Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 302118
AFDBOU

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

.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 00Z THURSDAY LATE AFTERNOON)
ISSUED AT 237 PM MDT WED JUL 30 2014

SHOWERS MOVING BACK INTO DENVER WILL KEEP AREAS OF IFR CONDITIONS
THROUGH 02Z...THEN CONDITIONS WILL BE IMPROVING. INSTRUMENT
APPROACHES MAY STILL BE NEEDED AT KDEN FOR A COUPLE MORE HOURS. IT
APPEARS LIKELY THAT THERE WILL BE AREAS OF LOW CLOUDS AND FOG
LATER TONIGHT WITH A PERIOD OF IFR OR LIFR CONDITIONS IN THE
DENVER AREA. CONDITIONS WILL LIKELY IMPROVE WITH VFR PREVAILING
AROUND DENVER BY 17Z. ONLY ISOLATED THUNDERSTORMS ARE EXPECTED
THURSDAY AFTERNOON WITH LITTLE IMPACT TO KDEN TRAFFIC.

&&

.HYDROLOGY...
ISSUED AT 237 PM MDT WED JUL 30 2014

RAIN ON THE PLAINS WILL GRADUALLY DECREASE THROUGH EARLY EVENING
WHILE SCATTERED SHOWERS AND THUNDERSTORMS MOVE OFF THE MOUNTAINS.
RAINFALL AMOUNTS WILL GENERALLY BE LESS THAN A QUARTER
INCH...THOUGH A FEW STRONG STORMS COULD GIVE UP TO AN INCH OF RAIN
IN 30 MINUTES THROUGH EARLY EVENING. THESE ARE MOST LIKELY OVER
THE FRONT RANGE AND ON THE PLAINS SOUTH OF INTERSTATE 70.
REMAINING LIGHTER SHOWERS WILL DIMINISH THIS EVENING.

ON THURSDAY THERE WILL BE SCATTERED THUNDERSTORMS MAINLY OVER THE
MOUNTAINS. THERE IS STILL A THREAT OF HEAVY RAIN...BUT THE RISK OF
FLASH FLOODING IS LOW.

RUNOFF FROM THE RAIN OF THE LAST 24 HOURS WILL PUSH THE CACHE LA
POUDRE AND SOUTH PLATTE RIVERS TO NEAR BANKFULL AT GREELEY AND
KERSEY...MINOR FLOODING OF LOW LYING AREAS ADJACENT TO THE RIVERS
IS POSSIBLE.

ANOTHER WIDESPREAD PRECIPITATION EVENT MAY OCCUR TUESDAY INTO
WEDNESDAY NEXT WHICH COULD PRODUCE RAINFALLS SIMILAR TO THE
ONGOING EVENT. THIS COULD RESULT IN SOME FLOODING CONCERNS.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...FLASH FLOOD WATCH UNTIL 6 PM
MDT THIS EVENING FOR COZ033>043-045>047.

&&

$$

SHORT TERM...GIMMESTAD
LONG TERM...ET
AVIATION...GIMMESTAD
HYDROLOGY...GIMMESTAD/ET


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