Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 270138
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
738 PM MDT SAT JUL 26 2014

.UPDATE...
ISSUED AT 738 PM MDT SAT JUL 26 2014

STILL SCATTERED CONVECTION AT THIS TIME WITH A FEW EMBEDDED WEAK
STORMS. OVERALL CONVECTION TREND HAS BEEN DECREASING AND WILL
CONTINUE TO DECREASE THROUGH THE EVENING. WILL RUN POPS TO AROUND
MIDNIGHT.

SOUTHEAST WINDS WILL DEVELOP LATE TONIGHT AND SUNDAY MORNING. THIS
WILL TRANSPORT MORE MOISTURE INTO THE AREA. EXPECT LOW CLOUDS TO
FORM SUNDAY MORNING...POSSIBLY AFTER SUNRISE.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 300 PM MDT SAT JUL 26 2014

A MOIST SUBTROPICAL PLUME CIRCULATING AROUND THE TOP OF AN
UPPER RIDGE CENTERED ON NEW MEXICO WILL CONTINUE TO PROVIDE THE
FUEL FOR SHOWERS AND THUNDERSTORMS IN THE MOUNTAINS AND NEARBY
PLAINS OF NORTH CENTRAL AND NORTHEAST COLORADO THIS AFTERNOON AND
EVENING. WESTERLY TRANSPORT WINDS WILL MOVE STORMS OFF THE FRONT
RANGE AND OVER THE ADJACENT PLAINS WHERE THE ENVIRONMENT APPEARS
LESS SUITABLE FOR STORM GROWTH. HAVE WITNESSED STORMS QUICKLY
COLLAPSING AS THEY MOVE OFF THE HIGH TERRAIN. HOWEVER LATER THIS
AFTERNOON WITH FURTHER HEATING AND CONTINUED UPSLOPE FLOW...SHOULD
SEE STORMS HOLDING TOGETHER AS THEY MOVE OUT ONTO THE PLAINS
WITH GUSTY OUTFLOW WINDS AND LIGHTNING MAIN THREATS. HOWEVER
PRECIPITABLE WATER AMOUNTS CONTINUE TO RISE WITH VALUES ALONG THE
FRONT RANGE NOW UP AROUND 1.10 INCH. AND WITH WEST-TO-EAST STORM
MOTIONS OF ONLY 15-20 MPH...CANNOT RULE OUT A FEW HEAVY RAINERS
WITH UP OF AN INCH OF RAIN POSSIBLE IN UNDER 30 MINS. MODEL
REFLECTIVITY AND QPF FIELDS SHOW AREAS OF PCPN SCATTERED ABOUT
THE CWA THROUGH MID-EVENING...THEN A DRAMATIC DROP OFF IN
ACTIVITY BY MIDNIGHT WITH THE FORMATION OF STRONG NIGHTTIME
INVERSION AS COOLER LOW-LEVEL AIR CONTINUES TO FUNNEL IN ON EAST-
SOUTHEASTERLY BNDRY LAYER FLOW.

ON SUNDAY..MODEL CROSS SECTIONS SHOW A LAYER OF SATURATED AIR
FORMING BETWEEN 800-650 MBS FROM THE FRONT RANGE EASTWARD DURING
THE EARLY MORNING HOURS...THE PRODUCT OF A MOIST SELY LOW-LEVEL
GRADIENT FLOW. COULD SEE A FEW POCKETS OF FOG ON THE PLAINS
EARLY...BUT NOTHING NOTABLE. AS THE MORNING PROGRESSES MODELS
SHOW THIS MOIST LAYER LIFTING/MIXING OUT ONLY TO REFORM AS A
SLIGHTLY HIGHER BROKEN TO OVERCAST CLOUD DESK BY THE AFTERNOON.
AS THE UPPER RIDGE AXIS SHIFTS WEST DURING THE DAY...FLOW ALOFT
BECOMES NORTHWESTERLY WHICH HELPS TO ADVECT COOLER AND MORE STABLE
AIR OVER THE PLAINS. AS A RESULT...STORM CHANCES TOMORROW WILL BE
LARGELY CONFINED TO THE MTNS...SOUTH PARK...SOUTHERN FOOTHILLS...
NEARBY PLAINS AND PALMER DIVIDE. AND WITH PW AMOUNTS CONTINUING TO
CLIMB ACROSS SOUTHERN PORTIONS OF THE CWA...LOCALLY HEAVY RAIN
WILL BE POSSIBLE...ESPLY ACRS SOUTH PARK AND THE SOUTHERN
FOOTHILLS SINCE A MOIST SOUTHEAST FLOW FAVORS THESE LOCATIONS. AS
FOR TEMPERATURES NEXT 24 HOURS...LOOKING FOR SLIGHTLY COOLER
READINGS ESPLY EAST OF THE MTNS WITH HIGHS IN THE LOW/MID 80S ON
THE PLAINS AND 60S/70S IN THE HIGH COUNTRY. HOWEVER SHOULD LOW
UPSLOPE CLOUDS LINGER ALONG THE FRONT RANGE BEYOND MIDDAY...ITS
POSSIBLE TEMPS MAY NOT CLIMB OUT OF THE 70S.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 300 PM MDT SAT JUL 26 2014

MODELS HAVE THE UPPER RIDGE STRETCHED FROM UTAH INTO NORTHERN
TEXAS SUNDAY NIGHT INTO MONDAY. IT SHIFTS A BIT EASTWARD MONDAY
NIGHT INTO TUESDAY. BY TUESDAY NIGHT...THE MODELS SHOW A WEAK
UPPER TROUGH TO MOVE IN. THE FLOW ALOFT IS WEST TO NORTHWESTERLY
THROUGH THE FIVE PERIODS. THE QG VERTICAL VELOCITY FIELDS SHOW
WEAK UPWARD MOTION OVER THE FORECAST AREA THROUGH TUESDAY NIGHT.
THE LOW LEVEL WINDS SHOULD ADHERE TO NORMAL DIURNAL TRENDS SUNDAY
NIGHT THROUGH MONDAY NIGHT...THEN UPSLOPE EASTERLY WINDS ON
TUESDAY AND TUESDAY NIGHT. MOISTURE REMAINS AMPLE THROUGH THE
PERIODS. THE PRECIPITABLE WATER PROGS ARE IN THE 0.70 TO 1.20 INCH
RANGE FOR THE PLAINS AND FOOTHILLS SUNDAY NIGHT INTO MONDAY...THEN
THEY INCREASE TO 0.80 TO 1.40 INCHES THE REST OF MONDAY WELL INTO
WEDNESDAY. THE LOW LEVEL DEW POINT READINGS ARE PROGGED IN THE
50S F SUNDAY NIGHT INTO MONDAY...THEN THEY INCREASE INTO THE MID
50S TO LOWER 60S F INTO WEDNESDAY. THERE IS SOME CAPE AROUND
SUNDAY EVENING MAINLY OVER THE MOUNTAINS AND FOOTHILLS. THE CAPE
FOR LATE DAY MONDAY AND LATE DAY TUESDAY IS 1000-2000 J/KG IN MANY
AREAS. THE QPF FIELDS SHOW PLENTY OF MEASURABLE RAINFALL FOR THE
CWA SUNDAY EVENING...LATE DAY MONDAY AND LATE DAY TUESDAY. WILL GO
WITH "CHANCE" POPS FOR THE SOUTHWESTERN CWA SUNDAY EVENING. FOR
BOTH LATE DAY MONDAY AND TUESDAY...WILL NEED 30-50% POPS FOR ALL
THE CWA. WILL EVEN KEEP SOME MINOR POPS GOING FOR THE 06-18Z
PERIODS BOTH DAYS. FOR TEMPERATURES...MONDAY`S HIGHS ARE 1-2 C
WARMER THAN SUNDAY`S. TUESDAY`S HIGHS ARE 1-2 C COOLER. FOR THE
LATER DAYS WEDNESDAY THROUGH SATURDAY...A WEAK UPPER TROUGH MOVES
DOWN IN THE NORTHWESTERLY FLOW. BY LATER THURSDAY...THE UPPER RIDGE
IS ORIENTED MORE NORTH-SOUTH AND THE AXIS BEGINS MOVING EASTWARD
FROM THE INTER MOUNTAIN WEST. ON FRIDAY AND SATURDAY...THE UPPER
RIDGE AXIS IS OVER THE WESTERN COLORADO BORDER. MOISTURE IS
PLENTIFUL THROUGH WEDNESDAY...THEN BEGINS DRYING OUT THURSDAY
THROUGH SATURDAY. TEMPERATURES STAY BELOW SEASONAL NORMALS ALL
FOUR DAYS.

&&

.AVIATION...(FOR THE TAFS THROUGH 06Z SUNDAY EVENING)
ISSUED AT 738 PM MDT SAT JUL 26 2014

JUST A SLIGHT CHANCE FOR A THUNDERSTORM THROUGH 03Z. GOOD CHANCE
AT SEEING A WEAK SHOWER AND ONE MORE WIND DIRECTION CHANCE THROUGH
03Z. ONCE THE CONVECTION DIES OFF...WINDS WILL SETTLE AT SOUTHERLY
DIRECTION THROUGH EARLY MORNING. BETWEEN 09Z TO 12Z...WINDS ARE
EXPECTED TO TURN SOUTHEASTERLY. THIS WILL TRANSPORT MOISTURE INTO
THE AREA. LOW CLOUDS SHOULD FORM AROUND 12Z TO 14Z WITH CEILINGS
AROUND 2000 FEET. THE LOW CLOUDS WILL LINGER INTO THE EARLY
AFTERNOON. ANOTHER GOOD CHANCE FOR SHOWERS AND STORMS LATE SUNDAY
AFTERNOON AND INTO THE EVENING.

&&

.HYDROLOGY...
ISSUED AT 300 PM MDT SAT JUL 26 2014

RAIN TOTALS OF 0.1 TO 0.3 INCH ARE PROBABLE WITH T-STORMS THROUGH
02Z THIS EVENING...WITH THE POTENTIAL FOR 0.5 TO 0.75 INCH OF
RAIN FROM ISOLATED STORMS PASSING OVER THE FRONT RANGE AND NEARBY
PLAINS. STORMS WEST OF THE CONTINENTAL DIVIDE MAY ALSO PRODUCE
SIMILAR RAIN AMOUNTS. STORM ACTIVITY SHOULD END IN MOST AREAS BY
04Z THIS EVENING. ON SUNDAY...MOISTURE WILL CONTINUE TO SPREAD
OVER SOUTHERN SECTIONS OF THE FORECAST AREA...SUCH AS SOUTH PARK
AND THE SOUTHERN FOOTHILLS...RESULTING IN A GREATER CHANCE OF
HEAVY RAINFALL DURING THE LATE MORNING AND AFTERNOON HOURS. LOCAL
AMOUNTS UP TO 1.25 INCHES WILL BE POSSIBLE IN THIS AREA. OTHERWISE
A COOLER AND LESS STABLE AIRMASS OVER REMAINING PORTIONS OF THE
FORECAST AREA WILL RESULT IN FEWER STORMS AND LIGHTER RAINFALL
AMOUNTS.

&&

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

$$

UPDATE...MEIER
SHORT TERM...BAKER
LONG TERM...RJK
AVIATION...MEIER
HYDROLOGY...BAKER/RJK


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