Severe Thunderstorm Warning 133, NWS Denver/Boulder, CO

NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER COLORADO
330 AM MDT MON AUG 13 2001

WATER VAPOR LOOP SHOWS HIGH AMPLITUDE UPPER LEVEL RIDGE CENTERED
OVER COLORADO AND WESTERN WYOMING.  MEANWHILE...A SIGNIFICANT SHORT
WAVE WAS TAKING SHAPE OVER WESTERN ARIZONA.  AS THE UPPER LEVEL
RIDGE SHIFTS SLOWLY EASTWARD THROUGH TONIGHT...THE SHORT WAVE WILL
RIDE UP THE BACK SIDE OF THE RIDGE AND INTO SOUTHWEST COLORADO BY
THIS EVENING.  THEREFORE...THIS DISTURBANCE WILL NOT IMPACT THE
PLAINS TODAY...BUT SHOULD HELP STORM COVERAGE IN THE MOUNTAINS FROM
LATE THIS AFTERNOON THROUGH TONIGHT WITH SOME UPWARD Q-G FORCING AND
PLENTY OF MOISTURE TO WORK WITH.

ON THE PLAINS...SURFACE HIGH PRESSURE TO THE EAST AND SOME
CLOUDINESS WILL HOLD BACK SURFACE WARMING A BIT.  QUESTION IS
WHETHER WE BREAK THE CAP THAT MODELS ARE HINTING AT.  SURFACE
PRESSURE FALLS OVER WYOMING AND ALONG THE FRONT RANGE LATER TODAY
WILL TIGHTEN THE PRESSURE GRADIENT AND INCREASE SOUTHEASTERLY LOW
LEVEL WINDS...THEREBY RESULTING IN A DENVER CONVERGENCE ZONE.
THEREFORE...EVEN IF TEMPS DONT HIT CONVECTIVE READINGS AROUND 86F...
WE SHOULD END UP WITH ENOUGH CONVERGENCE ALONG THE BOUNDARY TO BREAK
THROUGH THE CAP.  FOR THIS REASON WILL HAVE BEST POPS FROM DOUGLAS
COUNTY THROUGH EASTERN ADAMS AND ARAPAHOE COUNTIES THIS AFTERNOON
AND EVENING...WHILE LOWERING POPS A BIT ELSEWHERE THIS AFTERNOON
BECAUSE OF SLOW MOVEMENT OF SHORT WAVE.  WITH STRENGTH OF SOUTHEAST
LOW LEVEL FLOW (AT LEAST 15 KTS)...BOUNDARY MAY HAVE A TENDENCY TO
PUSH NORTHWESTWARD.  DAY SHIFT WILL HAVE TO WATCH THIS FOR POSSIBLE
IMPLICATIONS ON STORM CHANCES IN DENVER.  ALTHOUGH WIND SHEAR ALOFT
IS RATHER WEAK...COULD NOT RULE OUT A SEVERE STORM WITH STRENGTH OF
LOW LEVEL FLOW AND CAPES NEAR 1500 J/KG ALONG BOUNDARY.

ON TUESDAY...SHORT WAVE MOVES ACROSS THE CWA BUT TIMING WILL HAVE A
BIG AFFECT ON INTENSITY OF WEATHER.  PRELIMINARY INDICATIONS ARE
THAT STRONGEST STORMS MAY DEVELOP ALONG LOW LEVEL CONVERGENCE ZONE
WHICH MOVES TO JUST EAST OF FRONT RANGE URBAN CORRIDOR BY MID DAY.
SCATTERED POPS ALL AREAS LOOKS GOOD.

THEN COOLER SURGE COMES IN FOR WEDNESDAY AND THURSDAY SO HIGH TEMPS
IN THE 70S ARE ON THE RIGHT TRACK.  NO CHANGES TO EXTENDED.

BARJENBRUCH

.DEN...NONE.

COZ030>051-132000-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER CO
1100 AM MDT MON AUG 13 2001

THIS OUTLOOK PERTAINS TO THE FOLLOWING COLORADO COUNTIES

ADAMS     ARAPAHOE     BOULDER   CLEAR CREEK   DENVER       DOUGLAS
ELBERT    GILPIN       GRAND     JACKSON       JEFFERSON    LARIMER
LINCOLN   LOGAN        MORGAN    PARK          PHILLIPS     SEDGWICK
SUMMIT    WASHINGTON   WELD

SYNOPSIS...AN UPPER LEVEL RIDGE WILL REMAIN CENTERED OVER THE
ROCKY MOUNTAINS TODAY AND TONIGHT...BUT A STRONG UPPER LEVEL
DISTURBANCE WILL ROTATE NORTHWARD FROM ARIZONA INTO EASTERN UTAH
AND WESTERN COLORADO TONIGHT.  THIS SYSTEM WILL SPREAD MONSOONAL
MOISTURE NORTHWARD OVER THE COLORADO NORTH CENTRAL MOUNTAINS THIS
EVENING.  SURFACE HIGH PRESSURE WILL REMAIN OVER THE GREAT PLAINS.
WITH THE LOW LEVEL FLOW FROM THE SOUTHEAST OVER NORTHEASTERN
COLORADO...SURFACE DEWPOINTS WILL REMAIN IN THE 50S AND LOWER 60S.
THE FORMATION OF A DENVER MESOCYCLONE WILL DIRECT THIS MOISTURE
AGAINST THE FRONT RANGE AND CONTRIBUTE TO CONVECTIVE DEVELOPMENT
OVER THE FOOTHILLS.

ISOLATED SHOWERS AND THUNDERSTORMS WILL FORM OVER THE MOUNTAINS
AND EASTERN FOOTHILLS DURING THE EARLY AFTERNOON.  WITH LIGHT
WINDS ALOFT THESE STORMS WILL BE SLOW TO MOVE OFF THE FOOTHILLS
AND OVER THE URBAN CORRIDOR UNTIL LATE AFTERNOON.  SHOWERS AND
THUNDERSTORMS WILL INCREASE OVER THE MOUNTAINS THIS EVENING
AND MAY CONTINUE THROUGH THE NIGHT.  WITH THE INCREASE IN MOISTURE
AND INSTABILITY OVER THE MOUNTAINS THESE STORMS MAY PRODUCE LOCALLY
HEAVY RAIN ESPECIALLY THIS EVENING.  UP TO TWO INCHES OF RAIN IN AN
HOUR MAY CAUSE FLOODING OF SMALL STREAMS...NORMALLY DRY GULCHES AND
LOW LYING OR FLOOD PRONE AREAS.  THE RAIN MAY ALSO CAUSE MUD AND
ROCK SLIDES ON HIGHWAYS IN STEEP TERRAIN.

ONLY ISOLATED THUNDERSTORMS ARE EXPECTED OVER THE NORTHEASTERN
PLAINS FROM LATE THIS AFTERNOON THROUGH THE EVENING HOURS.  THESE
STORMS ARE NOT EXPECTED TO BECOME SEVERE.

SPOTTER ACTIVATION WILL NOT BE REQUIRED.

GARD...WFO BOULDER