Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 230927
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
327 AM MDT SAT AUG 23 2014

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 319 AM MDT SAT AUG 23 2014

A RATHER STG UPPER LEVEL TROUGH WILL MOVE ACROSS THE NRN ROCKIES
THRU TONIGHT WITH COLORADO BEING ON THE SRN EDGE OF THE TROUGH.
MEANWHILE AN UPPER LEVEL JET WILL REMAIN ACROSS NRN PORTIONS OF THE
AREA THRU THIS EVENING WITH SOME POTENTIAL VORTICITY IN THE MID TO
UPPER LEVELS.  THUS SHOULD SEE A GOOD CHC OF SHOWERS AND TSTMS IN
THE MTNS LATER THIS MORNING INTO THE AFTN HOURS.  OVER NERN CO LOW
LVL MOISTURE WILL MIX OUT SOME THRU THE DAY EXCEPT OVER THE FAR
NERN PLAINS.  CAPES WILL RANGE FM 500-1000 J/KG ALONG THE FRONT
RANGE WHILE OVER THE FAR NERN PLAINS VALES WILL BE ABOVE 1500 J/KG.
AS OUTFLOW BOUNDARIES FM CONVECTION OVER THE HIGHER TERRAIN MOVE
ACROSS BY EARLY TO MID AFTN EXPECT SCT TSTMS TO DVLP ALONG THE
FRONT RANGE AND THEN MOVE RATHER QUICKLY ACROSS THE PLAINS FM
LATE AFTN INTO THE EARLY EVEING HOURS.  WITH RATHER STG MID LVL FLOW
A FEW STORMS COULD PRODUCE WIND GUSTS UP TO 60 MPH.  OVER THE FAR
NERN PLAINS WHERE CAPES WILL BE BETTER SOME MARGINAL LARGE HAIL
COULD OCCUR AS WELL.  AS FOR HIGHS WILL KEEP READINGS MOSTLY IN THE
LOWER TO MID 80S ACROSS NERN CO.

BY THIS EVENING AS DRIER AIR BEGINS TO SPREAD INTO THE MTNS PRECIP
SHOULD GRADUALLY DECREASE OVER THE HIGHER TERRAIN.  OVER NERN CO
PCPN CHANCES SHOULD END BY EARLY EVENING ALONG THE FRONT RANGE AND
THEN BY MIDNIGHT OVER THE FAR NERN CORNER.



.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 319 AM MDT SAT AUG 23 2014

SUNDAY AND SUNDAY NIGHT...THE FLOW ALOFT REMAIN SOUTHWESTERLY.
ENOUGH SUBTROPICAL MOISTURE WILL BE AROUND VIA THE GFS/ECMWF
MODELS TO KEEP A CHANCE OF TSTMS IN THE AFTN/EVNG. THE BEST CHC
WL BE OVER THE MOUNTAINS. ON MONDAY...THE NEXT SYSTEM WILL
APPROACH CO FM THE NORTHWEST...WITH A SOUTHWESTERLY FLOW AHEAD OF
IT. THUNDERSTORMS WILL AGAIN DEVELOP OVER THE CWFA MONDAY
AFTN/EVNG WITH THE TROUGH ITSELF STILL OVER SRN ID/NRN UT BY 12Z
TUESDAY. THE ECMWF/NAM ARE SLOER THAN THE MORE PROGRESSIVE GFS
WHICH MAINTAINS AN OPEN WAVE TROUGH...THE NAM DRIVES A CLOSED
CIRCULATION INTO NORTHERN CA. THE ECMWF IS THE COMPROMISE
MDL...IT CLOSES THE UPPER LOW BUT STILL SHIFTS IT EASTWARD ACROSS
COLORADO...BUT SLOER...TUESDAY INTO WEDNESDAY. WL FOLLOW THIS
PLAN FOR NOW AT BUMP THE POPS UPWARD FOR TUESDAY NIGHT AND
WEDNESDAY. THURSDAY AND FRIDAY...WL CONTINUE WITH THE TREND OF
DRIER AND WARMER WITH A RIDGE PROGGED TO BUILD OVER THE WESTERN
U.S.

&&

.AVIATION...(FOR THE TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 319 AM MDT SAT AUG 23 2014


TRICKY FCST FOR THIS MORNING DUE TO POTENTIAL FOG AS TEMP-DEWPOINT
SPREADS ARE LOW AND WINDS ARE LIGHT.  HRRR HAS BEEN ALTERNATING
BETWEEN DENSE FOG AND NO DENSE FOG WITH EACH SUCCESSIVE RUN WHILE
THE RAP HAS SHOWN NOTHING THE ENTIRE TIME.  THE HRRR DOES SHOW SOME
TYPE OF WK CYCLONE DEVELOPING NR DIA WITH WINDS BECOMING LIGHT NNW
AROUND 12Z.  IF THIS HAPPENS THEN POTENTIAL FOR DENSE FOG WOULD
INCREASE IN THE 12Z-15Z TIME PERIOD.  DUE TO UNCERTAINTY OF FCST
WILL INTRODUCE A TEMPO GROUP FOR IFR CONDITIONS.

FOR THIS AFTN OUTFLOW BOUNDARIES FM MTN CONVECTON WILL PUSH ACROSS
BY 21Z WHICH MAY TRIGGER SCT TSTMS.  WITH DECENT MID LVL FLOW THE
STORMS WILL BE QUICK MOVING BUT COULD PRODUCE WIND GUSTS FM 40-50
MPH.  ALSO WITH UPPER LEVEL JET OVERHEAD THIS IS SOME POSSIBILITY
FOR STORM REGENERATION INTO THE EARLY EVENING HOURS THRU 02Z.  BY
MID EVENING THREAT OF STORMS SHOULD END.  WINDS WILL BE ESE BY
MIDDAY AND THEN SWITCH TO THE WNW BY 21Z AS INITIAL OUTFLOW
BOUNDARIES MOVE ACROSS.  BY EARLY EVENING WINDS WILL BE LIGHT NNW
AND THEN TRANSITION TO DRAINAGE BY 06Z.

&&

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

$$

SHORT TERM...RPK
LONG TERM...COOPER
AVIATION...RPK


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