Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 281603
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1003 AM MDT SUN SEP 28 2014

.UPDATE...
ISSUED AT 1002 AM MDT SUN SEP 28 2014

FORECAST ON TRACK WITH NUMEROUS SHOWERS/STORMS EXPECTED TO DEVELOP
IN THE HIGH COUNTRY THIS AFTERNOON WITH DEEP PLUME OF MOISTURE
SHIFTING SLOWLY EAST INTO THE FORECAST AREA. LATEST SHORT RANGE
MODELS IN AGREEMENT AS WELL. 12Z DENVER SOUNDING SHOWS A RATHER
DEEP STABLE LAYER ON THE PLAINS SO WILL DELAY THE STORM COVERAGE
ON THE PLAINS UNTIL LATER THIS AFTERNOON/EVENING. COULD STILL SEE
A MORE ORGANIZED LINE MOVING OFF THE FRONT RANGE IF WE DESTABILIZE
SUFFICIENTLY.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 323 AM MDT SUN SEP 28 2014

UPPER LEVEL LOW WILL SLOWLY MOVE ACROSS NEVADA TODAY AND INTO
COLORADO TONIGHT. SOUTHERLY FLOW ALOFT WILL INCREASE AND BECOME
SOUTHWESTERLY OVERNIGHT. QG ASCENT AND A DIFFLUENT FLOW ALOFT WILL
PRODUCE LIFT OVER NORTH CENTRAL COLORADO THIS AFTERNOON AND TONIGHT.
MOST OF THE SHOWERS AND THUNDERSTORMS CURRENTLY RESIDE OVER UTAH AND
FAR WESTERN COLORADO. SOME DRIER HAS MOVED INTO NORTH CENTRAL
COLORADO BRINGING THE CONVECTION TO AN END. THERE WILL BE PARTLY
CLOUDY SKIES THIS MORNING OVER THE MOUNTAINS DUE TO THE BRIEF
DRYING. BY AFTERNOON...LIFT AND INSTABILITY WILL INCREASE. CAPES
WILL BE 500-1000 J/KG. EXPECT SHOWERS AND STORMS TO FORM OVER NORTH
CENTRAL COLORADO THIS AFTERNOON AND LIFT NORTH-NORTHEAST THROUGH
EARLY EVENING. WILL HAVE LIKELY POPS IN THE FORECAST FOR THIS OVER
NORTH CENTRAL COLORADO. GOOD SHEAR COULD EVEN PRODUCE A FEW STRONG
TO SEVERE STORMS OVER THE HIGHER TERRAIN.

OVER NORTHEAST COLORADO...A SURFACE LOW/DENVER CYCLONE WILL BE
CENTERED NEAR DENVER TODAY. WINDS ARE ALREADY TURNING NORTH ALONG
NORTHERN PARTS OF THE FRONT RANGE. THIS WILL BRING COOLER AIR INTO
THE FRONT RANGE. CLOUDS WILL INCREASE THROUGH THE DAY. BIGGEST
QUESTION IS HOW FAR EAST WILL CONVECTION MAKE IT THIS EVENING. BEST
CHANCES WILL BE TO THE NORTH...MAINLY ALONG AND NORTH OF INTERSTATE
76.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 323 AM MDT SUN SEP 28 2014

AN UPPER LEVEL LOW OVER THE GREAT BASIN WILL EJECT ENE ACROSS THE
AREA MON AFTN INTO MON EVENING AND BE CENTERED OVER SERN WY BY LATE
MON NIGHT. FAVORABLE DIFFLUENT FLOW ALOFT COMBINED WITH DECENT
MID LVL QG ASCENT SHOULD LEAD TO A GOOD CHC OF SHOWERS/TSTMS MON
AFTN INTO MON EVENING OVER THE HIGHER TERRAIN WITH WIDESPREAD
ACTIVITY OVER THE NERN PLAINS. THERE IS CERTAINLY SOME POTENTIAL
FOR SVR STORMS OVER NERN CO MON AFTN INTO EARLY MON EVENING.
BELIEVE THE HI RES WRF HAS THE BEST HANDLE ON SFC PTRNS WITH A SFC
LOW SPINNING UP NR DENVER BY EARLY AFTN WITH A LOW LVL BNDRY
EXTENDING ENE TOWARDS AKRON. DEEPER LOW LVL MOISTURE WILL LIKELY
POOL ALONG AND NORTH OF THIS BNDRY WITH CAPES POSSIBLY IN THE
1000- 1500 J/KG RANGE NORTH OF A LINE FROM DENVER TO AKRON IF
HIGHS REACH THE MID 70S. CIPS ANALOG GUIDANCE SHOWS THIS TYPE OF
PTRN HAS PRODUCED SVR WX OVER NERN CO BEFORE SO COULD BE A RATHER
ACTIVE FM MID AFTN INTO THE EARLY EVENING HOURS. ALTHOUGH STORMS
WILL BE RATHER FAST MOVING MAY ALSO SEE SOME HEAVY RAINS OVER
PORTIONS OF THE NERN PLAINS IF STORMS TRAIN OVER THE SAME AREAS.

BY TUE THE UPPER LEVEL TROUGH WILL MOVE QUICKLY ENE AWAY FM THE AREA
WITH WNW FLOW ALOFT AS MID LVL DESCENT OCCURS THRU THE AFTN HOURS.
CROSS-SECTIONS STILL SHOW SOME MOISTURE IN THE MTNS THRU THE DAY
ALONG WITH FAVORABLE OROGAPHIC COMPONENT SO MAY SEE SOME LINGERING
SHOWERS THRU THE DAY ALONG WITH A FEW AFTN TSTMS DUE TO DECENT LAPSE
RATES.  OVER THE PLAINS WILL KEEP FCST DRY THRU THE AFTN HOURS
EXCEPT FOR A SLIGHT CHC OF EARLY MORNING SHOWERS OVER THE FAR NERN
CORNER.  AS FOR HIGHS WILL KEEP READINGS MAINLY IN THE LOWER 70S
OVER NERN CO. FOR TUE NIGHT THERE WILL CONTINUE TO BE A FLOW OF
MOISTURE IN THE MTNS IN WLY FLOW ALOFT SO THERE WILL STILL BE THE
POTENTIAL FOR OROGRAPHIC SHOWERS WITH SNOW ABV 10000 FEET. THE
ECMWF SHOWS SOME MINOR MID LVL QG ASCENT AS WELL WHICH COULD
ENHANCE ACTIVITY AS WELL.

BY WED ANOTHER UPPER LEVEL TROUGH WILL MOVE INTO THE AREA FM THE NW
WITH A COOL FNT MOVING ACROSS LATE IN THE AFTN OR BY EARLY EVENING.
BOTH THE ECMWF AND GFS SHOW ANOTHER SHOT OF MID LVL ASCENT WITH THIS
FEATURE ALONG WITH DECENT LAPSE RATES.  THE ECMWF IS ROUGHLY 6 HOURS
FASTER WITH THIS SYSTEM VS THE GFS. AS A RESULT THE ECMWF HAS AN
INCREASING CHC OF PCPN BY WED AFTN THROUGH EARLY WED EVENING WHILE
THE GFS KEEPS THE BEST CHC OF PCPN MAINLY WED NIGHT.  FOR NOW WILL
TREND TOWARD FASTER ECMWF SOLUTION.  HIGHER MTNS COULD SEE SOME
ADVISORY LEVEL SNOW AMOUNTS LATE WITH THIS SYSTEM.  AS FOR TEMPS
WILL KEEP HIGHS MAINLY IN THE MID TO UPPER 60S OVER NERN CO.

FOR THU THE UPPER LEVEL TROUGH WILL MOVE EAST OF THE AREA WITH DRIER
AIR SPREADING ACROSS SO PRECIP CHANCES SHOULD END.  HIGHS OVER NERN
CO WILL REMAIN IN THE 60S.  ON FRI DRY NWLY FLOW ALOFT WILL BE OVER
THE AREA AS ANOTHER COOL FNT MOVES ACROSS THE PLAINS. SO FAR NOT
MUCH MOISTURE IS SHOWN WITH THIS FNT SO WILL KEEP FCST DRY WITH
HIGHS IN THE LOWER TO MID 60S OVER NERN CO. BY SAT THE FLOW ALOFT
WILL CONTINUE NWLY WITH LITTLE MOISTURE SHOWN SO WILL KEEP A DRY
FCST IN PLACE WITH TEMPS RISING BACK TO NR NORMAL LEVELS.

&&

.AVIATION...(FOR THE TAFS THROUGH 18Z MONDAY MORNING)
ISSUED AT 1002 AM MDT SUN SEP 28 2014

MAIN CHANCE OF STORMS FOR THE FRONT RANGE AIRPORTS WILL BE AFTER
22Z-00Z AND THEN THROUGH ABOUT 03Z. MAY NEED TO GO TEMPO
THUNDER FOR PART OF THAT PERIOD DEPENDING ON AMOUNT OF DAYTIME
HEATING AND DESTABILIZATION. STORMS WILL BE MOVING NORTH/NORTHEAST
AHEAD OF TROUGH WITH GUSTY OUTFLOW WINDS TO 35-40 KTS POSSIBLE AS
MID LEVEL WINDS INCREASE. OTHERWISE VISUAL LANDING CONDITIONS WILL
PERSIST OUTSIDE OF STORMS. NORTH WINDS EXPECTED TO TURN MORE
EASTERLY IN THE AFTERNOON...THEN TOWARD WEAK DRAINAGE AFTER STORMS
PASS THIS EVENING.

&&

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

$$

UPDATE...BARJENBRUCH
SHORT TERM...MEIER
LONG TERM...RPK
AVIATION...BARJENBRUCH


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