Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 110412
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1012 PM MDT THU JUL 10 2014

.UPDATE...
ISSUED AT 1012 PM MDT THU JUL 10 2014

A WIDE BAND OF SHOWERS AND T-STORMS STRETCHED FROM EAGLE COUNTY
IN WRN COLORADO TO WELL UP ACRS SERN SOUTH DAKOTA THIS EVENING AND
HAS PRETTY MUCH REMAINED IN THIS POSITION FOR MOST OF THE DAY.
OUR CWA HAS BEEN ON THE SOUTHERN FRINGE OF THIS BAND. HAVE SEEN
LITTLE TO NO LIGHTNING ON THE PLAINS TODAY DUE IN LARGE PART TO
MARGINAL INSTABILITY AND MINIMAL CAPES. HIGH COUNTRY SAW THE BULK
OF THE CONVECTION/T-STORM ACTIVITY TODAY AND EVEN THIS EVENING
WITH THE NEXT WAVE OF STORMS NOW PASSING OVER THE GORE...PARK AND
TEN MILE RANGES. SWLY FLOW ALOFT IS EXPECTED TO CARRY THESE
STORMS ACRS NORTHERN AND CENTRAL PORTIONS OF THE FRONT RANGE IN
THE NEXT COUPLE OF HOURS SOME WEAKENING ALONG THE WAY. MEANWHILE
ON THE PLAINS...THE RAP AN HRRR INDICATE A RESURGENCE IN
SHOWER/STORM FORMATION ALONG THE WY/NE BORDERS AND ACRS THE NERN
CORNER OF THE STATE DURING THE LATE EVENING/ERLY MORNING HOURS.
GOOD SHEAR AND MOISTURE /LOW-MID 60F DEWPTS/ NOW IN PLACE ACRS
NERN WELD...MORGAN...WASHINGTON...LOGAN...SEDGWICK AND PHILLIPS
COUNTIES COULD LEAD TO THE DVLPMNT OF SHOWERS/T-STORMS IN THIS
AREA IN NEXT COUPLE OF HRS. AT THIS TIME...NOTHING GOING ON OUT
THERE...BUT OUTFLOW BNDYS FROM NEBRASKA STORMS AND A COLD FRONT
DROPPING IN FROM THE NORTH SHOULD PROVIDE THE NEEDED LIFT TO
GENERATE THIS CONVECTION...POSSIBLY AS FAR WEST AS THE DENVER
METRO AREA. COULD SEE THE BEST CHANCE FOR PRECIP ACRS NERN
COLORADO TONIGHT IN THE NEXT 2-4 HOURS. MADE ADJUSTMENTS TO THE
EVENING FORECAST PACKAGE TO REFLECT ALL OF THIS.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 329 PM MDT THU JUL 10 2014

STORMS HAVE FORMED OVER THE HIGHER TERRAIN DURING THE EARLY
AFTERNOON HOURS. WESTERLY FLOW ALOFT WILL PUSH SOME OF THE STORMS
OFF THE HIGHER TERRAIN. AIRMASS OVER THE FRONT RANGE URBAN CORRIDOR
IS DRY WITH DEW POINTS IN THE MID 30S TO MID 40S RESULTING IN A 50+
TEMPERATURE/DEW POINT SPREAD. THIS WILL MAKE IT DIFFICULT FOR STORMS
TO MAINTAIN OFF THE HIGHER TERRAIN...THOUGH A FEW WILL. RAINFALL
WILL MAINLY BE LIGHT BECAUSE OF THE DRY AIRMASS. BRIEF HEAVY RAIN
WILL BE POSSIBLE OVER THE HIGHER TERRAIN AND EASTERN PLAINS WHERE
THERE IS MORE MOISTURE.

THREAT FOR STORMS WILL DECREASE THIS EVENING. HOWEVER A COLD FRONT
WILL PUSH SOUTH TONIGHT AND INCREASE THE MOISTURE. BECAUSE OF
THIS...WILL KEEP LOW POPS IN THE FORECAST THROUGH THE NIGHT.

A MOIST AIRMASS WILL BE IN PLACE FRIDAY WITH PRECIPITABLE WATER
VALUES OF OVER AN INCH. DEW POINTS WILL BE IN THE 50S THROUGH THE
DAY. CAPES WILL BE HIGHER FRIDAY BECAUSE OF THE INCREASED
MOISTURE...POSSIBLY UP TO 1500 J/KG IF THE HIGHER DEW POINTS ON
THE GFS MODEL OCCURS. SHEAR WILL BE MARGINAL FOR SEVERE
STORMS...BUT MAY BE ENOUGH FOR A FEW SEVERE STORMS...MAINLY EAST.
HEAVY RAIN WILL LIKELY OCCUR WITH THE STRONGER STORMS. FORTUNATELY
WINDS ALOFT WILL BE 15 TO 25 KNOTS...SO STORMS SHOULD MOVE OFF TO
THE EAST ONCE THEY FORM. IF STORMS REFORM OR TRAIN OVER THE SAME
AREA...FLASH FLOODING WILL BE POSSIBLE.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 329 PM MDT THU JUL 10 2014

THUNDERSTORMS TO CONTINUE ACROSS THE AREA FRIDAY EVENING...MAINLY
ACROSS THE PLAINS AS BACK EDGE OF MID LEVEL TROUGH MOVES OVER THE
REGION. WITH PRECIPITABLE WATER VALUES OVER AN INCH ACROSS THE
PLAINS. LOCALLY HEAVY RAIN WILL BE POSSIBLE. IN ADDITION...WITH
CAPE VALUES OF AROUND 1000 J/KG EXPECTED FAR NORTHEAST CORNER SOME
HAIL CAN BE EXPECTED. LOOKS LIKE THERE WILL BE ENOUGH STORM MOTION
TO LIMIT THE THREAT FOR FLOODING. MOST STORMS TO END AROUND
MIDNIGHT AS SUBSIDENCE INCREASES.

ON SATURDAY...RIDGE RETROGRADES WITH FLOW BECOMING WESTERLY. STILL
A GOOD FETCH OF SUBTROPICAL MOISTURE ACROSS THE STATE WITH
PRECIPITABLE WATER VALUES OVER AN INCH ACROSS THE PLAINS. MID
LEVEL SHORTWAVE LOOKS TO MOVE SOUTHEAST ACROSS THE NORTHERN PLAINS
STATES DURING THE AFTERNOON WITH SOME MID LEVEL QG ASCENT ACROSS
NORTHEAST COLORADO. COMBINATION OF LIFT AND MOISTURE TO PROVIDE A
CHANCE OF THUNDERSTORMS MOST LOCATIONS DURING THE AFTERNOON.
MODELS GENERATE QPF ACROSS MUCH OF THE AREA...WITH THE GFS SHOWING
THE MOST. WITH SUFFICIENT MOISTURE AVAILABLE...STORMS COULD
PRODUCE LOCALLY HEAVY RAIN. APPEARS THERE IS ENOUGH STORM MOTION
TO KEEP THE STORMS MOVING...LIMITING THE FLASH FLOOD THREAT.
MODELS SHOW CAPE VALUES AROUND 1000-1500 J/KG NORTHEAST
PLAINS...SO HAIL ALSO A POSSIBILITY. COOLER AIRMASS OVER THE
AREA...WITH HIGHS IN THE MIDDLE 80S ACROSS THE PLAINS. FOR
SUNDAY...NORTHWEST FLOW ALOFT CONTINUES WITH UPPER RIDGE ACROSS
THE GREAT BASIN. CENTER OF THE HIGH LOOKS TO BE OVER EASTERN
NEVADA. WESTERLY FLOW ALOFT TO BRING SLIGHTLY DRIER AIR INTO
COLORADO...SHUNTING SOME OF THE SUBTROPICAL MOISTURE FEED SOUTH
AND EAST OF THE CFWA. STILL SUFFICIENT MOISTURE FOR A CHANCE OF
AFTERNOON AND EVENING THUNDERSTORMS MOST LOCATIONS...BUT MID LEVEL
SUBSIDENCE MAY LIMIT THE COVERAGE OF STORMS. STORMS COULD STILL
PRODUCE BRIEF HEAVY RAIN. LITTLE CHANGE IN TEMPERATURES EXPECTED
FROM SATURDAY...WITH HIGHS IN THE MIDDLE 80S OVER NORTHEAST
COLORADO. ON MONDAY...THE NORTHWEST FLOW ALOFT CONTINUES. MODELS
SHOW A MID LEVEL SHORTWAVE MOVING ACROSS CENTRAL PLAINS DURING THE
AFTERNOON WITH THE TAIL END INTO NORTHEAST COLORADO. WEAK FRONT
LOOKS TO PUSH INTO NORTHEAST PLAINS WITH SLIGHTLY COOLER AIR. BOTH
ECMWF AND GFS SHOW SUBTROPICAL MOISTURE PUSHING NORTHWARD AGAIN
WITH AN INCREASE IN PRECIPITABLE WATER. SHOULD SEE A CHANCE OF
AFTERNOON AND EVENING THUNDERSTORMS MOST LOCATIONS DUE TO THE LIFT
AND MOISTURE.

FOR THE LATER DAYS...TUESDAY THROUGH THURSDAY: MODELS SHOW
DEEPENING UPPER TROUGH ACROSS THE NORTHERN AND CENTRAL PLAINS
STATES TUESDAY AND WEDNESDAY WITH A MID LEVEL SHORTWAVE TROUGH
MOVING INTO NORTHEAST COLORADO TUESDAY AFTERNOON INTO WEDNESDAY.
SURFACE FRONT LOOKS TO PUSH INTO THE NORTHEAST PLAINS DURING THE
AFTERNOON. SUFFICIENT LIFT AND MOISTURE FOR A CHANCE OF MAINLY
AFTERNOON AND EVENING THUNDERSTORMS...BEST CHANCE EAST OF THE
CONTINENTAL DIVIDE. COOLER AIR TO SPILL INTO NORTHEAST COLORADO
BEHIND THE FRONT...WITH HIGHS EXPECTED TO ONLY BE IN THE MID AND
UPPER 70S ACROSS THE PLAINS. MODELS SHOW TROUGH MOVING INTO
SOUTHEAST COLORADO THURSDAY...WITH A DECREASING CHANCE FOR
THUNDERSTORMS. TEMPERATURES WARM SLIGHTLY BUT STILL BE A BIT
BELOW AVERAGE.

&&

.AVIATION...(FOR THE TAFS THROUGH 06Z FRIDAY EVENING)
ISSUED AT 1012 PM MDT THU JUL 10 2014

PARTLY CLOUDY SKIES OVER THE METRO AREA AT PRESENT TIME WILL BECOME
MOSTLY CLOUDY TO OVERCAST SOON AFTER THE PASSAGE OF A COLD FRONT/
STRONG THUNDERSTORM OUTFLOW BOUNDARY FROM THE NORTH. THIS FRONTAL
BOUNDARY NOW RACING SOUTH THROUGH CENTRAL WELD COUNTY...SHOULD
ARRIVE IN THE DENVER AREA BY 0430Z...IF NOT SOONER. EXPECT GUSTY
NORTH-NORTHEAST WINDS TO AROUND 25KTS FOR ABOUT AN HOUR OR SO
AFTER ITS PASSAGE THEN EAST-NORTHEAST WINDS OF 7-13KTS FOR THE
REST OF THE NIGHT. ALSO LOOK FOR SKIES TO FILL WITH LOW AND MID-
LEVEL CLOUDS AND A 30-40 PCT CHANCE OF SHOWERS AND ISOLATED
T-STORMS THROUGH 08Z. COULD SEE CEILINGS LOWERING TO AROUND 5000
FT ALG...PARTICULARLY AT APA AND BJC AFTER MIDNIGHT. MOSTLY CLOUDY
SKIES ARE EXPECTED TO LINGER UNTIL AROUND SUNRISE THEN SKIES WILL
PARTIALLY CLEAR.

&&

.HYDROLOGY...
ISSUED AT 329 PM MDT THU JUL 10 2014

THREAT FOR FLASHING FLOODING TODAY WILL BE VERY LOW DUE TO A
DRY AIRMASS AND STORMS MOVING AROUND 15 MPH.

THE THREAT FOR FLASH FLOODING WILL INCREASE FRIDAY. AIRMASS WILL
BECOME MOIST. THE NUMBER OF THUNDERSTORMS IS ALSO EXPECTED TO
INCREASE WITH HEAVY RAIN ACCOMPANYING THE STRONGER STORMS. STORMS
WILL BE MOVING AROUND 10 TO 20 MPH ON FRIDAY. IF STORMS REFORM OR
TRAIN OVER THE SAME AREA FLASH FLOODING WILL BE POSSIBLE.
THUNDERSTORMS WILL BE POSSIBLE SATURDAY AND SUNDAY. AIRMASS TO
REMAIN FAIRLY MOIST SATURDAY WITH SOME DRYING SUNDAY. LOCALLY
HEAVY RAIN WILL BE POSSIBLE WITH SOME OF THE STORMS SATURDAY...BUT
STORMS SHOULD BE MOVING AROUND 15 TO 20 MPH...LIMITING THE FLASH
FLOOD THREAT. &&

.BOU WATCHES/WARNINGS/ADVISORIES...

&&

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

$$

UPDATE...BAKER
SHORT TERM...MEIER
LONG TERM...D-L
AVIATION...BAKER
HYDROLOGY...MEIER



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