Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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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

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