Severe Thunderstorm Warning 137, NWS Hastings, NE

SOUTH CENTRAL NEBRASKA/NORTH CENTRAL KANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
300 PM CDT MON JUL 24 2000

...MAIN CONCERN IS THE POTENTIAL FOR SEVERE THUNDERSTORMS TONIGHT...

VIS SATL PIX THIS AFTERNOON CLEARLY SHOWING CAPPED AREA ACROSS
CENTRAL AND WESTERN NEBRASKA INVOF WARM HIGH PRESSURE RIDGE THAT HAS
BEEN DOMINATING AS OF LATE. A COUPLE OF VORT MAXES THOUGH WERE
DETECTED IN THE VW IMAGERY NEAR THE SD/NEB BORDER AND SHOULD
CONTINUE TO TREK EAST. AT THE SFC...SIGNIFICANT DEW POINTS WERE
FOUND ALONG A BROAD AREA OF LOW PRESSURE ACROSS THE NORTHERN PLAINS
INTO THE CENTRAL HIGH PLAINS. THE ATMOSPHERE IS FURTHER DESTABLIZING
IN AREAS WEST WHERE DAYTIME HEATING PREVAILS.

AS FOR THE MODELS...A FEW DIFFERENCES NOTED AT THE 0HR INITIALIZATION
THIS MORNING. BOTH THE ETA AND THE NGM DID A FAIR JOB WITH THE
VORT MAX OVER THE SD/NEB BORDER. THE AVN WAS RATHER UNORGANIZED. SO
WILL LEAN TOWARDS THE ETA.

TONIGHT...THE ETA SUGGEST THE POSSIBILITY FOR A SIGNIFICANT SEVERE
WEATHER OUTBREAK ACROSS CENTRAL NEBRASKA AND LOCATIONS FURTHER NORTH
AND NORTHEAST. BY TONIGHT A MID LEVEL WAVE AT 700 MB IS PROGGED TO
MOVE ACROSS NEBRASKA. FEELING IS THAT THIS WILL AID IN TEARING
DOWN SIGNIFICANT CAP OVER AREA AS SFC FRONTAL BNDRY MOVES IN. UPPER
LEVEL SUPPORT MAY NOT BE AS WEAK AS PREVIOUSLY THOUGHT AS ENERGY
MOVES THRU AREA OF 700-300MB DPVA. Q-VECTOR CONVERGENCE ACROSS THE
AREA INDICATES WIDE SPREAD SYNOPTIC LIFT WILL BE PRESENT.

ALMOST ALL STABILITY PARAMETERS KEY IN ON CENTRAL NEBRASKA BY 06Z.
AS FOR STORM TYPE...THE ETA DOES FAVORS SUPERCELL FORMATION. SFC-
300MB WIND SHEAR MAGNITUDE IS WELL OVER 40KT...BRN FOR THE MOST PART
ARE PROGGED IN THE MID TO UPPER 30S WITHIN THE CWA...AND 0-3KM SR
HELICITY SHOOTS ABOVE 500. AS FOR TORNADIC POTENTIAL...PARAMETERS
SUCH AS EHI...VGP AND BRN SHEAR VALUES ARE RATHER HIGH. BUT...A
CLOSER INSPECTION OF FORECAST SOUNDING SHOW THAT LFC HEIGHTS REMAIN
RATHER HIGH...INDICATING THAT TORNADOGENESIS WOULD BE LESS LIKELY.
NEVER-THE-LESS...FEEL THAT SEVERE WEATHER THREAT IS REASONABLE
ENOUGH TO MENTION IN FIRST PERIOD.

TUESDAY...THE ETA AND THE NGM SEEM TO STALL OUT THE FRONT ACROSS
OUR CWA EARLY ON...AND THEN MAKES A SECOND PUSH SOUTHEASTWARD. DRIER
AIR/SUBSIDENCE SHOULD FILL IN BEHIND FOR NEB CWA MOSTLY. OVER KS
CWA THOUGH EXPECT SOME LINGERING MORNING PCPN EVENTUALLY LEADING TO
SOME BREAKS IN THE CLOUDS.

TUESDAY NIGHT...SOME MEAN LAYER MOISTURE PRESENT OVER THE AREA SO
WILL COVER WITH PARTLY CLOUDY. DURING THE EARLY MORNING HOURS
THOUGH...THE ETA SWEEPS A PIECE OF ENERGY THRU NEB AND PLACES AREA
OF QPF OVER NEB CWA. SO WILL MENTION SLIGHT CHANCEd FOR
SHOWERS/THUNDERSTORMS TOWARDS DAWN.

WEDNESDAY...UPPER LEVEL RIDGE HANGS IN TIGHT TO THE WEST AND LOW
LEVEL SOUTHERLY FLOW SHOULD HELP WARM TEMPS UP. MOS GUID LOOKS
REASONABLE AND WILL USE.

.GID...NONE

DEE