY CONVECTIVE
PRECIPITATION THAT FORMS. SKIES SHOULD SEE SOME SIGNIFICANT CLEARING
BEGINNING AROUND NOON, AND TEMPERATURES ARE FORECAST TO WARM UP TO
THE HIGH 60S TO LOW 70S ACROSS THE PLAINS. HIGH MOUNTAIN VALLEYS
SHOULD MAKE IT TO THE 50S, BUT ELEVATIONS ABOVE 9,000' SHOULD REMAIN
IN THE 30S AND 40S FOR THE DAY. GUSTY WINDS ARE EXPECTED ACROSS THE
FORECAST AREA WITH WIND GUSTS BETWEEN 30-40 MPH POSSIBLE THROUGHOUT
THE AFTERNOON. ONCE THE LOW HAS MOVED OUT, MOSTLY CLEAR SKIES ARE
EXPECTED OVERNIGHT. TEMPERATURES ARE EXPECTED TO BE A FEW DEGREES
COOLER THAN SUNDAY NIGHT LEADING TO A FEW AREAS OF PATCHY FROST
DEVELOPING ACROSS PORTIONS OF THE PLAINS.
LONG TERM /TUESDAY THROUGH SUNDAY/
ISSUED AT 310 AM MDT MON OCT 21 2024
FOR TUE AND WED, THE FLOW ALOFT WILL BE MAINLY ZONAL WITH ONLY
SOME HIGHER LEVEL MOISTURE EMBEDDED IN THE FLOW. TEMPS ON TUE WILL
REMAIN ABOVE NORMAL WITH READINGS IN THE 70'S OVER THE PLAINS. ON
WED, A COOL FRONT IS STILL FCST TO AFFECT NERN CO. HOWEVER, IT
APPEARS THIS FRONT WILL ONLY DROP TEMPS BACK INTO THE UPPER 60S TO
MID 70'S OVER THE PLAINS.
BY THU, A WEAK UPPER LEVEL TROUGH WILL MOVE INTO THE NRN ROCKIES.
THE ECMWF IS A BIT FURTHER SOUTH AND STRONGER WITH THIS FEATURE
VERSUS THE GFS. AS A RESULT, THE ECMWF HAS SOME LIGHT PCPN OVER THE
NRN MTNS ON THU WHILE THE GFS IS DRY. MEANWHILE, THE ECMWF HAS A
BORA TYPE FRONT MOVING ACROSS THE PLAINS BY MIDDAY WHILE THE GFS
HAS A FRONT MOVING ACROSS THU EVENING. AT THIS POINT, IT'S NOT
CLEAR WHICH SOLUTION IS THE BEST SO WILL JUST GO WITH A BLENDED
SOLUTION FOR NOW. IF THE ECMWF VERIFIES THEN TEMPS WOULD DROP BACK
TO SEASONAL LEVELS OVER THE AREA.
ON FRI, DRY WNW FLOW ALOFT WILL BE OVER THE AREA WITH HIGH PRES AT
THE SFC. AS A RESULT, EXPECT DRY CONDITIONS WITH SEASONAL TEMPS.
FOR THE WEEKEND, A FLAT UPPER LEVEL RIDGE WILL DEVELOP OVER THE AREA
WITH DRY CONDITIONS. WITH DOWNSLOPE FLOW DEVELOPING, HIGHS WILL
RISE BACK TO ABOVE NORMAL LEVELS.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1145 PM MDT SUN OCT 20 2024
GUSTY SOUTHERLY WINDS HAVE SET IN AT ALL TAF SITES AS EXPECTED
TONIGHT. GUSTS ARE EXPECTED TO SETTLE DOWN IN THE NEXT HOUR OR
SO. AS AN UPPER LEVEL LOW MOVES ACROSS CO MONDAY MORNING,
SOUTHERLY WINDS ARE EXPECTED TO TRANSITION TO WESTERLY AS
SCATTERED SHOWERS MOVE EAST OF THE HIGHER ELEVATIONS BY AROUND
13Z. GUSTY WESTERLY OUTFLOWS WILL BE POSSIBLE AS SHOWERS MOVE
THROUGH, AND CEILINGS MAY DROP TO 5000-6000 FEET. DOWNSLOPING
WINDS WILL LIMIT THE EASTWARD PROGRESSION OF SHOWERS, AND AFTER
LATE MORNING, PRECIPITATION CHANCES WILL QUICKLY DIMINISH AS THE
LOW MOVES OUT OF THE REGION. WINDS ARE EXPECTED TO INCREASE IN THE
EARLY AFTERNOON AROUND 20Z AT DEN/APA AND REMAIN GUSTY THROUGH
THE EVENING, WITH GUSTS TO 30KTS POSSIBLE. BJC IS EXPECTED TO SEE
THE WINDS A FEW HOURS BEFORE THE OTHER TAF SITES (~16Z) WITH
SLIGHTLY HIGHER GUSTS EXPECTED, UP TO 35KTS, AND LINGERING UNTIL
~4Z.
BOU WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL NOON MDT TODAY FOR COZ033-034.
SHORT TERM...BONNER
LONG TERM...RPK
AVIATION...BONNER
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