Severe Thunderstorm Warning 262, NWS Denver/Boulder, CO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
258 AM MDT TUE AUG 18 2009

.SHORT TERM...A 60 KNOT JET AND UPPER LEVEL DISTURBANCE COMBINED
WITH STEEP MID LEVEL LAPSE RATES BROUGHT THE THUNDERSTORMS YESTERDAY
EVENING AND EARLY THIS MORNING. THE JET SLOWLY SLIDES EAST TODAY AND
WILL EXIT THE EASTERN PART OF THE FORECAST AREA THIS EVENING. A
SHORT WAVE CENTERED OVER NORTHERN UTAH AT THIS TIME WILL MOVE EAST
AND AFFECT THE AREA THIS AFTERNOON. THUNDERSTORM DEVELOPMENT WILL BE
EARLIER TODAY THAN THE PAST TWO DAYS BECAUSE OF THE EARLIER TIMING
OF THE SHORT WAVE. AIRMASS WILL BE MODERATELY UNSTABLE AGAIN WITH
CAPES UP TO 1500 J/KG OVER THE EASTERN PLAINS. THE INSTABILITY
TAPERS OFF TO 500-1000J/KG ALONG THE FRONT RANGE. ENOUGH SHEAR WILL
BE IN PLACE FOR SUPER CELLS TO FORM AGAIN. THE CHANCE FOR SEVERE
THUNDERSTORMS WITH LARGE HAIL AND DAMAGING WINDS WILL BE MAINLY EAST
OF A LINE FROM CASTLE ROCK TO FORT MORGAN. MODELS SHOW THE AIRMASS
WARMS A FEW DEGREES TODAY RESULTING IN HIGHS FROM THE MID 70S TO
LOWER 80S.

AIRMASS WILL QUICKLY DRY THIS EVENING AS DOWNWARD VERTICAL
VELOCITIES FOLLOW THE WAVE. EXPECT THE ENTIRE FORECAST AREA TO BE
DRY BY 04Z.

.LONG TERM...ON WEDNESDAY...AN UPPER LEVEL RIDGE OF HIGH PRESSURE
WILL BE BUILDING OVER THE WESTERN U.S. WITH A STRONG NORTHWESTERLY
FLOW OVER THE CWFA.  ONE MORE SHOT OF ENERGY IS PROGGED TO SLIDE
DOWN DOWN FM ERN MONTANA AND POSSIBLY CLIP NORTHEASTERN CO LATE
WEDNESDAY AFTN INTO WEDNESDAY EVENING.  MDLS DO NOT SHOW MUCH IN THE
WAY OF CAPE BUT WITH ANY KIND OF JET AROUND IT/S HARD TO NIX THE
TSTM POTENTIAL COMPLETELY.  WL KEEP ISOLD POPS FOR ZONES 48>51 TO
ACCOUNT FOR THIS PASSING SYSTEM.  IN ADDITION...A FRONTAL BOUNDARY
ASSOCIATED WITH THE PASSING SHORT WAVE WILL ALSO BE MOVING INTO THE
FRONT RANGE.  BEST POTENTIAL FOR ANY STORMS DVLPG ELSEWHERE WOULD
APPEAR TO BE ALONG THE PALMER DIVIDE SO WL KEEP ISOLD POPS IN AND
NEAR THERE AS WELL.  ELSEWHERE I OPTED TO DROP THE MENTION OF
TSTMS.  ON THURSDAY...THERE WILL BE ONE MORE RELATIVELY COOL DAY
WITH HIGH PRESSURE IN CHARGE AT THE SFC AND ALOFT.   IT WILL BE DRY
AND WARMER FOR FRIDAY INTO SATURDAY AS THE CENTER OF THE RIDGE IS
PROGGED TO PARK ITSELF OVER CO.  SEE NO REASON TO INCLUDE ANY POPS
THROUGH THIS TIME AS SUBSIDENCE ASSOCIATED WITH THE RIDGE WILL
REMAIN IN CONTROL.  THE GFS EVENTUALLY RETURNS THE PATTERN TO MORE
OF A LATE SUMMER MONSOON APPEARANCE WITH RIDGE IN THE VICINITY OF
THE OKLAHOMA AND TEXAS PANHANDLES BY LATE SUNDAY.  SOME SUBTROPICAL
PROGGED MAINLY OVER AZ AND UT BY THAT TIME AS WELL WITH A LITTLE
MORE ON MONDAY.  THERE MAY BE ENUF MSTR TO PROGGED A FEW STORMS IN
WRN AND NRN CO BY LATE IN THE EXTENDED PERIOD. THIS TREND ALREADY
REFLECTED IN THE GRIDS SO WL CONFINE ANY ADJUSTMENTS TO THE
WEDNESDAY/THURSDAY WINDOW.

&&

.AVIATION...MID LEVEL CLOUDS WILL BE OVER PARTS OF THE DENVER AREA
WITH CEILINGS FROM 4000 TO 6000 FEET THIS MORNING. THERE IS A SLIGHT
CHANCE FOR LOW CLOUDS UNTIL 15Z WITH CEILINGS OF 1500 TO 3000 FEET.
THE AIRMASS WILL BECOME UNSTABLE AGAIN THIS AFTERNOON. THE BEST
CHANCE FOR THUNDERSTORMS WILL BE EARLIER TODAY...18Z TO 00Z. WIND
GUSTS TO 40 KNOTS...SMALL HAIL AND HEAVY RAIN WILL ACCOMPANY THE
STORMS. DRIER AIR WILL MOVE OVER THE REGION THIS EVENING RESULTING
IN MOSTLY CLEAR SKIES AFTER 02Z.

&&

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

MEIER/COOPER

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DENVER CO
1048 AM MDT TUE AUG 18 2009

COZ030>051-191200-
JACKSON COUNTY BELOW 9000 FEET-WEST JACKSON AND WEST GRAND
COUNTIES ABOVE 9000 FEET-GRAND AND SUMMIT COUNTIES BELOW 9000
FEET-SOUTH AND EAST JACKSON/LARIMER/NORTH AND NORTHEAST GRAND/
NORTHWEST BOULDER COUNTIES ABOVE 9000 FEET-SOUTH AND SOUTHEAST
GRAND/WEST CENTRAL AND SOUTHWEST BOULDER/GILPIN/CLEAR CREEK/
SUMMIT/NORTH AND WEST PARK COUNTIES ABOVE 9000 FEET-LARIMER AND
BOULDER COUNTIES BETWEEN 6000 AND 9000 FEET-JEFFERSON AND WEST
DOUGLAS COUNTIES ABOVE 6000 FEET/GILPIN/CLEAR CREEK/NORTHEAST PARK
COUNTIES BELOW 9000 FEET-CENTRAL AND SOUTHEAST PARK COUNTY-LARIMER
COUNTY BELOW 6000 FEET/NORTHWEST WELD COUNTY-BOULDER AND JEFFERSON
COUNTIES BELOW 6000 FEET/WEST BROOMFIELD COUNTY-NORTH DOUGLAS
COUNTY BELOW 6000 FEET/DENVER/WEST ADAMS AND ARAPAHOE COUNTIES/
EAST BROOMFIELD COUNTY-ELBERT/CENTRAL AND EAST DOUGLAS COUNTIES
ABOVE 6000 FEET-NORTHEAST WELD COUNTY-CENTRAL AND SOUTH WELD
COUNTY-MORGAN COUNTY-CENTRAL AND EAST ADAMS AND ARAPAHOE COUNTIES-
NORTH AND NORTHEAST ELBERT COUNTY BELOW 6000 FEET/NORTH LINCOLN
COUNTY-SOUTHEAST ELBERT COUNTY BELOW 6000 FEET/SOUTH LINCOLN
COUNTY-LOGAN COUNTY-WASHINGTON COUNTY-SEDGWICK COUNTY-PHILLIPS
COUNTY-
1048 AM MDT TUE AUG 18 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL
COLORADO.

.DAY ONE...TODAY AND TONIGHT

ANOTHER ROUND OF THUNDERSTORMS IS EXPECTED THIS AFTERNOON AND EARLY
EVENING. ISOLATED THUNDERSTORMS WILL MOVE EAST ACROSS THE FRONT
RANGE AND INCREASE IN COVERAGE AS THEY MOVE OVER THE EASTERN PLAINS.
A FEW SEVERE STORMS WILL BE POSSIBLE ACROSS THE PLAINS...WITH THE
GREATEST THREAT EAST OF A LINE FROM CASTLE ROCK TO FORT MORGAN.
LARGE HAIL...DAMAGING WINDS AND HEAVY RAIN WILL BE POSSIBLE FROM THE
SEVERE STORMS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL MOST LIKELY NOT BE NEEDED TODAY OR TONIGHT.

KRIEDERMAN/BARJENBRUCH