Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 310231 CCA
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
750 PM MDT WED JUL 30 2014

.UPDATE...
ISSUED AT 726 PM MDT WED JUL 30 2014

THE LARGE PRECIPITATION SHIELD IN EASTERN COLORADO HAS STEADILY
ERODED THIS AFTERNOON...AND IS NEARLY GONE. WESTERLY FLOW HAS BEEN
MARCHING SHOWERS AND A VERY FEW THUNDERSTORMS ACROSS THE MOUNTAINS
AND ACROSS THE URBAN CORRIDOR WITH THE BIGGEST PUSH MOVING INTO
THE PALMER DIVIDE. WE DID ALLOW THE WATCH TO EXPIRE AT 6PM THIS
EVNING...AND RAINFALL RATES HAVE BEEN UP TO A HALF INCH AN
HOUR...WITH NO STATIONARY STORMS THIS EVENING. EXPECT THE ACTIVITY
TO CONTINUE THIS EVENING...THEN GRADUALLY DISSIPATE OVERNIGHT. WE
EXPECT SOME CLEARING...AND AREAS OF FOG TO DEVELOP AND PERSIST
INTO THE EARLY HOURS OF SUNLIGHT ON THURSDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 237 PM MDT WED JUL 30 2014

LARGE AREA OF RAIN IS FINALLY SLIDING SLOWLY SOUTHEAST. NOT MUCH
SIGN OF WEAKENING JUST YET...BUT DRIER AIR IS STARTING TO UNDERCUT
IT AND STILL EXPECTING IT TO SLOWLY DISSIPATE OVER THE NEXT
SEVERAL HOURS. MEANWHILE SOME WEAK CONVECTION HAS DEVELOPED AROUND
THE EDGES...MAINLY OVER THE MOUNTAINS. THESE SHOWERS WILL BE
COMING OVER THE DENVER AREA THROUGH THE EARLY EVENING. THE SHOWERS
WILL BE MOVING...BUT STILL A PRODUCTIVE ENVIRONMENT. FOR THE MOST
PART EXPECT THAT HEAVY RAINFALL WILL BE BRIEF...A QUICK QUARTER
INCH...BUT TRAINING OR GREATER INTENSITY STILL ENOUGH OF A THREAT
TO HOLD ONTO THE REMAINING PART OF THE FLASH FLOOD WATCH UNTIL IT
EXPIRES AT 6 PM.

ONLY MINOR CHANGES TO THE FORECAST...MAINLY SLOWING DOWN THE
DEPARTING RAIN BY A COUPLE OF HOURS. IF SKIES CLEAR WE HAVE A
PRETTY GOOD CHANCE OF GETTING FOG IN THE MORNING. MODELS SHOW THE
MID LEVEL CLOUDS HANGING AROUND ALL NIGHT BUT THERE ARE ALREADY
SIGNS OF CLEARING AND MUCH OF WHAT IS UPSTREAM IS FROM THE NEW
CONVECTION. THIS WILL LIKELY BE SLOW TO CLEAR...BUT I SUSPECT BY
THE EARLY MORNING HOURS IT WILL BE DISSIPATING. WENT AHEAD AND
ADDED AREAS OF FOG ACROSS THE PLAINS AND IN THE MOUNTAIN
VALLEYS...IT MAY WIND UP BEING FAIRLY WIDESPREAD.

FOR THURSDAY THE AIR ALOFT WILL BE DRYING AND WARMING...AND WITH
SOME MORNING CLOUD COVER THE LOW LEVELS WILL LAG BEHIND.
STILL A FAIRLY MOIST SURFACE SO WE SHOULD GET SOME
CONVECTION...BUT IT MAY NOT HAPPEN ON THE PLAINS UNTIL LATE. STILL
SOME HEAVY RAIN THREAT WITH HIGH SURFACE MOISTURE...BUT CAPES
LIMITED AND STORMS MOVING SO FLASH FLOOD THREAT LOOKS SMALL.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 237 PM MDT WED JUL 30 2014

NORTHWEST FLOW ALOFT WILL BE OVER THE STATE THURSDAY NIGHT WITH
SOME RESPECTABLE QG SUBSIDENCE OVER THE FAR NORTHEAST PLAINS
DURING THE EVENING. THIS SHOULD KEEP EVENING CONVECTION CONFINED
TO THE HIGHER TERRAIN AND NEARBY ENVIRONS.

UPPER LEVEL RIDGING WILL BE THE RULE FRIDAY THROUGH SUNDAY WITH
ENOUGH MOISTURE AROUND FOR DIURNAL CONVECTIVE ACTIVITY EACH DAY.
MOST OF THIS WILL BE TERRAIN DRIVEN.  PRECIPITABLE WATER VALUES
ARE SUFFICIENTLY HIGH AND WITH ONLY MODEST INSTABILITY HEAVY RAINS
WILL BE THE MAIN THREAT WITH THE CONVECTIVE ACTIVITY.

EARLY NEXT WEEK COULD PROVE INTERESTING AS THE MODELS ARE
ADVERTISING THE PASSAGE OF A RATHER SUBSTANTIAL UPPER TROUGH
ACROSS THE STATE. THERE IS SOME QG LIFT ASSOCIATED WITH THIS
SYSTEM WHICH WILL HELP BRING ANOTHER POSSIBILITY OF A WIDESPREAD
NON-DIURNAL PRECIPITATION EVENT TUESDAY INTO WEDNESDAY.

TEMPERATURES SHOULD REMAIN AT OR BELOW NORMAL THROUGH PERIOD WITH
MAXIMA IN THE 50S AND 60S IN THE MOUNTAINS AND SUB-90 DEGREE
READINGS ON THE PLAINS.

&&

.AVIATION...(FOR THE TAFS THROUGH 06Z THURSDAY EVENING)
ISSUED AT 726 PM MDT WED JUL 30 2014

IT HAS BEEN A CHALLENGING EVENING FOR TAFS...WITH SHOWERS MOVING
ACROSS AND VISIBILITIES GOING FROM 10 TO 2 AND BACK TO 10 AT DIA.
THIS VARIABILITY TO CONTINUE THIS EVENING AS SHOWERS CONTINUE TO
MOVE OFF THE MOUNTAINS AND INTO THE METRO AREA. SHOWERS WILL
SLOWLY DECREASE AND END AFTER MIDNIGHT...WITH AREAS OF FOG
DEVELOPING AFTER MIDNIGHT...FINALLY ERODING A COUPLE OF HOURS AFTER
SUNRISE THURSDAY. MORE THUNDERSTORMS WILL SKIRT THE METRO AREA IN
THE EARLY AFTERNOON WITH MVFR CONDITIONS POSSIBLE BY MID TO LATER
AFTERNOON.

&&

.HYDROLOGY...
ISSUED AT 726 PM MDT WED JUL 30 2014

SHOWERS AND A FEW THUNDERSTORMS WILL CONTINUE TO MOVE ACROSS THE
MOUNTAINS...AND INTO THE URBAN CORRIDOR AND PALMER DIVIDE THIS
EVENING. RAINFALL RATES UP TO A HALF INCH AN HOUR WILL BE
POSSIBLE...BUT STORMS ARE MOVING SO FLOOD THREAT THOUGH TONIGHT IS
LOW. DRYER AIR MOVING INTO NORTHEAST COLORADO HAS STEADILY ERODED
THE PERSISTENT RAIN THAT SAT ON THE PLAINS EARLIER TODAY. TOMORROW
WE WILL SEE THUNDERSTORMS OVER THE HIGHER TERRAIN AND EXTENDING
INTO THE URBAN CORRIDOR...BUT MUCH OF THE NORTHEAST PLAINS WILL BE
DRY.

&&

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

$$

UPDATE...RTG
SHORT TERM...GIMMESTAD
LONG TERM...ET
AVIATION...RTG
HYDROLOGY...RTG


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