Severe Thunderstorm Warning 129, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA NE
215 PM CDT TUE MAY 1 2001

ALL 12Z MODELS TENDING TO SLOW SOUTHWARD MOVEMENT OF FRONT  ACROSS
AREA TNGT INTO WED WITH THE AVN AND NGM SLOWER OF MAJOR OPERATIONAL
MODELS. BASED ON CURRENT MOVEMENT OF FRONT ALONG WITH OVERALL ETA
BETTER TRACK RECORD OF HANDLING OF COLD AIR INTRUSION WILL FOLLOW
NCEP LEAD AND LEAN MORE TOWARD ETA COLD FRONTAL POSITION THROUGH
AROUND 48 HRS. AS CAP IS BROKEN ANTICIPATE CONVECTION TO DEVELOP BY
BY AROUND 20Z TO 21Z ALONG FRONT FROM BETWEEN KODX AND KAUH TO NEAR
KSUX. CONVECTION TO GRADUALLY WORK SOUTH DURING THE NIGHT WITH THE
FRONT. WILL LIKELY RETAIN SOME POPS N OF FNT BUT LESS RISK SGFNT WX.
BESIDES THE THREAT FOR SVR WEATHER ASSOCIATED WITH CDFNT WITH SGFNT
CAPE AND SUFFICIENT SHEAR...POTENTIAL WILL ALSO INCREASE FOR AREAS OF
HEAVY RAIN DURING NIGHT IN EAST CENTRAL AND SOUTHEAST NEBRASKA AS
LOW LEVEL FLOW TENDS TO VEER WITH INFLUX OF INCREASING LOW LEVEL
MOISTURE.

TRENDING TOWARD ETA MODEL BELIEVE MAIN POTENTIAL FOR SHWRS AND AND
EMBEDDED TSTMS ON WED INTO WED EVE WILL BE MAINLY IN SE NEB INTO SW
IA. HOWEVER CHANCE FOR RAIN INCREASING ACROSS ENTIRE AREA AGAIN LATER
WED NIGHT INTO THU AS LOW LEVEL MOISTURE INFLUX INCREASES INTO THE
SFC BOUNDARY AS IT TRIES TO LIFT NWD. IN ADDITION SWLY UPPER FLOW
OVERRUNNING COOL DOME ALONG WITH DISTURBANCES COMING OUT OF UPPER
LOW OVER SW U.S. WILL HELP GENERATE GOOD CHANCE FOR RAIN AND
EMBEDDED TSTMS.

BEYOND 48HRS ETA MAY BE SHIFTING UPPER LOW A BIT FAST AND AVN MODEL
TREND BETTER IN EXTENDED PERIODS. EXTENDED LOOKS QUITE UNSETTLED AND
WET THROUGH WEEKEND.

.OMA...NONE.
WIESE
g

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-012230-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1150 AM CDT TUE MAY 1 2001

THERE IS A GOOD LIKELIHOOD STORM SPOTTERS WILL BE REQUIRED THIS
AFTERNOON AND TONIGHT IN EASTERN NEBRASKA AND SOUTHWEST IOWA.

A STRONG COLD FRONT EXTENDING FROM EASTERN SOUTH DAKOTA SOUTH ACROSS
NORTHEAST INTO SOUTHWEST NEBRASKA...WILL CONTINUE TO PUSH SOUTHEAST
THIS AFTERNOON AND TONIGHT...REACHING FROM NORTHEAST IOWA ACROSS
SOUTHEAST NEBRASKA INTO WESTERN KANSAS BY EARLY WEDNESDAY MORNING.

THE FRONT WILL BRING A GOOD CHANCE FOR THUNDERSTORMS LATER THIS
AFTERNOON INTO TONIGHT AS IT INTERACTS WITH AN UNSTABLE AND MOIST
AIR MASS. THE MOST LIKELY TIME FOR THUNDERSTORM FORMATION WILL
LIKELY BE AFTER 300 PM CDT. BASED ON THE AMOUNT OF ATMOSPHERIC
INSTABILITY AND WIND SHEAR...SOME OF THESE STORMS COULD BE SEVERE.
THE MAIN SEVERE RISK APPEARS TO BE LARGE HAIL AND DAMAGING WINDS
ESPECIALLY IN AREAS OF EAST CENTRAL AND SOUTHEAST NEBRASKA INTO
SOUTHWEST IOWA.  HOWEVER A FEW TORNADOES ARE POSSIBLE.

IN ADDITION...AS THE FRONT SLOWS...A LOW PRESSURE CENTER IS EXPECTED
TO DEVELOP IN WESTERN KANSAS. THIS LOW WILL HELP THE FEED OF LOW
LEVEL MOISTURE FOR THE THUNDERSTORMS...AND LOCALLY HEAVY RAINS MAY
FALL TONIGHT IN EAST CENTRAL AND SOUTHEAST NEBRASKA INTO SOUTHWEST
IOWA.

PEOPLE ARdE ADVISED TO MONITOR NOAA WEATHER RADIO AND LOCAL RADIO AND
TELEVISION MEDIA OUTLETS FOR WEATHER DEVELOPMENTS THIS AFTERNOON
THROUGH TONIGHT.

GW