Severe Thunderstorm Warning 98, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA NE
255 PM CDT SAT APR 21 2001

MAIN FORECAST CONCERN CONTS TO BE CONVECTION THREAT LATER TNGT THRU
SUN.  AS PER MODEL BIASES/NATIONAL DISCUSSION WL LEAN TWD ETAS
SOLUTION IN HANDLING UPR/SFC LOW...ALTHO ETA/AVN ARE PRETTY SIMILAR.

SHORT TERM...CDFNT HAS PUSHED INTO NERN KS/NRN PT OF CNTRL MO...AND
SFC DWPTS HAVE LOWERED INTO THE UPR 40S/LOWER 50S ACRS FCST AREA
(DWPTS PRBLY SVRL DEGREES TOO WRM SWRN IA).  INITIAL CONVECTION
THROUGH 03Z SHOULD STAY S OF FCST AREA NR SFC FNT BUT CONDS WL BE
CHANGING AFT THEN AS 850 MB JET BCMS SRLY AND INCREASES TO 40-55KTS
INTO SRN NEBR 06Z-12Z.  STG THETA E ADVCTN ARND 850 MB SHOULD HELP
ELEVATED CONVECTION DVLP/ADVCT ACRS MUCH OF FCST AREA BY 12Z.
INTENSITY STILL SOMEWHAT OF A CONCERN AS AFTN/EARLY EVENING
CONVECTION WL PRBLY ANCHOR SFC FNT S OF FCST AREA TIL UPR SYS BEGINS
LIFTING NEWD ON SUN.  THUS SFC BASED CAPE OFF MESOETA RMNS QUITE LOW
SERN NEBR THRU 12Z...GENERALLY ARND OR BELOW 100 J/KG AND SFC OR 850
MB BASED LIS ONLY DROP TO ZERO TO -1 THRU 12Z FAR S.  FCST
SOUNDINGS THOUGH INDICATED AROUND 1300 J/KG CAPE FAR SE BY 12Z ABV
LFC AND ALTHOUGH NO CAPE WAS COMPUTED ABV LFC FARTHER N...ARND
OMA...LIFTING PARCEL ABV INVERSION DOES YIELD SOME.  HOWEVER...STILL
WITH SOME QUESTION OF INSTABILITY...PLUS ELEVATED NATURE OF IT...
WL NOT MENTION PSBL SVR STORMS IN ZONES ATTM. ALTHOUGH NO DOUBTH
THERE WILL BE STG SHEAR IN LOWEST 3 KM.  WL BOOST POPS ALL AREAS
THOUGH.

STGR...PSBLY SVR...CONVECTION MORE LIKELY ACRS FCST AREA ON SUNDAY
AS DEEPER MOISTURE STREAMS NWD...UPR DIVERGENCE INCREASES AHD OF UPR
LOW AND PSBL HEATING EXTREME SRN NEBR OCCURS S OF WRMFNT.
SUPERCELLS POSSIBLE ALNG AND JUST N OF WRMFNT SRN NEBR...POSSIBLY AS
FAR N AS E CNTRL NEBR...WITH PRBL SQUALL LINE/BOWING SEGMENTS LATER
IN THE DAY ALONG/AHD OF COLD FRONT AS UPR LOW EJECTS E OF CO.  WITH
WRM FNT PSBLY MAKING IT TO NR A OLU-OMA LINE BY LATE AFTN WL RAISE
HIGHS JUST A LITTLE MOST AREAS...BUT KEEP N IN THE 50S.

PCPN SHOULD BE WINDING DOWN TOWARD 06Z MON IF MESOETA VERIFIES BUT
WL KEEP SOME SMALL POPS INTO MON AM IN CASE SYS EJECTS A LTL
SLOWER.  COLD AIR AT 850 MB ALREADY INTO NWRN ND/NE MT...AND THIS WL
BE DRAWN INTO BACK SIDE OF SYS SUN NIGHT.  WL MENTION SOME WET SNOW
NRN ZONES THEN.  BREEZY AND COOL CONDS FOR MON AFTN WITH TEMPS A
LTL BLO FWC GUID.  WL COUNT ON ENOUGH AFTN SUNSHINE THOUGH TO ALLOW
FOR MIXING CLOSE TO 850 MB.

WK SHRTWV TROF PIVOTS THROUGH ON TUE AND WE WILL MENTION CHC OF LGT
RAIN WITH IT.  OTHERWISE...DRY AND WARMING THEN INTO NEXT WEEKEND AS
UPR HEIGHTS RISE.

.OMA...NONE.
CHERMOK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1128 PM CDT SAT APR 21 2001

TIME(CDT)  .....CITY LOCATION..... STATE  ...EVENT/REMARKS...
           ....COUNTY LOCATION....

1120 PM    WEEPING WATER             NE   1.00 INCH HAIL
04/21/01   CASS