Severe Thunderstorm Warning 248, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA NE
313 AM CDT TUE JUN 12 2001

MAIN FORECAST CONCERNS CONTINUE TO BE THUNDERSTORMS AND TEMPERATURES.

IN THE SHORT TERM...RUC HAS DONE THE BEST JOB WITH CONVECTION...
ORRECTLY LEAVING OUR CWA CAPPED OVERNIGHT.  IT INDICATES INCREASING
850 WINDS FROM THE S THIS MRNG WITH N/S MOISTURE AXIS FROM SRN
PLAINS TO CNTRL/E NEBRASKA INTERSECTING THE MAIN E/W AXIS FROM
NORTHEAST NEB INTO SRN WI...WITH VERY STRON THETA E ADVN FROM N
CNTRL NEB INTO SERN SD.  THIS SUGGESTS THAT SFC FRONT CURRENTLY LNK
AND OMA VCNTY WILL BEGIN MOVING NORTH...AND CURRENT TSTMS IN WESTERN
NEB WILL TEND TO DEVELOP NORTHEAST INTO BEST THETA E ADVN...POSSIBLY
CLIPPING OUR NW COUNTIES.

HOT TEMPS IN LOW-MID 90S SHOULD PREVAIL AGAIN TODAY ALONG AND S OF
THE SFC FRONT.  850 TEMPS ARE SLIGHTLY COOLER THAN YDA...BUT NOT
MUCH.  FRONT MAY NOT MAKE IT THRU FAR NORTHERN COUNTIES.  WILL BE
INFLUENCED BY 06Z MESOETA WHEN AVBL.

THREAT VERY STRONG CONVECTION DEVELOPS BY LATE AFTN NEAR AND N OF
THE FRONT AS INCREASING LOW LEVEL MOISTURE AND HOT CAP AT MID LEVELS
RESULT IN VERY UNSTABLE AIRMASS.  AM IN GENERAL AGREEMENT WITH SPC
SCENARIO...BUT FEEL THAT CAP IS LIKELY TO BE STRONG ENOUGH TO PUSH
BEST CONVECTIVE THREAT SOMEWHAT FARTHER NORTH.

WHILE CONVECTIVE THREAT CONTINUES IN THE NORTH TONIGHT...CENTRAL AND
SRN ZONES LOOK QUITE WARM WITH MID LEVEL CAP HOLDING AND STRONG
LLJ DEVELOPING.

SE AND CENTRAL ZONES APPEAR TO HAVE BEST CHC TSTMS WED AFTERNOON AND
NIGHT AS 850 MB MOIST AXIS MOVES SLOWLY EWD INTO THE AREA...700 CAP
ERODES...AND UPPER DIVERGENCE IS SUGGESTED WITH VIGOROUS CLOSED 500
MB LOW APPROACHING ALONG WITH FAVORABLE QUAD OF JET SPEED MAX.  NW
ZONES APPEAR TO HAVE A LOWER POP AS SFC FRONT PASSES THRU EARLIER IN
THE DAY.  THE TIMING OF THIS FRONT IS SOMEWHAT UNCERTAIN BY
THEN...HOWEVER...AND MODELS DIFFER SUBSTANTIALLY IN DETAILS.)  THEY
HAVE TENDED TO BE TOO FAST RECENTLY...BUT NEW ETA ACTUALLY SPED UP
WEST COAST SYSTEM FROM PREVIOUS RUN...AND NEW MRF/AVN ARE FASTER
THAN ECMWF.

NO BIG CHANGES TO EXTENDED.

.OMA...NONE.
POLLACK

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-121700-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
558 AM CDT TUE JUN 12 2001

THERE IS GOOD CHANCE THAT STORM SPOTTERS WILL BE REQUIRED LATE THIS
AFTERNOON AND EARLY TONIGHT OVER NORTHEAST NEBRASKA...AND A SLIGHT
CHANCE FROM EAST CENTRAL NEBRASKA INTO WEST CENTRAL IOWA.

A WARM FRONT IS FORECAST TO LIFT INTO NORTHEAST NEBRASKA THIS
AFTERNOON.  HOT...HUMID AND UNSTABLE AIR WILL BUILD TO THE SOUTH OF
THE FRONT...BUT THUNDERSTORMS ARE EXPECTED TO BE SUPPRESSED BY A CAP
OF WARM AIR ALOFT.  THERE IS A GOOD CHANCE THAT THIS CAP WILL BE
BROKEN IN NORTHEAST NEBRASKA IN THE LATE AFTERNOON OR EVENING...
ESPECIALLY TO THE NORTHWEST OF A LINE FROM SCHUYLER TO DECATUR.
IT IS LESS LIKELY THAT THE CAP WILL BREAK TO THE SOUTH OF THE WARM
FRONT.

DUE TO THE MOIST AND VERY UNSTABLE AIR BELOW THE CAP...ANY
THUNDERSTORMS THAT DEVELOP WILL HAVE A CHANCE TO BECOME SEVERE.  THE
GREATEST THREATS WILL BE FROM LARGE HAIL AND DAMAGING STRAIGHT LINE
WINDS...BUT ENOUGH WIND SHEAR WILL BE AVAILABLE IN NORTHEAST NEBRASKA
FOR TORNADOES TO BEY POSSIBLE.

POLLACK