Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 172051
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
251 PM MDT SUN AUG 17 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 245 PM MDT SUN AUG 17 2014

THE CONVECTIVE CLOUDINESS IS MAINLY OVER THE FOOTHILLS...
ADJACENT PLAINS...ALONG WITH PARK AND DOUGLAS COUNTIES. THERE ARE
A FEW MOVING EASTWARD OVER THE FOOTHILLS AND URBAN CORRIDOR. THE
DEW POINTS ARE IN THE MID 30S TO MID 40S F FOR THE PLAINS AND
FOOTHILLS. THE FAR NORTHEAST CORNER STILL HAS SOME MID 40S TO
LOWER 50S F READINGS. THE AIRCRAFT SOUNDINGS SHOW LIMITED CAPE AT
THIS TIME. MODELS SHOW THE UPPER RIDGE AXIS TO SHIFT SLIGHTLY
EASTWARD OVERNIGHT AND MONDAY. THE FLOW ALOFT WILL BECOME MORE
WEST-NORTHWESTERLY OVERNIGHT INTO MONDAY. THE SYNOPTIC SCALE
ENERGY REMAINS BENIGN THE NEXT TWO PERIODS. FOR MOISTURE...IT WILL
REMAIN LIMITED THROUGH MONDAY AFTERNOON. PRECIPITABLE WATER VALUES
ARE IN THE 0.50 INCH RANGE OVER THE HIGH FOOTHILLS TO 1.00 INCH
OVER THE EASTERN PLAINS MONDAY AFTERNOON. MONDAY AFTERNOON`S DEW
POINTS ARE PROGGED IN THE LOWER 40S TO LOWER 50S FOR THE PLAINS
AND FOOTHILLS. MONDAY AFTERNOON`S CAPE VALUES ARE IN THE 500-1500
J/KG RANGE THROUGHOUT THE CWA. THE QPF FIELDS FROM THE GFS ONLY
HAVE A TINY BIT OF MEASURABLE RAINFALL PROGGED TONIGHT. THERE IS
SOME MEASURABLE RAINFALL PROGGED ON MOST OF THE MODELS FOR MONDAY
AFTERNOON...THE MOST OVER THE SOUTHERN HALF OF THE CWA. FOR POPS
...10-20%S OVER THE SOUTHERN CWA EARLY THIS EVENING. FOR MONDAY
AFTERNOON...10-20%S FOR MOST AREAS. TEMPERATURES LOOK TO BE
0.5-1.5 C COOLER MONDAY AFTERNOON THEN CURRENT READINGS.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 245 PM MDT SUN AUG 17 2014

LARGE UPPER RIDGE OVER COLORADO MONDAY NIGHT SHIFTS EAST OF THE
STATE ON TUESDAY AND CONTINUES ITS EASTWARD PROGRESSION OVER THE
CENTRAL GREAT PLAINS ON WEDNESDAY. WITH ITS PASSING...MEAN 0-5KM AGL
FLOW ACRS COLORADO TURN SOUTHWESTERLY...WHICH DRAWS MONSOONAL/
SUBTROPICAL MOISTURE UP FROM THE DESERT SOUTHWEST. MEANWHILE...AN
UPPER AIR CYCLONE SPINNING OFF THE WASHINGTON COAST TODAY IS PROGGED
TO MIGRATE SOUTHWARD EXPANDING INTO A DEEP UPPER TROUGH/CLOSED LOW
OVER NRN CALIFORNIA AND WESTERN NEVADA BY TUESDAY. MODELS SHOW A
COUPLE OF ENERGY SPOKES ROUNDING THE BASE OF THE TROUGH AND LIFTING
NEWRD OVER THE FOUR CORNERS REGION. THEY SHOW THE STRONGER OF THESE
SPOKES/SHORTWAVES ON THE NOSE OF AN +80KT JET PASSING OVER N-CNTRL/
NERN COLORADO TUESDAY AFTERNOON WITH YET ANOTHER POORLY ORGANIZED
WAVE WEDNESDAY EVENING. MID/UPPER-LEVEL QG VERTICAL VELOCITY FIELDS
INDICATE THE BEST LIFT OVER THE NERN CORNER OF COLORADO AROUND
00Z/WED WHERE LAYER PW VALUES IN THE 1.0 TO 1.3 INCH RANGE. AHEAD
THE SHORTWAVE SHEAR AND STABILITY PROFILES LOOKS SUITABLE FOR
ISOLATED TO WIDELY SCATTERED STORMS ONCE THE CIN DISAPPEARS ABOUT
21Z ACCORDING TO MODEL SOUNDINGS. ONE OR TWO STORMS IN THE CORNER
MAY PRODUCE HAIL AND LOCALLY HEAVY RAINFALL. BY EVENING SWLY BNDRY
LAYER FLOW APPEARS TO FLUSH OUT LOW-LEVEL MOISTURE ALONG THE FRONT
RANGE RESULTING A QUICK WEST-TO-EAST DROP OFF IN STORM ACTIVITY ON
THE PLAINS. HOWEVER ISOLATED SHOWERS/STORMS IN THE HIGH COUNTRY
COULD LINGER THRU THE EVENING WITH PASSING MID-LEVEL MOISTURE PLUME.

ON WEDNESDAY...MEAN 0-5KM FLOW TURNS MORE WESTERLY WHICH FURTHER
DRIES OUT THE BOUNDARY LAYER EAST OF THE MTNS. PW VALUES ALONG THE
FRONT RANGE START OUT AROUND AN INCH AND SUPPOSEDLY FALL TO AROUND
3/4 INCH BY EVENING. THAT/S EVEN WITH MID- AND HIGH-LEVEL MONSOON
MOISTURE CONTINUING TO FLOW IN FROM THE SOUTHWEST AHEAD OF THE WEAK
SHORTWAVE. CAN SEE SCATTERED TO BROKEN CLOUD COVER AND AT LEAST A
SLIGHT CHANCE OF AFTERNOON AND EVENING T-STORMS ON WEDNESDAY.
DOWNSLOPE FLOW OFF THE FRONT RANGE/PALMER DIVIDE WILL HELP TO WARM
TEMPERATURES 1-2 DEG C.

BY THURSDAY...LARGE SCALE HEIGHT AND CIRCULATION PATTERN ON THE
MOVE. GFS SHOWS THE 500MB TROUGH ALONG THE WEST COAST OPENING UP AND
MOVING EAST ACRS THE GREAT BASIN....WITH STRONG SWLY FLOW STILL OVER
COLORADO. ECMWF INDICATES A SPLIT FLOW PATTERN OVER THE WEST WITH A
CLOSED LOW IN THE SOUTHERN BRANCH OF THE JET DROPPING OFF OF SRN
CALIFORNIA AND AN OPEN WAVE PASSING OVER THE NRN ROCKIES. COLORADO
IN BETWEEN WITH NEARLY ZONAL FLOW ALOFT. AIRMASS OVER THE AREA LOOKS
COMPARATIVELY WET AND UNSTABLE ACCORDING TO THE GFS AND EVEN DRIER
AND WARMER AS PER THE EC. CANADIAN AND DGEX MODELS LOOK SOMEWHAT
SIMILAR TO THE EC. SO WILL TREND DRIER AND WARMER.

FRIDAY-SUNDAY...GFS MOVES THIS TROUGH EAST OF THE STATE ON FRIDAY
AND OTHER MODELS STILL HAVE THE AREA UNDER A RELATIVELY DRY WESTERLY
FLOW ALOFT. THEN OVER THE WEEKEND...MODELS SHOW ANOTHER TROUGH AND
COOL AIRMASS DROPPING OUT OF SWRN CANADA. THE GFS KEEPS THIS TROUGH
WEST-NORTHWEST OF COLORADO THROUGH SUNDAY...WHILE THE ECMWF RACES
EASTWARD ACRS MONTANA...WYOMING AND NRN COLORADO BY SUNDAY
AFTERNOON. THE SLOWER GFS SURGES MONSOON MOISTURE BACK UP OVER
COLORADO THIS WEEKEND WHILE THE MONSOON PLUME REMAINS CUT OFF WELL
SOUTH OF THE STATE. FOR THIS 3-DAY PERIOD...WILL GO WITH STICK WITH
LOW POPS MAINLY FOR THE HIGH TERRAIN AND TEMPERATURES NEAR TO
SLIGHTLY BELOW AVERAGE.

&&

.AVIATION...(FOR THE TAFS THROUGH 00Z MONDAY LATE AFTERNOON)
ISSUED AT 245 PM MDT SUN AUG 17 2014

THERE IS A PRETTY DECENT...ALTHOUGH SMALL...CELL TO MOVE JUST
SOUTH OF DIA THE NEXT HALF HOUR. NORMAL DIURNAL WIND PATTERNS
SHOULD PREVAIL TONIGHT AND MONDAY...AFTER THE STORM OUTFLOWS MOVE
AWAY. CEILINGS SHOULD STAY ABOVE 6000 FEET AGL EVEN WITH THE
STORM ALTHOUGH OUTFLOW WIND GUSTS COULD GET TO 35 KNOTS.

&&

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

$$

SHORT TERM...RJK
LONG TERM...BAKER
AVIATION...RJK


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