National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS65 KBOU 281759
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1059 AM MST FRI FEB 28 2014

.UPDATE...THE COLD FRONT HAS PUSHED SOUTH ACROSS THE EASTERN
PLAINS WITH LOW STRATUS AND FOG BEGINNING TO FORM BEHIND IT NEAR
THE NORTHERN STATE BORDER. THIS IS EXPECTED TO CONTINUE SOUTH AND
THEN EVENTUALLY PUSH WEST INTO THE URBAN CORRIDOR AROUND MID
AFTERNOON. STILL MONITORING THE FRONTAL POSITION AND COMPARING TO
THE HOURLY HIGH RESOLUTION MODELS FOR FROPA TIMING. SO
FAR...SOMETIME BETWEEN 21-23Z STILL SEEMS GOOD.

SATELLITE AND WEBCAMS SHOWING THE SNOW DECREASE IN THE MOUNTAINS
LAST THEM MORNING WITH JUST SCATTERED SNOW SHOWERS REMAINING MIXED
WITH SUN PEAKING THROUGH. AS THE NEXT SYSTEM IS
APPROACHING...MOUNTAIN TOP WINDS ARE TURNING MORE SOUTHWEST AND
BECOMING LESS FAVORABLE FOR MUCH OROGRAPHIC SNOW. GRIDS AND
FORECAST SHOW THIS WELL. THE NEXT THING TO LOOK AT WILL BE
TOMORROW WHEN THE JET MOVES OVERHEAD...WHICH EVEN THOUGH WITH
SOUTHWEST FLOW ALOFT...BANDING SNOW MAY BUILD UP ENOUGH FOR THE
NEED FOR HIGHLIGHTS FOR THE MOUNTAINS. WILL CONTINUE TO EVALUATE
THROUGH THIS AFTERNOON.

&&

.AVIATION...HAVE BOOSTED NORTHWEST WINDS AHEAD OF THE INCOMING
COLD FRONT CURRENTLY OVER NORTHEAST COLORADO. NORTHWEST WINDS WILL
BECOME NORTHEAST THEN SWITCH TO SOUTHEAST THROUGH THE
AFTERNOON/EVENING. GOOD HIGH PRESSURE TO THE EAST WILL KEEP THE
EASTERLY WINDS AROUND 10KTS OR HIGHER THROUGH THE NIGHT. STILL
EXPECTING A 21-23Z FROPA TIMING. CIGS BECOMING BKN 030-040 KFT
AGL AFTER 02Z...WITH MVFR CIGS/VSBYS FM 06Z-09Z. MID LEVEL
MOISTURE OVERRIDING THE ARCTIC AMS WILL BE VARIABLE...SO EITHER A
SLIGHT CHANCE OF SNOW AND/OR LIGHT FREEZING DRIZZLE AND FREEZING
FOG AFTER 06Z AS WELL. IFR CIGS/VSBYS LIKELY BY 12Z SATURDAY WITH
CIGS BELOW 010 AND VSBYS AT OR BELOW 1/2 MILE. THIS WILL BE THE
BEST CHANCE FOR SNOW AS WELL WITH AN INCREASE IN MIDLEVEL
MOISTURE. THE SURFACE DENVER CYCLONE WILL PLAY WITH WIND
DIRECTIONS OVERNIGHT AS IT WOBBLES AROUND THE AREA AIRPORTS...THEN
IT SHOULD DROP SOUTH AFTER 12Z FOR ALL AIRPORTS TO BECOME ENE
WINDS.

&&

.PREV DISCUSSION... /ISSUED 259 AM MST FRI FEB 28 2014/

SHORT TERM...STLT INDICATING WARMING CLOUD TOPS WITH DECREASING
RADAR ECHOES OVER THE NORTHEAST PLAINS THIS MORNING. THIS TREND
SHOULD CONTINUE AS MID LEVEL SUBSIDENCE CONTINUES BEHIND THE UPPER
LEVEL TROUGH AXIS THIS MORNING. THIS TREND WILL BE REFLECTED IN
THE MOUNTAINS AS WELL. SOME OROGRAPHIC SNOWFALL THIS MORNING...BUT
SPATIAL CROSS-SECTIONS SHOW MOISTURE DECREASING IN THE MOUNTAINS
AS WELL TODAY. SNOW AMOUNTS GENERALLY LESS THAN FORECAST OVERNIGHT
SO WL LIKELY CANCEL THE WINTER WEATHER ADVISORY WITH THE ISSUANCE
OF THE MORNING FORECAST PACKAGE. ACROSS THE NORTHEAST PLAINS...IT
WILL BE ANOTHER FAIRLY MILD DAY ALONG THE URBAN CORRIDOR THROUGH
EARLY THIS AFTERNOON. AN ARCTIC AMS WILL BE PUSHING INTO THE
CENTRAL GREAT PLAINS THIS AFTERNOON...WITH A COLD FRONT BACKING
INTO DENVER FM THE NORTH AND EAST LATE THIS AFTERNOON. MDLS STILL
WANT TO BRING IT THROUGH DENVER AROUND 23Z. TONIGHT...MOISTURE
WILL INCREASE IN THE MOUNTAINS WITH WEAK MID AND UPPER LEVEL QG
ASCENT REDEVELOPING AHEAD SOME DISORGANIZED SYSTEM OVER THE WEST.
THE WRF SIMULATED STLT SHOWS SOME COOLING CLOUD TOPS AS A SUBTLE
UPPER LEVEL DISTURBANCE PASSES FM SOUTHWEST TO NORTHEAST ACROSS
THE STATE TONIGHT. AS A RESULT...SOME LIGHT SNOW REDEVELOPING IN
THE MOUNTAINS. SWLY FLOW NOT VERY FAVORABLE WITH THE EXCEPTION OF
ZONE 31...SO WL GO WITH BEST SNOW ACCUMULATIONS THERE. AS FOR FOR
THE NORTHEAST PLAINS...THE COLD FRONT WILL SETTLE ALONG THE FRONT
RANGE FOOTHILLS AND PALMER DIVIDE AREA TONIGHT...WITH EAST-
SOUTHEASTERLY WINDS ADVECTING LOW LEVEL MOISTURE INTO THE
AREA...ESPECIALLY AFTER MIDNIGHT. DEPENDING ON HOW MUCH MOISTURE
IS AVBL IN THE MID LEVELS...WE COULD SEE EITHER A CHANCE OF SOME
LIGHT SNOW...MIXED WITH SOME FREEZING DRIZZLE OVERNIGHT. THAT IS
WHAT THE FORECAST SOUNDINGS APPEAR TO SUGGEST.

LONG TERM...SATURDAY THROUGH THURSDAY...STRONG PACIFIC STORM SYSTEM
WILL BE MOVING ONTO THE WEST COAST SATURDAY. A VERY MOIST SOUTHWEST
FLOW AHEAD OF THE TROUGH WILL BE OVER COLORADO. OROGRAPHIC LIFT IS
LIMITED UNDER SOUTHWEST FLOW. STILL EXPECT SNOW SATURDAY THROUGH
SUNDAY BECAUSE STEEP MID LEVEL LAPSE RATES AND QG ASCENT AHEAD OF
THE TROUGH. THIS SET UP WILL BRING PERIODS SNOW...POSSIBLE HEAVY AT
TIMES BECAUSE SOME OF THE SNOW WILL BE CONVECTIVE. HOWEVER...DO NOT
EXPECT PROLONGED HEAVY SNOW BECAUSE OF THE LACK OROGRAPHIC LIFT. THE
PACIFIC ORIGIN OF THIS SYSTEM WILL BRING MILD AIR WITH IT. THIS WILL
RESULT IN RAIN IN SOME OF THE VALLEYS. SNOW RATIOS WILL BE CLOSE TO
10 TO 1...WHICH WILL KEEP SNOW AMOUNTS LOWER. RIGHT APPEARS AMOUNTS
WILL BE BELOW WARNING CRITERIA AND IN MANY SPOTS BELOW ADVISORY. DO
NOT PLAN ON ANY HIGHLIGHTS AT THIS TIME.

FOR THE FRONT RANGE AND NORTHEAST PLAINS...THE ARCTIC AIR WILL
SETTLE OVER THE AREA SATURDAY MORNING...EXCEPT FOR AREAS NEAR THE
PALMER DIVIDE. THERE WILL BE A LARGE TEMPERATURE CONTRAST ACROSS THE
AREA...FROM LOWER TEENS OVER THE NORTHEAST CORNER TO LOWER 40S ALONG
THE PALMER DIVIDE. STILL UNCERTAIN IF THE PLAINS WILL SEE SNOW OR
NOT. WITH ALL THE MOISTURE IN THE PLACE...THERE WILL BE A
CHANCE...THOUGH NOT SEEING ANY ONE FEATURE TO BRING SNOW. BEST
CHANCE MAY BE WITH THE TROUGH PASSAGE SATURDAY NIGHT AND EARLY
SUNDAY EAST. COULD SEE FOG AND FREEZING DRIZZLE LATE FRIDAY AND
SATURDAY MORNING OVER THE EASTERN PLAINS AND PARTS OF THE FRONT
RANGE. EASTERLY LOW LEVEL FLOW WILL KEEP THE COLD AIR OVER THE AREA
SUNDAY WITH HIGHS BELOW FREEZING.

IT WILL MODERATE NEXT WEEK AS THE ARCTIC AIR RETREATS. A WEST TO
NORTHWEST FLOW ALOFT WILL USHER IN PACIFIC AIR. WILL HAVE LOW POPS
OVER MOUNTAINS MOST OF NEXT WEEK. THIS FOR A COUPLE OF WEAK WAVES
EMBEDDED IN THE FLOW ALOFT. RIGHT NOW IT APPEARS ANY SNOWFALL WILL
BE LIGHT. WILL KEEP THE PLAINS DRY. TEMPERATURES WILL WARM EACH DAY
WITH HIGHS NEAR 60 DEGREES OVER NORTHEAST COLORADO BY THURSDAY.

AVIATION...VFR CIGS/VSBYS THROUGH 23Z. NWLY WINDS THIS MORNING WILL
TRANSITION TO NE-ELY BY LATE THIS AFTERNOON AS A COLD FRONT
PUSHES INTO THE REGION FM THE NORTH AND EAST. CIGS BECOMING BKN
030-040 KFT AGL AFTER 02Z...WITH MVFR CIGS/VSBYS FM 06Z-09Z. MID
LEVEL MOISTURE OVERRIDING THE ARCTIC AMS WILL BE VARIABLE...SO
EITHER A SLIGHT CHANCE OF SNOW AND/OR LIGHT FREEZING DRIZZLE AND
FREEZING FOG AFTER 06Z AS WELL. IFR CIGS/VSBYS LIKELY BY 12Z
SATURDAY WITH CIGS BLO 010 AND VSBYS AT OR BLO 1/2 MILE. SFC WINDS
PRIMARILY E-SE AFTER 06Z.

&&

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

$$

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