Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 231039
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
339 AM MST TUE DEC 23 2014

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 333 AM MST TUE DEC 23 2014

FORECAST PRETTY MUCH ON TRACK AT THIS HOUR. MAIN CHANGE WAS TO
DROP THE HIGH WIND WATCH FOR TODAY AND EXTEND THE WARNING A COUPLE
OF HOURS LATER INTO THIS AFTERNOON. AREAS IN THE AFOREMENTIONED
WATCH WILL BE WINDY BUT EXPECT SPEEDS TO REMAIN BELOW CRITERIA.
THE UPPER LEVEL CYCLONE WILL GRADUALLY PULL AWAY FROM THE STATE
WITH BRISK NORTHERLY FLOW IN ITS WAKE. THERE HAS BEEN SOME WRAP
AROUND PRECIPITATION MOVING SOUTH ACROSS OUR PLAINS AREAS AND THIS
WILL CONTINUE MUCH OF THE DAY PRIOR TO COMING TO AN END LATE THIS
AFTERNOON. THIS ACTIVITY WILL COMBINE WITH THE STRONG WINDS TO
CREATE OCCASIONAL AREAS OF BLOWING SNOW TODAY OVER PORTIONS OF THE
PLAINS. SO FAR CDOT WEB CAMS AND SURFACE REPORTS SUGGEST THAT
THINGS ARE NOT TOO BAD BUT THEY COULD EASILY DETERIORATE FOR A
TIME IN AREAS OF HEAVIER SNOWFALL. THERE IS ENOUGH MOISTURE IN THE
FLOW TO KEEP SOME OROGRAPHIC SNOW SHOWERS GOING OVER THE HIGH
COUNTRY AS WELL TODAY. MODERATE QG SUBSIDENCE SPREADING OVER THE
CWA TONIGHT SHOULD PUT AN END TO ALL PRECIPITATION AT THAT TIME
ALONG WITH CLEARING SKIES AND COLD TEMPERATURES.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 333 AM MST TUE DEC 23 2014

A FLAT UPPER LEVEL RIDGE WILL BUILD OVER THE AREA ON WED WITH A SFC
LEE TROUGH DEVELOPING ALONG THE FRONT RANGE.  OVERALL OUTSIDE OF
SOME HIGHER LEVEL CLOUDS IT WILL BE DRY.  WILL SEE WARMER
TEMPERATURES OVER NERN CO WITH READINGS RANGING FM THE UPPER 40S TO
AROUND 50 AROUND DENVER TO THE UPPER 30S OVER THE FAR NERN PLAINS.

FOR CHRISTMAS DAY AN UPPER LEVEL TROUGH WILL MOVE SE INTO THE GREAT
BASIN WITH THE FLOW ALOFT BECOMING MORE SWLY.  MOISTURE WILL
GRADUALLY INCREASE IN THE MTNS THRU THE DAY WITH SNOW DEVELOPING
ESPECIALLY BY AFTN IN THOSE AREAS FAVORED BY SWLY FLOW AS SOME MID
LVL QG ASCENT OCCURS.  OVER NERN CO APPEARS SFC LOW PRES WILL
INTENSIFY OVER ECNTRL CO BY MIDDAY WHICH WOULD ALLOW FOR LOW LVL
WINDS TO BE MORE ENE IN THE AFTN.  AS SOME WK MID LVL ASCENT MOVES
INTO THE AREA BY LATE AFTN MAY SEE A SLIGHT CHC OF -SHRA NR THE WY
BORDER AND OVER THE URBAN CORRIDOR. AS FOR HIGHS WILL KEEP
READINGS IN THE UPPER 30S OVER THE FAR NERN PLAINS WITH MID 40S
AROUND THE DENVER AREA.

BY THU NIGHT INTO EARLY FRI THE UPPER LEVEL TROUGH OVER THE GREAT
BASIN WILL MOVE ACROSS THE AREA WITH SOME MID LVL ASCENT MAINLY THU
EVENING.  AS A RESULT WILL SEE PERIODS OF SNOW IN THE MTNS ALTHOUGH
OROGRAPHICS WILL BE RATHER WEAK SO AMOUNTS SHOULD STAY IN THE
ADVISORY RANGE. OVER NERN CO UPSLOPE FLOW WILL INCREASE THU
EVENING BEHIND A COLD FNT AND AS THE MAIN UPPER LEVEL TROUGH
MOVES ACROSS SHOULD SEE A GOOD CHC OF SNOW ESPECIALLY ALONG AND
NORTH OF A DENVER TO AKRON LINE. CIPS ANALOG GUIDANCE SHOWS THERE
IS SOME POTENTIAL FOR 3 TO 6 INCHES OF SNOW OVER NERN CO WITH
LOCALLY UP TO 8 INCHES CLOSER TO THE FOOTHILLS. SREF PLUME DATA IS
ALSO INDICATING THE SAME GENERAL RANGE AS WELL.

ON FRIDAY THE UPPER LVL TROUGH WILL MOVE AWAY FM THE AREA HOWEVER
ANOTHER PIECE OF ENERGY MAY MOVE SE ACROSS THE AREA LATER IN THE
AFTN INTO FRI NIGHT. THERE ARE SIGNIFICANT DIFFERENCES BETWEEN THE
ECMWF AND GFS WITH THIS SECOND FEATURE AS THE ECMWF KEEPS ALL OF THE
PCPN IN THE MTNS.  MEANWHILE THE GFS CONTINUES TO SHOW WEAK UPSLOPE
FLOW ALONG THE FRONT RANGE WITH MORE MOISTURE AND A CHC FOR LIGHT
SNOW.  AT THIS POINT WILL LEAVE IN SOME LOW POPS FOR THE AFTN AND
EARLY EVENING HOURS IN AND NR THE FOOTHILLS.  AS FOR HIGHS IT WILL
BE COLDER ON FRI AS HIGHS STAY IN THE 20S OVER NERN CO.

BY SAT DRIER AIR WILL BEGIN TO SPREAD INTO THE MTNS IN NWLY FLOW
ALOFT SO SNOW CHANCES SHOULD DECREASE.  OVER NERN CO IT SHOULD BE
DRY WITH COLD SFC HIGH PRES OVER THE RGN WITH HIGHS IN THE 25 TO 30
DEGREE RANGE.  ON SUN THE FLOW ALOFT WILL BE WNW WITH INCREASING
MOISTURE IN THE MTNS WHICH SHOULD LEAD TO A CHC OF SNOW ESPECIALLY
IN THE AFTN.  OVER NERN CO IT WILL REMAIN DRY WITH SOME MINOR
MODERATION IN HIGHS AS READINGS RISE BACK INTO THE 30S.

FOR SUN NIGHT INTO MON AN UPPER LEVEL TROUGH WILL MOVE SE FM THE
PACIFIC NW INTO THE GREAT BASIN AS ANOTHER STG CDFNT MOVES INTO NERN
CO. PCPN COULD BE ENHANCED AHEAD OF THIS SYSTEM DUE TO PLACEMENT
OF UPPER LEVEL JET. THUS SHOULD SEE ANOTHER GOOD CHC OF SNOW IN
THE MTNS AND POSSIBLY OVER NERN CO AS WELL. LATEST 850-700 TEMP
FCST INDICATES HIGHS COULD STAY IN THE TEENS OVER NERN CO ON MON.

&&

.AVIATION...(FOR THE TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 229 AM MST TUE DEC 23 2014

STRONG NORTHWESTERLIES WILL PERSIST MOST OF THE DAY AT KDEN AND
TO A SLIGHTLY LESSER EXTENT AT KAPA. GUSTS IN THE 30-35 KT RANGE
ARE NOT OUT OF THE QUESTION. LESS WIND IS EXPECTED AT KBJC. WINDS
AT ALL TERMINALS WILL SETTLE DOWN THIS EVENING WITH NORMAL
DRAINAGE PATTERNS EXPECTED BY MID TO LATE EVENING. THERE WILL BE
SOME SNOW SHOWER ACTIVITY AROUND WHICH COULD BRIEFLY LOWER
CEILINGS AND VISIBILITIES INTO THE HIGHER MVFR RANGE THIS MORNING
AND INTO THE EARLY AFTERNOON WITH THIS THREAT DIMINISHING AFTER
21Z. VFR EXPECTED OVERNIGHT.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL 3 PM MST THIS AFTERNOON FOR COZ042-044-
046>051.

&&

$$

SHORT TERM...ET
LONG TERM...RPK
AVIATION...ET



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