463
FXUS65 KBOU 130202
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
802 PM MDT MON AUG 12 2013
.UPDATE...STRONGEST CONVECTION HAS PUSHED OFF TO THE EAST OF THE
AREA. VERY HEAVY RAIN FELL WITH THE STRONGEST STORMS WITH AN INCH
FALLING IN 15 MINUTES IN A COUPLE OF LOCATIONS. SHOWERS AND
THUNDERSTORMS WILL REMAIN POSSIBLE THROUGH THE NIGHT AS AN UPPER
LEVEL WAVE SITS OVER WYOMING AND NORTHERN COLORADO. THE STORMS
STILL COULD PRODUCE HEAVY RAIN AND SMALL HAIL BUT NOT THE INTENSE
1 INCH IN 15 MINUTE RATE THAT OCCURRED EARLIER. WILL KEEP 20-40
POPS IN THE FORECAST THROUGH THE NIGHT.
&&
.AVIATION...WILL BE A SLIGHT CHANCE FOR STORMS THROUGH THE NIGHT
WITH THE BEST CHANCE BEING NOW THROUGH 04Z. OUTFLOW WINDS FROM
SHOWERS AND STORMS STILL CAUSING VARIABLE WINDS. EVENTUALLY WINDS
WILL SETTLE AT A SOUTHERLY DIRECTION...LIKELY BY 06Z. SKIES WILL
REMAIN MOSTLY CLOUDY WITH CEILINGS REMAINING ABOVE 6000 FEET.
SHOWERS AND STORMS ARE EXPECTED FOR TUESDAY WITH MOST OF THE
STORMS OCCURRING AFTER 18Z.
&&
.PREV DISCUSSION... /ISSUED 226 PM MDT MON AUG 12 2013/
SHORT TERM...CURRENT FRONT RANGE CONVECTION SHOULD PROGRESS
EASTWARD WITH AN ORGANIZED OUTFLOW BOUNDARY. PROBABLY NOT A SOLID
LINE BUT THERE SHOULD BE DECENT COVERAGE ON THE PLAINS EAST OF
DENVER THIS EVENING. FURTHER WEST THERE SHOULD BE A SUBSTANTIAL
AMOUNT OF LESS INTENSE CONVECTION THAT WILL SLOWLY FADE WITH
COOLING OVERNIGHT. WEAK LIFT IN A MOIST AIRMASS WILL PROGRESS
ACROSS THE AREA FROM WEST TO EAST TONIGHT INTO TUESDAY. THE CLOUD
COVER WILL RESTRAIN HEATING...SO WHILE THERE MAY BE A LOW LEVEL OF
WEAK CONVECTION CONTINUING THE MOISTURE ALOFT IS NOT NECESSARILY
FAVORABLE FOR MORE THUNDERSTORM ACTIVITY ON TUESDAY AFTERNOON.
WHILE THERE IS MORE MOISTURE THE COOLER TEMPERATURES WILL LIMIT
INSTABILITY...IT LOOKS LIKE CAPES WILL STILL BE AROUND 500
J/KG...PERHAPS CLOSER TO 1000 J/KG ON THE PLAINS. I DELAYED THE
INCREASE IN ACTIVITY UNTIL LATER IN THE AFTERNOON AND BACKED OFF
ON POPS A LITTLE BIT...STILL EXPECTING SCATTERED STORMS BY LATE
AFTERNOON. AGAIN STORMS WILL LIKELY BE MOVING...BUT SLOWLY. A
HEAVY RAIN THREAT BUT NOT TOO MUCH OF A FLOOD THREAT OUTSIDE OF
THE BURN AREAS.
LONG TERM...THE BEST POTENTIAL FOR THUNDERSTORMS TUESDAY EVENING
WILL BE IN THE EARLY EVENING WITH GRADUAL DECREASE THEREAFTER.
THERE WILL BE A LOW LEVEL EASTERLY FLOW WITH A WEAK NORTHWESTERLY
FLOW ALOFT. ON WEDNESDAY THE FLOW ALOFT WILL REMAIN NORTHWESTERLY
WITH PW VALUES PROGGED TO BE AROUND THREE QUARTERS OF AN INCH.
SCATTERED THUNDERSTORM COVERAGE AGAIN EXPECTED IN THE AFTN AND
EVENING. IN TERMS OF LOW LEVEL MOISTURE THERE WILL BE SOME DRYING
FROM THE FOOTHILLS WESTWARD BUT NOT ENOUGH TO AFFECT COVERAGE
ALTHO THE POTENTIAL FOR HEAVY RAIN MAY LESSEN SLIGHTLY. NOT MUCH
CHANGE IN THE GRIDS PLANNED FOR THURSDAY THROUGH SATURDAY. THE
UPPER LEVEL RIDGE WILL BUILD OVER THE WESTERN U.S. WITH A DRIER
NORTHERLY FLOW ALOFT. INCREASING STABILITY IN THE MID LEVELS WILL
LIKELY DELAY THE ONSET OF TSTMS UNTIL LATE AFTN AND EVENING OVER
THE NERN PLAINS. ON SUNDAY...THE RIDGE BREAKS DOWN AND THE MDLS
BRING A SHORT WAVE ACROSS COLORADO AROUND 18Z SUNDAY ACCORDING TO
THE ECMWF BUT ABOUT 24 HOURS LATER ACCORDING TO THE OPERATIONAL
GFS. AS A RESULT...ALTHO THERE ARE OBVIOUS TIMING DISCREPANCIES...
THUNDERSTORM COVERAGE SHOULD INCREASE BY THAT TIME.
AVIATION...SCATTERED THUNDERSTORMS IN THE DENVER AREA THROUGH
ABOUT 00Z THEN LESS NUMEROUS SHOWERS AND STORMS THROUGH THE
EVENING. MAIN THREAT IS GUSTY WINDS TO AROUND 30 KNOTS...THOUGH
THERE WILL BE SOME IFR CONDITIONS AND HAIL UNDER THE STRONGER
THUNDERSTORMS. THREAT OF IFR CONDITIONS IS MUCH LESS AFTER 02Z.
VFR CONDITIONS WILL PREVAIL LATER TONIGHT AND TUESDAY
MORNING. SCATTERED THUNDERSTORMS AGAIN TUESDAY AFTERNOON WITH
SIMILAR IMPACTS POSSIBLE.
HYDROLOGY...SLOW MOVING STORMS WILL PRODUCE HEAVY RAIN TODAY...UP
TO 1.5 INCHES IN AN HOUR. THIS COULD CAUSE SOME MINOR FLOODING.
BOUNDARY INTERACTIONS ON THE PLAINS COULD PRODUCE LOCALIZED
HIGHER AMOUNTS...BUT IN GENERAL THE STORMS WILL BE MOVING. THE
MAIN THREAT FOR THE BURN AREAS HAS LIKELY PASSED WITH THE STRONGER
STORMS MOVING ONTO THE PLAINS...SLIGHT CHANCE OF HEAVY RAIN STILL
BUT MOST STORMS OVER THE MOUNTAINS WILL ONLY HAVE LIGHT TO
MODERATE RAINFALL. ON TUESDAY THE THREAT APPEARS TO BE SIMILAR AS
STORMS SHOULD BE MOVING SLOWLY WITH A LOW THREAT OF FLASH FLOODING
MAINLY FOR THE BURN AREAS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...KALINA
LONG TERM....COOPER
AVIATION...MEIER