Littleton, CO Area Forecast Discussion Issued by NWS
57.0°F 
000 FXUS65 KBOU 032032 AFDBOU AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 233 PM MDT FRI SEP 3 2010 .SHORT TERM...VERY DRY AIR AND LIGHT WINDS WILL ALLOW FOR GOOD RADIATIONAL COOLING TONIGHT. DROPPED LOWS A LITTLE...IN LINE WITH GUIDANCE...AND IT MAY BE EVEN COLDER IN SOME OF THE MOUNTAIN VALLEYS WHICH ARE EXPERIENCING A 50 DEGREE DIURNAL SWING TODAY. THERE SHOULD BE A LITTLE BIT OF WIND IN THE FOOTHILLS...MOUNTAIN RIDGES...AND DENVER AREA TO KEEP IT WARMER TONIGHT IN THOSE AREAS. CONTINUED STEADY WARMING ALOFT AND STILL ENOUGH SUN TO MIX BY AFTERNOON SO HOT AND DRY ON SATURDAY AFTERNOON AFTER A COOL START. WITH SOME INCREASE IN WINDS ALOFT...MIXING OF WESTERLY WINDS MAY WIN OUT OVER DIURNAL UPSLOPE WINDS...HOWEVER SPEEDS DO NOT LOOK TOO STRONG YET. MAYBE SOME GUSTS IN THE 20-30 MPH RANGE IN THE MOUNTAINS/FOOTHILLS FOR A FEW HOURS...BUT MAINLY LESS THAN THAT. WITH WINDS MARGINAL AT BEST AND FUELS IN THE WINDIEST AREAS NOT THAT DRY...WE WILL NOT ISSUE A FIRE WEATHER HIGHLIGHT FOR SATURDAY. .LONG TERM...MODELS STILL KEEP A FLATTENING UPPER RIDGE OVER THE FORECAST AREA SATURDAY NIGHT INTO SUNDAY. BY LATE SUNDAY AND SUNDAY NIGHT...THE BOTTOM OF AN UPPER TROUGH MOVES ACROSS THE FORECAST AREA. PRETTY STRONG NORTHWESTERLY FLOW ALOFT IS PROGGED SATURDAY NIGHT...WITH AROUND 100 KNOTS OF ZONAL FLOW ALOFT OVER THE CWA SUNDAY AFTERNOON AND NIGHT. ON MONDAY...DECREASING ZONAL FLOW ALOFT IS PROGGED FOR THE FORECAST AREA. THE QG VERTICAL VELOCITY FIELDS HAVE UPWARD MOTION OVER THE FORECAST AREA SATURDAY NIGHT THROUGH MUCH OF SUNDAY NIGHT. PRETTY STRONG DOWNWARD MOTION IS PROGGED FOR MONDAY. BOUNDARY LAYER WIND PROGGS HAVE DOWNSLOPING FOR SUNDAY WITH TROUGHING EAST OF THE MOUNTAINS. A PRETTY DECENT COLD FRONT IS EXPECTED TO MOVE INTO THE FORECAST AREA SOMETIME AROUND 06Z SUNDAY NIGHT. THE BOUNDARY LAYER FLOW ON MONDAY IS NORTH- NORTHWESTERLY...THEN EASTERLY BY MONDAY NIGHT. FOR MOISTURE...THERE IS SOME MID LEVEL MOISTURE AROUND SATURDAY EVENING...THEN IT IS VERY DRY INTO SUNDAY AFTERNOON...BEFORE SOME MID LEVEL MOISTURE IS PROGGED AGAIN. SUNDAY NIGHT IS DRY...WITH A BIT OF INCREASING LOW LEVEL MOISTURE OVER THE PLAINS AFTER 06Z. THERE IS A BIT OF LOW LEVEL MOISTURE OVER THE PLAINS AND FOOTHILLS ON THE NAM ONLY FOR MONDAY...THE GFS IS DRY. BOUNDARY LAYER DEW POINT PROGGS ARE MAINLY IN THE 20S F FOR THE FORECAST AREA SATURDAY NIGHT...THEN TEENS F FOR SUNDAY AND SUNDAY EVENING. AFTER THE FRONT MOVES ACROSS THEY INCREASE INTO THE 40S FOR THE PLAINS INTO EARLY MONDAY. BY MONDAY AFTERNOON...THEY DRY OUT BACK INTO THE 20S F. PRECIPITABLE WATER VALUES ARE PROGGED IN THE 0.35 TO 0.45 INCH RANGE SATURDAY NIGHT ...0.25 TO 0.40 INCH RANGE SUNDAY AND MUCH OF SUNDAY NIGHT...AND THE 0.45 TO 0.60 INCH RANGE MUCH OF MONDAY. THERE IS NEARLY ZERO CAPE OVER THE FORECAST AREA THROUGH THE PERIOD. THERE IS NO MEASURABLE RAINFALL ON THE QPF FIELDS THROUGH THE PERIOD. FOR POPS...WILL GO ZERO SATURDAY NIGHT THROUGH MONDAY NIGHT. FOR TEMPERATURES... SUNDAY`S ARE 0-1 C WARMER THAN SATURDAY`S. MONDAY`S COOL DOWN 5 C WESTERN FORECAST AREA TO 15 C EASTERN FORECAST AREA. WITH THE HEAT AND DRYNESS PROGGED ON SUNDAY...JUST A BIT MORE WIND WOULD BE NEEDED FOR A RED FLAG SITUATION IN MOST AREAS. FOR THE LATER DAYS... TUESDAY THROUGH FRIDAY...MODELS HAVE THE UPPER RIDGE CENTERED OVER THE SOUTHEASTERN UNITED STATES...WITH AN UPPER TROUGH OVER THE NORTHWEST...AND SOUTHWESTERLY FLOW ALOFT FOR THE FORECAST AREA FOR MOST OF THE PERIOD. BY FRIDAY...MODELS SHOW AN UPPER TROUGH TO MOVE ACROSS THE CWA...BUT MOISTURE IS POOR ON BOTH THE GFS AND ECMWF. WILL GO WITH/OR LEAVE IN MINOR LATE DAY POPS LATE DAY WEDNESDAY ...LATE DAY THURSDAY...AND FRIDAY. .AVIATION...VFR CONDITIONS EXPECTED THROUGH SATURDAY. && .BOU WATCHES/WARNINGS/ADVISORIES...NONE. && $$ GIMMESTAD/RJK