Tornadoes and Hail in Colorado, August 28, 2002

SOUTH CENTRAL AND SOUTHEAST COLORADO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PUEBLO COLORADO
330 AM MDT WED AUG 28 2002

PRECIP CHANCES THE CONCERN AS WX PATTERN REMAINS RELATIVELY
UNCHANGED.

CURRENTLY...MCS FORMING OVER WRN NEBRASKA WITH NEW CONVECTION ON THE
SRN FLANK IN EXTREME NERN CO. ISOLATED CELL WHICH PRODUCED BRIEF
SEVERE WX OVER EL PASO COUNTY TUE EVENING ALMOST GONE WITH ONLY A
SMALL AREA OF LIGHT RAIN REMAINING. STRATUS FORMATION A LITTLE
SLOWER THAN LAST NIGHT...THOUGH LATEST OBS AND SATELLITE FOG/LOW
CLOUD IMAGE SUGGEST CLOUD COVERAGE HAS BEGUN TO INCREASE THE LAST
HOUR OR SO.

MODELWISE...00Z ETA STRUGGLING TO PORTRAY QPF PICTURE ACCURATELY...
WITH 12 HR FORECAST VALID AT 12Z SHOWING ERRONEOUS PRECIP BULLSEYES
IN E-CENT CO AND OVER THE TEX PANH. SUSPECT LACK OF FAVORABLE UPPER
JET DYNAMICS MAY BE THE CULPRIT IN CURRENT PRECIP NO SHOW.

TODAY...NO APPARENT OUTFLOW BOUNDARIES TO DEAL WITH THIS MORNING...
THOUGH INCREASING STRATUS MAY COVER MUCH OF THE PLAINS BY DAYBREAK.
WITH STRONG UPSLOPE GRADIENTS LACKING...WILL COUNT ON A FAIRLY QUICK
BREAK-UP OF LOW CLOUDS BY LATE MORNING. ONCE AGAIN...CAPES AND
SHEAR WILL BE SUFFICIENT FOR THUNDERSTORM ACTIVITY THIS AFTERNOON...
BUT QUESTION AS ALWAYS IS...WHAT MECHANISMS WILL INITIATE AND SUSTAIN
CONVECTION? PLUSES TODAY INCLUDE SLIGHTLY ENHANCED VERTICAL MOTION
DUE TO LEFT FRONT QUAD OF UPPER JET NOSING INTO CO BY 00Z...ALONG
WITH STRONGER SURFACE HEATING OVER THE ERN MTNS DUE TO LACK OF
DEEP LOW LEVEL OUTFLOW/COLD POOL OVER THE PLAINS. MAIN MINUS IS
CONTINUED PRESENCE OF FAIRLY THICK LAYER OF DRY AIR AS SHOWN BY
KGJT 00Z SOUNDING...WHICH HAS HELPED QUASH MOST MTN CONVECTION THE
LAST FEW DAYS. WILL GO WITH BROADBRUSH SLIGHT CHANCE MOST AREAS FOR
THE AFTERNOON FOR NOW AS MODELS AND LATEST SATELLITE PICS SUGGEST MID
LEVELS WILL BE MOISTENING DURING THE DAY. SEVERE POTENTIAL IS THERE
WITH STRONG DIRECTIONAL SHEAR AND CAPES ABOVE 1000 J/KG...BUT WILL
KEEP MENTION OUT OF THE ZONES AS THIS HAS BEEN THE CASE FOR SEVERAL
DAYS AND VERY LITTLE SEVERE WX HAS OCCURRED IN THE CWFA. GENERALLY
WENT CLOSE TO GUIDANCE NUMBERS FOR MAXES.

TONIGHT...IF CONVECTION CAN INITIATE OVER THE MTNS THIS AFTERNOON...
LOW LEVEL PARAMETERS STILL LOOK FAVORABLE FOR OVERNIGHT MCS
FORMATION ON THE PLAINS WITH LOW LEVEL JET CONVERGENCE SHOWING A
BULLSEYE OVER THE FAR EAST. CURRENT FORECAST LOOKS OK AND WILL JUST
MAKE SOME MINOR TWEAKS.

THURSDAY...APPEARS BEST MOISTURE CONVERGENCE AND INSTABILITY BEGIN
TO SHIFT NEWRD OUT OF THE AREA...SO WOULD WOULD EXPECT A DOWNTURN IN
CONVECTIVE POTENTIAL OVER THE ERN PLAINS. CURRENT GRIDS SHOW THIS
TREND AND WONT CHANGE.

FRIDAY-TUE...UPPER LOW OVER THE PACIFIC NW WEAKENS...ALLOWING UPPER
FLOW TO BECOME MORE WRLY. THIS SHOULD TEND TO ADVECT A DRIER AIRMASS
INTO CO...THOUGH ENOUGH RESIDUAL MOISTURE WILL BE AROUND TO KEEP A
SLIGHT CHANCE OF AFTERNOON/EVENING CONVECTION GOING THROUGH THE
PERIOD. AVN SHOWS A WEAK FRONT DROPPING INTO THE ERN PLAINS SUNDAY
WHICH MAY SERVE TO INCREASE CONVECTIVE CHANCES...OTHERWISE FEW
FEATURES OF NOTE TO FOCUS CONVECTION. CURRENT GRIDS LOOK FINE AND
WILL LEAVE UNCHANGED.

.PUB...NONE.

PETERSEN

COZ058>089-093>099-282000-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PUEBLO CO
1155 AM MDT WED AUG 28 2002

...THE HAZARDOUS WEATHER OUTLOOK FOR SOUTHEAST AND SOUTH CENTRAL
COLORADO THROUGH 7 AM TOMORROW...

...SPOTTER ACTIVATION MAY BE NECESSARY THIS AFTERNOON THROUGH
TONIGHT FOR A FEW SEVERE THUNDERSTORMS OVER THE SOUTHEAST PLAINS OF
COLORADO...

LATE WEDNESDAY MORNING...A DISTURBANCE WAS VISIBLE IN SATELLITE
PICTURES TRACKING NORTHEAST THROUGH THE SANGRE DE CRISTO MOUNTAINS.
THIS DISTURBANCE WAS LOCATED NEAR THE NOSE OF AN UPPER LEVEL
JETSTREAM POKING INTO SOUTH CENTRAL COLORADO.  AS THE DISTURBANCE
CONTINUES TRACKING NORTHEAST...SCATTERED SHOWERS AND THUNDERSTORMS
ARE EXPECTED TO SPREAD FROM THE MOUNTAINS ONTO THE ADJACENT PLAINS
DURING THE EARLY AFTERNOON HOURS.

AT THIS TIME...THE GREATEST THREAT OF SEVERE WEATHER FOR THE
AFTERNOON HOURS WOULD APPEAR TO BE ACROSS EL PASO COUNTY.  THIS AREA
IS MOST LIKELY TO SEE LIFT FROM THE APPROACHING UPPER LEVEL
DISTURBANCE.

ANY STORMS WHICH MOVE ONTO THE PLAINS THIS AFTERNOON WILL EVENTUALLY
MOVE SOUTHEAST ACROSS THE FAR SOUTHEASTERN PLAINS BY THIS EVENING
AND OVERNIGHT...WITH KIOWA...BENT...CROWLEY...OTERO...PROWERS AND
BACA COUNTIES HAVING THE GREATEST THREAT FOR SEVERE WEATHER AT THAT
TIME.

ANOTHER DISTURBANCE WAS VISIBLE AT LATE MORNING TRACKING NORTHEAST
INTO THE SOUTHWEST COLORADO MOUNTAINS.  THIS DISTURBANCE WILL BRING
SCATTERED SHOWERS AND THUNDERSTORMS TO THE EASTERN SAN JUAN
MOUNTAINS...THE LA GARITA MOUNTAINS...THE SAGUACHE RANGE...AND THE
SAN LUIS VALLEY...THROUGH THE AFTERNOON HOURS.

THE MAIN SEVERE WEATHER THREAT FROM STORMS THIS AFTERNOON WILL BE
LARGE HAIL TO AROUND 1.5 INCHES IN DIAMETER.  LATER TODAY AND
TONIGHT...THE MAIN THREATS WILL INCLUDE BOTH LARGE HAIL AND HIGH
WINDS...WITH WIND GUSTS IN EXCESS OF 60 MPH POSSIBLE.