Severe Thunderstorm Warning 125, NWS Denver/Boulder, CO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
255 PM MDT THU JUL 12 2007

.SHORT TERM...BATCH OF CONVECTION NOVING INTO NORTHERN COLORADO
PLAINS A TTHIS TIME. AMS UNSTABLE WITH APPROACHING SHORTWAVE...
CURRENTLY OVER CENTRAL WYOMING. FORECAST SOUNDINGS HAVE SHOWN CAPE
VALUES AROUND 2000 J/KG ACROSS NORTHEAST PLAINS. ALTHOUGH WINDS
ALOFT ARE FAIRLY WEAK AS CWA UNDER DEFORMATION AREA. BUT DESPITE
LIMITED SHEAR...SEVERE POTENTIAL ACROSS PLAINS EXISTS GIVEN THE CAPE
VALUES. SEVERE WATCH ALREADY ISSUED FOR POINTS NORTH OF A BOULDER TO
AKRON LINE...INCLUDING ALL OF WASHINGTON COUNTY...UNTIL 02Z. LOOKING
LIKE HAIL WILL BE THE MAIN THREAT IN THIS AREA...THOUGH STRONG WINDS
CERTAINLY A POSSIBILITY. FURTHER SOUTH...SEVERE THREAT MORE
UNCERTAIN AS WINDS ALOFT WEAKER. COULD SEE SOME MARGINAL SEVERE HAIL
WITH EXPECTED CAPES AROUND 1500 J/KG. ELSEWHERE...CONVECTION HAS
BEEN ONGOING AND LINGERING ACROSS PARK AND SOUTHERN JEFFERSON
COUNTIES THE LAST FEW HOURS WHILE THE CONVECTION ACROSS JACKSON AND
LARIMER COUNTIES SLOWLY MOVING SOUTHEAST. STORMS YET IN THE DENVER
METRO AREA. AS SHORTWAVE MOVES ACROSS CWA...SHOULD SEE STORMS SPREAD
ACROSS REMAINDER OF AREA...LIKELY POPS SEEM REASONABLE FOR MOST OF
CWA THIS EVENING. WITH PRECIPITABLE WATER VALUES AROUND NINE TENTHS
OF AN INCH...COULD SEE SOME HEAVY RAIN WITH THE STORMS AND THE SLOW
MOVEMENT COULD CAUSE SOME FLOODING PROBLEMS. CONVECTION SHOULD END
BY MIDNIGHT AS WAVE CLEARS CWA AND SUBSIDENCE INCREASES. BOUNDARY
LAYER WIND AND HUMIDITY PROGS SUGGEST POTENTIAL FOR LOW CLOUDS AND
FOG. HOWEVER...SURFACE PROGS INDICATE THAT THERE SHOULD BE
SUFFICIENT DRAINAGE FLOW TO OFFSET FOG DEVELOPMENT. ON FRIDAY...
MODELS SHOW DRIER AIR MOVING ACROSS CWA AS HIGH PRESSURE FROM THE
GREAT BASIN BEGINS TO BUILD OVER AREA. FORECAST SOUNDINGS SHOW
PRECIPITABLE WATER VALUES AROUND THREE QUARTERS OF AN INCH BY 21Z.
STILL SUFFICIENT MOISTURE FOR ANOTHER ROUND OF AFTERNOON STORMS...
BUT SHOULD BE LIMITED IN COVERAGE AS MODELS STILL SHOW QUITE A BIT
OF MID LEVEL WARMING. WILL NOT CHANGE MUCH FROM ONGOING AFTERNOON
POP GRIDS...WITH SCATTERED MOUNTAINS AND FOOTHILLS...LOWER POPS
ELSEWHERE. TEMPERATURE AND THICKNESS PROGS SUGGEST HIGHS IN THE MID
80S ACROSS PLAINS...IN LINE WITH GUIDANCE. CURRENT TEMPERATURE GRIDS
SEEM ON TRACK.

.LONG TERM...WEATHER PATTERN WILL BEGIN TO DRY OUT AND WARM UP AS A
LARGE UPPER LEVEL RIDGE SLOWLY MIGRATES TO THE NORTHEAST.  THE
PATTERN SHIFTS INTO A HIGH AMPLITUDE RIDGE TROUGH SYSTEM OVER THE
CONTINENTAL U.S. BY EARLY NEXT WEEK...SO THIS SHOULD HELP PROMOTE
WELL ABOVE NORMAL TEMPERATURES OVER OUR FORECAST AREA.  HIGHS SHOULD
BE ABLE TO CLIMB INTO THE LOWER TO MID 90S ACROSS THE PLAINS THROUGH
MUCH OF THE PERIOD.

THERE IS SOME MOISTURE STILL TRAPPED UNDER THE RIDGE SO THAT WOULD
STILL PROMOTE AFTERNOON AND EVENING CONVECTION...BUT COVERAGE WILL
BE LIMITED BY THE WARM MID LEVEL TEMPS AND LACK OF ANY FORCING
FEATURE.  MAIN THREAT OF STORMS WOULD REMAIN IN AND NEAR THE
MOUNTAINS.

&&

.AVIATION...SCATTERED SHOWERS AND THUNDERSTORMS WILL AFFECT DIA
THROUGH 04Z WITH HEAVY RAIN...SMALL HAIL AND ERRATIC WIND GUSTS UP
TO 35KTS A POSSIBILITY. CIGS/VSBYS COULD BRIEFLY LOWER TO MVFR
CONDITIONS WITH THUNDERSTORM PASSAGE. DRIER CONDITIONS FRIDAY WITH
ONLY A SLIGHT CHANCE OF THUNDERSTORMS AFTER 18Z.

&&

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

&&

D-L/BARJENBRUCH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DENVER CO
1101 AM MDT THU JUL 12 2007

COZ030>051-131200-
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-
1101 AM MDT THU JUL 12 2007

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

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS WILL FIRST DEVELOP ACROSS THE MOUNTAINS AND
FOOTHILLS THIS AFTERNOON...THEN OVER THE PLAINS LATE THIS AFTERNOON
AND EVENING. THE STORMS WILL BE MORE NUMEROUS ACROSS THE SOUTHERN
FRONT RANGE FOOTHILLS...PARK COUNTY AND PALMER DIVIDE REGION. THE
MAIN THREAT WILL BE HEAVY RAIN WITH RAINFALL RATES UP TO AN INCH IN
30 MINUTES AND POSSIBLE FLOODING. A FEW STORMS COULD BECOME SEVERE
WITH HAIL UP TO ONE INCH IN DIAMETER.

A MOIST ATMOSPHERE REMAINS IN PLACE OVER THE AREA WHILE AN UPPER
LEVEL DISTURBANCE WILL MOVE INTO WESTERN COLORADO LATER TODAY. THE
SEVERE WEATHER THREAT IS LOWER TODAY AS THE FLOW ALOFT IS A BIT
WEAKER. THE BEST CHANCE FOR SEVERE STORMS WILL BE NORTHEAST OF A
GREELEY TO LIMON LINE WHERE THE SHEAR IS MORE FAVORABLE.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THUNDERSTORM COVERAGE AND INTENSITY ARE EXPECTED TO BE ON THE
DECLINE BEGINNING FRIDAY AND ESPECIALLY OVER THE WEEKEND INTO EARLY
NEXT WEEK.  A RIDGE OF HIGH PRESSURE BUILDING OVER THE CENTRAL
ROCKIES WILL RESULT IN A WARMER AND DRIER AIRMASS BEGINNING THIS
WEEKEND.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED OVER THE NORTHEAST PLAINS OF
COLORADO AFTER 2 PM.

D-L/BARJENBRUCH