Severe Thunderstorm Warning 116, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
154 PM CDT (1254 PM MDT) SAT JUN 13 1998

...MAIN PROBLEM IS THIS AFTERNOON AND TONIGHT...STORMS AND THE
SEVERITY THEREOF...

NICE UPPER SYSTEM MOVING EAST TOWARD THE CWA AT THIS TIME AS SFC
LOW SPINS UP IN NORTHEAST CO.  JET PUNCHING IN OVER SOUTHERN
PORTIONS OF CWA WITH COLD POOL PROGGED (BY EXTRAPOLATION...NOT BY
MODEL) TO PASS OVER NORTHERN SECTIONS OF CWA.  BEST PRESSURE FALLS
INDICATE THAT LOW WILL TRACK EAST ACROSS SOUTHERN NEBRASKA...
LIKELY PULLING WARM FRONT NORTH TOWARD SOUTHERN NEBRASKA AS WELL.
LIKE THE SPC OUTLOOK FOR MODERATE...MAY HAVE MOVED IT A BIT
FARTHER NORTH AND WEST...BUT NOT MUCH.  CAP STILL FORMIDABLE...BUT
EXPECT IT TO BREAK WITH STRENGTH OF SYSTEM.

CONVERGENT AXIS EXTENDING FROM SOUTHEAST PANH OF NEBRASKA DOWN
INTO NORTHWEST KANSAS...AND EXPECT INITIAL THUNDERSTORM
DEVELOPMENT ALONG THAT AXIS AROUND 4 TO 5 PM.  THINK STORMS WILL
RAPIDLY BECOME SEVERE WITH WIND FIELD AND CAPE TO SUPPORT ISOLATED
TORNADOES ALONG AND NEAR THE WARM FRONT...ESPECIALLY.  WILL NEED
TO WATCH NORTH OF THE WARM FRONT AS WELL...SEEING THAT BOUNDARY
LAYER IS NOT WHAT ONE WOULD CALL STABLE.  STILL...HIGHEST THREAT
CLOSER TO WARM FRONT.

TONIGHT EXPECT NUMEROUS THUNDERSTORMS...WILL GO WITH CATEGORICAL
FOR ALL BUT PANHANDLE COUNTIES.  WOULD LIKE WORDING OF SEVERE IN
FOR ALL AREAS.  AS LOW PULLS EAST...WINDS SHOULD REMAIN HIGH AND
SWITCH TO NORTHWEST...CONTINUING THAT WAY INTO SUNDAY.

MODELS DIFFER ON DETAILS FOR THIS AFTERNOON AND EVENING...AND I AM
DEVOTING MOST OF MY TIME TO MESOANALYSIS OF THE SHORT-TERM SEVERE
THREAT...SO WILL HAVE LITTLE INPUT TO 2ND THROUGH 4TH PERIODS.
BEST GUESSES AT NUMBERS BELOW...BUT I HAVE PUT LITTLE TIME IN
ANALYZING LATER PERIODS.

PRELIMINARY GUIDANCE FOR COORDINATION ONLY.  OFFICIAL FORECASTS
CONTAINED WITHIN PRODUCT OMAZFPNE.

LBF EE 50/70/45/70/45 +44
VTN EE 45/68/43/69/45 +55

SPARKER

NEZ004>010-022>029-035>038-056>059-069>071-141200-

SEVERE WEATHER OUTLOOK FOR WESTERN AND NORTH CENTRAL NEBRASKA...
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1130 AM CDT (1030 AM MDT) SAT JUN 13 1998

THIS OUTLOOK PERTAINS TO THE FOLLOWING NEBRASKA COUNTIES...

ARTHUR     BLAINE     BOYD       BROWN      CHASE      CHERRY
CUSTER     DEUEL      FRONTIER   GARDEN     GARFIELD   GRANT
HAYES      HOLT       HOOKER     KEITH      KEYA PAHA  LINCOLN
LOGAN      LOUP       MCPHERSON  PERKINS    ROCK       SHERIDAN
THOMAS     WHEELER

...STORM SPOTTER ACTIVATION WILL BE REQUIRED THIS AFTERNOON AND TONIGHT
IN WESTERN AND NORTH CENTRAL NEBRASKA...

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVER PART OF THE
OUTLOOK AREA FOR THIS AFTERNOON AND TONIGHT.  THIS AREA IS GENERALLY
EAST AND SOUTH OF A LINE FROM CURTIS TO NORTH PLATTE TO DUNNING TO
BURWELL.  THE REMAINDER OF THE OUTLOOK AREA HAS A SLIGHT RISK FOR
SEVERE THUNDERSTORMS THIS AFTERNOON AND TONIGHT.  EVEN THOUGH THE TERM
SLIGHT IS USED TO DESCRIBE THE RISK FOR THE REMAINDER OF THE AREA...IT
REFERS MAINLY TO AREAL COVERAGE.  PLEASE UNDERSTAND THAT SEVERE STORMS
ARE EXPECTED OVER THE ENTIRE OUTLOOK AREA THIS AFTERNOON AND
EVENING...AND ON INTO THE NIGHT FOR NORTHCENTRAL NEBRASKA.

AN UPPER LEVEL STORM SYSTEM WILL MOVE EAST OUT OF THE CENTRAL ROCKIES
AND INTO NORTHEAST COLORADO THIS AFTERNOON...THEN MOVE EAST ALONG THE
NEBRASKA/KANSAS BORDER OVERNIGHT.  IN ADDITION...A STRONG SURFACE LOW
PRESSURE SYSTEM WILL MOVE FROM NORTHEAST COLORADO INTO SOUTHWEST
NEBRASKA THIS AFTERNOON...AND ALSO MOVE EAST ALONG OR JUST NORTH OF THE
NEBRASKA/KANSAS STATE LINE TONIGHT.  THE COUNTERCLOCKWISE CIRCULATION
AROUND THE SURFACE LOW PRESSURE SYSTEM WILL BRING WARM AND MOIST AIR
NORTHWARD INTO THE REGION THROUGHOUT THE DAY...AND THE UPPER LEVEL
SYSTEM WILL BRING COLDER TEMPERATURES ALOFT.  THIS COMBINATION WILL
RESULT IN AN UNSTABLE AIRMASS...CAPABLE OF PRODUCING SEVERE
THUNDERSTORMS OVER THE ENTIRE OUTLOOK REGION.

THE WIND FIELD WILL ALSO BE CONDUCIVE TO SEVERE THUNDERSTORM
FORMATION...ESPECIALLY IN THE MODERATE RISK AREA.  THERE...THE
COMBINATION OF THE WIND PROFILE...MODERATE LOW LEVEL MOISTURE AND
WARMTH...AND PROXIMITY TO A WARM FRONT THAT WILL DEVELOP AND MOVE
NORTHWARD INTO THE AREA THIS AFTERNOON...WILL RESULT IN CONDITIONS
FAVORABLE FOR TORNADOS.  STRONG STRAIGHT-LINE WINDS AND LARGE HAIL ARE
ALSO POSSIBLE.  IN THE REMAINDER OF THE OUTLOOK AREA...TORNADOES ARE
POSSIBLE BUT LESS LIKELY...WITH THE MAIN THREATS BEING LARGE HAIL AND
STRAIGHT-LINE WINDS.

PLEASE STAY IN TOUCH WITH WEATHER INFORMATION THIS AFTERNOON AS
CONDITIONS COULD DETERIORATE QUICKLY ONCE THUNDERSTORMS BEGIN. INITIAL
THUNDERSTORM DEVELOPMENT IS EXPECTED OVER THE EASTERN NEBRASKA PANHANDLE
AND SOUTHWEST NEBRASKA BY 5 PM...WITH STORMS MOVING AND DEVELOPING
EASTWARD AN NORTHEASTWARD AS THE EVENING PROGRESSES.

SPARKER