470
FXUS65 KBOU 241058
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
358 AM MST FRI JAN 24 2025
KEY MESSAGES
- WINDY THROUGH THIS MORNING FOR MOUNTAINS, FOOTHILLS AND ADJACENT
AREAS WITH AREAS OF BLOWING SNOW EXPECTED.
- ANOTHER ROUND OF SNOW WITH TRAVEL IMPACTS AND COLDER
TEMPERATURES ARRIVES THIS EVENING INTO SATURDAY. HIGH CONFIDENCE
(>80%) OF ACCUMULATING SNOW FOR THE MOUNTAINS, FOOTHILLS, AND
I-25 CORRIDOR, BUT ONLY 30-40% CONFIDENCE FARTHER EAST ON THE
PLAINS OF ANY IMPACTFUL SNOW.
- DRY WEATHER EXPECTED EARLY NEXT WEEK WITH MODERATING
TEMPERATURES.
- STILL WATCHING THE POTENTIAL RETURN OF SNOW (20-30% CHANCE)
TOWARD THE MIDDLE OF NEXT WEEK, CONFIDENCE IS LOW.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 326 AM MST FRI JAN 24 2025
CURRENT OBSERVATIONS SHOW A MOUNTAIN WAVE DOING MOUNTAIN WAVE
THINGS TONIGHT AS WINDS ARE GUSTING IN THE 50 AND 60MPH RANGE
ALONG THE EASTERN SLOPES OF THE FRONT RANGE AND HIGHER FOOTHILLS.
AS EXPECTED THERE HAVE BEEN A FEW HIGHER GUSTS AT SOME OF OUR WIND
PRONE SITES, WITH DAKOTA HILL (KC99) HAVING JUST REACHED 72MPH.
WNW FLOW ALOFT WILL INCREASE AND BECOME MORE ZONAL THROUGHOUT THE
MORNING AS A POSITIVELY TILTED UPPER-LEVEL TROUGH STARTS A
SOUTHWARD TREK OUT OF WESTERN CANADA, AND A 110-120KT 250MB JET
STREAK PUSHES SOUTH THROUGH WYOMING. MOISTURE IS EXPECTED TO
INCREASE BEGINNING IN THE MOUNTAINS, WHICH WILL HELP DESTABILIZE
THE CURRENT STABLE LAYER THAT RESIDES NEAR RIDGETOP, ALLOWING THE
MOUNTAIN WAVE TO DEAMPLIFY AND RETREAT BACK UP THE EASTERN SLOPES.
WITH THE RETREAT, WINDS SHOULD BEGIN TO DIMINISH BY LATE MORNING.
THERE ARE STILL SOME CONCERNS WITH BLOWING SNOW BEING A NUISANCE
FOR THE MORNING COMMUTE IN AREAS WHERE WINDS ARE STRONGEST,
HOWEVER, MOST OF THE LATEST SNOWFALL HAS ALREADY BEEN BLOWN
AROUND AND LIKELY SETTLED, WHICH WILL HELP KEEP CONDITIONS FAR
LESS IMPACTFUL COMPARED TO WHAT WAS WITNESSED EARLIER THIS WEEK.
WITH THE DOWNSLOPE WINDS IN PLACE THROUGH THE MORNING, TEMPERATURES
WILL WARM INTO THE UPPER 30S ACROSS THE PLAINS, WITH LOCATIONS AT
THE BASE OF THE FOOTHILLS BENEFITING MOST FROM THE COMPRESSIONAL
WARMING EFFECTS, REACHING THE LOW 40S. WE WILL ALSO START OUT WITH
MOUNTAIN WAVE CLOUDS IN PLACE ALONG THE FRONT RANGE THIS MORNING
BEFORE CLOUDS INCREASE FROM NORTH TO SOUTH AS A COLD FRONT PUSHES
SOUTH FROM WYOMING THIS AFTERNOON.
CROSS SECTIONS SHOW MID AND LOW LEVEL MOISTURE INCREASING ACROSS THE
MOUNTAINS LATE MORNING/EARLY AFTERNOON, AND OROGRAPHICS SHOULD
PROVIDE ENOUGH LIFT FOR SNOW SHOWERS TO INITIATE BY THIS SAME TIME
FRAME. THEY ALSO SHOW MID AND UPPER LEVEL MOISTURE PUSH EAST OFF
THE TERRAIN BY LATE EVENING, BUT THE LOW LEVELS DON'T MOISTEN UP
UNTIL SATURDAY MORNING, SO DESPITE THE COLD FRONT DIPPING SOUTH
THIS AFTERNOON, SNOW ISN'T EXPECTED TO BEGIN UNTIL LATE TONIGHT
OVER THE PLAINS. QG FIELDS SHOW MODEST BUT PERSISTENT ASCENT FROM
LATE THIS MORNING THROUGH THE SHORT TERM PERIOD, AND WITH THE
AFOREMENTIONED JET STREAK MOVING FAR ENOUGH SOUTH TO PUT NORTHERN
COLORADO IN ITS RIGHT ENTRANCE REGION, THERE SHOULD BE ENOUGH
UPWARD MOTION TO MAINTAIN SNOW SHOWERS INTO SATURDAY. THEREFORE, A
WINTER WEATHER ADVISORY WILL REMAIN IN PLACE FROM 5PM TODAY UNTIL
5AM SUNDAY FOR THE NORTHERN MOUNTAINS, AND FROM 9PM TONIGHT UNTIL
5AM SUNDAY FOR THE NORTHERN FRONT RANGE FOOTHILLS. SEE BELOW FOR
MORE DETAILS...
LONG TERM /SATURDAY THROUGH THURSDAY/
ISSUED AT 326 AM MST FRI JAN 24 2025
LIGHT TO MODERATE SNOW WILL CONTINUE THROUGH MOST OF THE DAY
SATURDAY, AS THE UPPER TROUGH SLOWLY DRIFTS SOUTHWESTWARD,
EVENTUALLY FORMING A CLOSED LOW OVER NORTH-CENTRAL CALIFORNIA. ALL
OF OUR SOURCES OF LIFT GRADUALLY DIMINISH THROUGH THE DAY - THE
UPPER JET STREAK MOVES OFF TO THE EAST, QG ASCENT SHIFTS OFF TO
THE WEST, WHILE WEAK/SHALLOW UPSLOPE HOLDS ON THROUGH THE EVENING
HOURS. WITH MODEST ASCENT TO BEGIN WITH, ACCUMULATING SNOW WILL BE
HARD TO COME BY ANYWHERE EAST OF I-25, WITH MOST OF THE MEANINGFUL
SNOWFALL STICKING TO THE HIGHER ELEVATIONS AND THE IMMEDIATELY
ADJACENT PLAINS.
GUIDANCE HAS WOBBLED A BIT WITH THE AXIS OF HEAVIEST QPF/SNOW OVER
THE PAST FEW CYCLES, THOUGH THIS SNOW HAS LARGELY BEEN FOCUSED
ALONG AND NORTH OF I-70. OVERALL SNOWFALL TOTALS ACROSS THE
FOOTHILLS AND NORTHERN MOUNTAINS WILL GENERALLY BE BETWEEN 5-12",
WITH HIGHER TOTALS POSSIBLE ACROSS SOME OF THE HIGHER MOUNTAINS. A
SHARP GRADIENT IN SNOW IS EXPECTED ALONG THE I-25 CORRIDOR, WITH
MOST LOCATIONS EAST OF I-25 ONLY LOOKING AT 1-2" OF SNOW. WE DID
DISCUSS ADDING THE BOULDER AND/OR FORT COLLINS ZONES INTO AN
ADVISORY, BUT WANTED TO WAIT ONE MORE CYCLE - WHICH WOULD GET MOST
OF THE STORM INTO THE WINDOW WHERE HIGH RESOLUTION GUIDANCE
PERFORMS WELL HERE.
QUIETER WEATHER IS EXPECTED ON SUNDAY, THOUGH SOME MOUNTAIN SNOW
SHOWERS WILL LIKELY CONTINUE. ANY ADDITIONAL ACCUMULATION THERE
WOULD BE OF LITTLE IMPACT. HIGHS ACROSS THE REGION SHOULD BE
CLOSER TO THE FREEZING MARK.
WE'LL START THE WEEK IN BETWEEN THE CUTOFF LOW TO OUR SOUTHWEST
AND THE STRONGER NORTHWESTERLY FLOW TO THE NORTHEAST, LEADING TO A
QUIET MONDAY AND TUESDAY. MODERATING TEMPERATURES ARE FORECAST
WITH HIGHS BACK IN THE 40S.
GUIDANCE CONTINUES TO EJECT THE CUTOFF LOW BACK INTO THE CENTRAL
PLAINS BY MID/LATE WEEK, WITH CONSIDERABLE VARIABILITY IN THE
DETERMINISTIC SUITE TONIGHT. THE SPREAD IN SOLUTIONS IS ALSO WELL
REPRESENTED ACROSS THE OVERNIGHT ENSEMBLE RUNS, WITH BETTER
CHANCES FOR RAIN OR SNOW ACROSS THE SOUTHEASTERN PORTION OF THE
STATE.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1041 PM MST THU JAN 23 2025
WINDS HAVE INCREASED AT KBJC AS A MOUNTAIN WAVE HAS DEVELOPED.
SOME GUIDANCE SUGGEST THAT GUSTS COULD SURPASS THE 45KT MARK IN
THE NEXT FEW HOURS AT KBJC (<30% CHANCE), BUT THE MORE LIKELY
OUTCOME WILL BE GUSTS TO 25-30KTS UNTIL ~12Z AT THIS LOCATION.
DRAINAGE WINDS SHOULD REMAIN THROUGH THE MORNING AT KDEN/KAPA. A
COLD FRONT WILL SHIFT WINDS TO THE NNE IN THE AFTERNOON FOLLOWED
BY LOWERING CEILINGS AS MOISTURE INCREASES IN THE MID AND LOWER
LEVELS AS OUR NEXT WINTER SYSTEM APPROACHES. MVFR CONDITIONS
SHOULD DEVELOP CLOSE TO MIDNIGHT AND IFR IS EXPECTED BY EARLY
MORNING AS SNOW SHOWERS COULD LOWER VISIBILITIES TO NEAR 1SM A
FEW HOURS PRIOR TO SUNRISE.
BOU WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 5 AM MST
SUNDAY FOR COZ031-033.
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 5 AM MST
SUNDAY FOR COZ035.
SHORT TERM...BONNER
LONG TERM...HIRIS
AVIATION...BONNER
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