096
FXUS65 KBOU 211840
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1240 PM 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 AND WEAK STORMS 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.
UPDATE
ISSUED AT 938 AM MDT MON OCT 21 2024
MOUNTAIN SNOW IS STILL OCCURRING THIS MORNING BUT AS THE TROUGH
CONTINUES TO MOVE EASTWARD, INTENSITY IS BEGINNING TO WEAKEN. SNOW
SHOULD COME TO AN END BETWEEN 1030-1130 AS THE BACK EDGE OF THE
MID TO UPPER LEVEL CLOUDS SHOWS UP WELL ON SATELLITE. SHOWERS THAT
ARE CONVECTIVE IN NATURE ARE SHOWING UP ON RADAR AND SATELLITE
THIS MORNING ACROSS BOULDER AND LARIMER COUNTIES. AS THE
DEFORMATION ZONE ON THE NORTHWEST SIDE OF THE TROUGH MOVES
THROUGH THE I-25 CORRIDOR, SHOWERS AND PERHAPS A COUPLE OF
THUNDERSTORMS WILL FORM. THE COVERAGE OF MEASURABLE RAIN MAY BE
LIMITED BUT A GOOD PORTION OF THE I-25 CORRIDOR WILL LIKELY SEE
SOME RAINDROPS. A BAND OF SHOWERS WILL LIKELY CONTINUE TO THE
CO/NE AND CO/KS BORDER THROUGH THE AFTERNOON. POPS WERE ADJUSTED
UP ACROSS THE PLAINS AND DOWN ACROSS THE MOUNTAINS LATE THIS
MORNING AND THROUGH THE AFTERNOON.
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 /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1235 PM MDT MON OCT 21 2024
A WAVE OF SHOWERS AND MID LEVEL CLOUDS IS MOVING AWAY FROM THE
TERMINALS AT THE TIME OF THIS WRITING. CEILINGS WILL QUICKLY
IMPROVE WITH CLEAR SKIES BEHIND THIS WAVE OF PRECIPITATION. GUSTY
WINDS MAY OCCUR ON AND OFF THROUGHOUT THE AFTERNOON. WHEN THE
WINDS ARE GUSTY, THE GUSTS COULD REACH 30 KNOTS BUT THE MAJORITY
OF THE TIME WILL BE SPENT WITH SUSTAINED WINDS AROUND 12 KNOTS OR
SO.
THERE ARE NO CONCERNS WITH THE TAFS THIS EVENING AND TOMORROW.
DRAINAGE FLOW IS EXPECTED TONIGHT WITH VFR CONDITIONS THAT LAST
THROUGH TUESDAY.
BOU WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...DANIELSON
SHORT TERM...BONNER
LONG TERM...RPK
AVIATION...DANIELSON
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