Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 300423
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
923 PM MST THU JAN 29 2015

.UPDATE...
ISSUED AT 920 PM MST THU JAN 29 2015

CLOUDS...MAINLY AT HIGH-LEVELS...ON THE INCREASE THIS EVENING.
MID AND HIGH-LEVEL MOISTURE WILL CONTINUE TO STREAM IN FROM THE
WEST OVERNIGHT AS THE UPPER RIDGE SLOWLY EXITS THE AREA. THEN
STEERING WINDS ALOFT BECOME PREDOMINANTLY SWLY IN DIRECTION ON
FRIDAY WHICH DRIVES DEEPER MOISTURE UP FROM THE FOUR CORNERS AREA.
THIS IS A MILD FLOW...SO AS SHOWERS DEVELOP IN THE HIGH COUNTRY ON
FRIDAY...SNOW LEVELS WILL START OUT HIGH...SAY UP AROUND
9500-10000 FEET ASL. HOWEVER A REVERSAL IN THE 850-700MB FLOW TO A
NORTH-NORTHEAST DIRECTION IN THE AFTERNOON WILL SEND TEMPS
DOWNWARD CAUSING SNOW LEVELS TO DROP. THE LATEST NAM NOW INDICATES
EVEN GREATER PRECIP COVERAGE LATE FRIDAY AFTERNOON AND FRIDAY NIGHT
WITH LIGHT SNOW ACCUMS POSSIBLE FOR PARTS OF THE I-25 URBAN
CORRIDOR...INCLUDING THE DENVER METRO AREA. MADE ADJUSTMENTS TO
ALL FCST FIELDS OUT THROUGH FRIDAY EVENING TO BETTER REFLECT
LATEST MODEL DATA. THIS INCLUDES NUDGING UP FRI NIGHT POPS AND
ADDING SOME LIGHT SNOW ACCUM IN THE DENVER METRO AREA. KEEP IN
MIND FINAL SNOW AMOUNTS AT LOWER ELEVATIONS ARE STILL QUITE
UNCERTAIN.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 211 PM MST THU JAN 29 2015

STRATOCUMULUS AND ALTOCUMULUS CLOUD COVER OVER THE PLAINS HAS ALL
BUT DISAPPEARED AT THIS TIME. MEANWHILE HIGH CLOUDS WERE STREAMING
UP FROM THE SOUTHWEST. THERE IS NO PRECIPITATION ANYWHERE WITHIN THE
CWA AT THIS TIME ACCORDING TO NETWORK RADARS. THE WIND FIELD OVER
THE FORECAST AREA FEATURES PRETTY WEAK FLOW WITH NO UNIFORMITY IN
DIRECTION. MODELS SHOW THE UPPER RIDGE NOW OVER COLORADO SLIDING
SLOWLY EASTWARD TONIGHT AND FRIDAY. THE STRONG ZONAL FLOW DECREASES
SLOWLY IN SPEED AND BECOMES MORE SOUTHWESTERLY ON FRIDAY. THERE IS
WEAK UPWARD QG VERTICAL VELOCITY FOR THE FORECAST AREA TONIGHT AND
FRIDAY. NORMAL DRAINAGE WINDS ARE EXPECTED OVERNIGHT WITH SOME
SOUTHWESTERLY DOWNSLOPING FRIDAY MORNING. A COLD FRONT WITH UPSLOPE
FLOW IN ITS WAKE IS PROGGED TO SPREAD SOUTH ACROSS THE PLAINS BY
MID/LATE AFTERNOON ON FRIDAY. FOR MOISTURE...IT IS DRY THIS
EVENING...THEN CLOUDS AND HUMIDITY APPROACH FROM THE WEST-SOUTHWEST
WITH THE ADVANCING CLOSED LOW OVER THE SOUTHWESTERN U.S. BY 12Z
FRIDAY MORNING...DEEP MOISTURE IS OVER THE WESTERN HALF OF THE CWA
WITH HIGH LEVEL MOISTURE OVER EASTERN SECTIONS. MOISTURE REMAINS
DEEP OVER THE MOUNTAINS ON FRIDAY...WITH PLENTY OF MID AND HIGH
LEVEL MOISTURE OVER THE PLAINS. THE QPF FIELDS BRING A TAD OF
MEASURABLE SNOWFALL TO THE WESTERN BORDER OF THE CWA AFTER MIDNIGHT
TONIGHT. FOR FRIDAY...THERE IS A TAD PROGGED OVER ALL THE MOUNTAINS
AND HIGH VALLEYS. FOR POPS...WILL GO WITH 30-50%S IN THE MOUNTAINS
AND HIGH VALLEYS ON FRIDAY. FOR THE PLAINS...THERE/S MOISTURE AND
WEAK LIFT...BUT NO COLD AIR ADVECTION AND NO HELP FROM OROGRAPHICS.
SO NO POPS FOR THE PLAINS JUST YET.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 211 PM MST THU JAN 29 2015

ALL THE MODELS SHOW AN UPPER LEVEL LOW PRESSURE SYSTEM CENTERED
OVER SOUTHERN CALIFORNIA FRIDAY NIGHT. THIS LOW ELONGATES AS IT
MOVES SOUTH INTO NORTHERN MEXICO OVER THE WEEKEND. MOST OF THE
MOISTURE AND LIFT WITH THIS SYSTEM STAYS SOUTH OF THE CWA. DESPITE
THE SYSTEM MOVING WELL SOUTH OF THE REGION...SHOULD SEE SOME
SCATTERED LIGHT SNOW SHOWERS DEVELOP ACROSS THE FRONT RANGE URBAN
CORRIDOR...PALMER DIVIDE AND FOOTHILLS AFTER MIDNIGHT...DUE TO
SOME WEAK UPSLOPE FLOW AND LIFT. THE LIGHT SNOW WILL DECREASE FROM
NORTH TO SOUTH ON SATURDAY...WITH SNOW ENDING OVER THE SOUTHERN
FOOTHILLS BY EARLY EVENING. SNOWFALL AMOUNTS ARE EXPECTED TO RANGE
FROM TRACE OVER THE PLAINS NORTH AND EAST OF DENVER TO POSSIBLY UP
TO 3 INCHES IN SOME SOUTHERN FOOTHILL AND MOUNTAIN LOCATIONS.

ON SUNDAY...AN UPPER LEVEL DISTURBANCE AND WEAK COLD FRONT MAY BRING
A FEW LIGHT SNOW SHOWERS TO THE NORTHEAST CORNER OF COLORADO SUNDAY
AFTERNOON. BY EARLY NEXT WEEK...A MOIST NORTHWESTERLY FLOW SETS UP
OVER COLORADO EARLY NEXT WEEK...WHICH SHOULD BRING WINDY CONDITIONS
AND PERIODS OF LIGHT SNOW TO THE HIGH COUNTRY FROM MONDAY THROUGH
WEDNESDAY. THIS PATTERN SHOULD ALSO BRING SOME DOWNSLOPE FLOW EAST
OF THE MOUNTAINS WHICH WOULD RESULT IN WARMER AND DRIER WEATHER
MONDAY AND TUESDAY. THE GFS AND ECMWF ARE SHOWING A COLD FRONT
MOVING INTO NORTHEASTERN COLORADO LATE ON TUESDAY. THIS FRONT WOULD
RESULT IN COLDER TEMPERATURES EAST OF THE MOUNTAINS ON
WEDNESDAY...WITH A POSSIBILITY OF SOME LIGHT SNOW ACROSS FAR
NORTHEASTERN COLORADO. DUE TO UNCERTAINTY AND BEING OUT IN DAY SEVEN
HAVE ONLY ADDED 10 POPS AT THIS TIME.|

&&

.AVIATION...(FOR THE TAFS THROUGH 06Z FRIDAY EVENING)
ISSUED AT 920 PM MST THU JAN 29 2015

VFR CONDITIONS LIKELY AT DENVER AREA TERMINALS THROUGH FRIDAY
AFTERNOON...ALTHOUGH CLOUD CIGS WILL GRADUALLY LOWER DURING THE
PERIOD. BY FRIDAY EVENING CIGS OVER THE METRO AREA COULD DROP TO
AS LOW AS 4000-5000 FT AGL AS LIGHT SNOW SHOWERS DEVELOP OVER
WESTERN PORTIONS OF THE METRO AREA. BY MID TO LATE EVENING...
EASTERN PORTIONS OF THE METRO AREA...INCLUDING KDEN AND KAPA
COULD SEE LIGHT SNOWFALL WITH CIGS LOWERING TO 2000-3000 FT AGL.
SNOW INTENSITY IS NOT EXPECTED TO BE ALL THAT GREAT. VSBYS MAY NOT
FALL MUCH BELOW 2 MILES AT KDEN PRIOR TO 06Z/SATURDAY.

&&

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

$$

UPDATE...BAKER
SHORT TERM...RJK
LONG TERM...KALINA
AVIATION...BAKER



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