Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 011756
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1156 AM MDT TUE SEP 1 2015

.UPDATE...
ISSUED AT 1150 AM MDT TUE SEP 1 2015

DRIER AIRMASS TODAY BUT STILL SOME MOISTURE AROUND. BAND OF DEEPER
MOISTURE AND WEAK LIFT HAS SHIFTED TO THE SOUTHEAST FRINGE OF OUR
AREA...THERE SHOULD BE SOME WEAK FORCING IN THIS AREA WHICH WILL
HELP CENTRAL MOUNTAIN/PALMER DIVIDE CONVECTION THIS AFTERNOON.
ACROSS NORTHEASTERN COLORADO IT SHOULD BE PRETTY WELL CAPPED.
THERE IS ALSO A LITTLE JET STREAK PRODUCING CONVECTION IN CENTRAL
UTAH AT THIS HOUR...THIS WILL PROBABLY MOVE ACROSS THE NORTHERN
MOUNTAINS IN THE LATE AFTERNOON/EARLY EVENING. MADE SOME MINOR
ADJUSTMENTS TO POPS AND CLOUDS TO REFLECT EXPECTED TIMING OF THESE
FEATURES.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 438 AM MDT TUE SEP 1 2015

WEAK WEST-SOUTHWESTERLY FLOW ALOFT IS GOING TO CONTINUE ACROSS
COLORADO TODAY WITH ADDITIONAL SUB-TROPICAL MOISTURE. ANOTHER
ROUND OF SHOWERS IS GOING TO BE POSSIBLE...ESPECIALLY OVER THE
MOUNTAINS. WINDS ALOFT WILL BE WEAK...WHICH COULD RESULT IN SLOW
STORM MOTIONS AND LOCALLY HEAVY RAINFALL. THE RAP AND NAM MODELS
KEEP MOST OF THE QPF OVER THE MOUNTAINS...ALTHOUGH THE NAM
PRODUCES SOME RAIN OUT ACROSS THE PALMER DIVIDE.

FORECAST WILL HAVE THE HIGHEST CHANCES OF PRECIPITATION OVER THE
MOUNTAINS...AND ISOLATED COVERAGE ACROSS THE PLAINS. TEMPERATURES
WILL BE SLIGHTLY WARMER THAN NORMAL. TURNING THE CALENDAR TO
SEPTEMBER HAS NOT QUITE BROUGHT AN END TO SUMMER YET.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 438 AM MDT TUE SEP 1 2015

THE FLOW ALOFT WILL CONTINUE SWLY BOTH WED AND THU AS AN UPPER LEVEL
TROUGH RESIDES OVER THE PACIFIC NW.  BOTH THE ECMWF AND GFS SHOW
SOME SUBTROPICAL MOISTURE EMBEDDED IN THE FLOW WHICH WILL BE OVER
THE AREA BOTH DAYS. PRECIPITABLE WATER VALUES WILL BE IN THE 0.5-0.6
INCH RANGE OVER THE MTNS WITH VALUES FM 0.8-1.0 INCHES OVER THE
PLAINS. OVERALL WILL KEEP IN A SLIGHT CHC OF STORMS BOTH DAYS ACROSS
THE AREA.  AS FOR HIGHS READINGS WILL REMAIN ABV NORMAL BOTH DAYS
WITH LOW TO MID 90S OVER NERN CO.

BY FRI LITTLE CHANGE IS EXPECTED AS AN UPPER LEVEL TROUGH REMAINS
OVER THE PACIFIC NW WITH SWLY FLOW ALOFT REMAINING OVER THE AREA
WITH SOME SUBTROPICAL MOISTURE STILL EMBEDDED IN THE FLOW.
PRECIPITABLE WATER VALUES INCREASE SLIGHTLY WITH 0.6-0.7 INCHES IN
THE MTNS WITH VALUES AOA AN INCH ACROSS THE PLAINS.  THUS THERE MAY
BE SOME INCREASE IN COVERAGE FOR FRI AFTN INTO FRI EVENING.  AS FOR
TEMPS READINGS WILL REMAIN ABV NORMAL OVER NERN CO WITH HIGHS IN THE
UPPER 80S TO LOWER 90S.

ON SAT THE UPPER LEVEL TROUGH WILL BEGIN TO SHIFT SLOWLY EASTWARD
WITH SWLY FLOW STILL OVER THE AREA.  BOTH THE ECMWF AND GFS SHOW
SOME MID LVL DRYING BY AFTN ESPECIALLY IN THE MTNS AS PRECIPITABLE
WATER VALUES DROP BELOW 0.50 INCHES SO TSTM ACTIVITY SHOULD BE
LESS OVER THE HIGHER TERRAIN. OVER NERN CO PRECIPITABLE WATER
VALUES ARE STILL FCST TO BE AOA AN INCH. MEANWHILE THERE APPEARS
TO BE A WK BNDRY THAT WILL BE OVER NERN CO IN THE AFTN WHICH MAY
ACT AS A FOCUS FOR TSTM DEVELOPMENT. AS FOR HIGHS 850-700 MB TEMPS
DROP A FEW DEGREES SO WILL KEEP READINGS IN THE 80S OVER NERN CO.

BY SUN THE THE UPPER LEVEL TROUGH WILL MOVE INTO THE NRN ROCKIES
WITH WSW FLOW ALOFT OVER THE AREA.  BOTH THE ECMWF AND GFS HAVE A
RATHER DRY AIRMASS OVER THE AREA WITH A SUBSTANTIAL DECREASE IN
PRECIPITABLE WATER VALUES.  IF THIS IS THE CASE THEN ANY TSTM
ACTIVITY WILL BE PRETTY ISOLD AND CONFINED TO THE PLAINS.  AS FOR
HIGHS READINGS WILL REMAIN ABV NORMAL WITH MID 80S TO LOWER 90S
ACROSS NERN CO.

ON MON THE FLOW ALOFT WILL REMAIN WSW AS A COOL FRONT IS SUPPOSED TO
MOVE ACROSS NERN CO...HOWEVER THE STRENGTH OF THIS FNT IS WEAKER
THAN WHAT THE MODELS SHOWED YESTERDAY. OVERALL THERE WILL BE
LIMITED MOISTURE SO WILL ONLY MENTION LOW POPS. HIGHS WILL DROP
BACK INTO THE UPPER 70S TO LOWER 80S OVER THE PLAINS.

&&

.AVIATION...(FOR THE TAFS THROUGH 18Z WEDNESDAY MORNING)
ISSUED AT 1150 AM MDT TUE SEP 1 2015

VFR THROUGH TONIGHT. ISOLATED THUNDERSTORMS EXPECTED IN THE LATE
AFTERNOON/EARLY EVENING...MOST LIKELY SOUTH OF DENVER. STILL A
GOOD CHANCE OF A SHORT PERIOD OF GUSTY WINDS TO 30 KNOTS...BUT
ONLY LOW PROBABILITIES OF ANY OTHER IMPACTS.

&&

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

$$

UPDATE...GIMMESTAD
SHORT TERM...DANKERS
LONG TERM...RPK
AVIATION...GIMMESTAD


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