Severe Thunderstorm Warning 69, NWS Denver/Boulder, CO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
315 PM MDT SUN JUN 20 2004

.SHORT TERM...RADAR SHOWING CONVECTION MOVING ACROSS MOUNTAINS AND
PUSHING ONTO PLAINS.  ACTIVITY SUPPORTED BY JET MAX MOVING ACROSS
NORTHWEST COLORADO...AS NOTED BY WATER VAPOR LOOPS.  ACARS SOUNDING
HAS SHOWN THAT CAP ACROSS PLAINS HAS ERODED...THOUGH LAPS ANALYSIS
INDICATED SOME WEAK CIN STILL AROUND.  CAPE VALUES IN THE 1000-2000
J/KG...SO ONCE CIN IS GONE..STORMS WILL HAVE POTENTIAL TO BECOME
SEVERE WITH LARGE HAIL THE MAIN THREAT.  SEVERE WATCH CURRENTLY IN
EFFECT FOR PLAINS ZONES THROUGH 02Z. ACTIVITY COULD LAST BEYOND
MIDNIGHT AS CWA WILL REMAIN UNDER FAVORABLE ASCENT REGION OF THE
JET.  DIV-Q PROGS ALSO SHOW UPWARD FORCING OVERNIGHT.  IN
ADDITION...FAIRLY STRONG SURGE EXPECTED TO MOVE ACROSS NORTHEASTERN
COLORADO AROUND 04Z...WHICH MAY AID IN LIFT. CURRENT GRIDS SHOW 40
PERCENT POPS WHICH LOOKS ON TRACK.  WAS TEMPTED TO RAISE THE
POPS...BUT FEEL THE SURGE AFTER FROPA MAY SUPRESS THINGS.  BOUNDARY
LAYER WINDS AND HUMIDITY PROGS DO NOT SUPPORT WIDESPREAD FOG
OVERNIGHT...AND ANY ONGOING SHOWERS SHOULD KEEP IT LIMITED.
STILL...THERE IS SUFFICIENT LOW LEVEL MOISTURE TO WARRANT AT LEAST A
MENTION OF SOME FOG.  ON MONDAY...UPPER TROUGH WILL PASS ACROSS
REGION...WITH COOLER AIR OVER AREA.  7H TEMPERATURES PROGGED TO COOL
TO +4 DEGREES CELSIUS BY AFTERNOON.  THE COOLER ALOFT SHOULD BE
ENOUGH TO DESTABILIZE THE ATMOSPHERE BY AFTERNOON.  WITH HELP FROM
DYNAMICS ALOFT...SHOULD SEE SOME AFTERNOON THUNDER.  WITH THE COOLER
AIR IN PLACE...AFTERNOON HIGHS ACROSS PLAINS MAY NOT REACH 70
DEGREES.  CURRENT ETA GUIDANCE SEEMS MORE REASONABLE THAN NGM.

.LONG TERM DISCUSSION...FLOW NR THE SFC ACRS THE ERN PLAINS SHUD
TURN TO THE SOUTH BY AFTN AS HIGH PRESSURE BLDS INTO NEBR AND KS.
THIS WILL ALLOW TEMPS TO WRM BACK UP INTO THE 70S TO LWR 80S
LOCALLY.  MESOETA SEEMS TO KEEP ATM CAPPED WITH LWR DWPTS IN THE
WAKE OF MONDAYS COLD FRONT.  SINCE THIS MDL DID A POOR JOB OF
INITIALIZATION THIS AFTN...WL GO WITH THE SLGTLY WETTER AND LESS
STBL GFS MDL FOR UPCOMING GRIDS/ZFP.  THIS WOULD YIELD SOME SCT TSTM
ACTIVITY DURING THE AFTN IN THE FOOTHILLS AND ISOLD TSTMS ELSEWHERE
...BUT MSTR SEEMS TO SPARTAN FOR A TYPICAL DAY-2 TYPE SCENARIO.

WED...FURTHER WARMING LOOKS PROBABLE AS AIRMASS MODERATES SOMEWHAT.
BUT MEAN FLOW WL STILL BE OUT OF THE NORTHWEST...MEANING TEMPS WL
STILL BE A FEW DEGREES BLO NRML FOR THIS TIME OF YEAR.  GFS DEPICTS
A WK DISTURBANCE MOVING INTO THE AREA ARND 00Z THURS WHICH COULD
TOUCH OFF SOME LATE DAY CONVECTION.  HWVR...A MUCH STRONGER
DISTURBANCE HAS BEEN CONSISTANTLY PROGGED TO MOV INTO THE AREA THURS
BY THE GFS.  THIS SHOULD LEAD TO ANOTHER COOLDOWN AND PERHAPS SOME
UPSLOPE PCPN.  UPLIFT AT THIS TIME LOOKS DECENT AND WL UP POPS
SLIGHTLY FOR THE LATTER HALF OF THE WORK WEEK.  IN ALL...A
CONTINUATION OF THE UNSEASONABLY COOL WX WITH DAILY CHANCES FOR AFTN
AND EVENING THUNDERSTORMS SHUD CONTINUE.

&&

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

D-L/046

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DENVER CO
1100 AM MDT SUN JUN 20 2004

COZ030>051-211200-
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-
1100 AM MDT SUN JUN 20 2004

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

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS WILL AGAIN DEVELOP ACROSS THE MOUNTAINS  AND
MOVE ACROSS PLAINS DURING THE AFTERNOON AND EVENING HOURS.  SOME
STORMS MAY BECOME SEVERE ALONG THE FOOTHILLS AFTER 2 PM...WITH THE
THREAT SHIFTING EASTWARD INTO THE EVENING.  LARGE HAIL WILL BE THE
MAIN THREAT WITH THE SEVERE STORMS.

RECENT RAINS ACROSS SOUTHERN LINCOLN COUNTY HAVE SATURATED THE
GROUND.  ADDITIONAL RAINFALL COULD CREATE LOCALIZED FLOODING
PROBLEMS.

THE STORMS WILL LIKELY LAST THROUGH MUCH OF TONIGHT AS ANOTHER COLD
FRONT AND UPPER LEVEL DISTURBANCE MOVES ACROSS THE AREA.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

AN ISOLATED THUNDERSTORM WILL BE POSSIBLE DURING THE EARLY MORNING
HOURS ACROSS THE FAR NORTHEASTERN PLAINS.  OTHERWISE...COOLER AND
MORE STABLE AIR INFILTRATING THE AREA WILL PUT A LID ON CONVECTION
ACROSS THE PLAINS FOR MONDAY.  SOME SCATTERED SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE IN THE FOOTHILLS AND NEARBY FRONT
RANGE LOCATIONS MONDAY AFTERNOON...BUT NO SEVERE ACTIVITY IS
EXPECTED.  SOUTHERLY FLOW WILL RETURN FOR TUESDAY AND WEDNESDAY
WHICH WILL LEAD TO BETTER CHANCES FOR AFTERNOON THUNDERSTORMS
RETURNING TO THE PLAINS.  ANOTHER DISTURBANCE WILL MOVE INTO THE
AREA THURSDAY AND PERHAPS FRIDAY.  THUS...THE THREAT OF SHOWERS AND
THUNDERSTORMS WILL CONTINUE THROUGH THE END OF THE WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED AFTER 2 PM.

D-L/046

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
313 PM MDT SUN JUN 20 2004

..TIME...   ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE...   ....MAG....     ..COUNTY LOCATION...ST.. ...SOURCE....
            ..REMARKS..

0300 PM     HAIL             E BRIGHTON              39.96N 104.79W
06/20/2004  0.75 INCH        ADAMS              CO   TRAINED SPOTTER

&&

SE

PRELIMINARY LOCAL STORM REPORT ... SUMMARY
NATIONAL WEATHER SERVICE DENVER CO
316 PM MDT SUN JUN 20 2004

..TIME...   ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE...   ....MAG....     ..COUNTY LOCATION...ST.. ...SOURCE....
            ..REMARKS..

0312 PM     HAIL             4 SE LOCHBUIE           39.96N 104.67W
06/20/2004  0.75 INCH        WELD               CO   TRAINED SPOTTER

0300 PM     HAIL             E BRIGHTON              39.96N 104.79W
06/20/2004  0.75 INCH        ADAMS              CO   TRAINED SPOTTER

&&

SE