Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 010301
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
801 PM MST SAT FEB 28 2015

.UPDATE...
ISSUED AT 801 PM MST SAT FEB 28 2015

LIGHT SNOW HAS BEEN FORMING ACROSS THE FOOTHILLS AND ADJACENT
METRO AREAS FOR THE LAST COUPLE HOURS...AND IS STILL EXPECTED TO
PUSH EAST ACROSS THE PLAINS. UPSLOPE FLOW IS VERY WEAK AND NOT
HELPING TO SQUEEZE OUT A LOT OF THE OVERRUNNING MOISTURE COMING
FROM THE MOUNTAINS. WITH THE EXPECTED INCREASING UPWARD QG MOTION
MOVING INTO THE AREA...STILL EXPECTING THE BEST TIMING FOR SEEING
ANY SNOW...BEING LIGHT...IS OVER THE NEXT 6 HOURS OR SO. HAVE
DECREASED THE CHANCES OF SNOW ACROSS THE FARTHER EASTERN PLAINS
WHERE FORECAST SOUNDINGS DON`T SHOW VERY MUCH MOISTENING...WILL
LIKELY STAY ONLY FLURRIES OUT THERE WITH LITTLE TO NO
ACCUMULATION.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 147 PM MST SAT FEB 28 2015

FOR TONIGHT...A RELATIVELY MOIST WEST/SOUTHWESTERLY FLOW ALOFT
WILL BE OVER COLORADO WITH AN UPPER TROUGH WELL TO THE WEST OVER
CENTRAL CALIFORNIA. SPATIAL CROSS-SECTIONS MAINTAIN SOME SHALLOW
LOW LEVEL MOISTURE AND WEAK UPSLOPE ALONG THE FRONT RANGE...WITH
VARYING AMOUNTS OF MID AND UPPER LEVEL MOISTURE OVERHEAD. IN THE
MOUNTAINS...SOME WEAK MID AND UPPER QG ASCENT THIS EVENING AS THE
SYSTEM TO THE WEST CONTINUES TO MIGRATE SOUTH. SNOWFALL IN THE
MOUNTAINS WILL BE FAIRLY LIGHT TONIGHT...WL DROP EXPECTED
AMOUNTS IN THE 1 TO 4 INCHES. ALONG THE FRONT RANGE...HAVE DELAYED
THE ONSET OF SNOW AND BACKED OF THE EXPECTED SNOW AMOUNTS. JUST
AROUND AN INCH OR SO. ON SUNDAY...THE SYSTEM IS PROGGED TO SHIFT
INTO SOUTHERN CA WITH RIDGING OVER COLORADO. WITH OVERRUNNING
PATTERN SNOW AMOUNTS WILL BE MINIMAL IN THE HIGH COUNTRY AS WELL.
OVER THE FRONT RANGE AND EASTERN PLAINS...ANOTHER SURGE OF HIGH
PRESSURE MAY HELP TO ENHANCE OF SNOWFALL THERE IS LEFT ALONG THE
FRONT RANGE AND PALMER DIVIDE LATE IN THE DAY TOWARDS 00Z...BUT WL
GO WITH CHC/SLGT CHC POPS THROUGH MUCH OF THE DAY.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 147 PM MST SAT FEB 28 2015

BROAD UPPER LEVEL TROUGH WILL REMAIN OVER THE SOUTHWEST CORNER OF
THE COUNTRY SUNDAY NIGHT AND MONDAY. THIS WILL PRODUCE A STRONG
SOUTHWEST FLOW ALOFT. THE STRONG FLOW ALOFT COMBINED WITH MOISTURE
WILL PRODUCE OROGRAPHIC SNOW...MAINLY OVER WESTERN COLORADO. THE
MOUNTAINS OF NORTH CENTRAL COLORADO ARE EXPECTED TO JUST SEE LIGHT
SNOW UNDER THIS PATTERN THROUGH MONDAY AFTERNOON. THE SOUTHWEST FLOW
WILL ALSO TRANSPORT WARMER AIR INTO THE AREA...EVEN ACROSS THE
PLAINS. WILL SEE A CHANCE FOR LIGHT SNOW DUE TO WARM AIR ADVECTION
SUNDAY NIGHT AND EARLY MONDAY. HIGHS ACROSS THE PLAINS WILL CLIMB
ABOVE FREEZING MONDAY AFTERNOON.

SNOW IS EXPECTED TO INCREASE MONDAY NIGHT AS A 150+ KNOT JET MAX
RACES ACROSS THE STATE. NORTH CENTRAL COLORADO LOOKS TO BE UNDER A
FAVORED QUADRANT OF THE JET MONDAY NIGHT...WHICH MAY PRODUCE A BAND
OF HEAVY SNOW. WILL INCREASE POPS OVER JACKSON...GRAND AND WESTERN
LARIMER COUNTIES FOR THIS. WILL SEE A CHANCE FOR SNOW ELSEWHERE AS A
PART OF THE UPPER LEVEL TROUGH OVER SOUTHERN CALIFORNIA LIFTS
NORTHEAST ACROSS THE STATE. AT THE SURFACE...A LOW WILL MOVE EAST
ACROSS CENTRAL COLORADO. NORTHERLY WINDS BEHIND THE LOW WILL PRODUCE
UPSLOPE FLOW AND PULL COLDER AIR INTO NORTHEAST COLORADO LATE MONDAY
NIGHT AND INTO TUESDAY. ONCE MODELS BETTER AGREE ON THE LOCATION OF
HEAVIER SNOW...MAY NEED A WINTER STORM WATCH AS THIS EVENT NEARS FOR
THE MOUNTAINS OF NORTH CENTRAL COLORADO.

ON TUESDAY...SNOW IS EXPECTED BEHIND A COLD FRONT DUE TO UPSLOPE
FLOW. A MOIST WESTERLY FLOW ALOFT IS EXPECTED TO KEEP SNOW GOING IN
THE MOUNTAINS. BEST CHANCE FOR SNOW WILL BE ALONG THE FRONT
RANGE AND IN THE MOUNTAINS.

DIFFERENCES BETWEEN THE GFS AND ECMWF ON HOW FAR SOUTH AND WEST THE
NORTHERN TROUGH DIGS WILL KEEP THE FORECAST CONFIDENCE LOW FOR
TUESDAY NIGHT AND WEDNESDAY. THE 12Z ECMWF NOW SHOWS MOST OF THE
ENERGY ASSOCIATED WITH THE TROUGH DIVING SOUTH OUT OF THE NORTHERN
ROCKIES STAYING EAST OF THE AREA. THIS WILL LEAD TO SNOW ENDING LATE
TUESDAY. THE GFS SHOWS THE TROUGH DIGGING TO SOUTHWEST COLORADO
WHICH KEEPS LIFT ALOFT AND UPSLOPE FLOW OVER NORTHEAST COLORADO INTO
EARLY WEDNESDAY. WILL KEEP CHANCE POPS IN THE FORECAST FOR THIS
UNTIL THINGS BECOME MORE CLEAR. IT WILL BE COLD BEHIND THE FRONT
TUESDAY WITH HIGHS IN THE UPPER TEENS AND LOWER 20S.

TEMPERATURES WILL BE CHALLENGING FOR WEDNESDAY AND THURSDAY DUE TO
THE DIFFERENCES BETWEEN THE MODELS. AIRMASS WILL DRY OUT WEDNESDAY
AS AN UPPER LEVEL RIDGE BUILDS OVER THE WESTERN STATES. THIS RIDGE
WILL REMAIN OVER THE WESTERN U.S. THROUGH THE END OF THE WEEK AND
INTO NEXT WEEKEND. THIS WILL KEEP COLORADO DRY. TEMPERATURES ARE
EXPECTED TO SLOWLY WARM THROUGH THE PERIOD WITH HIGHS CLIMBING TO
NEAR NORMAL NEXT WEEKEND.

&&

.AVIATION...(FOR THE TAFS THROUGH 06Z SUNDAY EVENING)
ISSUED AT 801 PM MST SAT FEB 28 2015

RECENT HIRES MODELS PICKED UP ON THE LIGHT SOUTHERLY WINDS AT
KDEN AND LIGHT NORTHERLY WINDS AT KBJC AND KAPA...THESE LOOK TO
HOLD FOR THE NEXT SEVERAL HOURS. AN INCREASE IN MID AND UPPER
LEVEL MOISTURE OVERHEAD WILL RESULT IN LIGHT SNOW CURRENTLY NEAR
THE FOOTHILLS TO INCREASE IN COVERAGE TONIGHT AS UPSLOPE
FLOW...ALBEIT WEAK...SETS IN BETTER OVER THE NEXT 6 HOURS OR SO.
ONCE THIS SPREADS EAST FROM THE FOOTHILLS...MVFR/IFR CONDITIONS
WILL BE PREVALENT THROUGH SUNDAY MORNING. SOME IMPROVEMENT BY THE
AFTN AS THE SNOW DECREASES...HOWEVER STILL SOME ILS RESTRICTIONS
REGARDING THE CIGS. LOWEST VSBYS WILL OCCUR NEAR KBJC AND KAPA
OVERNIGHT WITH BEST ACCUMULATIONS OF 1 TO 2 INCHES EXPECTED
THERE...UP TO ONE INCH AT KDEN.

&&

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

$$

UPDATE...KRIEDERMAN
SHORT TERM...COOPER
LONG TERM...MEIER
AVIATION...KRIEDERMAN



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