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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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