Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 310958
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
358 AM MDT MON AUG 31 2015

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 358 AM MDT MON AUG 31 2015

EARLY MORNING SATELLITE IMAGERY SHOWS A WELL DEFINED PLUME OF
MOISTURE STRETCHING NORTH/NORTHEAST FROM THE DESERT SOUTHWEST
ACROSS MUCH OF WESTERN AND CENTRAL COLORADO INTO THE NORTHERN HIGH
PLAINS. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WERE
OCCURRING THROUGHOUT THIS MOISTURE PLUME. AT THE SURFACE...A
COLD FRONT WAS PUSHING SOUTHWARD ACROSS EASTERN WYOMING. A FEW
SHOWERS WERE ALREADY BEGINNING TO SPILL ACROSS THE FRONT RANGE AS
ANTICIPATED...AND THIS TREND SHOULD CONTINUE THIS MORNING WITH THE
PLUME SHIFTING SLOWLY EASTWARD. WEAK Q-G ASCENT ALONG WITH THE
FRONTAL PASSAGE BY MID MORNING SHOULD ALSO HELP GENERATE A FEW
SHOWERS. HOWEVER...THIS LIFT ARRIVES DURING THE TYPICALLY DIURNAL
MINIMUM OF SHOWER ACTIVITY AROUND MID/LATE MORNING. STILL FEEL
ENOUGH FACTORS ARE THERE TO MENTION SCATTERED SHOWERS WITH A BAND
WORKING SLOWLY EAST/SOUTHEAST ACROSS THE MOUNTAINS...I-25 URBAN
CORRIDOR AND ADJACENT PLAINS THROUGHOUT THE MORNING.

BY AFTERNOON...THE AIRMASS WILL DESTABILIZE WITH DAYTIME HEATING
AND SCATTERED TO NUMEROUS SHOWERS AND STORMS ARE EXPECTED TO
REDEVELOP OVER THE HIGHER TERRAIN. ON THE PLAINS...THE AIRMASS
WILL BE MORE STABLE DUE TO THE MORNING CLOUDS...SHOWERS...AND
FRONTAL PASSAGE...SO WILL HAVE TO RELY ON PASSING UPPER LEVEL
SPEED MAX TO OUR NORTH TO HELP PRECIPITATION CHANCES ON THE
PLAINS. WITH THE RIGHT REAR ENTRANCE REGION OF THE UPPER LEVEL JET
NEARBY...THINK THERE WOULD BE ENOUGH SUPPORT TO KEEP A CHANCE OF
STORMS IN THE FORECAST EVEN IN THE LOWER ELEVATIONS. ELEVATED
TERRAIN OF THE PALMER DIVIDE MAY ALSO HELP SO WILL HAVE HIGHEST
AFTERNOON/EVENING POPS THERE WITH DECREASING POPS FARTHER NORTH.

EXPECT A GRADUAL DECREASE OF SHOWERS AND STORMS BY MID TO LATE
EVENING AS UPPER LEVEL SPEED MAX EXITS THE REGION AND DRIER AIR
WORKS IN FROM THE WEST.

TEMPERATURES WILL BE COOLER TODAY WITH THE CLOUDS AND SCATTERED
SHOWERS...BUT STILL NEAR NORMAL LEVELS. FINALLY...THE FRONT MAY
BRING IN A LITTLE MORE SMOKE BUT SO FAR VISIBILITIES ARE NOT BEING
OBSCURED TO ANYTHING LESS THAN 10 MILES BEHIND THE FRONT...SO IF
WE DO SEE SMOKE SHOULD NOT BE AS SIGNIFICANT AS THE LAST COUPLE
FRONTS.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 358 AM MDT MON AUG 31 2015

SWLY FLOW ALOFT WILL REMAIN OVER THE AREA BOTH TUE AND WED.  SOME
SUBTROPICAL MOISTURE WILL LINGER AS WELL ON TUE SO WILL KEEP A
CHC OF TSTMS IN THE MTNS WITH ISOLD TO WDLY SCT TSTMS ELSEWHERE.
ON WED THE ECMWF SHOWS SOME DRYING OCCURRING WHILE THE GFS SHOWS
ANOTHER SURGE OF SUBTROPICAL MOISTURE AFFECTING THE AREA. AT THIS
TIME WILL LEAN TOWARDS THE ECMWF AND ONLY MENTION A SLIGHT CHC OF
STORMS OVER THE MTNS. AS FOR HIGHS READINGS WILL CONTINUE ABV
NORMAL BOTH DAYS WITH READINGS RISING BACK INTO THE LOWER TO MID
90S OVER NERN CO BY WED.

FOR THU AND FRI LITTLE CHANGE IS EXPECTED AS THE AREA WILL REMAIN
UNDER SW FLOW ALOFT.  SOME SUBTROPICAL MOISTURE WILL BE OVER THE
AREA ON THU SO WILL MENTION A SLIGHT CHC OF STORMS ACROSS PORTIONS
OF THE PLAINS AND IN THE MTNS.  BY FRI THERE MAY BE AN INCREASE IN
SUBTROPICAL MOISTURE WHICH COULD LEAD TO A BETTER CHC OF STORMS.
HIGHS ON THU WILL REMAIN IN THE LOWER TO MID 90S OVER NERN CO BUT
MAY DROP BACK INTO THE UPPER 80S TO LOWER 90S BY FRI.

BY SAT THE GFS SHOWS AN UPPER LEVEL TROUGH MOVING ACROSS THE NRN
ROCKIES WHILE THE ECMWF KEEPS THIS TROUGH OVER THE PACIFIC NW.
EITHER WAY THE FLOW ALOFT WILL CONTINUE SWLY WITH SOME POTENTIAL FOR
ADDITIONAL SUBTROPICAL MOISTURE EMBEDDED IN THE FLOW.  THIS WILL
KEEP IN A SLIGHT CHC OF STORMS ACROSS THE AREA.  850-700 MB TEMPS
DROP A FEW DEGREES ON SAT SO WILL KEEP HIGHS IN THE 80S OVER NERN
CO.

FOR SUN THE GFS HAS MAINLY WLY FLOW ALOFT ACROSS THE AREA WHILE THE
ECMWF SLOWLY MOVES THE UPPER LEVEL TROUGH FM THE PACIFIC NW INTO
THE NRN ROCKIES WITH SWLY FLOW ALOFT. MEANWHILE THERE ARE LARGE
DIFFERENCES IN THE SFC PTRN AS THE GFS HAS A DECENT COLD FNT
MOVING ACROSS NERN CO WITH HIGHS ONLY IN THE 70S WHILE AT THE
SAME TIME THE ECMWF KEEPS THIS FNT TO THE NORTH AS READINGS STAY
IN IN THE 80S. AT THIS POINT HARD TO SAY WHICH SOLUTION IS THE
BEST BUT WILL GO WITH CONSENSUS FCST AND HAVE HIGHS IN THE 75 TO
80 DEGREE RANGE. AS FOR PCPN IF THE FNT DOES BLAST THROUGH LIKE
THE GFS SHOWS THEN A RATHER STABLE AIRMASS WILL BE IN PLACE EAST
OF THE MTNS WHICH WOULD KEEP MOST TSTM ACTIVITY COMBINED TO THE
HIGHER TERRAIN.

&&

.AVIATION...(FOR THE TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 358 AM MDT MON AUG 31 2015

WEST/NORTHWEST WINDS WILL TURN NORTH/NORTHEASTERLY AT 10-15 KNOTS
BEHIND COLD FRONT EXPECTED TO ARRIVE AROUND 15Z. SCATTERED LIGHT
RAIN SHOWERS IN THE VICINITY AS WELL...WITH MAIN CHANCE OF RAIN
FROM AROUND 13Z-17Z...THEN A CHANCE OF THUNDERSTORMS 21Z-02Z. VFR
CONDITIONS SHOULD PERSIST HOWEVER...WITH ONLY INSTRUMENT
APPROACHES AND LOWER CEILINGS TO AROUND 6000 FEET IN/NEAR
SHOWERS AND STORMS. SMOKE MAY INCREASE A LITTLE BEHIND FRONT BUT
AT THIS TIME NOT EXPECTED TO IMPACT SLANT VISIBILITY AS MUCH AS
PREVIOUS TWO FRONTS THIS PAST WEEK.

&&

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

$$

SHORT TERM...BARJENBRUCH
LONG TERM...RPK
AVIATION...BARJENBRUCH


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