Severe Thunderstorm Warning 152, NWS Denver/Boulder, CO

NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
253 PM MDT FRI AUG 1 2003

SHORT TERM DISCUSSION:  CONVECTION CURRENTLY FIRING ACROSS MOUNTAINS
AND FOOTHILLS...TRYING TO MAKE ITS WAY ACROSS ADJACENT PLAINS.
SHORTWAVE EVIDENT ON SATELLITE ACROSS SOUTHERN WYOMING.  ACARS
SOUNDINGS STILL INDICATE A BIT OF A CAP...ALSO NOTED ON LAPS DATA.
SHORTWAVE EVIDENT ON WATER VAPOR LOOPS ACROSS SOUTHERN WYOMING WHICH
SHOULD HELP TO BREAK CAP.  ONCE STORMS SURVIVE...POTENTIAL EXISTS
FOR A FEW OF THE STORMS BECOMING SEVERE AS LAPS CAPES AROUND 1500
J/KG.  LOW LEVEL WINDS BECOMING SOUTHEAST AND INCREASING...SO THE
SHEAR BECOMING A BIT BETTER.  LARGE HAIL AND WIND GUSTS STILL THE
MAIN THREAT...ALTHOUGH A BRIEF SPINUP TORNADO ALONG ANY BOUNDARY
CANNOT BE RULED OUT.  WILL WAIT TO THE LAST MINUTE TO DECIDE TO
MENTION SEVERE IN THE ZONES. FURTHER EAST...WILL KEEP THE ISOLATED
POPS GOING...THOUGH AIRMASS MAY STILL BE CAPPED.  MODELS IMPLY THAT
STORMS ACROSS SOUTHEAST CWA MAY LAST BEYOND MIDNIGHT.  SKIES SHOULD
CLEAR OVERNIGHT...THOUGH MODELS KEEP SOME CLOUD HANGING AROUND.
ON SATURDAY...MODELS CONTINUE TO ADVERTISE AN INCREASE IN
PRECIPITABLE WATER VALUES BY AFTERNOON ...AROUND AN INCH ALONG
FOOTHILLS AND UP TO SEVEN TENTHS OF AN INCH ACROSS THE MOUNTAINS.
AT THE SAME TIME...THETA-E RIDGE LINES UP OVER MOUNTAINS AND
ADJACENT PLAINS.  AT THE SURFACE...EASTERLY WINDS SHOULD KEEP
DEWPOINTS IN THE 50S.  DAYTIME HEATING AND INSTABILITY WILL CAUSE
THUNDERSTORM INITIATION OVER MOUNTAINS AND FOOTHILLS BY AFTERNOON
...THOUGH THERE SEEMS TO LITTLE DYNAMICS ALOFT TO AID IN
DEVELOPMENT.  PLAINS LOOK TO BE CAPPED INITIALLY...THEN SHOULD BE
FAVORABLE FOR SUSTAINING THE STORMS ONCE THEY MOVE OFF FOOTHILLS.
CURRENT POPS LOOK DECENT...SCATTERED MOUNTAINS AND ADJACENT PLAINS...
ISOLATED FURTHER EAST.  SHEAR NOT ALL THAT IMPRESSIVE FOR SEVERE
STORMS AS WINDS ALOFT ARE FORECAST TO WEAKEN.  SO CONCERN POINTS TO
SLOW MOVING STORMS AND POTENTIAL FOR HEAVY RAINFALL.  A BIT TOO
EARLY TO ISSUE ANY WATCH AT THIS TIME...THOUGH NEEDS TO BE LOOKED
INTO.  GUIDANCE TEMPERATURES LOOK REASONABLE.    D-L

LONG TERM DISCUSSION: BY SATURDAY EVENING...THE GRIDS SHOW THE UPPER
RIDGE AXIS ACROSS WESTERN COLORADO WITH 25 TO 40 KNOT JET LEVEL
ACROSS MUCH OF THE FORECAST OFFICE.  ON THE SUNDAY THE AXIS MOVES
EASTWARD INTO THE FORECAST AREA.  LATE SUNDAY NIGHT INTO THE
MONDAY...THE RIDGE FLATTENS SOMEWHAT WITH THE JET LEVEL FLOW
BECOMING WEST-SOUTHWESTERLY AT 25 TO 45 KNOTS.  WEAK DOWNWARD
SYNOPTIC SCALE FORCING IS PROGGED SATURDAY NIGHT...NEUTRAL FORCING
ON SUNDAY...WEAK ASCENT SUNDAY NIGHT...THEN NEUTRAL ON MONDAY.  IN
THE LOW LEVELS...GRIDS KEEP SHOWING AN EASTERLY COMPONENT TO THE
BOUNDARY LEVEL WINDS THROUGH MID DAY SUNDAY.  CONCERNING MOISTURE...
GRIDS SHOW A SIGNIFICANT THETA-E AXIS OVER MUCH OF THE FORECAST AREA
SATURDAY EVENING AND SUNDAY.  BY MONDAY...GRIDS SHOW THIS AXIS OVER
THE FAR NORTHEAST CORNER EARLY IN THE AFTERNOON...THEN EAST OF THE
FORECAST AREA BY 21Z.  CROSS SECTIONS ARE SHOWING DECENT POTENTIAL
INSTABILITY SATURDAY EVENING AND SUNDAY...BUT NOT VERY GOOD ON
MONDAY.  MOISTURE IS BEST ON SUNDAY...BUT PRETTY GOOD ON SATURDAY
EVENING...THE DRIEST ON MONDAY.  CROSS SECTIONS ARE SHOWING PRETTY
STEEP LAPSE RATES SATURDAY EVENING AND SUNDAY...BUT A MID LEVEL CAP
IS INDICATED ON MONDAY.   WILL PUT THE HIGHEST POPS ON SUNDAY...THE
LOWEST FOR LATE DAY MONDAY.  FOR TEMPERATURES...GRIDS ARE SHOW
LITTLE CHANCE THROUGH SUNDAY...WITH A 1-3 C WARM-UP FOR MONDAYS
HIGHS.

IN THE EXTENDED PERIOD...TUESDAY THROUGH FRIDAY...THE MEDIUM RANGE
MODELS SHOW THE TROUGH AXIS ACROSS THE FORECAST AREA WITH THE CENTER
OF THE RIDGE OVER NEW MEXICO.  BY FRIDAY...THE RIDGE CENTER IS
PROGGED TO MOVE UP INTO THE FORECAST AREA.  THE MOISTURE DECREASES
SOMEWHAT DURING THE LATER PART OF THE WEEK...SO WILL GO WITH A
SLIGHT CHANCE.     RJK

.DEN...NONE.

COZ030>051-021200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DENVER CO
1100 AM MDT FRI AUG 01 2003

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

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS WILL DEVELOP OVER THE MOUNTAINS EARLY THIS
AFTERNOON...THEN SPREAD AND DEVELOP SOUTHEASTWARD ACROSS THE PLAINS
BETWEEN 3 PM AND MIDNIGHT.  INSTABILITY AND WIND SHEAR IN THE
ATMOSPHERE SHOULD BE SUFFICIENT FOR THE DEVELOPMENT OF SEVERE
THUNDERSTORMS.  LARGE HAIL AND DAMAGING WINDS WILL BE THE MAIN
THREATS.  THE GREATEST POTENTIAL FOR SEVERE THUNDERSTORMS EXISTS
FROM THE INTERSTATE 25 URBAN CORRIDOR EASTWARD TOWARD THE FORT
MORGAN AND LIMON AREAS.

STRONGER STORMS WILL ALSO BE CAPABLE OF PRODUCING RAINFALL RATES IN
EXCESS OF 1 INCH IN 30 MINUTES.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS CAN BE EXPECTED BOTH
SATURDAY AND SUNDAY.  HEAVY RAINS ARE POSSIBLE BOTH DAYS WITH THE
STORMS. BY MONDAY THE ATMOSPHERE DRIES OUT SOMEWHAT SO ONLY A SLIGHT
CHANCE OF THUNDERSTORMS CAN BE EXPECTED.  ENOUGH MOISTURE WILL BE
AROUND THROUGH THE NEST OF NEXT WEAK TO CONTINUE THIS TREND.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED ACROSS THE FRONT RANGE METRO
AREAS AND ADJACENT PLAINS BY 3 PM.

D-L/RJK