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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS65 KBOU 012226
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
326 PM MST SUN MAR 1 2015

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 325 PM MST SUN MAR 1 2015...CORRECTED

A MOIST WEST TO SOUTHWESTERLY FLOW ALOFT WILL BE OVER COLORADO
TONIGHT. SNOWFALL ACTIVITY WILL BE LIMITED IN THE MOUNTAINS NORTH
OF I70 THIS EVENING...WITH THE MAIN PLUME OF MOISTURE FURTHER
SOUTH OVER THE CENTRAL COLORADO MTNS. LATER TONIGHT THE PLUME OF MSTR
SHIFTS NORTHWARD INTO ZONES 31 AND 33. THE SWLY OROGRAPHIC COMPONENT
WILL FAVOR THOSE MOUNTAIN ZONES THE MOST.  SINCE A PROLONGED PERIOD OF
SNOW IS EXPECTED TO CARRYOVER INTO TUESDAY...WL GO AHEAD AND HOIST
A WINTER STORM WARNING FOR ZONE 31 AFTER MIDNIGHT. IN ZONE 34...THE
SNOWFALL WILL BE LIMITED BY LESS FAVORABLE OROGRAPHIC COMPONENT AND
MID LEVEL WARM AIR ADVECTION. ACROSS THE NORTHEAST PLAINS...WL KEEP
A CHANCE OF LIGHT SNOW IN THE DENVER AREA ESPECIALLY THROUGH 06Z W/
BETTER MOISTURE IN THE MID AND UPPER LEVELS RIDING OVER THE ARCTIC
AIRMASS. SNOWFALL WILL BE LIMITED...MAYBE AN INCH WEST OF I25 AND
SOUTH OVER THE PALMER DIVIDE. LESSER POPS NORTHEAST OF DENVER. THE
FOCUS OF PCPN BY 12Z MONDAY WILL SHIFT NORTH TO NEAR THE
WYOMING/NEBRASKA BORDER. ON MONDAY...THERE WILL BE A BIT OF A BREAK
IN THE SNOW COVERAGE OVER THE MOUNTAINS IN THE MORNING THEN BY THE
AFTERNOON...MOISTURE WILL INCREASE AS THE TROUGH OVER SRN CA MOVES
EASTWARD INTO EASTERN NV/WESTERN UT. THE BEST MID AND UPPER LEVEL
QG ASCENT WILL BE IN THE AFTN...WITH SNOW AGAIN INCREASING IN THE
MOUNTAINS AT THAT TIME. ACROSS THE URBAN CORRIDOR AND NORTHEAST
PLAINS...COULD AGAIN SEE SOME PATCHY FOG IN AND AROUND DENVER EARLY.
THE ARCTIC AMS WILL LOOSEN ITS GRIP ON DENVER THROUGH THE DAY BUT IT
MAY BE A LITTLE SLOER TO MOVE OUT THAN THE MDLS SUGGEST. WL KEEP
SOME LOW 40S OVER SRN/SWRN PARTS OF THE DENVER AREA WITH COOLER
TEMPERATURES FURTHER NORTH. IN THE FOOTHILLS AND PARTS OF THE URBAN
CORRIDOR...THERE COULD BE MORE OF A MIX OF RAIN/SNOW WITH PCPN IN THE
AFTERNOON WITH WARMER MID LEVEL AIR FILLING INTO THE AREA AND THE
ARCTIC AMS SHIFTING EAST.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 158 PM MST SUN MAR 1 2015

ON MONDAY NIGHT...A PIECE OF THE UPPER LEVEL TROUGH OVER THE
SOUTHWEST PART OF THE COUNTRY WILL EJECT NORTHEAST ACROSS COLORADO.
THIS WILL KEEP SNOW GOING IN THE MOUNTAINS OVERNIGHT. DEEP MOISTURE
COMBINED WITH THE STRONG FLOW ALOFT AND THE JET MOVING
OVERHEAD...WILL PRODUCE HEAVY SNOW AT TIMES...MAINLY OVER NORTH
CENTRAL COLORADO. FLOW ALOFT WILL TURN WESTERLY BEHIND THE EJECTING
WAVE AND KEEP SNOW GOING IN THE MOUNTAINS TUESDAY.

FOR THE PLAINS...A SURFACE LOW WILL MOVE ACROSS EASTERN COLORADO
MONDAY NIGHT. STILL PLENTY OF UNCERTAINTY WHERE IT WILL TRACK. THE
12Z ECMWF HAS THE LOW GOING ACROSS LINCOLN COUNTY WHERE THE GFS IS
CLOSER TO AKRON AND THE NAM12 TRACK IS NEAR THE WYOMING BORDER. A
COLD FRONT WILL PUSH INTO NORTHEAST COLORADO BEHIND THE LOW AS IT
EXITS THE STATE. TIMING OF THE FRONTAL PASSAGE IS UNCERTAIN DUE TO
THE TRACK OF THE LOW. EVENTUALLY THE COLD FRONT WILL PUSH SOUTH
THROUGH THE STATE. AN UPSLOPE NORTH TO NORTHEAST FLOW WILL DEVELOP
BEHIND IT AND PRODUCE SNOW ALONG THE FRONT RANGE. OVER THE PLAINS
EAST OF DENVER...SNOW WILL BE LIGHTER. WILL HAVE HIGHS POPS IN THE
FORECAST FOR TUESDAY AND TUESDAY NIGHT FOR THIS. TEMPERATURES WILL
BE COLD TUESDAY AND TUESDAY NIGHT WITH READINGS 20 TO 30 DEGREES
BELOW NORMAL.

FOR WEDNESDAY...UPPER LEVEL TROUGH AXIS WILL MOVE ACROSS COLORADO
AND CAUSE FLOW ALOFT TO TURN NORTHWESTERLY THROUGH THE DAY.
ALSO...THERE MAY BE A WEAK WAVE AND IT COULD BE SLIGHTLY UNSTABLE...
SO WILL KEEP A MENTION OF SNOW IN THE FORECAST THROUGH WEDNESDAY.
MODELS STILL DISAGREE ON HOW FAR SOUTH THE TROUGH WILL DIG AND THE
AMOUNT OF COLD AIR THAT WILL MAKE IT INTO THE STATE. THE 12Z NAM HAS
VERY COLD AIR OVER NORTHEAST COLORADO WEDNESDAY WHICH WOULD KEEP
HIGHS IN THE SINGLE DIGITS. THE GFS AND ECMWF ARE NOT QUITE AS
COLD...WITH HIGHS CLOSER TO 20 DEGREES. WILL KEEP WITH THE TREND OF
THE CURRENT FORECAST WITH HIGHS MAINLY IN THE TEENS.

FOR THURSDAY AND FRIDAY...THE RIDGE OVER THE WESTERN STATES KEEPS
GETTING SHIFTED WEST BY THE MODELS. THIS WILL KEEP A COOL AND DRY
NORTHWEST FLOW OVER COLORADO LATE IN THE WEEK.

NORTHWEST FLOW ALOFT WILL REMAIN OVER COLORADO NEXT WEEKEND. MODELS
ARE SHOWING A WEAK WAVE EMBEDDED IN THE NORTHWEST FLOW MOVING ACROSS
THE STATE SOMETIME NEXT WEEKEND. IF THIS PANS OUT...WOULD EXPECT A
SHOT OF COOLER AIR AND PERHAPS SOME SNOW. WILL PUT LOW POPS IN THE
FORECAST FOR SATURDAY AND SATURDAY NIGHT FOR THIS SYSTEM. WILL ALSO
KEEP TEMPERATURES BELOW NORMAL FOR SATURDAY AND SUNDAY.

&&

.AVIATION...(FOR THE TAFS THROUGH 00Z MONDAY LATE AFTERNOON)
ISSUED AT 158 PM MST SUN MAR 1 2015

MAINLY MVFR CIG/VSBY THROUGH TONIGHT AT KDEN...WITH THE POTENTIAL
FOR IFR RESTRICTIONS HIGHER AT KBJC AND KAPA. LGT WINDS AND THE
POTENTIAL FOR A WEAK CYCLONE COULD AGAIN BRING FOG IN DIA LATE
TONIGHT...SO HAVE ADDED TEMPO GROUP OF 1/2 MILE VSBY AFTER
12Z...COULD HOWEVER BE LOWER BUT WL HOLD OFF INCLUDING THAT
POSSIBILITY AT KDEN. CIGS/VSBYS WILL IMPROVE AT ALL THE AIRPORTS
AFTER 15Z...WITH VFR CONDITIONS IN THE AFTN.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 5 PM MST TUESDAY
FOR COZ031.

WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY
AFTERNOON FOR COZ033.

&&

$$

SHORT TERM...COOPER
LONG TERM...MEIER
AVIATION...COOPER