079
FXUS65 KBOU 281820
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1120 AM MST TUE JAN 28 2025
KEY MESSAGES
- DRY TODAY THROUGH MOST OF WEDNESDAY WITH NORMAL/SEASONAL
TEMPERATURES.
- STILL WATCHING THE POTENTIAL RETURN OF SNOW (NOW UP TO 20-60%
CHANCE) TOWARD WEDNESDAY NIGHT AND THURSDAY. HIGHEST CHANCES
STILL APPEAR TO BE SOUTH AND EAST OF DENVER.
- WARMER BUT BREEZY FRIDAY INTO THE WEEKEND.
UPDATE
ISSUED AT 1116 AM MST TUE JAN 28 2025
QUIET DAY LOOKS ON TRACK, WITH TEMPERATURES VARYING BASED ON
SHALLOW INVERSIONS BREAKING. MOST OF THE PLAINS HAS A LITTLE WIND
NOW WITH TEMPERATURES ABOVE FREEZING. FORECAST TEMPERATURES LOOK
PRETTY GOOD, IT COULD BE SLIGHTLY WARMER ON THE PLAINS. WE'LL MAKE
SOME ADJUSTMENTS IN GRAND AND JACKSON COUNTIES WHERE THE RIDGES
ARE QUITE WARM (LOTS OF 30S IN THE 10 TO 11 THOUSAND FOOT BAND)
WHILE THE VALLEY BOTTOMS ARE COLD (STILL BELOW ZERO SOME SPOTS) UNDER
A VERY STRONG INVERSION THAT'S UNLIKELY TO MIX OUT.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 204 AM MST TUE JAN 28 2025
THERE HAS BEEN LITTLE CHANGE TO THE SYNOPTIC PATTERN OVER THE LAST
24 HOURS, AND TODAY'S FORECAST IS QUITE SIMILAR TO MONDAY'S. UNDER
CLEAR SKIES, THE USUAL MOUNTAIN COLD SPOTS ARE IN FACT COLD, WITH
FRASER FLATS AND WINDY GAP IN GRAND COUNTY IN THE -20S. DRAINAGE
WINDS HAVE KEPT THE SOUTHWEST METRO MILD WHILE THERE'S A FEW
SINGLE DIGIT READINGS NEAR ERIE/LONGMONT.
WE SHOULD WARM BACK UP INTO THE 40S THIS AFTERNOON UNDER MOSTLY
CLEAR SKIES. WINDS ALOFT INCREASE EVER SO SLIGHTLY TODAY, BUT
SURFACE WINDS SHOULD END UP PRETTY LIGHT ACROSS THE FORECAST AREA.
QUIET CONDITIONS WILL CONTINUE THROUGH MOST OF TONIGHT. AN UPPER
LOW SHOULD CONTINUE TO DRIFT EAST/NORTHEASTWARD TOWARDS NORTHERN
NEW MEXICO, WITH A GRADUAL INCREASE IN MOISTURE AND CLOUD COVER
OVERNIGHT - MAINLY ACROSS THE HIGHER ELEVATIONS.
LONG TERM /WEDNESDAY THROUGH MONDAY/
ISSUED AT 204 AM MST TUE JAN 28 2025
MAIN CONCERN FOR LATER WED THRU THU WILL BE THE TRACK OF AN UPPER
LEVEL LOW FROM THE SWRN US. OVERALL, THE ECMWF AND GFS HAVE A
SIMILAR TRACK AS THE LOW MOVES FROM CENTRAL ARIZONA INTO NORTH
CENTRAL NEW MEXICO BY WED EVENING AND THEN INTO SERN CO BY THU
MORNING. THE UPPER LEVEL LOW THEN MOVES MORE EASTWARD THRU THU AFTN
INTO THU EVENING AS IT TRACKS INTO KANSAS AND OKLAHOMA.
DESPITE THE MODELS HAVING A DECENT HANDLE ON THE OVERALL TRACK OF
THE SYSTEM, THERE ARE MAJOR DIFFERENCES IN HOW MUCH PRECIP MAY
OCCUR, OVER PARTS OF THE CWA, WED NIGHT THRU THU AFTN. THE
OPERATIONAL RUNS OF THE NAM AND GFS HAVE FAR MORE PRECIP OCCURRING
OVER PORTIONS OF THE PLAINS AND PALMER DIVIDE AS COMPARED TO THE
ECMWF AND GEM WHICH ARE CONSIDERABLY DRIER.
MEANWHILE, LOOKING AT ENSEMBLE DATA, THE MEAN PRECIP FROM THE GFS
MATCHES UP WELL WITH ITS OPERATIONAL RUN. ON THE OTHER HAND, THE
ECMWF AND GEM ENSEMBLE MEANS ARE WETTER AS COMPARED TO THEIR
OPERATIONAL RUNS.
HISTORICALLY, THESE TYPES OF SYSTEMS HAVE BEEN DIFFICULT TO
FORECAST, ESPECIALLY WHEN THE SFC PATTERN LACKS A DEFINED UPSLOPE
COMPONENT AS THIS ONE WILL HAVE. MY GUESS WOULD BE THERE WILL BE A
BAND OF HEAVIER PRECIP SOMEWHERE TO THE WEST AND NORTHWEST OF THE
MAIN UPPER LEVEL LOW. HOWEVER, CONFIDENCE IN WHERE THIS BAND WILL
BE IS STILL VERY LOW AT THIS POINT. AS A RESULT, HAVE NOT ALTERED
THE BLENDED SOLUTION FOR PRECIP AND POPS DUE TO ALL OF THE
UNCERTAINTY THAT REMAINS. TEMPS WILL BE COLD ENOUGH FOR SNOW AND
SOME AREAS MAY SEE ADVISORY AMOUNTS BEFORE THE SNOW ENDS BY LATE
THU AFTN OR THU EVENING ACROSS THE PLAINS.
LOOKING AHEAD TO FRI THROUGH THE WEEKEND, THE FLOW ALOFT WILL BE
MAINLY ZONAL. CROSS-SECTIONS SHOW VARYING AMOUNTS OF MOISTURE
AFFECTING THE MTNS THRU THE PERIOD WITH A CHC OF OROGRAPHIC SNOW AT
TIMES. HOWEVER, IT APPEARS THE MORE SUBSTANTIAL SNOWFALL WILL OCCUR
FURTHER NORTH OVER THE NRN ROCKIES. MEANWHILE, THERE WILL BE
PERIODS OF GUSTY WINDS AS WELL THRU SUN, WITH THE STRENGTH OF THE
WINDS DEPENDING ON HOW WELL DEFINED THE MTN WAVE IS. IN ADDITION,
WITH DOWNSLOPE WARMING IN PLACE, HIGHS SHOULD BE 10-15 DEGREES
ABOVE NORMAL OVER NERN CO.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1116 AM MST TUE JAN 28 2025
VFR THROUGH TONIGHT WITH LIGHT WINDS.
BOU WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...GIMMESTAD
SHORT TERM...HIRIS
LONG TERM...RPK
AVIATION...GIMMESTAD
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