Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 251629
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
929 AM MST THU DEC 25 2014

.UPDATE...
ISSUED AT 929 AM MST THU DEC 25 2014

HAVE REINITIALIZED THE FORECAST GRIDS WITH THE LATEST
OBSERVATIONS. FRONTAL PUSH HAS BEGUN TO DROP INTO NORTHERN
COLORADO WITH SNOW ALREADY BEING REPORTED IN CHEYENNE. SOME DRYING
IS MOVING IN WITH THE SOUTHWEST FLOW ALOFT WHICH IS CLEARING
SKIES OVER MOST OF THE AREA EXCEPT FAR NORTHERN COLORADO. HOWEVER
WITH THE FRONT PUSHING DOWN AND UPSLOPE FLOW INCREASING...EXPECT
THE NORTHERN FRONT RANGE TO INCREASE IN CLOUD COVER OVER THE
COUPLE HOURS. A SECONDARY PUSH IS STILL SHOWN IN THE MODELS AROUND
5 PM TONIGHT WITH STRONGER WINDS AND BETTER MOISTURE...WHICH WILL
LIKELY BRING THE HEAVIER SNOWFALL. THIS STILL LINES UP WELL WITH
THE CURRENT HIGHLIGHTS...SO WILL NOT ADJUST ANYTHING AT THIS TIME.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 346 AM MST THU DEC 25 2014

AN UPPER LEVEL LOW WILL CLOSE OFF OVER UTAH TODAY AND THEN MOVE INTO
THE FOUR CORNERS AREA BY LATE TONIGHT.  AT THE SFC LOW PRES WILL
INTENSIFY JUST SOUTH OF DENVER THRU THE AFTN AND THEN MOVE SE INTO
SERN CO BY EARLY THIS EVENING.  MEANWHILE A SURGE OF COOLER AIR WILL
GRADUALLY MOVE INTO NERN CO THRU THE DAY WITH INCREASING UPSLOPE
FLOW NORTH OF THE BNDRY LATER THIS AFTN INTO THE EVENING HOURS.

MEANWHILE WILL SEE SOME MID LVL ASCENT ACROSS THE AREA LATER THIS
AFTN INTO TONIGHT WITH DIFFLUENT FLOW ALOFT.  SNOW WILL INCREASE IN
THE MTNS THIS AFTN AND AT LOWER ELEVATIONS NR THE WY BORDER BY 21Z
WITH ADDITIONAL DEVELOPMENT SPREADING SOUTH ACROSS THE NRN FOOTHILLS
AND IN AREAS FROM FORT COLLINS TOWARDS BOULDER.  AM SOMEWHAT
CONCERNED WITH INCREASING ENE FLOW AND POTENTIAL FOR HEAVIER
SNOWFALL IN ZNS 38 AND 39 FOR THIS EVENING ALONG AND WEST OF I-25.
LATEST RAP IS SHOWING INCREASING POTENTIAL FOR 6 TO 8 INCHES OVER A
3 TO 4 HOUR PERIOD FROM 23Z TO 03Z.  THUS WILL UPGRADE ADVISORY TO A
WARNING FOR THESE AREAS.  FURTHER SOUTH OVER DENVER HEAVIER SNOW MAY
ALSO DEVELOP OVER THE WRN SUBURBS AT SOME POINT WITH SOME POTENTIAL
FOR WARNING CRITERIA LATER THIS EVENING HOWEVER OVERALL CONFIDENCE
IS NOT AS HIGH SO WILL KEEP CURRENT ADVISORY IN PLACE.

OVER THE PLAINS WILL SEE SNOW GRADUALLY DEVELOP THIS EVENING WITH
ADVISORY AMOUNTS POSSIBLE IN SOME AREAS.  WINDS WILL NOT BE REAL
STRONG HOWEVER WILL PROBABLY SEE SOME REDUCED VISIBILITIES AT
TIMES. IN THE MTNS AND FOOTHILLS WILL KEEP PREVIOUS HIGHLIGHTS
INTACT ALTHOUGH SRN FOOTHILLS AND PALMER DIVIDE MAY NOT SEE
HEAVIER SNOWFALL UNTIL AFTER 03Z.

FOR LATER TONIGHT AROUND MIDNIGHT SNOW INTENSITIES MAY BEGIN TO
DECREASE HOWEVER WILL LIKELY SEE AREAS OF STEADIER LIGHT SNOW
THROUGH SUNRISE IN MOST AREAS.


.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 346 AM MST THU DEC 25 2014

ON FRIDAY...THE UPPER TROUGH WILL BE IN THE VICINITY OF THE FOUR
CORNERS AT 12Z...IT WILL GRADUALLY OPEN UP AND SHIFT EASTWARD
THROUGH THE DAY. THE TROUGH AXIS ITSELF IN PROGGED TO SHIFT TO THE
EAST OF COLORADO BY FRIDAY EVENING. WEAK QG ASCENT WILL BE PRESENT
FRIDAY MORNING...THEN DECREASE THROUGH THE REST OF THE DAY.
ADDITIONAL ACCUMULATIONS ON FRIDAY WILL BE LIGHT...MAYBE ANOTHER 1
TO 4 INCHES IN THE HIGH COUNTRY...AND ANOTHER 1 TO 2 INCHES OVER
THE NORTHEAST PLAINS. A DRIER NORTHWEST TO WESTERLY FLOW ALOFT
WILL DEVELOP LATE FRIDAY NIGHT INTO SATURDAY. LINGERING MOISTURE
AROUND FRIDAY NIGHT SO WL KEEP CHC POPS IN THE MOUNTAINS. MAIN
ADJUSTMENT TO THE GRIDS ON FRIDAY AND FRIDAY NIGHT WAS TO SLOW THE
TIMING A BIT. SATURDAY AND SATURDAY NIGHT...A SHORT WAVE RIDGE
WILL BE OVER THE REGION WITH THE FLOW ALOFT INCREASING AHEAD OF
THE NEXT SYSTEM IN THE PACIFIC NORTHWEST. MOISTURE WILL INCREASE
OVER THE MOUNTAINS BY SUNDAY AFTERNOON WITH INCREASING MID AND
UPPER LEVEL QG ASCENT DEVELOPING AS THE TROUGH MOVES INTO SRN
ID/SWRN WY. THE MDLS KEEP THE TROF AXIS TO THE NORTH AND WEST OF
COLORADO SUNDAY NIGHT WITH A 100 KT WEST TO EAST UPPER JET
TRANSLATING SOUTHWARD ACROSS THE STATE. COULD SEE SOME ENHANCED
CSI BANDS DEVELOP AS WE SLIP TO THE NORTHERN SIDE OF THE JET MAX.
WL GO WITH LIKELY POPS IN THE MOUNTAINS...AND AGAIN SOME
HIGHLIGHTS MAY NEED TO BE POSTED AT SOME POINT. AN ARCTIC COLD
FRONT WILL MOVE INTO THE FRONT RANGE SUNDAY NIGHT INTO MONDAY
MORNING. TEMPERATURES ON MONDAY WL ONLY REACH THE UPPER TEENS. WL
GO WITH CHC POPS AS WELL. ALTHOUGH TIMING WL AGAIN BE AN
ISSUE...WL GO WITH THE TREND OF DRIER BUT CONTINUED COLD FOR
TUESDAY AND WEDNESDAY.

&&

.AVIATION...(FOR THE TAFS THROUGH 18Z FRIDAY MORNING)
ISSUED AT 929 AM MST THU DEC 25 2014

STILL LOOKS AT THIS TIME THAT EVEN THOUGH LIGHT SNOW MAY BEGIN MID
AFTERNOON AT KDEN AND KBJC...IT APPEARS BEST CHANCE FOR HEAVIER SNOW
WILL HOLD OFF UNTIL AFTER 5 PM WITH A SECONDARY COLD PUSH. THEN
EXPECT AN INCREASE IN COVERAGE AND INTENSITY THRU THE EARLY
EVENING HOURS AS IT PUSHES DOWN TO KAPA. SNOW INTENSITY WILL
DECREASE BY MIDNIGHT...BUT WILL CONTINUE TO SEE LIGHT SNOW THRU
SUNRISE. RIGHT NOW WILL GO WITH ACCUMULATIONS IN THE 3 TO 5 INCH
RANGE FOR DIA...5 TO 8 INCH RANGE FOR KBJC AND KAPA FROM 5 PM
THRU 5 AM.

AS FOR WINDS...OVERALL CONFIDENCE IS NOT THAT HIGH FOR LATER THIS
MORNING THRU THE AFTN. THE FIRST INITIAL PUSH HAS COME THROUGH THE
AIRPORTS TO SWITCH THEM TO THE NORTHWEST. LATEST HRRR AND RAP
HAVE HAD VERY DIFFERENT SOLUTIONS FOR THE WIND FIELDS AROUND THE
AIRPORT AS THE LOW PUSHES SOUTH. WITH NORTHWEST WINDS SHOWING
UP...IT SEEMS AS THE RAP HAS THE BETTER HANDLE ON THE SITUATION.
WILL SWITCH THE WINDS TO THE NNW THEN WILL HAVE THEM SLOWLY BACK
TO THE NE OR E BEFORE THE SECOND NORTHERLY PUSH IS EXPECTED
AROUND 01Z.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON MST FRIDAY
FOR COZ035-036-039.

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

WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO 8 AM MST FRIDAY
FOR COZ038.

WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 8 AM MST
FRIDAY FOR COZ042-043.

WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO NOON MST
FRIDAY FOR COZ040-045-046.

WINTER STORM WARNING FROM 5 PM THIS AFTERNOON TO NOON MST FRIDAY
FOR COZ041.

&&

$$

UPDATE...KRIEDERMAN
SHORT TERM...RPK
LONG TERM...COOPER
AVIATION...KRIEDERMAN


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