Boulder Office Area Forecast Discussion

000
FXUS65 KBOU 300946
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
346 AM MDT FRI JUL 30 2010

.SHORT TERM...VERY MOIST AIRMASS IN PLACE AGAIN TODAY. PRECIPITABLE
WATER VALUES WILL RANGE FROM 0.9 OVER THE MOUNTAINS TO 1.4 OVER THE
URBAN CORRIDOR TODAY, WHICH IS WELL ABOVE AVERAGE FOR THIS TIME OF
YEAR. A SURGE FROM THE NORTH WILL PUSH ACROSS NORTHEAST COLORADO
THIS MORNING. THIS  COMBINED WITH SCATTERED MID AND HIGH CLOUDS WILL
KEEP TEMPERATURES A FEW DEGREES COOLER THAN YESTERDAY. THIS MAY HELP
CAP THE PLAINS THIS AFTERNOON. DEW POINTS WILL BE A LITTLE HIGHER
TODAY WITH READINGS IN THE UPPER 50S TO LOWER 60S. ANOTHER THING
THAT WILL ADD TO THE POTENTIAL FOR HEAVY RAIN FALL WILL BE A WEAK
EASTERLY UPSLOPE FLOW UP TO ABOUT 650MB. BIGGEST QUESTIONS TO THE
FORECAST WITH REGARDS TO FLASH FLOODING POTENTIAL ARE STORM MOVEMENT
AND NUMBER OF THUNDERSTORMS. WEST-NORTHWEST 500MB WINDS WILL BE
AROUND 15 KNOTS OVER NORTHERN COLORADO. HOWEVER ACROSS SOUTHERN
PARTS OF THE FORECAST AREA 500MB WINDS BECOME LIGHT. THIS WILL
INCREASE THE  FLASH FLOODING THREAT OVER THE SOUTHERN PORTION OF THE
FORECAST AREA. NOT SEEING A WELL DEFINED SHORT ON SATELLITE OR IN
THE MODEL...SO THINK CONVECTION WILL BE SCATTERED AND INITIALLY FORM
OVER THE HIGHER TERRAIN. WOULDN`T BE SURPRISED TO SEE A COUPLE OF
STORM ANCHORED TO THE HIGHER TERRAIN INITIALLY. AS OUTFLOWS SPREAD
EASTWARD WOULD EXPECT STORM DEVELOPMENT TO SHIFT EAST WITH THE
OUTFLOW BOUNDARIES. WILL GO AHEAD AND ISSUE A FLASH FLOOD WATCH FOR
THE PALMER DIVIDE...SOUTHERN FOOTHILLS...PARK COUNTY AND OUR
SOUTHERN MOUNTAINS WITH THE MAIN CONCERN BEING THE HAYMAN BURN AREA.

.LONG TERM...ON SATURDAY THE UPPER LEVEL RIDGE WILL BE CENTERED OVER
THE TEXAS PANHANDLE WITH A WEAK W-SWLY FLOW ALOFT OVER NRN CO.  A
NICE STREAM OF SUBTROPICAL MSTR WILL BE MIGRATING THROUGH THE WEST
SIDE OF THE RIDGE.  THIS PATTERN IS EXPECTED TO PERSIST THROUGH AT
LEAST MONDAY.  INTERACTIVE SOUNDINGS INDICATE PW VALUES WILL REMAIN
WELL OVER ONE INCH (1.1-1.3) WITH WEAK STEERING WINDS ALOFT.  FCST
CAPES ON SATURDAY WILL BE AROUND 900-1100 J/KG AT DEN...WITH
1800-2400 J/KG ACROSS THE NERN PLAINS.  HARD TO FIND ANYTHING
UPSTAIRS TO SET IT ALL OFF...BUT PLENTY OF FUEL TO WORK WITH ONCE
THE THUNDERSTORMS GET STARTED.  FOR NOW WL STICK WITH THE AFTN/EVNG
SCENARIO...BUT SOME CONVECTION MAY CARRY AFTER MIDNIGHT.  NOT MANY
ADJUSTMENTS AT THIS POINT.  WL BUMP POPS TO HIGHER SCT CATEGORY IN
THE MTNS...BUT LEAVE THE URBAN CORRIDOR/NERN PLAINS AS THEY WITH
BASICALLY 20 PERCENT COVERAGE FOR NOW.  THE MSTR MAY START TO CUTOFF
SOMEWHAT BY WEDNESDAY AS THE FLOW ALOFT IS PROGGED TO MORE WLY AS
THE RIDGE SPREADS ACROSS THE ENTIRE SWRN/SCENTRAL UNITED STATES.

&&

.AVIATION...AIRMASS WILL BE VERY MOIST THE NEXT 24 HOURS. THIS WILL
LEAD TO MID AND HIGH CLOUDS THROUGH THE MORNING. SCATTERED
THUNDERSTORMS WILL FORM THIS AFTERNOON. MAIN THREAT FROM
THUNDERSTORMS WILL BE HEAVY RAIN AND GUSTY OUTFLOWS UP TO 30 KNOTS.
BEST TIME FOR THUNDERSTORMS WILL BE 21Z TO 02Z.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...FLASH FLOOD WATCH FROM NOON UNTIL
9 PM FOR THE PALMER DIVIDE...SOUTHERN FOOTHILLS...PARK COUNTY AND
THE SOUTHERN MOUNTAINS. (ZONES 34..36..37..41)

$$

MEIER/COOPER

NWS BOU Office Area Forecast Discussion