Severe Thunderstorm Warning 56, NWS Hastings, NE

SOUTH CENTRAL NEBRASKA/NORTH CENTRAL KANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
332 PM CDT MON JUN 19 2000

...AMMENDED FOR SEVERE THUNDERSTORM WATCH IN EFFECT UNTIL 9 PM...

MAIN CONCERN FOR THIS FORECAST PACKAGE IS TSRA CHANCES TONITE. WV
SATL PIX AND PROFILERS SHOW UPPER LEVEL PATTERN PROGRESSIVELY
ALTERING. TO THE WEST UPPER TROF NEAR THE PAC NW CONTINUES TO DIG
SOUTHWARD WITH ACCOMPANYING MOISTURE. ELSEWHERE RIDGE AXIS HAS
SHIFTED EAST OF THE CWA. AT THE SFC LOW PRESSURE OVER NW SD WITH
ASSOCIATED WARM FRONT EXTENDING EASTWARD ALONG THE ND/SD BORDER WITH
A WEAKER SECONDARY WARM FRONT ALSO INDICATED ACROSS SE KS. MEANWHILE
STRONG SOUTHERLY WINDS CONTINUE TO PUMP MOISTURE INTO THE CWA. DRY
LINE FOUND THRU SW SD/WRN NEB/WRN KS.

AS FOR THE MODELS THE NGM IS STILL THE QUICKEST BRINGING THE
COLD FRONT INTO THE CWA TONITE...WHILE THE ETA IS NEXT FOLLOWED BY
THE AVN. THE NGM MAY BE A BIT TOO AGGRESSIVE WITH THE TIMING OF THE
FRONT DUE TO IT POSSIBLY OVER EXAGGERATING THE DEEPENING AND
SOUTHWARD EXTENT OF THE UPPER LEVEL TROF OVER TIME. ETA SOLUTION
PREFERRED.

TONITE...CONVECTION EXPECTED TO DEVELOP BY LATE THIS AFTN OVER
WESTERN NEB ALONG SFC TROF/DRY LINE IN A LINE FROM NEAR VTN TO JUST
WEST OF LBF. THIS TROF WILL CONTINUE TO MOVE EAST INTO MOISTURE
RICH...UNSTABLE AIR MASS. A LOOK AT LATEST LAPS DATA SUGGEST THIS
AREA ALREADY VERY UNSTABLE WITH CAPES AOA 2400 J/KG AND LI'S AOB -6
WITH DEW POINTS ALREADY INTO THE 60S. WV LOOP INDICATING VORT MAX
INVOF AREA WHICH SHOULD HELP DESTABILIZE ATM EVEN FURTHER. ATTM
OVERALL IT LOOKS AS IF BEST CHANCES FOR PCPN WILL BE NE OF THE CWA...
OVER THE ERN DAKOTAS AND WRN MIN. AS FOR THE CWA...BEST CHANCES SEEM
TO BE FOR AREAS MAINLY NORTH OF GRI. KS CWA APPEARS TO BE ON TAIL END
OF SYSTEM SO WILL GO WITH SMALL POPS DOWN THERE. SEVERE POTENTIAL
TONITE WITH STORMS THAT DEVELOP. DAMAGING WINDS AND LARGE HAIL SEEM
TO BE THE MAIN THREAT...BUT GIVEN INCREASING PROGGED VALUES OF EHI...
VGP AND BRNSHR...ONE CANNOT RULE OUT A FEW ROTATING SUPERCELLS THIS
EVENING. OTHERWISE TRAILING COLD FRONT TO CRASH THRU THE CWA
SOMETIME TOWARDS DAWN IN NEB CWA.

.TUESDAY...TIME SECTIONS SUGGEST CLOUDS SHOULD SUBSIDE DURING THE
LATE MORNING HOURS FOR THE MOST PART. WILL ADD SMALL POPS THOUGH FOR
THE EARLY MORNING HOURS FOR ANY LINGERING TSRA'S. FWC SUGGESTS WINDS
NW 20-30 THRU THE DAY SO WILL GO WINDY ENTIRE CWA. CAA BEHIND FRONT
NOT ALL THAT GREAT. MOST PLACES SHOULD SEE TEMPS NEAR 80 REALIZED BY
DAYS END.

.TUESDAY NITE AND WED...NW FLOW SHOULD PROVIDE ADEQUATE SUBSIDENCE
ACROSS THE AREA AS UPPER LEVEL SYSTEM SHIFTS EASTWARD. TEMPS
RATHER COOL OVERNITE WITH HIGHS AGAIN IN THE LOWER 80S EXPECTED. IN
THE MEANTIME RIDGING BUILDS INTO THE WRN US WHICH EVENTUALLY WITH
SHOOT WARMER TEMPS BACK INTO OUR CWA WITHIN THE EXTENDED PERIOD...
WHICH APPEARS TO BE DRY AS WELL.

GID...SEVERE THUNDERSTORMS WATCH IN EFFECT UNTIL 9PM FOR
      KSZ005>007-017>019
      NEZ039-040-046-047-060>062-072>075-082>085.

DEE