Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 161121
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
421 AM MST TUE DEC 16 2014

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 421 AM MST TUE DEC 16 2014

SATELLITE IMAGERY SHOWS A LARGE SWATH OF MID/HIGH CLOUDS
STREAMING TOWARD THE FORECAST AREA. THESE CLOUDS WILL OVERSPREAD
THE AREA FROM SOUTHWEST TO NORTHEAST THROUGH THE EARLY MORNING
HOURS WITH GENERALLY MOSTLY CLOUDY SKIES ANTICIPATED THROUGH THE
DAY.

MOST OF THE INCOMING MOISTURE IS AT OR ABOVE 600 MB PER UPSTREAM
SOUNDINGS...BUT WEAK AND PERSISTENT Q-G LIFT SHOULD BRING ENOUGH
SUPPORT FOR SLIGHT MOISTENING. THAT SHOULD RESULT IN AN AREA OF
LIGHT SNOW/FLURRIES DEVELOPING OVER THE MOUNTAINS BY MID/LATE
MORNING AND THEN PEAKING AROUND NOON BEFORE DECREASING LATER IN
THE AFTERNOON. OVERALL...SEE ANY SNOW ACCUMULATION LESS THAN 2
INCHES FROM THIS WEAK WAVE.

ON THE PLAINS...DRY BUT RATHER STAGNANT CONDITIONS WILL PERSIST
WITH COLD HIGH PRESSURE LOCKED IN ACROSS THE CENTRAL U.S.
TEMPERATURE FORECAST IS CHALLENGING CONSIDERING THE COLD START AND
STRONG BUT SHALLOW INVERSIONS. THE CLOUDS WILL LIMIT HEATING...AND
WITH PLENTY OF SNOW TO OUR EAST AND LOW LEVEL WINDS TURNING LIGHT
EASTERLY...EXPECT HIGH TEMPERATURES WILL BE STRUGGLING TO PUSH
INTO THE 30S. HAVE LOWERED HIGH TEMPS BASED ON ABOVE FACTORS AND
NEARLY THE LOWEST SUN ANGLE OF THE YEAR. SOUTHERN FOOTHILLS STILL
HAVE A CHANCE OF BEING WARMER GIVEN WARM ADVECTION ALOFT AND
LITTLE IF ANY INVERSION THERE.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 421 AM MST TUE DEC 16 2014

THE UPPER LEVEL FLOW PATTERN ACROSS COLORADO IS EXPECTED TO BE
FAIRLY TRANSITIONAL THROUGH THE UPCOMING SEVEN DAYS. UPPER LEVEL
RIDGING OVER THE REGION TODAY WILL BE REPLACED BY BROAD UPPER
LEVEL TROUGHINESS OVER THE GREAT BASIN AND THEN COLORADO BY
WEDNESDAY AND WEDNESDAY NIGHT. THIS UPPER LEVEL TROUGH IS THEN
EXPECTED TO STAY IN PLACE THROUGH FRIDAY WHEN AN UPPER RIDGE IS
FORECAST TO DEVELOP OVER THE NORTHERN AND CENTRAL ROCKIES. BEYOND
THAT...A DIRTY RIDGE BUILDS OVER THE WEST COAST WITH LOTS OF
MOISTURE STREAMING FROM THE PACIFIC NORTHWEST ACROSS COLORADO ON
PERSISTENT NORTHWESTERLY FLOW ALOFT. THE NORTHWEST FLOW ALOFT IS
THEN EXPECTED TO CONTINUE THROUGH THE MIDDLE OF NEXT  WEEK.

WEATHERWISE...THE UPPER LEVEL TROUGHINESS OVER COLORADO FROM
WEDNESDAY NIGHT THROUGH FRIDAY IS GOING TO LEAD TO A SLIGHTLY
UNSETTLED AIRMASS OVER THE FORECAST AREA. MOUNTAIN AREAS ARE MOST
LIKELY TO SEE SCATTERED SNOW SHOWERS FROM WEDNESDAY AFTERNOON
THROUGH FRIDAY. SNOWFALL ACCUMULATIONS WILL GENERALLY BE LIGHT IN
THE ABSENCE OF ANY STRONG FORCING FOR ASCENT. DRIER AND MORE
SETTLED WEATHER WILL RETURN SATURDAY AS THE UPPER RIDGE PASSES
ACROSS THE REGION. NEXT WEEK LOOKS LIKE A PROLONGED PERIOD OF
SNOWFALL IN THE MOUNTAINS ALONG WITH PERIODS OF LIGHT SNOW DOWN
ONTO THE PLAINS AS THE MOIST...NORTHWESTERLY FLOW PATTERN
ESTABLISHES ITSELF ACROSS THE REGION. IT COULD ALSO BE WINDY AT
TIMES SINCE THE MAIN UPPER JET WILL BE ARCHING OVER THE STATE AT
TIMES.

MUCH OF THIS FORECAST REASONING IS BASED ON THE SOLUTION PRESENTED
BY THE ECMWF SOLUTION. THE GFS HINTS AT SOME OF THE TROUGH
PASSAGES CONTAINING MORE AMPLITUDE THAN THE ECMWF SOLUTION. AT THE
SAME TIME...THE GFS MAINTAINS THE PROGRESSIVE NATURE TO THE FLOW
PATTERN THAT THE ECMWF CONTAINS. FOR THE TIME BEING...WILL ACCEPT
THE ECMWF SCENARIO. TEMPERATURES THROUGH THE FORECAST PERIOD WILL
BE IN THE NEIGHBORHOOD OF SEASONAL NORMALS.

&&

.AVIATION...(FOR THE TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 421 AM MST TUE DEC 16 2014

VFR CONDITIONS WILL PERSIST. SOUTH/SOUTHEAST FLOW AROUND 10 KNOTS
WILL PERSIST TIL AROUND 16Z...THEN SHOULD SEE WINDS BECOMING
NORTH/NORTHEAST AROUND 5 KNOTS TOWARD 18Z-19Z. WINDS MAY BECOME
LIGHT/VARIABLE WITH WEAK DENVER CYCLONE DEVELOPING TONIGHT. THERE
IS A SLIGHT 10-20% CHANCE OF FOG DEVELOPMENT BY 12Z WEDNESDAY
GIVEN DENVER CYCLONE PATTERN IN PLACE AND MARGINAL LOW LEVEL
MOISTURE.

&&

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

$$

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


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