Severe Thunderstorm Warning 99, NWS Hastings, NE

SOUTH CENTRAL NEBRASKA/NORTH CENTRAL KANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
328 AM CDT WED JUL 5 2000

...WILL A FLASH FLOOD WATCH FOR AREAS SOUTH OF I-80 BE NEEDED IS THE
QUESTION...

AT 06Z...LAPS OBJECTIVE ANALYSIS SHOWED 4300 J/KG CAPE OVER MY FAR
SW CWFA.  MCK 07Z SURFACE DEWPOINT 75...WITH 74 AND IML.  VERY SHARP
QUASI-STATIONARY SURFACE BOUNDARY EXISTS ALONG THE KS/NE BORDER THEN
INTO SE NEBRASKA.  CONVECTION CURRENTLY INCREASING OVER NEBRASKA
PANHANDLE... APPARENTLY IN RESPONSE TO UPSLOPE FLOW AND
CONVERGENCE...AND POSSIBLY FROM SPEED MAX/SMALL WAVE MOVING THROUGH
ROCKIES.  WATERVAPOR IMAGERY SHOWING THE MOIST SUBTROPICAL PLUME
JUST SOUTH OF CWFA...BUT IT MAY BE SLOWLY CREEPING BACK NORTH INTO
MY COUNTIES.

KUEX VWP SHOWING 40 KNOT LOW LEVEL JET ON SECOND GATE.  ALSO SEEING
GOOD OUTFLOW FROM THE SD MCS MOVING SOUTH.

00Z H7 TEMPERATURES WERE 16 AT DDC AND 14 AT LBF/OAX.  LAPS CINH
ANALYSIS SHOWED HUGE NEGATIVE AREAS...ON THE ORDER OF SEVERAL
HUNDRED J/KG.  CAPPING WAS UNDERFORECAST BY YESTERDAYS MODELS...AND
THIS CAP CONTINUES TO SUPPRESS CONVECTIVE DEVELOPMENT ABOVE THE
BOUNDARY.

ALL MODELS IN DECENT AGREEMENT WITH BRINGING A SHORTWAVE OUT OF CO
TODAY.  BY 21Z THE MESOETA REDUCES THE CAP SIGNIFICANTLY...AND
GENERATES CONVECTION BETWEEN 15Z AND 18Z OVER NORTH CENTRAL
NEBRASKA...WHERE IT SHOWS 22 MICROBARS/SEC OMEGA AT 18Z.  THIS LOOKS
GOOD...AS THE SD MCS OUTFLOW WILL BE IN THAT AREA BY THEN...AIDING
THE Q-G LIFTING MECHANISMS.  THE 10KM NCAR MM5 IS ALREADY DOING WELL
WITH THE HIGH PLAINS CONVECTION CURRENTLY DEVELOPING...AND IT SHOWS
ADDITIONAL DEVELOPMENT ACROSS THE PANHANDLE AND INTO NC NEBRASKA BY
15Z...THEN BECOMING A MCS AND HEADING EAST INTO THE EVENING...
REMAINING NORTH OF I-80.

HOWEVER THE PROBLEM IS THAT ALL OF THIS REMAINS NORTH OF THE MAIN
SYNOPTIC BOUNDARY.  BY 00Z THE MESO-ETA SHOWS THE BOUNDARY CLOSER TO
I-80 AND BY 06Z BACK NEAR THE KS/NE BORDER...AND BY THEN THE SUBTROPICAL
PLUME MAY BE SLIGHTLY OVER MY SRN COUNTIES.  PER QPFERD...THERE IS
THE POTENTIAL FOR A CLASSIC MADDOX FRONTAL TYPE MCC SOMEWHERE IN MY
CWFA...WITH GOOD HEAVY RAIN POTENTIAL.  WITH RECENT HEAVY RAINS
SOUTH OF I-80 AND RIVERS ALREADY IN FLOOD...A FLASH FLOOD WATCH WILL
BE NEEDED IF THESE RAINS CAN MOVE ACROSS THAT AREA.  AREAS NORTH OF
I-80 SHOULD BE ABLE TO HANDLE A COUPLE INCHES OF RAIN...WHERE MUCH
LESS RAIN FELL MON NT.

MY BIGGEST CONCERN WITH BRINGING THE HEAVY RAINS SOUTH IS THE FACT
THAT THE WARM H7 TEMPERATURES ARE ALREADY IN PLACE ACROSS KS...AND
ALTHOUGH THE MESOETA WEAKENS THAT CAP OVER NRN NEBRASKA...IT STILL
SHOWS 200+ J/KG CINH OVER FAR SRN NEBRASKA AT 06Z...AS THE UPPER
RIDGE BUILDS BACK INTO OK/KS AREA.  WITH THE MODELS ALL KEEPING THE
BULK OF THE RAIN NORTH OF THE THREAT AREA...WILL HOLD OFF FOR NOW ON
FLASH FLOOD WATCH.  HOWEVER IF THERiE ARE ANY INDICATIONS THAT THE
HEAVY RAINS WILL SHIFT SOUTH AND AFFECT THE AREA SOUTH OF I-80 TODAY
OR TONIGHT...I WILL LIKELY ISSUE A WATCH THIS MORNING.

.GID...NONE.

NIETFELD

KSZ005>007-017>019-NEZ039>041-046>049-060>064-072>077-082>087-051700-

SEVERE WEATHER OUTLOOK - SOUTH CENTRAL NEBRASKA/NORTH CENTRAL KANSAS
NATIONAL WEATHER SERVICE HASTINGS NE
620 AM CDT WED JUL 5 2000

...SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EARLY
THIS EVENING OVER PARTS OF CENTRAL...AND POSSIBLY SOUTH CENTRAL
NEBRASKA...

VERY UNSTABLE AIR WILL REMAIN IN PLACE TODAY...GIVEN SUCH HIGH
HUMIDITY AND WARM TEMPERATURES.  A FRONTAL BOUNDARY WILL BE FOUND
NEAR INTERSTATE 80...AND UPPER LEVEL DISTURBANCES WILL MOVE INTO
WESTERN NEBRASKA...HELPING TO TRIGGER THUNDERSTORM DEVELOPMENT.

THERE WILL BE PLENTY OF OPPORTUNITIES FOR STORMS TO DEVELOP OR MOVE
INTO AREAS NORTH OF INTERSTATE 80.  THUNDERSTORMS WHICH DEVELOPED
OVER WESTERN NEBRASKA EARLY THIS MORNING WILL CONTINUE TO BE
SCATTERED OVER THE NORTHERN HALF OF NEBRASKA TODAY.  OTHER STORMS MAY
ALSO DEVELOP OVER SOUTHWEST NEBRASKA.  SOME OF THESE COULD MOVE INTO
SOUTH CENTRAL OR CENTRAL NEBRASKA.  IN ADDITION...OUTFLOW FROM SOME
OF THESE STORMS COULD TRIGGER NEW STORMS OVER AREAS NORTH OF
INTERSTATE 80...MAINLY THIS AFTERNOON.

THE WIND SHEAR OVER AREAS TO THE NORTH OF INTERSTATE 80 WILL SUPPORT
ROTATING STORMS...AND THE EXTREME INSTABILITY WILL RESULT IN VERY
STRONG STORMS.  THUS THERE IS THE POSSIBILITY OF LARGE HAIL...BRIEF
DAMAGING WIND GUSTS...AND TORNADOES.

THE AMOUNT OF MOISTURE IN THE AIR ALSO SUGGESTS THE POTENTIAL FOR
VERY HEAVY RAIN.  THOSE LOCATIONS WHICH RECEIVED HEAVY RAIN MONDAY
NIGHT SHOULD MONITOR STORM DEVELOPMENT...AND BE AWARE OF POSSIBLE
FLOODING CONCERNS.

LOCATIONS TO THE NORTH OF INTERSTATE 80 APPEAR TO HAVE THE HIGHEST
THREAT FOR SEVERE WEATHER...GENERALLY BETWEEN NOON AND 9 PM.

THE NATIONAL WEATHER SERVICE IN HASTINGS RECOMMENDS EMERGENCY
MANAGERS AND SPOTTER ORGANIZATIONS PAY CLOSE ATTENTION TO THE
FORECASTS TODAY...AND BE PREPARED FOR THE POSSIBILITY OF SEVERE
THUNDERSTORMS AND FLOODING.  ANOTHER SEVERE WEATHER OUTLOOK WILL BE
ISSUED LATER THIS MORNING...BETWEEN 11 AM AND NOON.

DDN