Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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000 FXUS65 KBOU 232229 AFDBOU AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER/BOULDER CO 329 PM MST SUN NOV 23 2014 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 329 PM MST SUN NOV 23 2014 SOME SNOW SHOWERS ON THE RADAR RIGHT NOW. BEST OVER THE HIGH MOUNTAINS...WITH A FEW OVER THE FOOTHILLS AND IMMEDIATE PLAINS. THERE IS A FAIRLY STRONG NORTH-NORTHWESTERLY WIND FIELD OVER MOST OF THE PLAINS RIGHT NOW. THERE ARE SOME GUSTS TO AROUND 35 KNOTS OVER THE NORTHERN AND EASTERN PLAINS. MODELS SHOW THE UPPER TROUGH AXIS THROUGH THE CWA WITH NORTHWESTERLY FLOW ALOFT TONIGHT AND MONDAY. THE SPEEDS ARE 40 TO 70 KNOTS AND INCREASING BY 00Z MONDAY AFTERNOON LATE. THERE IS PRETTY STRONG DOWNWARD QG MOTION FOR THE CWA BOTH TONIGHT AND MONDAY. THE BOUNDARY LAYER FLOW IS ALL NORTHWESTERLY DOWNSLOPING FOR ALL THE CWA TONIGHT AND MONDAY. FOR MOISTURE...IT STAYS PRETTY DEEP IN THE MOUNTAINS TONIGHT AND MONDAY. AFTER THIS EVENING`S CONVECTION...THE PLAINS DO NOT HAVE A LOT OF MOISTURE OVER THEM. IT INCREASES ON MONDAY...ESPECIALLY JUST EAST OF THE URBAN CORRIDOR IN THE MORNING...THEN MOISTURE IS PRETTY GOOD OVER ALL THE PLAINS BY AFTERNOON. THE QPF FIELDS SHOW MEASURABLE SNOWFALL TONIGHT AND MONDAY IN THE MOUNTAINS...WITH A TAD OVER THE PLAINS MONDAY AFTERNOON. FOR POPS...WILL GO WIDESPREAD FOR THE MOUNTAINS TONIGHT AND MONDAY CONTINUING THE HIGHLIGHTS FOR THE THREE HIGH MOUNTAIN ZONES. NO OTHER HIGHLIGHTS. FOR THE WESTERN HALF OF THE PLAINS EARLY THIS EVENING...10-30%S. ON MONDAY AFTERNOON WILL GO WITH 20%S FOR THE PLAINS FOR SNOW SHOWERS. FOR TEMPERATURES...MONDAY`S HIGHS ARE CLOSE TO A TAD COOLER THAN TODAY`S. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 329 PM MST SUN NOV 23 2014 A STRING OF SHORTWAVES CONTINUES TO MOVE THROUGH THE NORTHWEST FLOW ALOFT THIS WEEK. STILL GOOD AGREEMENT ON THE RIDGE GRADUALLY BUILDING UPSTREAM DURING THE WEEK WITH FLOW GOING MORE WESTERLY AS IT UNDERCUTS THE RIDGE BY THIS WEEKEND. STILL HUGE DISAGREEMENTS ON THE EXACT DETAIL OF HOW FAR NORTH THE BAROCLINIC ZONE WITH BIG IMPLICATIONS FOR TEMPERATURES AND ANY THREAT OF SNOW FROM THURSDAY ON. MAIN CHANGE IN THE SHORT TERM WAS TO BEEF UP THE CHANCE OF SNOW IN THE MOUNTAINS AS THE MOISTURE RETREATS NORTHWARD MORE SLOWLY THAN PREVIOUSLY FORECAST. THIS WILL GENERALLY BE LIGHT...AND STABILITY GOES AWAY AS WARM ADVECTION ALOFT KICKS IN. HOWEVER MOISTURE AND WIND ARE BOTH SUBSTANTIAL TUESDAY NIGHT...AND THERE IS MOIST WARM ADVECTION AT MID LEVELS...SO THERE SHOULD BE MORE WIDESPREAD SNOW WITH SOME ACCUMULATION. FOR THE PLAIN I REINTRODUCED SOME 10-20 PERCENT CHANCES AS THE SHORTWAVES PASS MONDAY EVENING AND AGAIN LATE TUESDAY...BUT IF THESE DO DEVELOP THEY SHOULD ONLY BE LIGHT SHOWERS. THERE WILL ALSO BE A FAVORABLE PERIOD FOR AN AMPLIFIED MOUNTAIN WAVE. THIS LOOKS BEST LATE MONDAY NIGHT THROUGH THE DAY TUESDAY...THEN IT WILL REMAIN WINDY INTO WEDNESDAY BUT THE PROSPECTS FOR AMPLIFICATION WILL BE LESS. LOOKS LIKE A DECENT HIGH WIND THREAT FOR THE FRONT RANGE MOUNTAINS AND FOOTHILLS. PLAINS WILL BE WINDY BUT MAINLY DUE TO MIXING AND DOES NOT LOOK LIKE A HIGH WIND THREAT THERE EXCEPT SOME STEADY THE MOUNTAIN WAVE HOT SPOTS RIGHT NEXT TO THE FOOTHILLS. WEDNESDAY IS A WARM DAY WITH DECREASING WINDS. WE STILL HAVE THE SAME DILEMMA WITH THE POSITION OF THE COLD FRONT AND JET FOR THURSDAY INTO THE WEEKEND. OPERATIONAL RUNS CONTINUE TO HOLD THE FRONT STALLED ACROSS NEBRASKA ON THURSDAY...THEN SAGGING A LITTLE BY FRIDAY...THEN PULLING BACK TOWARD THE NORTHEAST AS THE FLOW ALOFT GOES MORE WESTERLY THIS WEEKEND. CRITICAL QUESTION IS HOW MUCH SOUTHWARD PROGRESS THE FRONT MAKES AND HOW SOON. MODELS CONTINUE TO OSCILLATE WITH MOST OF THE ENSEMBLE RUNS COLDER...AND SOME QUITE COLD. FOR EXAMPLE THE 12Z OPERATIONAL GFS MOS HAS A HIGH OF 70 IN DENVER FRIDAY WHILE THE OPERATIONAL ECMWF MOS BRING THE COLD AIR IN STRONGLY AND HAS A HIGH OF 27. SINCE THESE FRONTS DO TEND TO DROP SOUTH MORE THAN THE MODELS SHOW...WE WILL CONTINUE TO HEDGE DOWNWARD BELOW THE OPERATIONAL GFS. IT COULD EASILY BE 10 DEGREES WARMER...OR 20 DEGREES COLDER...OR PERHAPS BOTH SOMEWHERE IN OUR AREA. THERE IS ALSO A SMALL CHANCE OF LIGHT RAIN OR SNOW AS THE JET OVERRUNS THE FRONT...BUT ODDS OF ANYTHING SIGNIFICANT IN OUR AREA CONTINUE TO LOOK PRETTY SMALL. && .AVIATION...(FOR THE TAFS THROUGH 00Z MONDAY LATE AFTERNOON) ISSUED AT 329 PM MST SUN NOV 23 2014 PRETTY STRONG NORTHERLY WINDS WILL CONTINUING INTO THE EARLY EVENING HOURS...BECOMING MORE NORTHWESTERLY AND DECREASING BY MID EVENING. THEY EVEN GET MORE WESTERLY INSTEAD OF NORMAL DRAINAGE. PRETTY STRONG NORTHWESTERLIES RETURN BY MID MORNING MONDAY. THE CEILINGS COULD GET DOWN TO BKN040 THROUGH 01Z THIS EVENING...THEN AGAIN AFTER 19Z ON MONDAY WITH A PASSING SHSN. && .BOU WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 5 PM MST MONDAY FOR COZ031-033-034. && $$ SHORT TERM...RJK LONG TERM...GIMMESTAD AVIATION...RJK

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