Severe Thunderstorm Warning 66, NWS Denver/Boulder, CO

NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER COLORADO
ISSUED BY NWS PUEBLO CO
230 PM MDT TUE JUL 18 2000

MAIN PROBLEMS ARE SEVERE CONVECTION THREAT THIS EVENING AS WELL AS
FOR THE NEXT COUPLE OF DAYS.

CURRENTLY NORTHWEST FLOW WITH STRONG SHEAR PROFILE...FOR MID
JULY...IS OVER THE REGION.  WIND SPEEDS OF 60 TO 70 KNOTS ARE OVER
NORTHERN COLORADO THIS AFTERNOON...WITH WINDS OF 30 TO 40 KNOTS AT
500MB.  THE MAIN PROBLEM IS GETTING ENOUGH LOW LEVEL MOISTURE TO GET
HIGH ENOUGH CAPES.  THROUGHOUT THE DAY...SURFACE WINDS HAVE BEEN
FROM THE WEST TO NORTHWEST OVER EASTERN WYOMING BEHIND A WEAK LOW
PRESSURE CENTER OVER CENTRAL NEBRASKA. THIS SURFACE LOW IS IN THE
LEFT EXIT REGION OF THE JET.  THE MODELS GENERALLY AGREE ON
WEAKENING THIS LOW AS IT MOVES FURTHER EAST ALLOWING EAST TO
SOUTHEAST FLOW TO DEVELOP OVER THE PLAINS.  AT 2PM (20 Z)...THE FLOW
ONLY HAS A WEAK EASTERLY COMPONENT ON THE PLAINS.  EACH SUCESSIVE
RUN OF THE RUC HAS BEEN DELAYING THE DEVELOPMENT OF THE STRONGER
EASTERLY FLOW LATER INTO THE EVENING.  HOWEVER...THERE IS PLENTY OF
MOISTURE IN KANSAS TO TAP INTO AS THE UPSLOPE DEVELOPS. RUC
SOUNDINGS FOR THE EASTERN PLAINS HAS CAPES OF 1800 TO 2500 LATE THIS
AFTERNOON AND EVENING WITH HELICITIES AS HIGH AS 50.  I WILL
DOWNPLAY THE SEVERE THREAT SOME.  THERE STILL IS A CHANCE FOR A
SEVERE STORM...BUT I WILL NOT MENTION ANYTHING IN THE ZONES.

OVER THE MOUNTAINS AND HIGH VALLEYS...THE ATMOSPHERE HAS BECOME
DRIER THAN YESTERDAY AND EXPECT ONLY TYPICAL EVENING CONVECTION.

ON WEDNESDAY...UPSLOPE FLOW BECOMES ESTABLISHED ON THE PLAINS
WITH ETA CAPES FROM 2000 TO 3000.  SHEAR LOOKS PRETTY GOOD WITH
SURFACE WINDS FROM THE SOUTHEAST AT 5 TO 15 KNOTS AND 500MB WINDS
FRON THE WEST AT 30 TO 35 KNOTS.  DAY 2 OUTLOOK HAS SLIGHT RISK FOR
PORTIONS OF THE PLAINS AND I SEE NO REASON TO DISAGREE WITH IT.
UPSLOPE MAKES IT TO THE FOOTHILLS AND SCATTERED POPS AND COOLER
TEMPERATURES LOOK REASONABLE.  AN MCS MAY DEVELOP AROUND THE
NORTHEAST CORNER OF THE STATE.  OVER THE MOUNTAINS...THERE IS A
MODEST AMOUNT OF MIDDLE AND UPPER LEVEL MOISTURE FOR WIDELY
SCATTERED CONVECTION.

ON THURSDAY...THE PATTERN REMAINS NEARLY THE SAME WITH ANOTHER
UPSLOPE SURGE ON THE EASTERN PLAINS TO REINFORCE THE LOW LEVEL
MOISTURE.  IN THE MOUNTAINS THERE WILL BE ENOUGH MOISTURE FOR
CONTINUED AFTERNOON AND EVENING CONVECTION.

IN THE EXTENDED...THE MRF...ECMWF AND UKMET CONTINUE HAVING USPLOPE
SURGES OVER THE REGION ON FRIDAY AND SATURDAY.  CURRENT EXTENDED
WITH CONVECTION AND COOLER THAN NORMAL TEMPERATURES ON THE PLAINS
LOOK REASONABLE.  BY SUNDAY...THE MRF HOWS AN IMPRESSIVLEY HIGH
AMPLITUDE RIDGE...FOR THIS TIME OF THE YEAR...TO THE WEST OF THE
REGION...WITH NORTHWEST FLOW ALOFT OVER THE REGION.  ECMWF AND UKMET
SHOW A LESS AMPLIFIED FLOW WITH THE RIDGE AXIS OVER THE REGION.
CURRENTLY...I AM FAVORING THE MORE CLIMATOLOGICALLY REASONABLE ECMWF
AND UKMET.  FOR SUNDAY...WILL KEEP SOME CONVECTION AROUND BUT WARM
TEMPERATURE TO NEAR SEASONABLE VALUES.

WOLYN WFO PUEBLO

.DEN...NONE.

COZ030-032>050-190600-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER CO
ISSUED BY NWS PUEBLO
1115 AM MDT TUE JUL 18 2000

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:

NORTHWEST FLOW WITH STRONG WIND SHEAR WILL REMAIN OVER THE REGION
THIS AFTERNOON AND TONIGHT.  WITH WEAK NORTHWEST FLOW AT THE
SURFACE...THE AMOUNT OF LOW LEVEL MOISTURE WILL BE LESS THAN
MONDAY...BUT THERE IS STILL SUFFICIENT MOISTURE FOR SCATTERED
THUNDERSTORM DEVELOPMENT THIS AFTERNOON AND EVENING.

SCATTERED THUNDERSTORMS WILL DEVELOP DURING THE EARLY AFTERNOON OVER
THE FRONT RANGE AND FOOTHILLS.  AS THE THUNDERSTORMS MOVE SOUTHEAST
...THEY HAVE THE POSSIBILITY OF DEVELOPING INTO SUPERCELLS AND
REACHING SEVERE LIMITS.  THE MAIN THREATS FOR SEVERE WEATHER ARE
LARGE HAIL AND STRONG WINDS.

THE BEST THREAT FOR SEVERE WEATHER IS NORTH AND EAST OF A LINE FROM
APPROXIMATELY...WEST OF CHEYENNE WYOMING...THROUGH FORT COLLINS...
LIMON...AND BURLINGTON.  THE POTENTIAL FOR SUPERCELLS INCREASES
FURTHER NORTHEAST OF THIS LINE AS THERE WILL BE GREATER INSTABILITY
DUE TO INCREASED LOW LEVEL MOISTURE.

THERE ARE ALSO SOME INDICATIONS THAT A WEAK UPSLOPE SURGE WILL
DEVELOP LATE THIS AFTERNOON.  IF THIS SURGE DOES DEVELOP...THE
THREAT FOR STRONG TO SEVERE THUNDERSTORMS WILL LINGER INTO THE
EVENING.

SPOTTER ACTIVATION WILL BE LIKELY AFTER 2 PM.

WOLYN WFO PUEBLO