Severe Thunderstorm Warning 8, NWS Omaha, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
320 PM CDT TUE APR 29 2003

FORECAST CHALLENGES...SEVERE/HEAVY RAIN POTENTIAL TONIGHT AND SEVERE
POTENTIAL FOR WEDNESDAY.

ATMOSPHERE TRYING TO RELOAD ACRS ERN NEBRASKA IN WAKE OF MORNING
MCS.  ELEVATED CONVECTION DVLPD IN 18Z-19Z PD JUST W OF CWA...BUT IT
HAD WEAKENED AS IT MOVD INTO THE SLGTLY MORE STABLE ENVIRON OF ERN
NEBR. ACTIVITY WAS NEAR 850 MB WRMFNT AS SFC WRMFNT HAD BEEN
SUPPRESSED TO NRN KS. ADDITIONAL TSTMS XPCTED TO DVLP SHORTLY...
EITHER IN CU FIELD NEAR WARMFNT OR ALNG 850 MB FNT W OF OR OVR WRN
CWA.  SITUATION SETTING UP FOR ANOTHER MCS OR TWO TO TRACK ACRS SRN
CWA TNGT AS STG LOW LVL JET WL CONT FOCUSED TWD SERN NEBR THRU 12Z
WED WITH SFC FNT MAKING LTL OR NO NWD PROGRESSION.  BESIDES SVR
THREAT...PER SWOMCD...SITUATION FAVORABLE FOR HEAVY RAIN AS
PRECIPITABLE WATER VALUES QUITE HIGH AND TRAINING LIKELY.  HEAVIER
RAIN HAS BEEN SOMEWHAT LIMITED THUS FAR AND MOST AREAS ARE
RELATIVELY DRY...THUS NO FLASH FLOOD WATCH ATTM.  WL MENTION HEAVY
RAIN ALONG WITH SVR THREAT THIS EVENING SRN ZONES.  12Z ANLYS ALSO
SHOWD SECONDARY 850 MB BOUNDARY NRN NEBR WITH ACTIVITY N OF THIS FNT
OVR SERN SD. THIS FRONT FCST TO SAG SWD AND WEAKEN OVERNIGHT WHICH
SHOULD ALLOW OTHER ELEVATED CONVECTION TO BREAK OUT OVR NRN AND
SPCLY NWRN CWA.  IN OTHER WORDS...WL CONT CATEGORICAL POPS MUCH OF
CWA TNGT.  TEMPS DIDNT WARM QUITE AS MUCH AS EARLIER THOUGHT
TDA..AND THUS LOWERED MOST LOWS.

FOR WED...ANOTHER ACTIVE WEATHER DAY SHAPING UP AS A RATHER LARGE
PIECE OF ENERGY EJECTS EWD OUT OF ELONGATED WEST COAST UPR LOW. ETA
HAS COME AROUND TWD A FTHR SOUTH SOLUTION WITH RESPECT TO TRACK OF
SFC LOW.  GFS HAS BEEN LEANING TWD THAT SOLUTION NOW FOR THE LAST
SVRL RUNS.  LOOKING AT THE FRONTS PSN TDA...AND PSBL REINFORCEMENT
DUE TO CONVECTION TNGT...THIS LOOKS REASONABLE.  THUS WL ADJUST FCST
AND ALLOW ONLY FAR SERN ZONES TO MAKE IT INTO THE WARM SECTOR WHICH
MEANS LOWERING TEMPS A CATEGORY OR TWO MANY AREAS.  WL CONT HIGH
POPS WED AND WED NGT.  ALTHO TORNADO THREAT MAY BE SUPPRESSED A LTL
FTHR S THAN EARLIER ETA SUGGESTED...ELEVATED SVR STORMS STILL
POSSIBLE AND WL LEAVE SVR THREAT MENTIONED SRN 1/2 OR SO OF CWA.  WL
DOWNPLAY THE SVR THREAT FAR NWRN CWA.

GFS AND ETA DIVERGE ON SOLUTIONS ON THURSDAY AS GFS DVLPS A
SECONDARY UPR LOW IN BROAD TROF AND MOVS IT ACRS CWA LATE THU.  PREV
FCST ALREADY HAD CHC SHWRS NWRN ZONES AND THIS LOOKS GOOD.  ADDED
SLGT CHC A LTL FTHR SE ON THU AS EVEN WEAKER ETA KEEPS BROAD UPR
TROF OVR AREA AND KEEPS GENERATING QPF.  WK RIDGING THEN EXPECTED
FRI/SAT AND LEFT THOSE DAYS DRY.  LATEST ECMWF AND GFS BRING NEXT
UPR TROF TWD AREA SUN INTO MONDAY WITH CWA PRBLY RMNING ON COOL
SIDE.  THUS INCREASED POPS AND LOWERED TEMPS.  LEFT TUE DRY FOR NOW.

.OMA...NONE.

CHERMOK

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-301100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
540 PM CDT TUE APR 29 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF EASTERN NEBRASKA
AND SOUTHWEST IOWA.

.DAY ONE...TONIGHT AND WEDNESDAY

STRONG TO SEVERE THUNDERSTORMS MAY DEVELOP THIS EVENING ACROSS
FAR SOUTHERN NEBRASKA AND SOUTHWEST IOWA...ESPECIALLY ALONG AND
SOUTH OF INTERSTATE 80. DAMAGING WINDS AND LARGE HAIL WOULD BE
THE PRIMARY HAZARDS FOR THIS AREA. ADDITIONAL STRONG TO POSSIBLY
SEVERE THUNDERSTORMS WILL BE POSSIBLE OVERNIGHT ACROSS MUCH OF
THE OUTLOOK AREA...ESPECIALLY ALONG AND SOUTH OF A LINE FROM
NELIGH TO WAYNE. DAMAGING WINDS AND LARGE HAIL WILL AGAIN BE THE
PRIMARY HAZARDS OVERNIGHT.

A WARM FRONT WILL REMAIN OVER NORTHERN KANSAS AS LOW PRESSURE
MOVES FROM EASTERN COLORADO TO WESTERN KANSAS BY MORNING. LOW
LEVEL WINDS WILL CONTINUE TO INCREASE THIS EVENING WHICH WILL
LIFT MOIST UNSTABLE AIR OVER THIS FRONTAL BOUNDARY.  AS A
RESULT...MUCH OF THE OUTLOOK AREA REMAINS IN A SLIGHT RISK OF
SEVERE WEATHER THROUGH WEDNESDAY MORNING.

AS LOW PRESSURE CONTINUES TO MOVE THROUGH CENTRAL KANSAS ON
WEDNESDAY...THERE WILL BE A MODERATE RISK OF SEVERE THUNDERSTORMS
WEDNESDAY AFTERNOON SOUTH OF A LINE FROM YORK TO FREMONT TO
TEKAMAH... WITH A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
REMAINDER OF EASTERN NEBRASKA. DAMAGING WINDS AND VERY LARGE HAIL
WOULD BE THE PRIMARY HAZARDS...HOWEVER AN ISOLATED TORNADO MAY
OCCUR ACROSS EXTREME SOUTHEAST NEBRASKA OR FAR SOUTHWEST IOWA
WEDNESDAY AFTERNOON. WIND SHEAR WILL COMBINE WITH WARM MOIST AND
VERY UNSTABLE AIR TO CREATE FAVORABLE CONDITIONS FOR SUPERCELL
THUNDERSTORMS DURING THIS PERIOD.

.DAYS TWO THROUGH SEVEN...WEDNESDAY NIGHT THROUGH TUESDAY

STRONG TO SEVERE THUNDERSTORMS WILL CONTINUE WEDNESDAY
NIGHT...MAINLY ACROSS FAR SOUTHEAST NEBRASKA AND SOUTHWEST IOWA
WITH HAIL AND DAMAGING WINDS STILL POSSIBLE.

THE NEXT CHANCE FOR THUNDERSTORMS WILL BE THROUGHOUT THE WEEKEND
AND INTO EARLY NEXT WEEK ON SATURDAY...SUNDAY AND MONDAY.

.SPOTTER INFORMATION STATEMENT...

STORM SPOTTER ACTIVATION MAY BE REQUESTED TONIGHT IF SEVERE
WEATHER DEVELOPS ACROSS THE OUTLOOK AREA. SPOTTER ACTIVATION MAY
BE LIKELY ON WEDNESDAY.

DEWALD