Severe Thunderstorm Warning 128, NWS Denver/Boulder, CO

AREA FORECAST DISCUSSION FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER COLORADO
305 AM MDT WED SEP 1 1999

MAIN CONCERN WILL BE WHERE COLD FRONT OVER SOUTHERN WYOMING AND
NEBRASKA PANHANDLE ENDS UP...AND THUS THREAT OF SEVERE WEATHER.
MODEL RUNS HAVE BEEN PROGRESSIVELY WEAKER AND FARTHER NORTH WITH
FINAL FRONTAL POSITION.  LATEST 06Z RUC NOW INDICATES THAT FRONT MAY
HANG UP OVER THE CHEYENNE RIDGE BY 18Z.  08Z MAPS ANALYSIS INDICATES
ONLY VERY WEAK PRESSURE RISES NORTH OF FRONT...WHICH WOULD SUPPORT
THIS SOLUTION.  IN FACT...FRONT MAY HAVE A TENDENCY TO PUSH BACK
SLIGHT NORTHWARD LATE THIS AFTERNOON...SPURRED ON BY STRONG
SOUTHERLY FLOW ALOFT AND INCREASED SURFACE HEATING AND MIXING.
THUS...BEST CHANCE OF STORMS WILL BE NEAR THE WYOMING/NEBRASKA
BORDERS LATE AFTERNOON AND EVENING.  POINTS FARTHER SOUTH LIKE LIMON
MAY VERY WELL REMAIN CAPPED THIS AFTERNOON.

ANY STORMS THAT DEVELOP WILL BE CAPABLE OF TAKING ON SUPERCELL
CHARACTERISTICS AND BECOMING SEVERE.  SHEAR PROFILE AND LENGTH OF
HODOGRAPH IS MORE THAN SUFFICIENT TO PROMOTE SUSTAINED ROTATING
UPDRAFTS.  THEREFORE...EVEN THOUGH MONSOON FLOW IN PLACE...STORMS
WITH LARGE HAIL AND DAMAGING WINDS ARE POSSIBLE.  STORM RELATIVE
HELICITY REMAINS MAINLY BELOW 100 M2/S2...SO THREAT OF ANY TORNADOES
IS FAIRLY LOW AT THIS TIME.

AS LOW LEVEL JET INTENSIFIES THIS EVENING...STORMS MAY ALSO START
TRAINING AND PRODUCE FLOODING RAINS.

AGAIN...MUCH OF THIS OCCURRING DEPENDS ON POSITION OF FRONT THIS
AFTERNOON AND EVENING.  LATEST TRENDS AND INDICATIONS POINT TO THE
WYOMING AND NEBRASKA BORDER AREA.

LATER PERIODS LOOK OK WITH MONSOON FLOW STILL IN PLACE THROUGH
THURSDAY.  HOWEVER...AVN/MRF KEEPING UP WITH THEIR TRICKS BY ONCE
AGAIN RETURNING TO A MORE PROGRESSIVE SOLUTION WITH WEST COAST TROF.

BARJENBRUCH

.DEN...NONE.

COZ030-032>050-010600-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER CO
1045 AM MDT   WEDNESDAY   SEPTEMBER 1 1999

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:  THE FLOW OF MONSOON MOISTURE CONTINUES IN FULL SWING
OVER THE MOUNTAINS AND WESTERN COLORADO.  THE EASTERN EDGE OF THIS
MOISTURE IS OVER THE FRONT RANGE FOOTHILLS.  STRONG SOUTHWEST
WINDS ALOFT CONTINUE OVER THE AREA AS WELL.  THE COMBINATION OF
THE MOIST MONSOON AIRMASS AND UNSTABLE AIR CAUSED BY STRONG SOLAR
HEATING WILL SPAWN SCATTERED SHOWERS AND THUNDERSTORMS AGAIN THIS
AFTERNOON AND EVENING.  THE THREAT OF THUNDERSTORMS EXIST IN ALL
AREAS THIS AFTERNOON BUT THE MOST LIKELY LOCATIONS FOR THUNDERSTORMS
WILL BE THE FOOTHILLS...MOUNTAINS AND I-25 CORRIDOR AND IN WELD...
LOGAN...SEDGWICK AND PHILLIPS COUNTIES.

WITH THE STRONG FLOW ALOFT AND THE SUBSTANTIAL INSTABILITY OF THE
ATMOSPHERE...THE POTENTIAL EXISTS FOR SOME THUNDERSTORMS TO BE
SEVERE WITH WIND GUSTS TO NEAR 60 MPH AND PERHAPS SOME LARGE HAIL.
IF ANY SEVERE THUNDERSTORMS DO DEVELOP THEY ARE MOST LIKELY GOING
TO OCCUR NEAR THE WYOMING BORDER.  RAINFALL FROM THE THUNDERSTORMS
WILL BE ON THE ORDER OF 1/2 TO 1 INCH SINCE THE WINDS ALOFT WILL
PUSH THEM NORTHEAST ABOUT 25-30 MPH.

SPOTTER ACTIVATION IS NOT EXPECTED THIS AFTERNOON OR EVENING SINCE
MOST OF THE ACTIVITY IS EXPECTED TO BE NORTH AND EAST OF THE DENVER
METRO AREA...HOWEVER SIGNIFICANT WEATHER AND RAINFALL REPORTS WILL
BE GREATLY APPRECIATED.

END...BOODA...WFO DENVER