Severe Thunderstorm Warning 122, NWS Denver/Boulder, CO

AREA FORECAST DISCUSSION FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER COLORADO
248 AM MDT SAT AUG 28 1999

QUITE A FEW SHOWERS/STORMS STILL GOING EARLY THIS MORNING AS
OUTFLOW/LOW LEVEL JET INTERACTION CONTINUE TO SPARK NEW CONVECTION
OVER THE NORTHEAST PLAINS.  SHOWERS SHOULD SLOWLY WEAKEN THROUGH
EARLY MORNING BUT STILL EXPECT A FEW AROUND AT SUNRISE.  MODELS
CONTINUE TO INDICATE MAIN THRUST OF SHORT WAVE TO PASS THROUGH
WYOMING TODAY...BUT EASTERN COLORADO STILL EXPECTED TO SEE SOME
EFFECT OF TRAILING END OF WAVE PER DIV-Q AND POT VORT FIELDS.
LATEST RUC AGREES THAT EDGE OF WAVE SHOULD BE REACHING NORTHEAST
COLORADO 21Z-00Z WHICH COINCIDES WITH TIME OF MAX HEATING.
MARGINALLY UNSTABLE AIRMASS WITH EXPECTED CAPES OF 1400-2000 J/KG
AND PLENTY OF MOISTURE TO GO AROUND WITH PRECIPITABLE WATER VALUES
OF 1.10 TO 1.35 INCHES.

BIGGEST QUESTION IS IF WE CAN GET ENOUGH SURFACE HEATING FOR MAX
INSTABILITY AND STRONG SURFACE BASED CONVECTION.  AT THIS TIME...
APPEARS WE SHOULD BE IN SOMEWHAT OF A CLOUD BREAK FOR AT LEAST
PARTLY SUNNY CONDITIONS THIS MORNING WHICH SHOULD BE ENOUGH TO BOOST
TEMPS INTO THE LOWER 80S.  THUS...SURFACE BASED CONVECTION ON THE
PLAINS SHOULD BE REALIZED.  SHEAR PROFILE INCREASES INTO MARGINAL
CATEGORY SO WOULD NOT RULE OUT A COUPLE BRIEF SEVERE STORMS LATE
THIS AFTERNOON.  EVEN THOUGH STEERING WINDS WILL INCREASE INTO THE
15-20 KNOT RANGE BY AFTERNOON...AN ORGANIZED STORM WITH SUSTAINED
UPDRAFT WILL LIKELY ONLY MOVE AT 8-10 KNOTS AND MORE TO THE EAST.
IN ADDITION...THERE MAY ALSO BE SOME TRAINING STORMS.  THEREFORE...
POTENTIAL OF HEAVY RAIN AND LOCAL FLOODING PROBLEMS STILL EXIST
TODAY.  NO FLASH FLOOD WATCH YET THOUGH DUE TO SOME UNCERTAINTY OF
SURFACE HEATING AND SOMEWHAT FASTER MOVEMENT OF CELLS.

LOOKS LIKE SUBSIDENCE ON SUNDAY MAY BE WEAKER THAN ORIGINALLY
FORECAST.  IN ADDITION...LOTS OF LOW LEVEL MOISTURE AND THETA-E AXIS
HOLDS OVER THE AREA.  THUS...WILL BOOST POPS SLIGHTLY TO 20 PERCENT.

.DEN...NONE.

BARJENBRUCH

COZ030-032>050-290600-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER CO
1100 AM MDT SAT AUG 28 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...A BAND OF MONSOONAL MOISTURE FROM MEXICO WILL CONTINUE TO
STREAM NORTHWARD ON SOUTH TO SOUTHWESTERLY FLOW ALOFT OVER NORTHEAST
AND NORTH CENTRAL COLORADO THROUGH THE AFTERNOON AND EVENING HOURS.
RESIDUAL MOISTURE AT LOW LEVELS FROM YESTERDAYS HEAVY RAINS HAS
INCREASED OVER THE PLAINS.  AN UPPER LEVEL DISTURBANCE WILL AID IN
DESTABILIZING THIS VERY MOIST AIR MASS OVER THE AREA.  WITH FREEZING
LEVELS SLIGHTLY LOWER AND STRONGER WINDS ALOFT PROVIDING MORE SHEAR
THAN YESTERDAY THE THREAT OF SEVERE THUNDERSTORMS PRODUCING LARGE HAIL
AND DAMAGING WINDS WILL INCREASE.  IN ADDITION...WITH THE AMOUNT OF
MOISTURE IN THE AIR MASS AT 170 PERCENT OF NORMAL FOR THIS TIME OF
YEAR...THE THREAT OF HEAVY THUNDERSTORM RAINFALL WILL CONTINUE TO BE
HIGH EVEN THOUGH THE STORMS WILL BE MOVING AT A FASTER RATE OF SPEED.
THE THREAT OF THE HEAVY RAIN PRODUCING FLOODING WILL BE INCREASED DUE
TO ALREADY SATURATED SOILS.  THE THREAT OF DEADLY CLOUD TO GROUND
LIGHTNING FROM THESE STORMS WILL CONTINUE TO BE PRESENT.

BY MIDDAY SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM OVER THE
MOUNTAINS AND EASTERN FOOTHILLS AND MOVE TO THE NORTHEAST OVER THE
FRONT RANGE URBAN CORRIDOR AND THE NORTHEASTERN PLAINS DURING THE
AFTERNOON AND EVENING.  A FEW OF THESE STORMS OVER THE URBAN CORRIDOR
AND ON THE PLAINS MAY BE SEVERE...PRODUCING LARGE HAIL AND DAMAGING
WINDS.  THE STRONGEST THUNDERSTORMS WILL BE CAPABLE OF PRODUCING UP
TO 3 INCHES OF RAIN IN AN HOUR.  THIS HEAVY AMOUNT OF RAIN WILL CAUSE
LOCAL FLOODING OF STREETS...HIGHWAYS AND UNDERPASSES...NORMALLY DRY
GULCHES...SMALL CREEKS AND STREAMS AND LOW LYING OR FLOOD PRONE
AREAS.  THE HEAVY RAIN MAY ALSO TRIGGER MUD AND ROCK SLIDES IN
CANYONS AND STEEP TERRAIN.

SPOTTER ACTIVATION MAY BE REQUIRED THIS AFTERNOON.

GARD...WFO BOULDER

COZ030-032>050-290600-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER CO
1100 AM MDT SAT AUG 28 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...A BAND OF MONSOONAL MOISTURE FROM MEXICO WILL CONTINUE TO
STREAM NORTHWARD ON SOUTH TO SOUTHWESTERLY FLOW ALOFT OVER NORTHEAST
AND NORTH CENTRAL COLORADO THROUGH THE AFTERNOON AND EVENING HOURS.
RESIDUAL MOISTURE AT LOW LEVELS FROM YESTERDAYS HEAVY RAINS HAS
INCREASED OVER THE PLAINS.  AN UPPER LEVEL DISTURBANCE WILL AID IN
DESTABILIZING THIS VERY MOIST AIR MASS OVER THE AREA.  WITH FREEZING
LEVELS SLIGHTLY LOWER AND STRONGER WINDS ALOFT PROVIDING MORE SHEAR
THAN YESTERDAY THE THREAT OF SEVERE THUNDERSTORMS PRODUCING LARGE HAIL
AND DAMAGING WINDS WILL INCREASE.  IN ADDITION...WITH THE AMOUNT OF
MOISTURE IN THE AIR MASS AT 170 PERCENT OF NORMAL FOR THIS TIME OF
YEAR...THE THREAT OF HEAVY THUNDERSTORM RAINFALL WILL CONTINUE TO BE
HIGH EVEN THOUGH THE STORMS WILL BE MOVING AT A FASTER RATE OF SPEED.
THE THREAT OF THE HEAVY RAIN PRODUCING FLOODING WILL BE INCREASED DUE
TO ALREADY SATURATED SOILS.  THE THREAT OF DEADLY CLOUD TO GROUND
LIGHTNING FROM THESE STORMS WILL CONTINUE TO BE PRESENT.

BY MIDDAY SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM OVER THE
MOUNTAINS AND EASTERN FOOTHILLS AND MOVE TO THE NORTHEAST OVER THE
FRONT RANGE URBAN CORRIDOR AND THE NORTHEASTERN PLAINS DURING THE
AFTERNOON AND EVENING.  A FEW OF THESE STORMS OVER THE URBAN CORRIDOR
AND ON THE PLAINS MAY BE SEVERE...PRODUCING LARGE HAIL AND DAMAGING
WINDS.  THE STRONGEST THUNDERSTORMS WILL BE CAPABLE OF PRODUCING UP
TO 3 INCHES OF RAIN IN AN HOUR.  THIS HEAVY AMOUNT OF RAIN WILL CAUSE
LOCAL FLOODING OF STREETS...HIGHWAYS AND UNDERPASSES...NORMALLY DRY
GULCHES...SMALL CREEKS AND STREAMS AND LOW LYING OR FLOOD PRONE
AREAS.  THE HEAVY RAIN MAY ALSO TRIGGER MUD AND ROCK SLIDES IN
CANYONS AND STEEP TERRAIN.

SPOTTER ACTIVATION MAY BE REQUIRED THIS AFTERNOON.

GARD...WFO BOULDER