Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 180456
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
956 PM MST WED DEC 17 2014

.UPDATE...
ISSUED AT 948 PM MST WED DEC 17 2014

THERE IS A LITTLE LIGHT SNOW OUT THERE...BUT THE WEAK RADAR ECHOES
APPEAR TO BE MOSTLY VIRGA. BACKED OFF SLIGHTLY FROM POPS
OVERNIGHT. ALSO EXPANDED THE AREAS OF FOG ACROSS THE NORTHEAST
CORNER THROUGH MID MORNING. WITH LOW LEVEL GRADIENT TENDING MORE
SOUTHERLY...NOT EXPECTING THIS TO PUSH BACK TOWARD DENVER THOUGH
THINNING CLOUDS COULD ALLOW SOME PATCHY LOW CLOUDS AND FOG TO
DEVELOP. NOT LOOKING LIKE THERE WILL BE A LOT OF CLEARING OF THE
HIGHER CLOUDS HOWEVER. WITH THE CLOUD COVER AND DEW POINTS A BIT
HIGHER...RAISED LOW TEMPERATURES A COUPLE DEGREES.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 310 PM MST
WED DEC 17 2014

FREEZING DRIZZLE HAS BEEN REPORTED ACROSS THE BORDER IN KANSAS AND
NEBRASKA THIS MORNING...BUT HAVE SEEN NO EVIDENCE HERE IN COLORADO.
THIS WILL BE ONE THING FOR THE EVENING SHIFT TO CONSIDER AS  IF
FEEDER-SEEDER ISSUES DEVELOP.  THERE HAS BEEN SOME RESIDUAL FOG IN
NORTHEAST COLORADO AND ADDED FOG THIS EVENING TO THE NORTHEAST
CORNER.  AS A RESULT OF THE SNOW COVER AND FOG...THE MAX TEMPS HAVE
REMAINED IN THE 20S TODAY.

THE UPPER LEVEL WEATHER SYSTEM WILL LIFT ACROSS SOUTHEAST COLORADO
THIS EVENING.  RADAR ALREADY SHOWS ECHOES ACROSS THE PALMER
DIVIDE... BUT THUS FAR NOTHING HAS BEEN REPORTED AT THE SURFACE.
WILL LEAVE POPS IN THE FORECAST ESPECIALLY OVER THE PALMER DIVIDE...
BUT EXPECT ONLY A TRACE OF SNOW AWAY FROM THE PALMER DIVIDE...MAY
SEE AN INCH OR SO ON THE DIVIDE.

IN THE MOUNTAINS...SNOW WILL CONTINUE TONIGHT AND THURSDAY.  THE
FIRST DISTURBANCE WILL BE FOLLOWED ON THURSDAY WITH A TROUGH DIVING
INTO ARIZONA.  AS A RESULT SNOW WILL STILL LINGER IN THE MOUNTAINS
WITH THE DRYING HOLDING OFF UNTIL THURSDAY NIGHT.

TEMPERATURES WILL BE COLD TONIGHT WITH TEENS OVER THE SNOWFIELD IN
NORTHEAST COLORADO...SINGLE DIGITS AND TEENS IN THE MOUNTAINS AND
20S OVER THE URBAN CORRIDOR.  THURSDAY WILL FEATURE A SLIGHT WARMUP
TO NEAR FREEZING IN NORTHEAST COLORADO...AND AROUND 40 ALONG THE
URBAN CORRIDOR.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 310 PM MST WED DEC 17 2014

WEAK UPPER TROUGH MOVES INTO THE CENTRAL PLAINS STATES ON FRIDAY
WITH A NORTHWEST FLOW ALOFT DEVELOPING OVER COLORADO. THERE WILL BE
JUST ENOUGH MOISTURE AVAILABLE TO PRODUCE SCATTERED LIGHT SNOW
SHOWERS OVER THE MOUNTAINS THURSDAY EVENING. SNOW CHANCES SHOULD
DECREASE AFTER MIDNIGHT AS WEAK RIDGING AND DOWNWARD FORCING MOVES
INTO THE REGION. DRY WEATHER AND NEAR NORMAL TEMPERATURES WILL
CONTINUE OVER THE PLAINS THROUGH SATURDAY. SOME WEAK DOWNSLOPE FLOW
WILL KEEP FRIDAY MORNING LOW TEMPERATURES UP FROM PREVIOUS MORNINGS
ALONG THE FRONT RANGE URBAN CORRIDOR.

MAJOR CHANGE IN THE PATTERN OVERNIGHT SATURDAY INTO SUNDAY AS STRONG
AND MOIST JET STREAM MOVES INTO COLORADO FROM THE NORTHWEST. THIS
PATTERN LOOKS TO BE SETTING UP A PROLONGED PERIOD OF SNOW AND WIND
ACROSS THE MOUNTAINS FROM SUNDAY THROUGH THE END OF THE PERIOD. SNOW
AND WIND ARE EXPECTED TO INCREASE ACROSS THE MOUNTAINS DURING THE
DAY ON SUNDAY...HOWEVER...WARM AIR ADVECTION SHOULD KEEP THE SNOW ON
THE LIGHT SIDE. DRY WEATHER AND SLIGHTLY ABOVE NORMAL TEMPERATURES
ARE EXPECTED ON THE PLAINS DUE TO DOWNSLOPE FLOW. CROSS SECTIONS
ALSO SHOW WINDY CONDITIONS OVER THE FRONT RANGE FOOTHILLS FROM LATE
SUNDAY THROUGH ABOUT NOON MONDAY.

FROM MIDDAY MONDAY THROUGH TUESDAY MORNING...THE GFS AND ECMWF SHOW
A NORTH NORTHWEST TO SOUTH SOUTHEAST ORIENTED 140+ KT JET MAX OVER
CENTRAL COLORADO. THIS COMBINED WITH PLENTY OF MOISTURE AND COLD AIR
ADVECTION...WILL BRING THE POTENTIAL FOR HEAVY SNOW AND VERY WINDY
CONDITIONS TO THE HIGH COUNTRY. WARM ADVECTION WILL MOVE INTO THE
MOUNTAINS DURING THE DAY ON TUESDAY AS THE UPPER JET MOVES OVER
EASTERN COLORADO. THIS SHOULD RESULT IN A DECREASE IN SNOW
INTENSITY. HOWEVER...WINDY CONDITIONS AND LIGHT SNOW SHOULD STILL
PERSIST. MONDAY AND TUESDAY LOOK TO BE SOMEWHAT WINDY ON THE PLAINS
AS A GRADIENT SETS UP BETWEEN A SURFACE LOW OVER THE NORTHERN PLAINS
AND HIGHER PRESSURE OVER WESTERN COLORADO. THE NORTHWEST WINDS
SHOULD KEEP OVERNIGHT LOWS ON MONDAY MORNING AT ABOVE NORMAL
LEVELS. THE GFS AND ECMWF ARE HINTING AT SOME ANTICYCLONIC TURNING
ON MONDAY...WHICH MAKES ITS WAY INTO THE DENVER AREA BY 00Z
TUESDAY. IF THIS HAPPENS, I WOULDN`T BE SURPRISED TO SEE SOME SNOW
BANDS OVER THE NORTHEASTERN PLAINS MONDAY MORNING MOVING INTO THE
DENVER AREA BY AFTERNOON. THEREFORE...I HAVE INCREASED THE POPS ON
MONDAY FOR THESE AREAS.

LOOKING FURTHER AHEAD TO THE CHRISTMAS HOLIDAY...THE UPPER JET
CONTINUES ORIENTED OVER THE COLORADO WHICH SHOULD KEEP SNOW FALLING
OVER THE HIGH COUNTRY. THE GFS AND ECMWF BOTH SHOWING THE
POSSIBILITY OF LIGHT SNOW ACROSS THE FRONT RANGE URBAN CORRIDOR
CHRISTMAS EVE DAY. FOR NOW HAVE ONLY ADDED A 10 POP FOR DENVER DUE
TO THE FACT THAT THIS IS WAY OUT IN DAY SEVEN.

&&

.AVIATION...(FOR THE TAFS THROUGH 06Z THURSDAY EVENING)
ISSUED AT 948 PM MST WED DEC 17 2014

THERE IS A SLIGHT CHANCE OF FLURRIES IN THE DENVER AREA
OVERNIGHT...BUT NO ACCUMULATION IS EXPECTED. ALSO A SLIGHT CHANCE
OF SOME LOW CLOUDS OR FOG WITH IFR CEILINGS. HOWEVER IT WILL
PROBABLY BE DRY WITH HIGH CLOUDS PROVIDING VFR CONDITIONS. WINDS
WILL REMAIN LIGHT.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...GIMMESTAD
SHORT TERM...RTG
LONG TERM...KALINA
AVIATION...GIMMESTAD



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