Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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000
FXUS65 KBOU 202224
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
324 PM MST SAT DEC 20 2014

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 320 PM MST SAT DEC 20 2014

EXPECT SNOW TO INCREASE LATE THIS AFTERNOON AND EARLY EVENING OVER
THE MOUNTAINS AS THE NEXT PACIFIC WAVE MOVES ACROSS THE STATE. MAIN
FORCING WILL BE OROGRAPHIC...THOUGH THERE WILL BE HELP FROM A JET
STREAK. EXPECT UP TO 3 INCHES OF SNOW BY SUNDAY MORNING. SNOW
WILL LIKELY DECREASE LATE TONIGHT BEFORE IT RAMPS UP ON SUNDAY.
SNOW WILL BECOME WIDESPREAD AND INCREASE IN INTENSITY SUNDAY
AFTERNOON AS LIFT FROM THE JET AND OROGRAPHIC LIFT INCREASE.
EXPECT WIDESPREAD MODERATE TO HEAVY SNOW AROUND SUNSET 4-5PM
SUNDAY AFTERNOON. SNOWFALL RATES MAY REACH 1-2 INCHES PER HOUR.
THE HEAVY SNOW COMBINED WITH GUSTY WINDS WILL CAUSE ROAD
CONDITIONS TO RAPIDLY DETERIORATE. MANY ROADS MAY BECOME
UNPASSABLE SUNDAY EVENING.

FOR THE FRONT RANGE...A MILD AIRMASS AND CLOUD COVER TONIGHT WILL
RESULT IN A MILD NIGHT. A LEE SIDE TROUGH WILL DEEPEN SUNDAY. BY
AFTERNOON...EXPECT BREEZY CONDITIONS ACROSS THE FRONT RANGE AND
EASTERN PLAINS. NEAR THE WYOMING BORDER...GUSTS TO 50 TO 60 MPH
WILL BE POSSIBLE. THE DOWNSLOPE WINDS WILL ALSO RESULT IN MILD
TEMPERATURES WITH HIGHS IN THE 50S ALONG THE FRONT RANGE. IT WILL
BE COOLER OVER THE NORTHEAST CORNER WHERE SNOW REMAINS ON THE
GROUND.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 320 PM MST SAT DEC 20 2014

THE NORTHERN COLORADO HIGH COUNTRY IS IN FOR A BLAST OF WINTRY
WEATHER SUNDAY NIGHT THROUGH MONDAY. A DEEP PLUME OF MOIST
PACIFIC AIR EXTENDING WELL OFF THE OREGON COAST WILL BE DRIVEN
SEWRD INTO NORTHERN COLORADO BY A POWERFUL JET STREAM DURING THIS
PERIOD. MTN AREAS ABOVE TIMBERLINE AND WEST-NORTHWEST FACING
MTN SLOPES COULD SEE 2-3 INCH PER HOUR SNOWFALL RATES SUNDAY
NIGHT ACCOMPANIED BY 30-40KT SUSTAINED WINDS AND PEAK GUSTS
TO AS HIGH AS 70KTS. HEAVY SNOWFALL AND FIERCE WINDS ARE LIKELY
TO PRODUCE TREACHEROUS WHITEOUT CONDITIONS POTENTIALLY LEADING TO
MTN ROAD CLOSERS. MTN VALLEYS NOT LIKELY TO SEE AS MUCH SNOWFALL
OR WINDS...ALTHOUGH THE UPPER COLORADO RIVER BASIN IN GRAND
COUNTY COULD POSSIBLY PICK UP AS MUCH AS 8 INCHES OF SNOW BY
MONDAY AFTERNOON. MEANWHILE NORTH PARK WILL PROBABLY SEE LIGHTER
SNOW AMOUNTS DUE TO LESS FAVORABLE OROGRAPHICS...AND SOUTH PARK
EVEN LESS SNOW FOR THE SAME REASON. ALTHOUGH NORTH PARK COULD SEE
SEVERAL HOURS OF MODERATE SNOWFALL ON MONDAY WHEN WINDS ALOFT TURN
MORE NORTHERLY WHICH IS A MORE FAVORABLE DIRECTION FOR SNOW
PRODUCTION IN ZONE 30.

AS FOR THE PLAINS...A STRONG WLY FLOW MOVING DOWN OFF THE FRONT
RANGE WILL LIKELY SUPPRESS SNOW PRODUCTION ALONG THE FOOTHILLS
SUNDAY NIGHT. THIS SAME AREA COULD SEE W-NWLY WINDS GUSTING IN
THE 25-35KT RANGE LATE SUNDAY NIGHT WITH STRONG MID-LEVEL COLD
AIR ADVECTION KICKING IN. FARTHER OUT ON THE PLAINS JET BANDED
SNOWFALL COULD LAY DOWN A FEW RIBBONS OF 1/2-1 INCH SNOW
ACCUMULATION ACRS THE NORTHEAST CORNER OF THE STATE LATE SUNDAY
NIGHT.

ON MONDAY...MODELS SHOW A COLD FRONT SWEEPING DOWN FROM WYOMING
EARLY CAUSING A SHIFT TO N-NELY SFC WINDS. POST-FRONTAL BOUNDARY
LAYER AIR DOES NOT LOOK ALL THAT MOIST. STILL AREAS CLOSE TO THE
FOOTHILLS COULD SEE SOME BANDED PRECIP IN THE FORM OF RAIN/SNOW
SHOWERS DURING THE DAY MONDAY. ANY SNOW ACCUMULATION SHOULD
GENERALLY BE UNDER AN INCH. IN THE HIGH COUNTRY...SNOWFALL AND
WIND SPEEDS WILL GRADUALLY DECREASE FROM NORTH TO SOUTH DURING
THE DAY AS THE JET STREAM SAGS SOUTH OF THE FORECAST AREA BY
EVENING. COULD SEE ANOTHER 3-7 INCHES OF SNOW IN THE HIGH COUNTRY
BY MONDAY EVENING...WITH STORM TOTAL SNOWFALL AMTS OF 12-24
INCHES BY LATE MONDAY EVENING.

TUESDAY THROUGH EARLY WEDNESDAY LOOK DRY AND SLIGHTLY WARMER OVERALL
WITH SHORTWAVE RIDGING. BY CHRISTMAS DAY...MODELS SHOW YET ANOTHER
POTENT UPPER AIR WEATHER SYSTEM DROPPING DOWN FROM THE PACIFIC
NORTHWEST. UNFORTUNATELY THERE/S QUITE A BIT OF UNCERTAINTY IN
THE MODELS REGARDING THE TIMING...TRAJECTORY AND MAGNITUDE OF
THIS SYSTEM. FOR NOW...WILL HANG ONTO A SLIGHT CHANCE OF SNOW AT
LOWER ELEVATIONS AND A CHANCE OF SNOW IN THE HIGH COUNTRY
BEGINNING LATE ON THURSDAY AND FRIDAY.

&&

.AVIATION...(FOR THE TAFS THROUGH 00Z SUNDAY LATE AFTERNOON)
ISSUED AT 320 PM MST SAT DEC 20 2014

CLOUDS WILL INCREASE AGAIN AFTER 00Z AS THE NEXT SURGE OF PACIFIC
MOISTURE MOVE ACROSS COLORADO. CEILINGS ARE EXPECTED TO REMAIN ABOVE
6000 OVERNIGHT. LIGHT WINDS WILL TURN NORMAL DRAINAGE DIRECTION
AFTER 00Z. SKIES ARE EXPECTED TO REMAIN MOSTLY CLOUDY THROUGH
TONIGHT AND SUNDAY WITH CEILINGS GREATER THAN 6000 FEET. SOUTHWEST
TO WEST WINDS WILL INCREASE SUNDAY AFTERNOON WITH GUSTS UP TO 25
KNOTS POSSIBLE.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM NOON SUNDAY TO MIDNIGHT MST MONDAY
NIGHT FOR COZ031>034.

WINTER WEATHER ADVISORY FROM NOON SUNDAY TO MIDNIGHT MST MONDAY
NIGHT FOR COZ030.

&&

$$

SHORT TERM...MEIER
LONG TERM...BAKER
AVIATION...MEIER


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