Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 151715
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1015 AM MST SAT NOV 15 2014

.UPDATE...
ISSUED AT 954 AM MST SAT NOV 15 2014

RADAR SHOWS SNOW BANDS INCREASING WHILE CLOUD TOPS ARE ALSO
COOLING ACROSS THE REGION. AIRMASS IS POTENTIALLY UNSTABLE PER 12Z
GRAND JUNCTION SOUNDING AND NOSE OF FIRST UPPER LEVEL SPEED MAX IS
AIDING UPPER LEVEL DIVERGENCE. CONVECTIVE SHOWERS EVIDENCED ON THE
WESTERN SLOPE RADAR WHILE BANDS OF HEAVIER SNOW HAVE ALREADY MOVED
ACROSS THE NORTHERN PLAINS INCLUDING FORT COLLINS WHICH PICKED UP
A QUICK ONE HALF TO ONE INCH OF SNOW WHEN A BAND MOVED ACROSS.
FIRST SPEED MAX WILL PASS OFF TO THE NORTH LATER THIS MORNING
WHILE NEXT JET MAX WILL PLOW INTO WESTERN COLORADO LATE THIS
AFTERNOON/EVENING. LIFT ASSOCIATED WITH THIS NEXT SURGE SHOULD
BRING ANOTHER INCREASE IN SNOW MAINLY ALONG AND SOUTH OF THE I-70
CORRIDOR. AS A RESULT...WILL UPGRADE THE ADVISORY IN THE I-70
CORRIDOR OF THE MOUNTAINS INCLUDING SUMMIT COUNTY...ZONE 34...TO
A WINTER STORM WARNING THROUGH MIDNIGHT. OTHER MAIN CHANGES WERE
TO INCREASE POPS AND SNOW AMOUNTS ON THE PLAINS PER LATEST
TRENDS...AND ALSO DELAY ENDING OF SNOW MAINLY FROM DENVER AND
LIMON SOUTHWARD THIS EVENING AS NEXT BATCH OF LIFT SEEN IN THE Q-G
FIELDS PROVIDE AT LEAST WEAK UPPER LEVEL LIFT. TEMPERATURE
FORECAST ON TRACK WITH FALLING TEMPS IN ARCTIC AIRMASS THROUGH THE
REST OF THE DAY AND BELOW ZERO READINGS MUCH OF THE PLAINS
TONIGHT.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 450 AM MST SAT NOV 15 2014

TWO WEATHER FEATURES TO CONTEND WITH THIS MORNING. FIRST IS THE
ARCTIC FRONT SLIPPING SOUTH THROUGH WELD AND WASHINGTON COUNTIES
AT THE MOMENT. A PRE-FRONTAL WIND SHIFT HAS ALREADY SWEPT THROUGH
THE DENVER METRO AREA...BUT THE COLDER AIR AND LOWER CLOUDS ARE
OBSERVED NORTH OF THE MAIN FRONTAL BNDRY. AT PRESENT SPEED COULD
SEE THE FRONT INTO THE GREATER DENVER METRO AREA WITH THE NEXT30
MINS OR SO. PRESSURE RISES BEHIND THIS FRONT NOTHING LIKE THOSE
PRESENT BEHIND THE STRONGER ARCTIC FRONT LAST MONDAY.
NEVERTHELESS...SHOULD SEE TEMPERATURES SLIPPING ON THE PLAINS
THROUGH THE MORNING WITH GUSTY N-NELY. GOOD BET TEMPERATURES HAVE
ALREADY MAXED OUT FOR TODAY ON THE PLAINS. GUIDANCE INDICATING
SINGLE DIGIT TEMPERATURES BY THIS AFTERNOON.
FURTHERMORE...SNOWFALL EAST OFF THE MTNS IS STILL UP IN
WYOMING...BUT WITHIN NEXT FEW HOURS SHOULD SEE A BAND OF LIGHT
SNOW MAKING ITS WAY SOUTHWARD ACRS THE CWA ACCORDING TO THE HRRR
AND RAP. ACCUMULATION RATES SHOULD REMAIN ON THE LIGHT
SIDE...GENERALLY UNDER A QUARTER INCH PER HOUR THROUGH MIDDAY.
HOWEVER MODELS SHOW A BAND OF HEAVIER SNOW DEVELOPING ALONG THE
I-70 CORRIDOR DURING THE MID TO LATE AFTERNOON HOURS WITH SNOWFALL
RATES AROUND 1/2 TO 3/4 INCH PER HOUR. SHOULD SEE PRECIP COMING
TO AN END FROM NORTH TO SOUTH DURING THE EVENING HOURS AS LIFT AND
INSTABILITY SHIFT SOUTH OF THE AREA.

IN THE HIGH COUNTRY...AN INFLUX OF PACIFIC MOISTURE ON THE NOSE OF
A 110+ KT JET WILL RESULT IN A STEADY INFLUX OF SNOWFALL ACROSS
THE HIGH COUNTRY THROUGH THE MORNING. WEST FACING ASPECTS IN BEST
POSITION TO PICK UP GREATEST SNOW AMOUNTS OVER THE NEXT 18 HOURS.
WINTER WEATHER ADVISORY FOR SNOW AND BLOWING SNOW NOW IN EFFECT
FOR MTN ZONES. MTN VALLEYS ZONES 30 AND 32 HAVE BEEN ADDED TO THE
ADVSY. 5-12 INCH ACCUMS EXPECTED IN MTN ZONES...WITH 3-7 INCH
TOTALS ON THE VALLEY FLOORS. INCREASING WEST WINDS WITH ARRIVAL
OF THE JET LATER THIS MORNING WILL LIKELY PRODUCE BLOWING AND
DRIFTING SNOW IN OPEN AREAS IN THE HIGH COUNTRY MAKING TRAVEL
DIFFICULT IF NOT HAZARDOUS FOR A TIME THIS AFTERNOON.

JET...MOISTURE AND DYNAMICS ARE FORECAST TO MIGRATE SOUTH AND EAST
OF THE AREA THIS EVENING PUTTING A GRADUAL END TO SNOWFALL AND
WINDS STARTING IN THE NORTHERN AREAS. CLEARING SKIES LATE TONIGHT
WILL RESULT IN BITTER OVERNIGHT LOWS AND POSSIBLY SOME DENSE FOG
ON THE PLAINS BEFORE MORNING.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 450 AM MST SAT NOV 15 2014

THE UPPER LEVEL TROF AXIS WILL SAG SOUTHWARD OVER SOUTHERN
COLORADO SUNDAY MORNING WITH DRYING AIRMASS. HOWEVER WILL STILL
HAVE RATHER COLD TEMPERATURES DURING THE DAY SUNDAY WITH FRESH
SNOW COVER AND LINGERING LOW LEVEL INVERSIONS.  BY SUNDAY
AFTERNOON AND EVENING AN UPPER LEVEL TROF SWEEPS ACROSS THE
NORTHERN HIGH PLAINS WITH SOME REFLECTION AT THE SURFACE OVER FAR
NORTHEAST COLORADO. STILL REMAINS A SUBSIDENT AIRMASS BUT A MID
LEVEL DECK OF CLOUDS EXPECTED. WILL KEEP CONDITIONS DRY FOR NOW
BUT GUSTY NORTHWEST WINDS OVER THE PLAINS.

MUCH OF NEXT WEEK THROUGH WEDNESDAY WILL BE CHARACTERIZED WITH A
STRONG NORTHWEST FLOW PATTERN WITH HIGH AMPLITUDE RIDGING ALONG
WEST COAST AND STRONG LOW OVER GREAT LAKES REGION. THERE WILL BE A
SLOW MODERATION OF TEMPERATURES WHILE GUSTY WINDS CONTINUE AT
TIMES OVER THE HIGH MOUNTAINS. COULD SEE SOME GUSTS UP TO 50 MPH
OVER THE MOUNTAIN PASSES.

BY THURSDAY AND FRIDAY...SOME PACIFIC MOISTURE BEGINS TO STREAM
INTO THE MOUNTAINS WITH A WEAK DISTURBANCE. WILL HAVE LOW POPS IN
FOR NOW. FOR LOWER ELEVATIONS...GENERALLY MILD WITH READINGS IN
THE 40S ALONG WITH DRY CONDITIONS.

&&

.AVIATION...(FOR THE TAFS THROUGH 18Z SUNDAY MORNING)
ISSUED AT 954 AM MST SAT NOV 15 2014

LIGHT SNOW AND IFR/MVFR CEILINGS/VSBYS OVER HAVE OVERSPREAD THE
FRONT RANGE AIRPORTS THIS MORNING. THESE CONDITIONS WILL CONTINUE
THROUGH THE AFTERNOON HOURS ALTHOUGH A COUPLE HEAVIER SNOW BANDS
COULD DROP VSBYS TO 1/4-1/2SM FOR A 30-45 MINUTE PERIOD. MAIN
CHANGE WAS TO DELAY THE ENDING OF SNOW AS NEXT UPPER LEVEL
DISTURBANCE COULD VERY WELL KEEP SNOW IN THE FORECAST TIL AROUND
06Z/07Z. LATEST SHORT RANGE RAP AND HRRR ALSO POINT TO THIS. TOTAL
SNOW ACCUMULATIONS 1-3 INCHES EXPECTED.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 8 PM MST THIS EVENING FOR
COZ030>033.

WINTER STORM WARNING UNTIL MIDNIGHT MST TONIGHT FOR COZ034.

&&

$$

UPDATE...BARJENBRUCH
SHORT TERM...BAKER
LONG TERM...ENTREKIN
AVIATION...BARJENBRUCH



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