000
FXUS65 KBOU 071123
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
415 AM MST WED JAN 7 2009

.SHORT TERM...EVERYTHING IS STILL ON TRACK FOR HIGH WINDS...ALTHOUGH
DEVELOPMENT IS RUNNING JUST A TAD BEHIND.  PASSAGE OF UPPER LEVEL
JET MAX TO THE EAST OF THE FRONT RANGE AROUND MIDNIGHT DID NOT
RESULT IN AN INCREASE IN WINDS...SO LOOKS LIKE WE WILL HAVE TO WAIT
FOR THE GRADIENT AND INCREASING MID LEVEL WINDS TO DO ITS WORK.
PRESENTLY...WINDS HAD TEMPORARILY INCREASED IN PORTIONS OF THE
FOOTHILLS WITH A GUST TO 63 KNOTS ON A MESONET STATION NEAR GOLD
HILL WEST OF BOULDER.  HOWEVER...AT THE SAME TIME WINDS HAD
DECREASED IN THE HIGHER FOOTHILLS WHICH SOMETIMES OCCURS WITH AN
INCREASE IN MOUNTAIN SNOWFALL.  THIS HEAVIER SNOW SHOULD BE ON THE
WANE DURING THE EARLY MORNING HOURS AS SOME DRIER AIR WORKS IN FROM
THE NORTHWEST AS EVIDENCED BY SNOW DECREASING TO FLURRIES IN CRAIG
AND HAYDEN IN NORTHWEST COLORADO.  EXPECT WINDS TO INCREASE IN ALL
AREAS LATER THIS MORNING AS THIS DRIER AND PERHAPS MORE SUBSIDENT
AIR MOVES ACROSS THE FRONT RANGE.  THE CURRENT SANGSTER HIGH WIND
PROGRAM SHOWS DP/DN VALUES AROUND 260 RIGHT NOW...AND FORECAST FROM
THE VARIOUS MODELS KEEP THAT STRONG GRADIENT THROUGH AT LEAST 18Z.
MEANWHILE...THE GFS 700 MB WINDS MAX OUT BETWEEN 50 AND 60 KNOTS
THIS AFTERNOON BUT CROSS MOUNTAIN COMPONENT IS ONLY AROUND 40
KNOTS.  FOR REFERENCE... THE DECEMBER 30TH EVENT HAD 60-70 KNOTS OF
CROSS MOUNTAIN COMPONENT.  WE SHOULD SEE SOME MOUNTAIN WAVE
ENHANCEMENT WITH THIS EVENT THOUGH AS MOUNTAIN TOP STABLE LAYER IS
IN PLACE TODAY...SO WE WILL KEEP THE HIGH WIND WARNING GOING.  MORE
THAN LIKELY THE WARNING WILL BE ABLE TO EXPIRE EARLY THIS EVENING AS
GRADIENT RELAXES.

WITH REGARD TO MOUNTAIN SNOW...HEAVIEST SNOW RIGHT NOW IS EXPECTED
TO TAPER OFF AS THAT DRIER AIR WORKS IN.  CANT RULE OUT A FEW
PERIODS OF HEAVIER SNOWFALL DURING THE DAY...BUT LAPSE RATES ARE
SIMPLY NOT CONDUCIVE TO THAT.  WILL KEEP THE WINTER WEATHER
ADVISORIES IN EFFECT THROUGH THE REST OF THE TODAY WITH ANOTHER 2-6
INCHES OF SNOW...PER SNOW MODEL...AND CONSIDERABLE BLOWING AND
DRIFTING IN OPEN AREAS AND ABOVE TIMBERLINE WHERE WINDS WILL REALLY
HOWL.  SNOW TAPERS OFF TONIGHT AS AIRMASS GRADUALLY DRIES AND
BECOMES EVEN MORE STABLE.

TEMPERATURES WILL BE TURNING CONSIDERABLY WARMER TODAY WITH WARM
ADVECTION AND A LITTLE MORE SUNSHINE EXPECTED ACROSS THE PLAINS BY
AFTERNOON.

.LONG TERM...THE LATEST MODEL RUNS HAVE CHANGED LITTLE WITH THEIR
SOLUTIONS.  PERSISTENT NORTHWESTERLY FLOW ALOFT APPEARS TO BE OUR
FATE THROUGH THE MIDDLE OF NEXT WEEK.  ON THURSDAY...A WEAK UPPER
RIDGE WILL MOVE OVER THE REGION WITH WARM TEMPERATURES...DRY
CONDITIONS AND MORE MODEST WINDS THAN WE HAVE SEEN FOR THE PAST FEW
DAYS.  BUT THE BENIGN WEATHER WILL BE SHORT LIVED AS FRIDAY WILL
BRING A RAPIDLY MOVING UPPER TROUGH OVER WYOMING AND COLORADO.  THE
MOUNTAINS WILL BEAR THE BRUNT OF THE PRECIPITATION FROM THIS SYSTEM
AS WINDS THROUGH MOST OF THE ATMOSPHERE WILL REMAIN NORTHWESTERLY.
THE GFS AND NAM SHOW A BIT OF A COLD FRONT MOVING ACROSS EASTERN
COLORADO ON FRIDAY MORNING...BUT THE FAST MOVING NATURE OF THE
OVERALL SYSTEM WILL NOT ALLOW ANY UPSLOPE WIND COMPONENT TO LAST
VERY LONG.  HAVE STUCK WITH ONLY 10 PERCENT POPS ACROSS THE PLAINS
WITH 40-60 PERCENT POPS IN THE MOUNTAINS.  TEMPERATURES ON FRIDAY
COULD BE SOME 20 DEGREES COOLER THAN THURSDAYS WARM TEMPERATURES.

AFTER FRIDAY...A STRONG RIDGE BUILDS OVER THE WESTERN U.S. WHICH
WILL PUT COLORADO UNDER PERSISTENT AND AT TIMES STRONG NORTHWESTERLY
FLOW ALOFT.  THIS WILL KEEP THE OROGRAPHIC SNOW MACHINE GOING IN THE
NORTHERN MOUNTAINS AND PLACE THE FRONT RANGE UNDER ADDITIONAL
THREATS FOR PERIODS OF GUSTY TO STRONG WINDS.  TEMPERATURES WILL BE
NEAR TO SLIGHTLY HIGHER THAN NORMAL...DEPENDING ON WHETHER THE UPPER
JET IS OVERHEAD OR TO THE NORTH OF US.  OTHER THAN SOME ADJUSTMENTS
TO A FEW OF THE TEMPERATURE GRIDS AND VARIOUS SKY GRIDS...DID NOT
MAKE TOO MANY CHANGES TO THE PREVIOUS PACKAGE OF GRIDDED FORECASTS.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL THROUGH TONIGHT.  WEST WINDS
WILL BE DIFFICULT TODAY WITH CHINOOK PATTERN IN PLACE AND MOUNTAIN
WAVE ACTIVITY.  WINDS COULD LITERALLY GO FROM CALM TO GUSTING TO 40
KNOTS IN A SHORT PERIOD OF TIME.  MAIN THREAT OF THESE STRONGER
WINDS WILL OCCUR BETWEEN 15Z AND 00Z.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...HIGH WIND WARNING UNTIL MIDNIGHT
    TONIGHT FOR THE FRONT RANGE FOOTHILLS AND NEARBY ADJACENT
    PLAINS...ZONES 35..36..38..AND 39.
   WINTER WEATHER ADVISORY UNTIL 5 PM MST FOR THE NORTH CENTRAL
    MOUNTAINS...ZONES 31..33..AND 34.

$$
BARJENBRUCH/KDRBY

NWS BOU Office Area Forecast Discussion