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000
FXUS65 KBOU 111606
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1006 AM MDT TUE MAR 11 2014

.UPDATE...

&&

.SHORT TERM...FRONT CURRENTLY PUSHING SOUTH ACROSS PLAINS...
REACHED DENVER AT 15Z. NORTHERLY WINDS BEHIND FRONT...CURRENTLY
GUSTING IN THE 35 TO 40 MPH RANGE. WINDS STILL EXPECTED TO
INCREASE...WITH RUC AND HRRR INDICATING GUSTS OF 40 TO 50 MPH.
BLOWING DUST ADVISORY SEEMS REASONABLE FOR LINCOLN COUNTY. AT THIS
TIME...WINDS SHOULD REMAIN BELOW HIGH WIND CRITERIA. AS FOR SNOW
...MOUNTAIN AREAS SEEING ACCUMULATING SNOW AT THIS TIME. THERE MAY
BE A BIT OF A DECREASE LATER THIS MORNING AS SLIGHTLY DRIER AIR
MOVES OVER THE AREA. BUT A GOOD BATCH OF MOISTURE OVER WYOMING
SHOULD SPREAD BACK INTO THE MOUNTAINS. WILL CONTINUE WITH THE
CURRENT FORECAST TRENDS WITH ROUGHLY 3 TO 6 INCHES...NO
ADVISORIES AT THIS TIME. ACROSS PLAINS...SNOWING LIGHTLY NORTH OF
THE BORDER AT CHEYENNE AND KIMBLE. RADAR SHOWING SOME ECHOES
ACROSS NORTHERN LARIMER COUNTY NEAR THE WYOMING BORDER. SHOULD SEE
THE PRECIPITATION DEVELOP BEHIND THE FRONT WITHIN THE NEXT HOUR OR
SO AS THE LOWER LEVELS OF THE ATMOSPHERE GRADUALLY MOISTEN. WITH
TEMPERATURES FALLING BEHIND THE FRONT...THE PRECIPITATION WILL BE
MAINLY SNOW WITH SOME RAIN MIXED IN FOR A SHORT PERIOD OF TIME.
LATEST MODEL TRENDS INDICATING A 1 OR 2 INCH SNOWFALL FOR THE
DENVER AREA WITH AS MUCH AS 4 INCHES FOR THE PALMER DIVIDE.
INITIALLY THE SNOW SHOULD MELT BEFORE ANY ACCUMULATION OCCURS.
LESS ACCUMULATION ELSEWHERE DUE TO DOWNSLOPE COMPONENT. BLOWING
SNOW POSSIBLE WITH THE STRONG WIND AND ACCUMULATION. DON`T THINK
AN ADVISORY FOR SNOW AND BLOWING SNOW WILL BE NEEDED FOR THE
PALMER DIVIDE AT THIS TIME DUE TO THE INITIAL MELTING EXPECTED.
WILL CONTINUE TO MONITOR TO SEE IF ONE WILL BE NEEDED. SNOW TO END
FROM NORTH TO SOUTH DURING THE EVENING WITH SUBSIDENCE AND DRIER
AIRMASS. OVERALL...CURRENT FORECAST LOOK REASONABLE WITH SOME
ADJUSTMENTS DUE TO TIMING OF FRONT.

.AVIATION...FRONT MOVING ACROSS DIA WITH NORTHERLY WINDS GUSTING
TO 28 KTS. FRONT SHOULD BE MOVING INTO KBJC AND KAPA WITHIN THE
NEXT ONE HALF HOUR WITH WINDS SHIFTING TO THE NORTH AND INCREASING
TO 25 TO 30 KTS. SOME GUSTS TO 40 KTS POSSIBLE DURING THE
AFTERNOON. SNOW TO DEVELOP BY 18Z WITH MVFR CONDITIONS. IFR
CONDITIONS POSSIBLE WITH THE HEAVIER SNOW SHOWERS. SNOW EXPECTED
TO END BETWEEN 00Z AND 01Z WITH DECREASING WINDS. AT THIS TIME THE
FRONT RANGE AIRPORTS SHOULD SEE BETWEEN ONE AND TWO INCHES OF SNOW
ACCUMULATION. THERE IS A SLIGHT CHANCE THAT KAPA COULD RECEIVE
AROUND 3 INCHES IF CONVECTION IS A BIT MORE PRONOUNCED. STILL
EXPECTING VFR CONDITIONS WITH LIGHTER WINDS OVERNIGHT. AT THIS
TIME...FOG OR LOW CLOUDS ARE NOT EXPECTED TO DEVELOP.


&&

.PREV DISCUSSION... /ISSUED 420 AM MDT TUE MAR 11 2014/

SHORT TERM...STILL A COMPLEX WEATHER SCENARIO FOR THE FORECAST
AREA TODAY. BUT COLD...STRONG WINDS...AND SNOW STILL ON THE WAY.
PREFRONTAL WIND SHIFT IS ALREADY OCCURRING ACROSS THE NORTHEAST
PLAINS PER LATEST OBS. MAIN COLD FRONT HAD JUST PUSHED THROUGH
CASPER WYOMING SO THATS ON TRACK TO REACH THE BORDER SHORTLY
BEFORE DAYBREAK AND DENVER METRO AROUND 9 AM. BIG SURFACE
PRESSURE RISES ARE OCCURRING BEHIND THE FRONT AND INCREASING...SO
A SLIGHTLY EARLIER ARRIVAL IS POSSIBLE. WINDS WILL INCREASE WITH
AND JUST BEHIND THE FRONT WITH WIDESPREAD GUSTS OF 40 TO 55
MPH...STRONGEST ON THE EASTERN PLAINS. LOCATIONS AROUND LINCOLN
COUNTY HAVE BEEN DRIER THERE RECENTLY THAN ANYWHERE ELSE SO
BLOWING DUST WILL BE A CONCERN BEFORE ANY WIDESPREAD PRECIPITATION
THIS AFTERNOON...SO HAVE ISSUED A BLOWING DUST ADVISORY THERE.

WITH REGARD TO SNOWFALL...MOUNTAINS WERE ALREADY SEEING ONE BATCH
OF SNOW...BUT THIS WILL LIKELY DECREASE A BIT EARLY THIS MORNING
AS SOME TEMPORARILY DRIER AIR MOVES ACROSS. MORE WIDESPREAD SNOW
IS EXPECTED TO DEVELOP BEHIND THE FRONT PER UPSTREAM OBS. LOW/MID
LEVELS ARE INITIALLY DRY...SO LOOK FOR PRECIPITATION TO DEVELOP
WITHIN ABOUT 2-4 HOURS OF FRONTAL ARRIVAL. TEMPERATURES WILL BE
COLD ENOUGH FOR ALMOST ALL SNOW AND WILL GET COLDER THROUGH THE
DAY. THERE MAY BE A BIT OF LIGHT RAIN ON THE LEADING EDGE OF
PRECIP. SATELLITE SHOWS CONVECTION ASSOCIATED WITH UPPER LEVEL
COLD POOL NOW MOVING ACROSS NORTHERN UTAH AND WYOMING...WHICH WILL
REACH THE FRONT RANGE BY 18Z. THE COMBINATION OF UPSLOPE AND COLD
POOL ALOFT MEANS A MOISTENING AIRMASS WITH VERY STEEP LAPSE
RATES...SO CONVECTIVE POTENTIAL IS THERE. OVERALL...THINK THE
CONVECTIVE POTENTIAL WILL HELP OFFSET THE SPARSE MODEL QPF. ADDED
A LITTLE MORE SNOW TO THE NORTHEAST CORNER LATER THIS MORNING INTO
THE AFTERNOON BASED ON LATEST MESOSCALE MODEL OUTPUT AND BETTER
MOISTURE THERE...WHILE CUT BACK AMOUNTS ON THE DOWNSLOPE SIDE OF
THE CHEYENNE RIDGE GIVEN STRONG NORTHERLY FLOW IN PLACE. DENVER
AREA STILL EXPECTED TO SEE A 1-2 INCH SNOWFALL BUT STILL SOME
UNCERTAINTY FOR HIGHER OR LOWER AMOUNTS BASED ON CONVECTIVE
NATURE. THE MOST FAVORED LOCATION FOR SNOW IN THIS FLOW PATTERN
WOULD BE FOOTHILLS OF JEFFERSON/DOUGLAS COUNTIES AS WELL AS THE
PALMER DIVIDE...SO WILL GO WITH HEAVIER AMOUNTS OF 2-5 INCHES
POSSIBLE THERE. GIVEN THE STRONG WINDS...ALSO MENTIONED AREAS OF
BLOWING SNOW WHERE MORE THAN AN INCH OR TWO OF ACCUMULATION IS
EXPECTED. MOUNTAIN LOCATIONS SHOULD SEE STORM TOTALS MOSTLY IN THE
3-6 INCH RANGE.

SNOW WILL DECREASE LATE THIS AFTERNOON INTO EARLY EVENING FROM
NORTH TO SOUTH AS AIRMASS DRIES AND SUBSIDENCE BUILDS IN. SKIES
WILL THEN CLEAR OUT FOR OVERNIGHT. WINDS WILL DECREASE BY OR
SHORTLY AFTER SUNSET.

LONG TERM...MEDIUM AND LONG RANGE PORTIONS OF THE FORECAST
INCLUDE GENERALLY DRY AND MILD WEATHER AS A WESTERN U.S. RIDGE
PRODUCES WARM NORTHWESTERLY FLOW OVER COLORADO. ON WEDNESDAY AND
THURSDAY...THE UPPER RIDGE WILL BE HELD OVER COLORADO WHILE A
WEAK...CUTOFF LOW MEANDERS FROM SOUTHERN NEVADA TO CENTRAL NEW
MEXICO. OUR REGION WILL BE LEFT UNDER THE DEFORMATION REGION WITH
WEAK FLOW ALOFT. THE UPPER FEATURE SHOULD EVENTUALLY KICK OUT ONTO
THE SOUTHERN PLAINS BY ABOUT FRIDAY WITH LITTLE ADDITIONAL IMPACT
ON NORTHERN COLORADO WEATHER. FROM FRIDAY THROUGH
SATURDAY...NORTHWEST FLOW ALOFT WILL INCREASE OVER THE STATE AS
THE UPPER LOW DEPARTS. LATER ON SATURDAY...A WEAK SHORT WAVE
EMBEDDED IN THE NORTHWEST FLOW PATTERN IS FORECAST TO SLIDE OVER
THE STATE. THIS FEATURE WILL BRING A CHANCE OF SNOW TO THE
MOUNTAINS AND MAY BRING SOME PRECIPITATION TO THE PLAINS THROUGH
SATURDAY NIGHT. EACH OF THE SYNOPTIC MODELS HAVE VARIOUS IDEAS ON
THE TIMING OF THE SOUTHWESTERN CUTOFF LOW EJECTING AND SUBSEQUENT
PASSAGE OF UPPER TROUGH ACROSS COLORADO. FOR NOW HAVE FAVORED THE
GFS SOLUTION...AS THE CANADIAN AND ECMWF LOOK A LITTLE TOO FAST.
BEYOND THAT...MORE WESTERN U.S. RIDGING IS FORECAST WITH SUBSIDENT
NORTHWESTERLY FLOW EXPECTED OVER COLORADO. DRY WEATHER AND WARMER
TEMPERATURES WILL BE THE RESULT.

TEMPERATURE FORECASTS THROUGH THE PERIOD WERE A COMPROMISE BETWEEN
THE TOO WARM GFS MOS GUIDANCE AND CONSERVATIVE GENERALLY
CONSERVATIVE NUMBERS FROM ECMWF MOS GUIDANCE. FORECASTING THE
PRECIPITATION TYPE ON THE PLAINS IS GOING TO BE CHALLENGING AND
DEPEND ON THE TIME OF DAY OR NIGHT WHEN THE WEATHER SYSTEMS PASS
OVER THE AREA. DAYTIME PRECIPITATION WILL BE IN LIQUID FORM WHILE
EVENING AND OVERNIGHT TIME PERIODS WILL FAVOR SNOW OR A RAIN/SNOW
MIX.

AVIATION...STRONG COLD FRONT EXPECTED TO REACH THE FRONT RANGE
AIRPORTS AROUND 15Z...PERHAPS A BIT EARLIER AT KDEN. SOME STRATUS
AND POTENTIAL FOR MVFR CEILINGS TO DEVELOP BEHIND THE FRONT...THEN
SNOW WILL BECOME LIKELY BY 18Z-21Z WITH IFR CONDITIONS IN HEAVIER
SNOW SHOWERS. WINDS WILL INCREASE SIGNIFICANTLY BEHIND THE FRONT
WITH GUSTS TO 35-40 KTS LIKELY FROM ALMOST DUE NORTH. SNOW WILL
END BY 00Z-01Z WITH WINDS DECREASING SIGNIFICANTLY BY THEN AS
WELL. FRONT RANGE AIRPORTS MOST LIKELY TO SEE 1-2 INCH SNOW
TOTALS...WITH POTENTIAL FOR A LITTLE MORE THAN THAT AT KAPA IF
CONVECTION BECOMES MORE WIDESPREAD. VFR CONDITIONS AND LIGHTER
WINDS OVERNIGHT.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
BLOWING DUST ADVISORY UNTIL 7 PM MDT THIS EVENING FOR COZ046-047.

&&

$$

SHORT TERM...D-L
LONG TERM....DANKERS
AVIATION...D-L