Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 231654
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
954 AM MST SUN NOV 23 2014

.UPDATE...
ISSUED AT 931 AM MST SUN NOV 23 2014

NOT MUCH SNOW FALLING IN THE HIGH COUNTRY RIGHT NOW.  THE NORTH-
NORTHWESTERLY LOW LEVEL WINDS ON THE PLAINS ARE BEGINNING TO PICK
UP RIGHT NOW. WIND FORECAST IN THE GFE GRIDS LOOKS ON TRACK. WILL
MAKE A FEW ADJUSTMENTS TO SKY AND MOUNTAIN POPS AND BLOWING SNOW
AREAS TOO. NOTHING HUGE. HOWEVER...WILL KILL THE HIGHLIGHTS IN
NORTH AND MIDDLE PARK...AND EVEN IF SNOW BECOMES LIKELY AGAIN...
HIGHLIGHT CRITERIA AMOUNTS ARE NOT LIKELY.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 359 AM MST SUN NOV 23 2014

STRONGEST WAVE OF MOISTURE AND ENERGY IS MOVING ACROSS THE
FORECAST AREA EARLY THIS MORNING. THERE IS A SECONDARY WAVE NOTED
IN FAR NORTHWEST COLORADO/NORTHEAST UTAH/SOUTHWEST WYOMING WHICH
WILL REACH THE FORECAST AREA LATER THIS MORNING. IN BETWEEN...
THERE IS SLIGHT DRYING SO WILL SEE A TEMPORARY DECREASE IN SNOW
INTENSITY ACROSS THE MOUNTAINS EARLY THIS MORNING. ON THE
PLAINS...PRECIPITATION WAS BLOSSOMING ON THE PALMER DIVIDE AREA
AND THIS AREA SHOULD CONTINUE TO AFFECT MAINLY AREAS SOUTH AND
EAST OF DENVER THROUGH EARLY MORNING. THERE MAY BE SOME
REDEVELOPMENT BEHIND THE MAIN FEATURE AS LARGE SCALE LIFT IS STILL
SEEN IN THE Q-G FIELDS THIS MORNING...BUT OVERALL LATEST PROFILER
DATA SHOWS WINDS A SLIGHT WESTERLY COMPONENT JUST OFF THE DECK
WHICH WOULD LIMIT ANY PRECIP REDEVELOPMENT FROM DENVER NORTH.
COULD SEE A COUPLE QUICK INCHES OF SNOW ACCUMULATION DUE TO
INTENSITY OF PRECIP ON THE PALMER DIVIDE AREA...MAINLY ABOVE 5500
FEET WHERE TEMPS ARE COLD ENOUGH.

OTHERWISE...THE PRECIPITATION ON THE PLAINS WILL LIKELY COME TO AN
END BY MID MORNING AS FLOW TURNS MORE NORTH/NORTHWEST AND SOME
DRYING OCCURS BEHIND FIRST WAVE. WINDY CONDITIONS WILL DEVELOP
MOST AREAS AND REMAIN IN PLACE THROUGH THE AFTERNOON. WITH SOME
SUNSHINE RETURNING AND STEEP LAPSE RATES...SHOULD SEE ISOLATED
SHOWERS REDEVELOP THIS AFTERNOON...MAINLY SNOW DUE TO RELATIVELY
LOW WET BULB ZERO HEIGHTS. AGAIN THESE WOULD FAVOR THE PALMER
DIVIDE AREA.

MOUNTAIN LOCATIONS WOULD ALSO SEE A KICK UP OF SNOW INTENSITY WITH
MORE OF A CONVECTIVE SCENARIO GETTING UNDERWAY THIS AFTERNOON.
THOSE ARE EXPECTED TO DECREASE IN INTENSITY THIS EVENING THEN AS
AIRMASS STABILIZES...ONLY TO HAVE MORE WIDESPREAD SNOW REDEVELOP
BEFORE DAYBREAK MONDAY AS ANOTHER WAVE MOVES INTO THE AREA IN
NORTHWEST FLOW ALOFT. HEAVIEST SNOW WITH THIS EVENT OCCURRED IN
THE EARLY MORNING HOURS...BUT IMPACTS WILL REMAIN IN PLACE THROUGH
TODAY AND TONIGHT AND HEAVIER SNOW EXPECTED AGAIN TOMORROW SO WILL
LEAVE WARNINGS FOR THE MOUNTAINS AND ADVISORIES IN PLACE FOR THE
HIGH MOUNTAIN VALLEYS. GENERALLY LOOK FOR ANOTHER 2-4 INCHES
TODAY AND ANOTHER 2-4 TONIGHT ON AVERAGE ABOVE 9000 FEET.

FINALLY...SHOULD SEE THE WIND INCREASE AGAIN LATER TONIGHT AS
MOUNTAIN TOP STABILITY PROFILE BECOMES MORE FAVORABLE BUT STILL
MARGINAL WITH HIGH COUNTRY SNOW. THE STRONGEST WINDS WITH GUSTS
IN THE 55-65 MPH RANGE WILL REMAIN IN THE HIGHER ELEVATIONS BUT
AREAS RIGHT NEXT TO THE FOOTHILLS COULD SEE A FEW GUSTS INTO THE
30-50 MPH RANGE. SURFACE GRADIENTS ARE A LITTLE WEAK SO THAT
SHOULD HELP THE STRONGER WINDS STAY UP HIGH.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 359 AM MST SUN NOV 23 2014

NWLY FLOW ALOFT WILL REMAIN OVER THE AREA ON MON AS WEAK
DISTURBANCES EMBEDDED IN THE FLOW MOVE QUICKLY ACROSS.  MOISTURE
DEPTH WILL IMPROVE IN THE MTNS WITH FAVORABLE LAPSE RATES AND
OROGRAPHIC COMPONENT SO SHOULD SEE PERIODS OF MDT TO HEAVY SNOW THRU
THE DAY WITH CONSIDERABLE BLOWING SNOW.  AT LOWER ELEVATIONS STEEP
LAPSE RATES WILL COMBINE WITH ABUNDANT MID LVL MOISTURE AND PASSAGE
OF DISTURBANCE IN THE AFTN TO ALLOW FOR AT LEAST A SLIGHT CHC OF
-SHSN OVER NERN CO. GUSTY NNW WINDS WILL CONTINUE AS WELL. HIGHS
TEMPS WILL BE A FEW DEGREES COLDER AS READINGS STAY IN THE UPPER
30S TO NEAR 40. THERE COULD BE A BRIEF PERIOD OF STRONGER WINDS
IN AND NR THE FOOTHILLS MON MORNING WHICH MAY GET CLOSE TO HIGH
WIND CRITERIA IN THE TYPICAL WINDY SPOTS.

BY MON NIGHT MOISTURE WILL BEGIN TO DECREASE IN THE MTNS WITH LAPSE
RATES BEGIN TO STABILIZE THUS SNOWFALL SHOULD BEGIN TO DECREASE
HOWEVER IT WILL REMAIN WINDY WITH AREAS OF BLOWING SNOW.  ALTHOUGH A
MTN TOP STABLE LYR WILL BE PRESENT COMPONENT ALONG WINDS ARE ONLY
FCST TO BE IN THE 35 TO 40 KT RANGE SO THREAT OF HIGH WINDS LOOKS
LOW AT THIS TIME.  ON TUE MOISTURE WILL INCREASE ONCE AGAIN IN THE
MTNS IN NWLY FLOW HOWEVER LAPSE RATES WILL BE POOR SO ADDITIONAL
SNOWFALL WILL BE ON THE LIGHT SIDE.  ONCE AGAIN WILL SEE AREAS OF
BLOWING SNOW.  AT LOWER ELEVATIONS IT WILL BE DRY WITH GUSTY WNW
WINDS AT TIMES.  850-700 MB TEMPS BEGIN TO RISE WHICH SHOULD ALLOW
FOR READINGS TO RISE BACK TO SEASONAL NORMALS.

FOR TUE NIGHT INTO WED PERSISTENT NW FLOW ALOFT WILL CONTINUE
WITH SOME MOISTURE EMBEDDED IN THE FLOW. ALTHOUGH OROGRAPHICS WILL
REMAIN FAVORABLE LAPSE RATES WILL CONTINUE POOR WHICH SHOULD LIMIT
ACCUMULATIONS IN THE MTNS. MEANWHILE LATEST DATA SUGGEST AN
INCREASING THREAT FOR A HIGH WIND EVENT FOR AREAS IN AND NR THE
FOOTHILLS TUE NIGHT INTO WED MORNING AS STG MTN WAVE DEVELOPS AND
COMBINES WITH DECENT LOW LVL PRESSURE GRADIENT. COMPONENT ALONG
WINDS ARE FCST TO BE AOA 65 KTS BY 12Z WED. AS FOR TEMPS WITH
DOWNSLOPE LOW LVL FLOW INCREASING ON WED THIS MAY LEAD TO MUCH
WARMER HIGHS ESPECIALLY ALNG THE FRONT RANGE AS READINGS APPROACH
60 DEGREES. MEANWHILE FURTHER EAST OVER THE PLAINS READINGS MAY
STAY IN THE LOWER 50S NR THE WY-NE BORDER.

BY THANKSGIVING DAY THERE IS NO AGREEMENT AT ALL BETWEEN THE LONGER
RANGE MODELS.  THE ECMWF HAS FLIP FLOPPED BACK TO ITS PREVIOUS
SOLUTION OF A FEW DAYS AGO AS IT BRINGS A CDFNT INTO NERN CO DURING
THE DAY.  MEANWHILE THE GFS HAS STG DOWNSLOPE WARMING ACROSS NERN CO
WITH THE FNT STAYING WAY OFF THE EAST OF THE AREA.  TO COMPLICATE
MATTERS EVEN FURTHER THE GEM AND NOGAPS SHOW A STG CDFNT MOVING INTO
NERN CO BY THU MORNING.  AS A RESULT TEMP GUIDANCE FOR THU IS ALL
OVER THE PLACE WITH HIGHS RANGING FM THE 20S TO NEAR 70 DEPENDING ON
WHICH MODEL YOU WANT TO BELIEVE.  IN ADDITION THE GEM AND NOGAPS
SHOW A STG UPPER LEVEL JET IN NWLY FLOW OVER THE AREA WHICH WOULD
ENHANCE SNOW POTENTIAL IF THE FNT COMES IN LIKE THEY SHOW.  THE
ECMWF FOR NOW AT LEAST KEEPS THE JET FURTHER TO THE NORTH WITH PCPN
STAYING OUT OF THE AREA.  AT THIS POINT WILL GO WITH AN IN BETWEEN
SOLUTION UNTIL IT BECOMES MORE CLEAR WHAT IS GOING TO TRANSPIRE.
THUS WILL KEEP A DRY FCST WITH READINGS RANGING FROM THE MID 40S
OVER THE FAR NERN PLAINS WITH 50S CLOSER TO THE FOOTHILLS.

THE SAME ISSUES CONTINUE ON FRI AS THE GFS HAS A FLAT UPPER LEVEL
RIDGE OVER THE AREA WITH HIGHS IN THE 60S TO NR 70 OVER NERN CO
ALONG WITH DRY CONDITIONS.  MEANWHILE THE ECMWF HAS ANOTHER SURGE OF
COLDER AIR MOVING INTO NERN CO WITH THE UPPER LEVEL JET SAGGING OVER
THE AREA WITH A CHC OF SNOW.  THE GEM KEEPS THE COLD AIR OVER THE
AREAS AS WELL BUT HAS NO PCPN.  ONCE AGAIN WILL JUST BROADBRUSH THE
FCST FOR NOW.

&&

.AVIATION...(FOR THE TAFS THROUGH 18Z MONDAY MORNING)
ISSUED AT 931 AM MST SUN NOV 23 2014

THE NORTH-NORTHWESTERLY BOUNDARY LAYER FLOW WAS CREATING A BIT OF
A LONGMONT ANTI-CYCLONE AND SOME EASTERLY COMPONENT TO THE WEAK
SURFACE WINDS ARE DIA EARLIER. TO THE NORTH OF THE AIRPORT...THE
ATMOSPHERE HAS MIXED OUT AS EVIDENT BY THE TEMPERATURES AND
NORTH-NORTHWESTERLY WINDS. THIS SHOULD GET TO DIA BY 18Z. THERE
ARE SOME HIGH STRATOCUMULUS CLOUDS AROUND...ABOUT 070...BUT NOT A
CEILING. MOISTURE PROFILES ON MOST OF THE MODELS DO NOT SUGGEST
THAT THERE WILL BE ANY CEILING ISSUES AT THE BIG AIRPORT.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 5 PM MST MONDAY FOR COZ031-033-034.

&&

$$

UPDATE...RJK
SHORT TERM...BARJENBRUCH
LONG TERM...RPK
AVIATION...RJK


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