Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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000 FXUS65 KBOU 282047 AFDBOU AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER/BOULDER CO 247 PM MDT SAT MAR 28 2015 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 247 PM MDT SAT MAR 28 2015 UPPER LEVEL SHORTWAVE TROUGH IN TANDEM WITH A SFC COLD FRONT NOW MAKING THEIR WAY ACROSS NWRN WYOMING AND NRN UTAH. DO NOT SEE MUCH IN THE WAY OF MOISTURE/PCPN WITH THIS SYSTEM ATTM...AND QG VERTICAL VELOCITY FIELDS ARE INDICATING ONLY MODEST DEEP LAYER ASCENT BEHIND THE SFC FRONT. DETERMINISTIC MODELS AND SYNTHETIC SATELLITE IMAGERY SHOW THIS UPPER AIR FEATURE RACING SEWRD ACRS WYOMING EARLY THIS EVENING AND DOWN ACRS N-CNTRL AND NERN COLORADO OVERNIGHT. MEANWHILE MODELS DIFFER ON THE ARRIVAL TIME OF THE SFC FRONT. WRF...RAP...GFS...ECMWF AND CANADIAN MODELS ALL SHOW BNDRY LAYER WINDS ON THE PLAINS TURNING GUSTY FROM THE NORTHWEST WITH FRONTAL PASSAGE LATE THIS EVENING. WHEREAS THE NAM DELAYS THE ARRIVAL OF THE FRONT AND ITS WIND SHIFT UNTIL SOMETIME BETWEEN 06Z AND 09Z. MOST OF THESE SAME MODELS SHOW A NARROW BAND OF LOW- LEVEL CONVERGENCE AND STEEP LAPSE RATES ACROSS THE NORTHEAST PLAINS LATE THIS EVENING AND HINTS OF A TRIPLE POINT JUST BEYOND THE NERN CORNER OF THE STATE JUST AHEAD OF THE COLD FRONT. CROSS SECTIONS AND MODEL SOUNDINGS SHOW MID-LEVELS SATURATING WITH WEAK QG ASCENT SUFFICIENTLY TO GENERATE A FEW HIGH BASED SHOWERS AND PERHAPS A WEAK SHORT-LIVED T-SHOWER OVER THE NERN CORNER. OTHERWISE ONLY GUSTY N-NWLY WINDS...FALLING TEMPERATURES AND RISING HUMIDITIES UNDER MOSTLY CLEAR/PARTLY CLOUDY SKIES EXPECTED WITH PASSAGE OF THIS WEAK SYSTEM...AND PERHAPS A FEW LIGHT SNOW SHOWERS OVER THE NRN MTN RANGES. SUNDAY...LOOKS DRY AND COOLER WITHIN THE POST-FRONTAL ENVIRONMENT WITH GUSTY NLY WINDS ON THE PLAINS AND STG/GUSTY NWLY WINDS IN THE FRONT RANGE MTNS DURING THE MORNING HOURS. FLOW ALOFT WEAKENS DURING THE AFTERNOON AS THE UPPER RIDGE BUILDING OUT WEST MOVES CLOSER TO THE STATE. SHOULD THEN SEE WIND SPEEDS SUBSIDING EVEN IN THE HIGH COUNTRY WITH HARDLY A CLOUD IN THE SKY WITH STG MID- LEVEL SUBSIDENCE. HIGHS TOMORROW ARE EXPECTED TO RUN 10-15 DEG F BELOW THOSE OBSERVED TODAY. THAT/S STILL ABOVE AVERAGE FOR THE DATE. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 247 PM MDT SAT MAR 28 2015 A RELATIVELY DRY AND WARM PERIOD THROUGH NEXT WEDNESDAY WITH RIDGE OF HIGH PRESSURE ALOFT OVER PORTIONS OF THE WESTERN U.S. THE RIDGE WILL SHIFT INTO THE PLAINS BY MID WEEK AS FLOW SHIFTS WEST AND SOUTHWEST FOR WEDNESDAY AND THURSDAY. TEMPERATURES WILL BE WAY ABOVE NORMAL WITH READINGS IN THE 70S ACROSS LOWER ELEVATIONS THROUGH WEDNESDAY. THERE IS ONLY A SLIGHT CHANCE OF AFTERNOON AND SHOWERS IN THE MOUNTAINS...MAINLY SOUTH OF INTERSTATE 70 AND ACROSS PARK COUNTY WITH A BIT BETTER MOISTURE THERE. AS THE FLOW TURNS ZONAL ON WEDNESDAY THERE IS A WEAK FRONTAL BOUNDARY WHICH MOVES THROUGH WEDNESDAY AM ALONG WITH A SLIGHT CHANCE OF SHOWERS. A STRONGER SYSTEM DEVELOPS OVER THE GREAT BASIN ON THURSDAY BEFORE SLOWLY SHIFTING ACROSS COLORADO SOMETIME IN THE LATE THURSDAY AND FRIDAY TIME FRAME. THERE ARE SOME TIMING DIFFERENCES BETWEEN EUROPEAN AND GFS SOLUTION SO FOR NOW WILL JUST KEEP LOW POPS AND COOLER TEMPERATURES. && .AVIATION...(FOR THE TAFS THROUGH 00Z SUNDAY LATE AFTERNOON) ISSUED AT 247 PM MDT SAT MAR 28 2015 LOOK FOR GUSTY WESTERLY WINDS AT KBJC AND KDEN FOR THE REMAINDER OF THE AFTERNOON UNDER MOSTLY CLEAR SKIES. GUSTS WILL RUN IN THE 15-25KT RANGE. AFTERNOON WINDS AT KAPA WILL BE MUCH LIGHTER FROM A NWLY DIRECTION. BY NIGHT FALL WIND SPEEDS SHOULD QUICKLY FALL OFF AS WINDS SHIFT TO A SOUTHWESTERLY COMPONENT. HOWEVER BY LATE EVENING...SKIES WILL BEGIN FILLING WITH MID-LEVEL CUMULUS TYPE CLOUDS WITH THE APPROACH OF A WEAK UPPER LEVEL TROUGH AND SFC COLD FRONT. LATEST INDICATIONS POINT TO A FRONTAL PASSAGE IN DENVER AROUND 06Z. AT THIS TIME DO NOT EXPECT TO SEE ANY PCPN OR LOW CLOUDS WITH ITS PASSAGE AS THE AIR BEHIND THIS FRONT IS ALSO DRY BUT COOLER. ON SUNDAY...STRONG NORTHWEST FLOW ALOFT IS EXPECTED TO PRODUCE NORTH-NORTHEAST SFC WINDS OF 12-22KT AT KDEN AND KAPA PRIOR TO 18Z. NLY WIND AT KBJC ARE NOT EXPECTED TO BE AS STRONG BUT COULD SEE A FEW LOWER CLOUDS FORM BY AROUND 15Z. REST OF THE DAY...WINDS WEAKEN AND TURN ELY UNDER NEARLY CLOUDLESS SKIES. && .FIRE WEATHER... ISSUED AT 247 PM MDT SAT MAR 28 2015 FIREWEATHER ZONE 238..239 AND 242 REMAIN IN A RED FLAG WARNING OUNTIL 1800 MDT. GUSTY WEST WINDS...LOW RELATIVE HUMIDITY AND ABNORMALLY WARM TEMPERATURES WILL COMBINE WITH DRY FUEL CONDITIONS TO PRODUCE POTENTIALLY CRITICAL RANGELAND FIRE BEHAVIOR THIS AFTERNOON. LIGHTER WINDS...COOLER TEMPERATURES AND GRADUAL RH RECOVERY CAN BE EXPECTED THIS EVENING. .BOU WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 6 PM MDT THIS EVENING FOR COZ238-239-242. && $$ SHORT TERM...BAKER LONG TERM...ENTREKIN AVIATION...BAKER

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