Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 251050
AFDBOU

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

.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 VISBILITIES 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 12Z FRIDAY MORNING)
ISSUED AT 346 AM MST THU DEC 25 2014

AT THIS TIME IT APPEARS BEST CHC OF SNOW AT DIA WILL HOLD OFF UNTIL
AFTER 5 PM WITH AN INCREASE IN COVERAGE AND INTENSITY THRU THE EARLY
EVENING HOURS.  SNOW INTENSITY WILL DECREASE BY MIDNIGHT HOWEVER
WILL CONTINUE TO SEE LIGHT SNOW THRU SUNRISE.  RIGHT NOW WILL GO
WITH ACCUMULATIONS IN THE 3 TO 5 INCH RANGE FOR DIA FM 5 PM THRU 5
AM.

AS FOR WINDS OVERALL CONFIDENCE NOT THAT HIGH FOR LATER THIS MORNING
THRU THE AFTN.  LATEST HRRR AND RAP HAVE BEEN SHOWN A SFC LOW
DEVELOPING JUST TO THE SOUTH OF THE AIRPORT BY MID TO LATE MORNING
WHICH SHIFTS SLOWLY SOUTH THRU THE AFTN.  AS A RESULT SSW WINDS THIS
MORNING MAY BECOME MORE ELY BY 18Z AND STAY THAT WAY THRU LATE AFTN.
AFTER 00Z WINDS MAY WILL BECOME MORE NELY AND THEN MORE NLY AROUND
MIDNIGHT.

&&

.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.

&&

$$

SHORT TERM...RPK
LONG TERM...COOPER
AVIATION...RPK


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