Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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000
FXUS65 KBOU 141550
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
950 AM MDT THU AUG 14 2014

.UPDATE...
ISSUED AT 950 AM MDT THU AUG 14 2014

A COUPLE OF OPPOSING FORCES WILL IMPACT THINGS TODAY. FIRST ON THE
SYNOPTIC SCALE LATEST RAP ANALYSES SHOW SLOWLY INCREASING
QUASIGEOSTROPHIC SUBSIDENCE BEGINNING TO OVERSPREAD WESTERN
COLORADO. THIS MODEL AS WELL AS OTHERS SHOW THIS INCREASING TREND
IN BOTH STRENGTH AND AREAL COVERAGE OF THE SUBSIDENCE THROUGHOUT
THE DAY AND INTO THIS EVENING. IN ADDITION LOW LEVEL HEIGHT FALLS
TO OUR EAST ARE PRODUCING DOWNSLOPE FLOW EAST OF THE MOUNTAINS.
NEITHER OF THESE PHENOMENA BODE WELL FOR AIDING CONVECTIVE
ACTIVITY. ON THE OTHER HAND PRECIPITABLE WATER VALUES ARE
SUBSTANTIAL...1.40 CURRENTLY AT GJT WITH 1.10 AT BOULDER.
ADDITIONALLY THERE IS AN ONGOING AREA OF CONVECTION APPROACHING
THE CONTINENTAL DIVIDE AND SOME HOLES SHOWING UP IN THE MIDLEVEL
CLOUD DECK. BOTH OF THESE ARE GOOD SIGNS OF COURSE. WHICH IS GOING
TO WIN OUT IS STILL IN QUESTION BUT THE PRESENT FORECAST SEEMS
REASONABLE CONSIDERING ALL OF THE ABOVE FACTORS. CONSEQUENTLY
THERE ARE NO CHANGES PLANNED AT THIS TIME.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 400 AM MDT THU AUG 14 2014

FORECAST ON TRACK WITH TRENDS OF HIGHER CHANCES OF SHOWERS AND
COOLER TEMPERATURES TODAY OVER THE FRONT RANGE AND NORTHEAST
PLAINS. WATER VAPOR IMAGERY SHOWING THE RIDGE ALOFT SHIFTING EAST
INTO THE CENTRAL PLAINS WHILE A WEAK WAVE ALOFT NOW LIFTING
NORTHEAST OVER WESTERN COLORADO AND EASTERN UTAH. RADAR IMAGERY
SHOWING GOOD COVERAGE OF SHOWERS OVER WESTERN COLORADO AND THIS
SWATH OF SHOWERS WILL GRADUALLY SHIFT EAST OVER BOU CWA MOUNTAINS
DURING THE MORNING HOURS. INTEGRATED PW VALUES FROM GPS SHOWING
SUBSTANTIAL INCREASE OF AROUND A THIRD OF AN INCH IN THE PAST
18 HRS AND VALUES ARE NOW OVER AN INCH OF PRECIPITABLE WATER.

DESPITE THE INCREASE IN MOISTURE LEVELS...THE INSTABILITY IS NOT
ALL THAT GREAT TODAY GIVEN CONSIDERABLE CLOUD COVER AHEAD OF THE
WAVE. THIS WILL RESULT IN COOLER AFTERNOON TEMPERATURES AND LESS
INSTABILITY WITH SURFACE BASED CAPES LESS THAN 500J/KG OVER THE
FRONT RANGE. SOMEWHAT BETTER INSTABILITY OVER THE FAR NORTHEAST
PLAINS GIVEN HIGHER DEWPOINTS IN THE LOWER 60S AND POTENTIAL
HIGHER CAPES UP AROUND 1000J/KG.  EXPECT HEAVY RAIN AND GUSTY
WINDS WITH THE SHOWERS AND STORMS TODAY. GIVEN STORM MOTIONS OF
10-15KT EXPECT OVERALL FLASH FLOOD THREAT ON THE LOW SIDE DESPITE
THE HIGH MOISTURE VALUES. BURN SCARS WILL HAVE THE HIGHEST IMPACT
FOR FLOOD POTENTIAL BUT NOT WIDE SPREAD ENOUGH TO ISSUE ANY FLASH
FLOOD WATCHES. BASED ON LATEST MODEL CONSENSUS MOST OF THE STORMS
MAY BE DONE OVER THE MOUNTAINS/ADJ PLAINS AROUND 00Z AND THEN
ENDING OVER THE PLAINS BY MIDNIGHT. WILL MAKE SOME ADJUSTMENTS FOR
FASTER ENDING OF STORMS DURING THE EVENING FROM WEST TO EAST.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 400 AM MDT THU AUG 14 2014

THE SHORTWAVE TROUGH PASSING OVER THE FCST AREA TODAY WILL HAVE
MOVED EAST OF THE STATE BY EARLY ON FRIDAY AS THE UPPER RIDGE
REGAINS ITS HOLD ON THE FOUR CORNERS REGION. WITH THE CORE OF THE
UPPER RIDGE IN THIS POSITION THE RECENT NORTHWARD INTRUSION OF
MONSOON MOISTURE WILL SHUT OFF...LEADING TO DRIER AND WARMER
CONDITIONS ACROSS THE FORECAST AREA FOR FRIDAY AND SATURDAY. HOWEVER
THERE SHOULD BE SUFFICIENT MID-LEVEL MOISTURE AROUND TOGETHER WITH
STG SOLAR HEATING TO GENERATE ISOLATED TO SCATTERED T-STORMS OVER
AND NEAR THE FRONT RANGE MTNS BOTH DAYS. AND WITH THE RIDGE AXIS
SITTING OVER THE UTAH/COLORADO LINE...THE LIGHT FLOW ALOFT WILL BE
NWLY. IN THE PRESENCE OF A LOW CAPE ENVIRONMENT...THE FEW HIGH-
BASED STORMS THAT MANAGE TO DRIFT SEWRD OFF THE FRONT RANGE SHOULD
QUICKLY COLLAPSE BEFORE VENTURING TOO FAR OUT ONTO THE PLAINS.
NEAR AVERAGE TEMPERATURES ARE FCST FOR BOTH DAYS.

FOR THE PERIOD SUNDAY-MONDAY...MODELS SHOW TO UPPER RIDGE CONTINUING
ITS SLOW WESTWARD MIGRATION OVER THE GREAT BASIN AND DESERT
SOUTHWEST AS A MORE ORGANIZED SHORTWAVE TROUGH TRACKS EWRD ACROSS
MONTANA AND WYOMING ON SUNDAY...AND ACROSS THE NORTHERN GREAT
PLAINS ON MONDAY. MODELS SHOW THE SOUTHERN TIP OF THIS TROUGH
BRUSHING NERN COLORADO LATE ON SUNDAY...WITH POSSIBLY ANOTHER
GLANCE OF THIS EXITING TROUGH ON MONDAY. THIS SECOND BRUSH WITH
THE TROUGH MAY INCLUDE A WEAK COLD FRONT WHICH MODELS SHOW
BACKING THRU NERN COLORADO DURING THE MORNING HOURS. DO NOT EXPECT
MUCH COOLING WITH ITS ARRIVAL...BUT THE LIGHT...SLIGHTLY MORE
MOIST E-NELY UPSLOPE FLOW BEHIND THE FRONT WILL HELP PRODUCE
ISOLATED LATE DAY T-STORMS OVER AND NEAR THE FRONT RANGE.

DURING THE TUESDAY-WEDNESDAY TIME FRAME...THE AIRMASS OVER NERN
COLORADO TURNS DRIER AS THE UPPER RIDGE OUT WEST FLATTENS AS YET
ANOTHER MORE POTENT UPPER TROUGH TRACKS EAST ALONG THE NWRN
U.S./SWRN CANADA BORDER. THIS PLACES COLORADO UNDER ZONAL FLOW
RESULTING IN LITTLE DAY-TO-DAY CHANGE IN TEMPERATURE.

&&

.AVIATION...(FOR THE TAFS THROUGH 18Z FRIDAY MORNING)
ISSUED AT 950 AM MDT THU AUG 14 2014

CURRENT TAFS APPEAR IN ORDER AND DO NOT FORESEE ANY BIG CHANGES
NEEDED WITH THE 18Z ISSUANCE.

&&

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

&&

$$

UPDATE...ET
SHORT TERM...ENTREKIN
LONG TERM...BAKER
AVIATION...ET


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