Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 250450
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
950 PM MST WED DEC 24 2014

.UPDATE...
ISSUED AT 950 PM MST WED DEC 24 2014

WILL NOT BE MAKING ANY CHANGES TO THE CURRENT SET OF HIGHLIGHTS.
MODELS CONTINUE TO INDICATE THAT THE SURFACE COLD FRONT WILL PASS
OVER NORTHEAST COLORADO BY EARLY AFTERNOON WITH UPSLOPE CLOUDINESS
AND PRECIPITATION BEGINNING BY EVENING. SNOW WILL ALSO BE
INCREASING IN THE MOUNTAINS BY EARLY AFTERNOON AS THE UPPER LEVEL
LOW MOVES INTO ITS POSITION NEAR THE FOUR CORNERS. QUASI-
GEOSTROPHIC DIAGNOSTICS CONTINUES TO INDICATE STRONG DYANAMICS
WILL BE IN PLACE OVER THE STATE FROM TOMORROW AFTERNOON THROUGH
FRIDAY MORNING. SNOW IS EXPECTED TO DEVELOP THROUGH THE AFTERNOON
AND BECOME MODERATE AT TIMES OVERNIGHT.

ONLY CHANGES TO THE FORECAST WILL BE MAKING SOME ADJUSTMENTS TO
TEMPERATURES IN THE UPPER COLORADO VALLEY AND INCREASING CLOUD
COVER OVER THE PLAINS TONIGHT. ALSO BUMPED UP THE WIND SPEEDS ON
THE PLAINS TOMORROW AFTERNOON A FEW MILES PER HOUR.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 305 PM MST WED DEC 24 2014

A VIGOROUS PACIFIC STORM IS EXPECTED TO DEVELOP INTO A UPPER
LEVEL FOUR CORNERS LOW BY THURSDAY EVENING PROMISING A WHITE
CHRISTMAS AT LEAST LATE IN THE DAY.

FOR THIS EVENING THROUGH CHRISTMAS MORNING MILD AND DRY WEATHER
WILL BE OVER THE AREA THANKS TO AN UPPER LEVEL RIDGE. UPPER LEVEL
MOISTURE WILL RESULT IN CONSIDERABLE CIRRUS WAVE CLOUDS. A LEE
SIDE SURFACE LOW AND MODERATELY STRONG WESTERLIES AT 700 MB MAY
LEAD TO GUSTY WINDS OF ABOUT 30-40 MPH IN AND NEAR THE FOOTHILLS
THIS EVENING AND OVERNIGHT. BUT THE UPPER FLOW SHOULD BECOME MORE
SOUTHWESTERLY IN THE MORNING WHICH WILL REDUCE THE CHANCE FOR
MOUNTAIN WAVE INDUCED WIND IN AND ALONG THE LOWER FOOTHILLS.
THERE MAY BE SOME AREAS OF SNOW BY MORNING IN THE FAR WESTERN PART
IF THE CWA.

MODEL CONSENSUS A COLD FRONT SWEEPING DOWN THE FRONT RANGE FROM
LATE MORNING THROUGH EARLY AFTERNOON. THE AIR WILL BE PRETTY DRY
AT FIRST BUT THE COMBINATION OF COLDER AIR AND SOME MOISTURE FROM
THE EAST WILL RESULT IN SATURATION OF THE LOWER ATMOSPHERE BY LATE
AFTERNOON. DEEP UPSLOPE IS JUST BEGINNING TO FORM BY NIGHTFALL
ALONG WITH SOME QG FORCING AND ISENTROPIC LIFT. LOW STRATUS AND
LIGHT SNOW WILL LIKELY DEVELOP ALONG THE NORTHERN FRONT RANGE
DURING THE AFTERNOON AND SPREAD SOUTH THROUGH THE DENVER AREA BY
NIGHTFALL. WITH RAPIDLY FALLING TEMPERATURES LOCAL TRAVEL
CONDITIONS COULD DETERIORATE RAPIDLY IN THE EVENING.

WINTER STORM WARNINGS BEGIN AT 22Z IN THE FRONT RANGE FOOTHILLS
AND ADVISORIES BEGIN IN THE LATE AFTERNOON FOR THE DENVER TO FORT
COLLINS URBAN CORRIDOR.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 338 AM MST WED DEC 24 2014

SNOW PROSPECTS LOOK VERY GOOD FOR LATE THURSDAY THROUGH FRIDAY
MORNING FOR THE ENTIRE FORECAST AREA. UPPER TROUGH INTENSIFYING
OVER THE FOUR CORNERS AREA ON THURSDAY IS PROGGED TO TRACK SLOWLY
ACROSS COLORADO THURSDAY NIGHT AND FRIDAY. AS THE TROUGH PASSES
OVERHEAD...MOIST UPSLOPE FLOW DEVELOPS AND DEEPENS EAST OF THE
MTNS FOLLOWING THE PASSAGE OF A COLD FRONT ON THURSDAY. ISSUED A
WINTER STORM HIGHLIGHTS FOR THE MTNS...FOOTHILLS AND PORTIONS OF
THE HIGH PLAINS MOST GO INTO EFFECT LATE THURSDAY AFTERNOON AND
RUN THROUGH MIDDAY FRIDAY. SNOW TOTALS RANGE FROM 8-12 INCHES IN
THE FOOTHILLS TO JUST A FEW INCHES MTN VALLEYS AND FAR NORTHEAST
PLAINS. MANY OF THE HIGHLIGHTS HAVE BEEN MOVED UP A COUPLE OF
HOURS...BUT KEEP IN MIND THAT ACCUMULATING SNOWFALL WILL FIRST
BEGIN IN THE MTNS AND NRN FOOTHILLS AND THEN SPREAD SOUTH AND EAST
THROUGH THE EVENING ON THURSDAY. PRECIP SHOULD BE ALL SNOW WITH
FALLING TEMPERATURES THROUGH THE EVENING. WINDS DO NOT APPEAR TO
BE A SERIOUS CONCERN WITH THIS STORM SYSTEM...BUT ON THE PLAINS
LATE THURSDAY NIGHT AND FRIDAY...GUSTY NORTHERLY WINDS OF 15-30
MPH WILL LIKELY PRODUCE AREAS OF BLOWING SNOW. SEE BEST CHANCE FOR
BLOWING SNOW AND POOR VISIBILITIES ACROSS ERN ELBERT AND NORTHERN
LINCOLN COUNTIES NOW COVERED BY A WINTER WEATHER ADVISORY FOR SNOW
AND BLOWING SNOW.

ON FRIDAY...AREA STILL UNDER THE INFLUENCE OF THE UPPER TROUGH AND
COLD AIRMASS...BUT SNOWFALL SHOULD GRADUALLY DIMINISH DURING THE
AFTERNOON BUT NOT END ENTIRELY AS SLIGHTLY DRIER AIR FILTERS DOWN
FROM WYOMING. COULD SEE PERIODS OF LIGHT SNOW ALL NIGHT BUT WITH
LITTLE IF ANY ADDITIONAL ACCUMULATION. GUSTY NORTHERLY WINDS ON THE
PLAINS SHOULD ALSO EASE UP OVERNIGHT.

LOOKING AHEAD TO THE WEEKEND...REGIONAL AIRMASS GRADUALLY DRIES ON
SATURDAY WITH THE TROUGH MOVING EAST...BUT TEMPERATURES REMAIN WELL
BELOW AVERAGE ON SATURDAY EVEN WITH DECREASING CLOUD COVER. FLOW
ALOFT REMAINS NORTHWESTERLY.

BY SUNDAY...MODELS CARVE OUT A BROAD TROUGH OVER THE GREAT BASIN AND
ROCKY MTN REGIONS. THIS TROUGH IS PACKING MORE ARCTIC AIR THAN THE
TROUGH PASSING BY CHRISTMAS NIGHT. MODELS SHOW MOISTURE STREAMING IN
FRO THE NORTHWEST OVER THE NRN MTNS BY SUNDAY AFTERNOON POSSIBLY
RESULTING IN SCATTERED SNOW SHOWERS OVER HIGHER ELEVATIONS. PLAINS
AND SOUTH PARK STILL DRY AND SLIGHTLY WARMER WITH DOWNSLOPE FLOW. BY
SUNDAY EVENING MODELS SHOW LIGHT SNOW SPREADING FROM THE MTNS TO THE
PLAINS...MAINLY NORTH OF I-70 WITH EAST-SOUTHEASTERLY UPSLOPE FLOW.

MONDAY AND TUESDAY...MODELS CARVE OUT A COLD UPPER TROUGH AND SWING
IT OVER COLORADO. TEMPERATURE GUIDANCE INDICATING A BIG TEMP DROP
MONDAY INTO TUESDAY. AS IT APPEARS NOW...MAY NOT SEE MAX TEMPS
WARMER THAN THE LOWER TEENS AT LOWER ELEVATIONS BY TUESDAY WITH NEAR
ZERO READINGS IN THE HIGH COUNTRY. LOWS MONDAY NIGHT MAY TURN OUT TO
BE AS COLD AS THOSE OBSERVED IN EARLY NOVEMBER OF THIS YEAR.

DRY AND SLIGHTLY WARMER TEMPERATURES MAY THEN RETURN FOR WEDNESDAY.

&&

.AVIATION...(FOR THE TAFS THROUGH 06Z THURSDAY EVENING)
ISSUED AT 950 PM MST WED DEC 24 2014

CEILINGS WILL REMAIN HIGH OVERNIGHT AND THURSDAY MORNING. BUT THEY
WILL NOT TAKE VERY LONG TO COME DOWN AFTER THE COLD FRONT MOVES
THROUGH AROUND MIDDAY. SIGNIFICANT SNOWFALL IS EXPECTED TO DEVELOP
THURSDAY EVENING AND CONTINUE OVERNIGHT.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 5 PM THURSDAY TO NOON MST FRIDAY FOR
COZ041.

WINTER WEATHER ADVISORY FROM 3 PM THURSDAY TO 6 AM MST FRIDAY
FOR COZ038.

WINTER WEATHER ADVISORY FROM 5 PM THURSDAY TO NOON MST FRIDAY
FOR COZ039-040.

WINTER WEATHER ADVISORY FROM 6 PM THURSDAY TO NOON MST FRIDAY
FOR COZ046.

WINTER STORM WARNING FROM 3 PM THURSDAY TO NOON MST FRIDAY FOR
COZ035-036.

WINTER WEATHER ADVISORY FROM 2 PM THURSDAY TO NOON MST FRIDAY
FOR COZ031-033-034.

&&

$$

UPDATE...DANKERS
SHORT TERM...KELSCH/MEIER
LONG TERM...BAKER
AVIATION...DANKERS



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