Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 171118
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
418 AM MST WED DEC 17 2014

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 418 AM MST WED DEC 17 2014

SATELLITE LOOP SHOWS UPPER LEVEL DISTURBANCE MOVING EAST/NORTHEAST
THROUGH ARIZONA AT THIS TIME. THE VARIOUS SHORT RANGE MODELS
INDICATE THE BEST Q-G VERTICAL MOTION ASSOCIATED WITH THIS
FEATURE PASSING JUST TO OUR SOUTH THIS AFTERNOON AND EARLY
EVENING...BUT STILL WEAK LIFT FORECAST FOR MOST OF THE FORECAST
AREA. THERE IS ALREADY A BIT OF LIGHT SNOW ON THE WESTERN SLOPE
PER LATEST OBS AND GRAND JUNCTION RADAR. THIS LIGHT SNOW WILL
CONTINUE TO PUSH NORTHEAST AND INCREASE IN COVERAGE THROUGH THE
AFTERNOON AS UPPER LEVEL LIFT INCREASES. THE BEST SNOW IS EXPECTED
TO DEVELOP ALONG AND SOUTH OF THE I-70 CORRIDOR IN THE MOUNTAINS
THIS AFTERNOON ENHANCED BY AN AREA OF WEAK MID LEVEL CONVERGENCE.
THESE SITUATIONS USUALLY FAVOR AREAS FROM THE MOSQUITO RANGE
THROUGH BOREAS PASS AND MOUNT EVANS AREA...OR ALONG THE
SUMMIT/PARK/CLEAR CREEK COUNTY BORDERS SO ADJUSTED THOSE AMOUNTS
UP A BIT ACCORDINGLY. COULD SEE LOCAL 2-5 INCH ACCUMULATIONS THERE
WITH AN INCH OR LESS MOST OTHER MOUNTAIN LOCALES.

ON THE PLAINS...STILL UNSURE HOW THIS PANS OUT AS MOISTURE IS
LIMITED BELOW ABOUT 5000-6000 FT AGL. LOCATIONS ALONG THE PALMER
DIVIDE WOULD SEE THE BEST CHANCE OF SNOW DEVELOPING BY LATE
AFTERNOON WHILE THERE COULD BE A SHARP CUTOFF TO THE NORTH. THERE
ARE SOME INDICATIONS A WEAK UPSLOPE COMPONENT DEVELOPS BY LATE
THIS AFTERNOON AND EVENING SO WILL CONTINUE THE CHANCE OF SNOW
DEVELOPING FARTHER NORTH INTO THE BOULDER/DENVER METRO
AREAS...WITH LOWER OR NO POPS FARTHER NORTH/EAST.

PRECIPITATION IS EXPECTED TO DECREASE BY MID/LATE EVENING AS
LARGE SCALE SUBSIDENCE DEVELOPS OVER THE FORECAST AREA. COULD
STILL SEE SHOWERS LINGER IN THE HIGH COUNTRY THOUGH WITH WEAK
OROGRAPHICS AS FLOW TURNS MORE WESTERLY BEHIND UPPER LEVEL
DISTURBANCE. TEMPERATURES SHOULD REMAIN BELOW NORMAL AGAIN WITH
MORE CLOUDS AND RATHER COOL START TO THE MORNING.

AREAS OF FOG ON THE PLAINS LOOKS THIS MORNING PER LATEST OBS AND
CIMMS GOES-R PROVING GROUND IFR PRODUCT.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 418 AM MST WED DEC 17 2014

THE FORECAST PERIOD WILL BEGIN WITH A RATHER MEAGER UPPER LEVEL
DISTURBANCE PASSING TO OUR SOUTH...BEFORE THE UPPER AIR PATTERN PATTERN
BECOMES MORE ACTIVE LATE IN THE WEEKEND THROUGH NEXT WEEK.

ON THURSDAY...AN OPEN WAVE WILL BE MOVING ACROSS ARIZONA AND NEW
MEXICO WITH WEAK FLOW ALOFT IN PLACE OVER COLORADO. THE WEAK
DYNAMIC FORCING WITH THIS DISTURBANCE MAY PRODUCE SOME SNOW
SHOWERS OVER THE MOUNTAINS BUT WILL HAVE LITTLE IMPACT OVER THE
NORTHEAST COLORADO PLAINS. DRIER NORTHWESTERLY FLOW WITH SUBSIDENT
UPPER LEVEL RIDGING WILL SPREAD OVER THE STATE ON FRIDAY...
BRINGING MOST PRECIPITATION IN THE MOUNTAINS TO AN END. AS THE
NORTHWESTERLY FLOW CONTINUES INTO THE WEEKEND...PACIFIC MOISTURE
WILL BEGIN INCREASING...BRINGING SNOW BACK INTO THE MOUNTAIN
AREAS.

AS THE WEEKEND WRAPS UP...A STRONG AND MOIST UPPER LEVEL JET WILL
MOVE OVER THE STATE FROM THE PACIFIC NORTHWEST. AS THE STRONG
WINDS ALOFT CONTINUE INTO MONDAY...OROGRAPHIC SNOWFALL IN THE
NORTHERN MOUNTAINS IS EXPECTED TO INCREASE. THIS COULD BECOME A
SIGNIFICANT SNOW PRODUCER IN THE MOUNTAINS ALONG WITH A DOWNSLOPE
WIND EVENT OVER THE FOOTHILLS AND ADJACENT PLAINS. AT THIS TIME
MODELS POINT TO SUNDAY NIGHT AND MONDAY AS THE WINDIEST PERIOD AND
MONDAY BEING THE SNOWIEST PERIOD IN THE MOUNTAINS. AFTER A BIT OF
A REPRIEVE ON TUESDAY AND WEDNESDAY...ANOTHER DISTURBANCE IS
EXPECTED TO BE APPROACHING THE STATE ON THURSDAY WITH MORE SNOW IN
THE MOUNTAINS AND POSSIBLY ON THE PLAINS.

&&

.AVIATION...(FOR THE TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 418 AM MST WED DEC 17 2014

MONITORING POTENTIAL FOR FOG DEVELOPMENT AT DIA EARLY THIS MORNING
WITH WEAK DENVER CYCLONE TURNING WINDS MORE WEST/NORTHWEST.
HOWEVER...PRESENT T/TD SPREADS TO THE NORTH AND INCREASING CLOUDS
WOULD BE SUFFICIENT TO KEEP THREAT LESS THAN 30 PERCENT.
OTHERWISE VFR CONDITIONS WILL PREVAIL. HOWEVER...CEILINGS WILL
LIKELY LOWER TO ILS LANDINGS BY 22Z-01Z AS MOISTURE AND LIFT
INCREASE. CHANCE OF LIGHT SNOW STARTING THEN AS WELL BUT ONLY
ABOUT 30-40 PERCENT CHANCE OF 2-3SM IN LIGHT SNOW. THAT CHANCE
WILL END BY 04Z-06Z WITH GRADUAL CLEARING OVERNIGHT. LIGHT AND
VARIABLE SURFACE WINDS.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...BARJENBRUCH
LONG TERM...DANKERS
AVIATION...BARJENBRUCH



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