Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 230323
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
923 PM MDT FRI AUG 22 2014

.UPDATE...
ISSUED AT 729 PM MDT FRI AUG 22 2014

A LARGE BATCH OF THUNDERSTORMS CONTINUE MOVING NORTH ACROSS
NORTHEAST COLORADO THIS EVENING...LOCAL RAINFALL RATES HAVE
BEEN AS HIGH AS AN INCH AN A QUARTER PER HOUR...ONE SPOTTER IN
SOUTHEAST ELBERT COUNTY RECORED 2.2 INCHES IN THE STORMS...MOST
AREAS SAW CLOSER TO AN INCH. GOOD STORM MOTIONS HAVE HELPED.

CONVECTION HAS ALL TURNED TO RAIN WITH A NEAR ZERO THREAT OF ANY
MORE SEVERE WEATHER. I AM ENDING THE WATCH IN OUR REMAINING
COUNTIES. I WILL UPDATE ZONES AGAIN.  WILL KEEP ISOLATED TO
SCATTERED RAIN IN MOUNTAINS...FOOTHILLS AND URBAN COORIDOR...THERE
ARE A FEW SHOWERS MOVING OFF THE FOOTHILLS THIS EVENING...WITH
MORE OVER THE MOUNTAINS.

AFTER ALL THIS RAIN...COOLING TONIGHT MAY RESULT IN SOME AREAS OF
FOG...ESPECIALLY ALONG THE SOUTH PLATTE. WILL ADD PATCHY FOG ON
THE PLAINS.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 336 PM MDT FRI AUG 22 2014

SHORTWAVE MOVING INTO WESTERN COLORADO NOW WITH A LARGE SHIELD OF
RAIN SHOWERS OVER THE MOUNTAINS. MORE STABLE AIR IN THE LARGE RAIN
SHIELD HAS LIMITED LIGHTNING THERE...WITH STRONGER CONVECTION
AROUND THE EDGES. ON THE PLAINS WE WOUND UP WITH A HYBRID OF THE
LEADING EDGE OF THE LIFT AND THE EAST/WEST CONVERGENCE ZONE.
SURFACE WINDS ARE NORTHEAST AT 10-15 KNOTS FEEDING INTO THIS
DEVELOPING RAINBAND. ANOTHER EAST/WEST BAND HAS DEVELOPED NEAR THE
SOUTHERN COLORADO BORDER AND WILL ALSO COME NORTH THIS EVENING
AHEAD OF THE MAIN RAIN AREA. THERE HAS BEEN SOME SEVERE WEATHER ON
THE EAST END OF THE CONVECTION IN KIT CARSON AND CHEYENNE
COUNTIES...THREAT SHOULD BE LOWER FURTHER WEST BUT STILL ENOUGH
ENERGY FOR SOME THREAT IN OUR EASTERN TIER OF COUNTIES. AS FOR THE
HEAVY RAIN THREAT...EVERYTHING SEEMS TO BE MOVING. SOME HEAVY RAIN
BUT BACKBUILDING/TRAINING POTENTIAL APPEARS LIMITED.

SLOWED DOWN THE CLEARING IN THE MIDDAY UPDATE AND WILL STICK WITH
THE EXISTING FORECAST. IT WILL TAKE HALF THE NIGHT FOR THE MAIN
AREA OF RAIN TO GET PAST DENVER...AND THERE WILL LIKELY STILL BE
SOME WEAKER CONVECTION BEHIND THAT...SO THREAT OF MORNING FOG IS
LOOKING LOW. IF IT DID CLEAR OUT NICELY THAN THERE COULD BE SOME
DENSE FOG.

ON SATURDAY THERE WILL BE DRYING AND WARMING ALOFT AND IT LOOKS
LIKE CONVECTION WILL BE FAIRLY WELL CAPPED. STILL EXPECTING SOME
ISOLATED SHOWERS AND STORMS...MOST LIKELY OVER THE NORTHERN
MOUNTAINS WHERE TEMPERATURES ALOFT WILL BE SLIGHTLY COOLER AND
THERE MAY BE A LITTLE LIFT FROM THE WAVE PASSING NORTH OF US.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 336 PM MDT FRI AUG 22 2014

A DEEPENING UPPER LEVEL TROUGH OVER THE PACIFIC NORTHWEST IS
EXPECTED TO SLIGHTLY INCREASE THE CHANCE OF SHOWERS AND T-STORMS
ACROSS THE FCST AREA SATURDAY NIGHT INTO SUNDAY. ON SUNDAY...MODELS
SHOW THE TROUGH CLOSING OFF OVER THE NORTHERN ROCKIES AND A WEAK
COLD FRONT SLIPPING SOUTH INTO NERN COLORADO EARLY SUNDAY
MORNING. 700-500MB SPEC HUMDITIES GRADUALLY RISE TO AROUND 6G/KG
IN NERN COLORADO DURING THE DAY SUNDAY. NAM AND GFS SHOW POST-
FRONTAL E-SELY BNDRY LAYER LAYER DEVELOPING DURING THE DAY. GFS
GENERATES AN AREA OF LIGHT QPF OVER AND ALONG THE FRONT RANGE AND
CHEYENNE RIDGE DURING THE AFTERNOON. EUROPEAN AND CANADIAN MODELS
ARE LESS OPTIMISTIC ABOUT OUR RAIN CHANCES ON SUNDAY. ALL INDICATE
SWLY STEERING WINDS OF 20-30KTS. SO ANY STORMS SHOULD MOVE AT A
FAIRLY GOOD CLIP. BEST SHEAR AND LOW-LEVEL MOISTURE CONVERGENCE IS
PROGGED TO MOVE AWAY FROM THE NRN FRONT RANGE AND OVER THE NERN
CORNER OF THE CWA SUNDAY EVENING.

ON MONDAY...THIS SAME SOUTHWEST FLOW ALOFT APPEARS TO DRY SLOT
THE FCST AREA IN THE MORNING. ALTHOUGH LATER IN THE DAY...A SECOND
WAVE OF ANOMALOUSLY LOW HEIGHTS ASSOCIATED WITH SIGNIFICANT
COOLING ALOFT SWINGS SOUTHWARD OUT OF THE PACIFIC NORTHWEST. JET
SHEAR INDUCED LIFT ON THE SOUTHEAST SIDE OF THIS TROUGH WILL
COMBINE WITH POST-FRONTAL LOW- LEVEL UPSLOPE FLOW ON THE PLAINS
RESULTING IN ANOTHER SHOT OF PRECIP. HOWEVER...MONDAY PRECIPITABLE
WATER AND SPECIFIC HUMIDITY VALUES LOWER THAN CURRENT VALUES. SO
PRECIP AMOUNTS MONDAY AFTERNOON AND NIGHT FROM ISOLATED TO
SCATTERED STORM COVERAGE NOT EXPECTED TO BE SIGNIFICANT.

GFS SHOWS THE UPPER TROUGH AXIS AND MAIN COLD POOL ALOFT PASSING
OVER THE FCST AREA DURING THE DAY TUESDAY. WHILE THE 12Z ECMWF AND
CANADIAN GEM SHOW THIS UPPER TROUGH AND COLD AIR ALOFT PASSING
OVERHEAD WEDNESDAY MORNING. THAT SET...ALL THREE MODELS SHOW
COOLER TEMPERATURES AND A CONTINUED CHANCE OF SHOWERS/T-STORMS ON
TUESDAY...GENERALLY EAST OF THE MTNS. BY MID-WEEK...MOISTURE AND
COOL AIR FLUSH OUT WITH NWLY FLOW ALOFT AS A LARGE HIGH PRESSURE
RIDGE BUILDING OVER THE WESTERN CONUS.

&&

.AVIATION...(FOR THE TAFS THROUGH 00Z SATURDAY LATE AFTERNOON)
ISSUED AT 336 PM MDT FRI AUG 22 2014

AS WE SEE AT KBJC...A FEW SHOWERS WILL CONTINUE MOVE THROUGH THE
AREA THIS EVENING...BUT WE SHOULD AVOID ANY THUNDER. WILL KEEP
VCSH IN TAFS UNTIL 06Z. LOOKS SCATTERED SHOWERS WILL INCREASE
LATER THIS AFTERNOON WITH ISOLATED THUNDERSTORMS. THERE WILL BE
AREAS OF MVFR CEILINGS AND VISIBILITIES THIS EVENING...WITH
CONDITIONS LIFTING BETWEEN 04Z AND 08Z. THERE IS A SLIGHT CHANCE
OF IFR/LIFR IN FOG EARLY SATURDAY MORNING...THEN VFR CONDITIONS
ARE EXPECTED FOR THE REST OF SATURDAY WITH ONLY ISOLATED
THUNDERSTORMS IN THE AFTERNOON.


&&

.HYDROLOGY...
ISSUED AT 336 PM MDT FRI AUG 22 2014

THE REMAINING STORMS CONTINUE TO MOVE NORTHEAST WITH RAINFALL
RATES BETWEEN A HALF OF AN INCH AND AN INCH. THREAT OF SERIOUS
FLOODING WILL BE LOW FOR THE REST OF THE NIGHT. A FEW SHOWERS WILL
ALSO MOVE OFF THE FOOTHILLS WITH VERY LIGHT PRECIPITATION.

&&

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

$$

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



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