Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 211531
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
931 AM MDT TUE APR 21 2015

.UPDATE...
ISSUED AT 930 AM MDT TUE APR 21 2015

FEW CHANGES NECESSSARY TO FORECAST GRIDS AT THIS TIME. ONLY
MADE MINOR ADJUSTMENTS TO SKY COVER...TEMP AND WIND GRIDS IN 1ST
AND 2ND PERIODS. NOTE ADDITIONAL COMMENTS ON THE CHANGE IN WIND
DIRECTION IN THE DENVER METRO AREA TODAY AND THE POSSIBILITY OF
GUSTY WINDS ASSOCIATED WITH ISOLATED MOSTLY DRY SHOWERS MOVING OFF
THE FOOTHILLS LATE THIS AFTERNOON.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 210 AM MDT TUE APR 21 2015

NW FLOW ALOFT WILL BE OVER THE RGN THRU TONIGHT.  A WEAK DISTURBANCE
EMBEDDED IN THE FLOW MAY MOVE ACROSS NRN CO LATE THIS AFTN INTO THE
EARLY EVENING HOURS.  THERE WILL BE ENOUGH MOISTURE COMBINED WITH
DECENT LAPSE RATES FOR SCT SHOWERS AND ISOLD STORMS OVER THE
HIGHER TERRAIN THIS AFTN WITH WDLY SCT ACTIVITY ALONG THE FRONT
RANGE MAINLY THIS EVENING. AS FOR HIGHS 850-700 MB TEMPS WOULD
SUPPORT HIGHS IN THE 60S ACROSS NERN CO THIS AFTN. FOR TONIGHT
PRECIP CHANCES SHOULD DECREASE BY MID TO LATE EVENING AS THE
DISTURBANCE EXITS NE COLORADO.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 210 AM MDT TUE APR 21 2015

THE MDLS APPEAR TO BE FAIRLY SIMILAR WITH THE TIMING OF
THE OVERALL PATTERN FROM WEDNESDAY INTO THE WEEKEND.  ON WEDNESDAY A
WEAK UPPER LEVEL RIDGE AXIS WILL MOVE ACROSS COLORADO.  THE FLOW
ALOFT WILL BE FAIRLY WEAK...TRANSITIONING FROM NORTHWEST/WESTERLY
THROUGH THE DAY AS WEAK UPPER LEVEL RIDGE AXIS SHIFTS FM UTAH INTO
WESTERN COLORADO.  SOME MID LEVEL MOISTURE DOES MOVE OVER WESTERN CO
THROUGH THE DAY.  IN ADDITION...SOME LOW LEVEL CONVERGENCE ALONG THE
FRONT RANGE WITH SFC EAST TO SOUTHEASTERLY WINDS IN THE AFTN WHICH
WOULD INDUCE A DENVER CYCLONE. STRONGEST SHEAR WOULD BE IN THE LOW
LEVELS...WITH THE WEAKER FLOW ALOFT.  NAM12 FORECAST CAPES AROUND
900 J/KG BY LATE IN THE AFTN. STABILITY OF THE AIRMASS INCREASES
FURTHER EAST.  ON THURSDAY...THE FLOW ALOFT WEAK AND SWLY AS THE
RIDGE AXIS TRANSLATE EASTWARD.  THERE WILL BE A SURFACE TROF OVER
EASTERN COLORADO.  THE LOWER LEVELS WILL BE DRIER BUT ENOUGH MID
LEVEL MOISTURE AROUND TO GO WITH MORE AFTN/EVNG TSTMS.  CAPES IN
DENVER AROUND 500 J/KG IN THE AFTN.  THURSDAY NIGHT...THE MDLS
BRINGS THE UPPER TROUGH OVER BAJA CA INTO ARIZONA BY 12Z FRIDAY...
THEN ACROSS SOUTHERN AND EASTERN COLORADO FRIDAY AFTN AND FRIDAY
NIGHT.  MODERATE MID AND UPPER LEVEL QG ASCENT WITH THIS SYSTEM OVER
THE SOUTHERN PART OF THE CWA WITH SOME EMBEDDED TSTMS WITH ITS
PASSAGE FRIDAY AFTN/EVNG.  THE WEEKEND WILL REMAIN UNSETTLED...THE
MDLS BRING A SECONDARY TROUGH ACROSS NORTHERN COLORADO LATE SATURDAY
INTO SUNDAY FOR ANOTHER ROUND OF SHOWERS/PSBL TSTMS. THE AIRMASS
DOES NOT APPEAR TO DRY OUT UNTIL EARLY NEXT WEEK...WHEN A STRONGER
UPPER LEVEL RIDGE ESTABLISHES ITSELF OVER THE CENTRAL
ROCKIES...MONDAY INTO TUESDAY.

&&

.AVIATION...(FOR THE TAFS THROUGH 18Z WEDNESDAY MORNING)
ISSUED AT 930 AM MDT TUE APR 21 2015

MAIN ADJUSTMENT TO DENVER AREA TERMINAL FORECASTS INVOLVED ADDING A
TEMPO GROUP FOR GUSTY WINDS WITH MOSTLY DRY SHOWERS MOVING OFF
THE FRONT RANGE LATE THIS AFTERNOON. POSSIBLE GUSTS IN THE 15-25
KT RANGE. OTHERWISE COUNT ON A GRADUAL CLOCKWISE SHIFT IN AREA WINDS
FROM S-SWLY TO WLY TO N-WLY WINDS BY EARLY AFTERNOON...THEN E-NELY
WINDS LATER IN THE AFTERNOON...AND THEN BACK TO A S-SWLY WIND
WITH NIGHTFALL. PREVAILING SPEEDS GENERALLY UNDER 12 KTS. BUT
KEEP IN MIND...MAY SEE LOCALIZED GUSTS WITH PASSING MOSTLY DRY
SHOWERS AFTER 21Z OR SO.

&&

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

$$

UPDATE...BAKER
SHORT TERM...RPK
LONG TERM...COOPER
AVIATION...BAKER


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