Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 201634
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1034 AM MDT SAT SEP 20 2014

.UPDATE...
ISSUED AT 1007 AM MDT SAT SEP 20 2014

NO CHANGES TO THE CURRENT FORECAST. OVERALL...GENERALLY DRY AND
STABLE TODAY. ONLY EXCEPTION WILL OCCUR IN THE MOUNTAINS WEST AND
SOUTHWEST OF DENVER...AFTER 20Z. THIS ALREADY HANDLED SO WL LEAVE
THINGS AS IS.
&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 435 AM MDT SAT SEP 20 2014

DRIER AIR IS MOVING OVER NORTHERN COLORADO BEHIND LAST NIGHTS
SHORTWAVE. AT THE SURFACE A WEAK COLD FRONT...ACTUALLY SPREAD OVER
TWO WIND SHIFTS...WILL DROP SOUTH ACROSS OUR AREA THIS MORNING
BRINGING SOME COOLING AT THE SURFACE. WITH WARM DRY AIR
ALOFT...AROUND -7C AT 500 MB...THERE WILL NOT BE MUCH INSTABILITY
TO WORK WITH TODAY. FURTHERMORE THERE IS SOME SUBSIDENCE BEHIND
THE TROUGH...THOUGH THIS WILL BE FADING THIS AFTERNOON. EXPECT
NEARLY CLEAR SKIES THIS MORNING AND THEN SOME WEAK CONVECTION OVER
THE MOUNTAINS. MODELS HAVE A THEME OF DEVELOPING A BATCH OF
THUNDERSTORMS OVER THE SUMMIT COUNTY MOUNTAINS AND THEN MOVING
THEM EAST AND SOUTHEAST THROUGH EARLY EVENING TOWARD THE PALMER
DIVIDE REGION. THIS AREA WILL HAVE BETTER DEEP MOISTURE AND A
TREND TOWARD SOUTHERLY WINDS AT LOW LEVELS IN THE MOUNTAINS WOULD
ALSO PRODUCE CONVECTION THERE...SO TRENDED THE FORECAST A BIT MORE
TOWARD THIS IDEA WITH LESS CLOUDS AND POPS FURTHER NORTHEAST.

TONIGHT THERE WILL BE WEAK LIFT AND MOISTURE CONVERGENCE AT LOW-
MID LEVELS AS THE LOW LEVEL WINDS TURN MORE E-SE AND THE RIDGE
AXIS SLIDES EASTWARD. USEFUL CIRA SIMULATED CLOUD IMAGERY SHOWS A
DECK OF LOW-MID LEVEL CLOUDS DEVELOPING OVER THE PLAINS DURING THE
NIGHT...COULD HAVE SOME WEAK SHOWERS BUT NOT LOOKING LIKE AMOUNTS
SHOULD BE MUCH. MEANWHILE SOME HIGHER CLOUDS OVER THE MOUNTAINS
MORE ASSOCIATED WITH THE APPROACHING TROUGH COULD ALSO PRODUCE
SOME WEAK SHOWERS. I LOWERED TEMPERATURES A LITTLE TONIGHT
EXPECTING LESS CLOUD COVER IN THE EVENING AND A BIT STRONGER COLD
ADVECTION IN THE MODELS.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 435 AM MDT SAT SEP 20 2014

THERE IS AN UPPER RIDGE AXIS RIGHT OVER THE CWA ON SUNDAY. IT
MOVES EASTWARD SUNDAY NIGHT...WITH A WEAK UPPER TROUGH TO PUSH
EASTWARD ACROSS COLORADO MONDAY AND MONDAY NIGHT. THE UPPER TROUGH
AXIS IS OVER THE EASTERN COLORADO BORDER AT 12Z TUESDAY MORNING.
THE FLOW ALOFT IS BASICALLY ZONAL THROUGH MUCH OF THE PERIOD...
NORTHWESTERLY BY TUESDAY MORNING. WEAK UPWARD QG VERTICAL
VELOCITY IS EXPECTED OVER THE CWA SUNDAY THROUGH MUCH OF MONDAY
NIGHT. THE BOUNDARY LAYER FLOW IS PROGGED TO BE SOUTHEASTERLY ON
SUNDAY...WITH NORMAL DIURNAL TRENDS ON MONDAY. MOISTURE IS QUITE
PREVALENT SUNDAY THROUGH MONDAY NIGHT ON MANY MODELS.
PRECIPITABLE WATER VALUES ARE PROGGED IN THE 0.60 TO 1.30 INCH
RANGE SUNDAY INTO MONDAY EVENING...THEN THEY DECREASE. THE
BOUNDARY LAYER DEW POINTS ARE IN THE 45 TO 60 F RANGE ACROSS THE
CWA THROUGH THE FOUR PERIODS. THERE IS LIMITED CAPE PROGGED FOR
THE WESTERN TWO-THIRDS OF THE CWA LATE DAY SUNDAY. THERE IS BETTER
CAPE FOR LATE DAY MONDAY...WITH THE BEST VALUES OVER THE PLAINS.
THE QPF FIELDS SHOW MEASURABLE RAINFALL OVER THE WESTERN HALF OF
THE CWA ON SUNDAY. SUNDAY NIGHT THERE IS MEASURABLE OVER ALL THE
CWA. THERE ARE PRETTY DECENT AMOUNTS PROGGED FOR MOST OF THE CWA
MONDAY AND MONDAY EVENING. WILL GO WITH PRETTY GOOD POPS SUNDAY
THROUGH MONDAY EVENING...30-60%S. FOR TEMPERATURES...SUNDAY`S
HIGHS ARE 2-4 C COOLER THAN TODAY...COOLER ON THE NAM. MONDAY`S
HIGHS ARE 0-2 C WARMER THAN SUNDAY`S. FOR THE LATER DAYS...TUESDAY
THROUGH FRIDAY...MODELS HAVE AN UPPER RIDGE MOVE IN AND IT STICKS
AROUND ALL FOUR DAYS. MOISTURE IS SPARSE. TEMPERATURES WILL
CERTAINLY WARM UP AND BE A BIT ABOVE SEASONAL NORMALS.

&&

.AVIATION...(FOR THE TAFS THROUGH 18Z SUNDAY MORNING)
ISSUED AT 1007 AM MDT SAT SEP 20 2014

VFR THROUGH THIS EVENING. SCT STORMS OVER THE MOUNTAINS MAINLY
WEST AND SOUTHWEST OF DENVER AFTER 20Z...A WEAK STORM COULD SLIP
INTO THE DENVER AREA 23Z-02Z. AFTER 06Z TONIGHT...BKN CIGS
(050-060 KFT AGL) DEVELOP THAT WILL LIKELY REQUIRE ILS APPROACHES
TO KDEN SUNDAY MORNING DUE TO SCT LIGHT SHOWERS.

&&

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

$$

UPDATE...COOPER
SHORT TERM...GIMMESTAD
LONG TERM...RJK
AVIATION...COOPER



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