Severe Thunderstorm Warning 276, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
300 AM CDT THU OCT 15 1998

...MAIN FORECAST PROBLEM WILL BE TEMPS AND POPS THRU THE PERIOD...

06Z SFC ANALYSIS HAS STATIONARY FRONT LOCATED FROM NEAR OFK-AUH...THEN
SWWD TO HLC TO GLD. MAIN LOW IS IN EC CO ATTM WITH DRYLINE EXTENDING
INTO SWRN KS. GOES10 SHOWS COOLING TOPS IN SWRN PART OF THE STATE AND
PULSE STORMS HAVE GENERATED GOLF BALL HAIL IN DEUEL COUNTY EARLIER.

THE 24 HR PROG FROM THE 00Z WED ETA DID A GOOD JOB IN SFC LOW PLACEMENT
FOR 00Z-06Z THU. ETA CONTINUES TO BE THE MODEL OF CHOICE IN THE OUTER
PERIODS AS NGM PLACES THE SFC LOW TOO FAR TO THE NW BY TONIGHT. ETA
ALSO VERIFIED MUCH BETTER WITH SFC WINDS THAN DID THE NGM FOR WED
AFTERNOON. WATER VAPOR LOOP SHOWS A SERIES OF SHORT WAVES EMBEDDED IN
THE LONG WAVE TROF OVER THE WRN STATES. FRONT MOVES NWD DURING THE DAY
AND ACCORDING TO THE ETA...SETS UP AS A WARM FRONT ACROSS NRN NEBR BY
MIDNIGHT. 850MB DEW POINTS POOL IN THIS AREA AND FAIRLY STRONG SHORT
WAVE PROGGED TO ENTER THE AREA AS WELL. HLCY IN THIS AREA ALSO
MAXIMIZED AND AS UPPER JET MOVES OVER THE REGION...WOULD EXPECT STORMS
TO FIRE AND HAVE THE POTENTIAL TO SUSTAIN MID LEVEL ROTATION...HENCE
THE OUTLOOK BY SPC. IT WOULD BE TEMPTING TO ADJUST THAT OUTLOOK FURTHER
TO THE W (I.E. TWD THE MERRIMAN AND HYANNIS AREA)...HOWEVER LOW LEVEL
COLD ADVECTION MAY BE TOO PROMINENT FOR SVR TO OCCUR...SO WILL GO WITH
SPC BOUNDARIES AND SPS FOR SVR OUTLOOK WILL BE ISSUED LATER THIS
MORNING. POPS WARRANTED EVERYWHERE AND TEMPS WILL BE DEPENDANT ON CLOUD
COVER. FAN GUIDANCE IS AGAIN COOLER AND FWC WARMEST...BUT WILL STICK TO
THE MIDDLE OF THE ROAD BASED ON WED HIGHS.

FOR FRIDAY...A SIMILAR SCENARIO SETS UP EXCEPT POSSIBLY A LITTLE
FURTHER SEWD TWD CENTRAL NEBR. BEST MOISTURE POOLS THERE AND CAPE
VALUES MAXED THERE. GOOD LOW LEVEL JET SETS UP E OF FRONT WHICH SHOULD
BE LOCATED SOMEWHERE NEAR A ANW-LBF LINE BY LATE AFTERNOON. TIMING OF
UPPER JET WILL BE CRUCIAL TO TSRA DEVELOPMENT AND ETA SHOWS THIS COULD
HELP INITIATION OF TSRA BY EARLY AFTERNOON. IN THE LARGE SCALE
PICTURE...LIKE THE ETA WHICH CUTS OFF THE LOW IN ERN UT BY 48HRS BASED
ON JET POSITION AND THE TIMING AT WHICH THE UPPER FLOW AND THICKNESS
FIELD BECOME IN PHASE. FOR TEMPS...WILL GO CLOSER TO FWC FOR AREAS AHEAD
OF THE FRONT...BUT CLOSER TO FAN IN THE NWRN CWA.

PRELIMINARY GUIDANCE FOR COORDINATION ONLY. OFFICIAL FORECASTS ARE
CONTAINED WITHIN PRODUCT OMAZFPLBF...

.LBF...NONE

CCF
LBF BB 072/049 066/042 057 -34
ONL BB 072/057 070/050 058 +45
VTN BB 066/047 067/040 054 +44

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NEZ004>010-022>029-035>038-056>059-069>071-161200-

SEVERE WEATHER OUTLOOK FOR WESTERN AND NORTH CENTRAL NEBRASKA
NATIONAL WEATHER SERVICE NORTH PLATTE NE
700 AM CDT (600 AM MDT) THU OCT 15 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 MAY BE REQUIRED ACROSS PARTS OF SOUTHWEST
AND NORTH CENTRAL NEBRASKA LATE THIS AFTERNOON AND TONIGHT...

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EAST OF A LINE FROM
VALENTINE TO OGALLALA TO HAYES CENTER BY TONIGHT. OTHER THUNDERSTORM
DEVELOPMENT IS POSSIBLE LATE THIS AFTERNOON AND TONIGHT OVER THE
REMAINDER OF THE OUTLOOK AREA...BUT ARE NOT EXPECTED TO REACH SEVERE
LIMITS.

A WARM FRONT IS EXPECTED TO BE POSITIONED OVER PARTS OF THE OUTLOOK
AREA BY LATE AFTERNOON...ROUGHLY ALONG A LINE FROM AINSWORTH TO
OGALLALA. AHEAD OF THIS FRONTAL SYSTEM...SOUTHERLY WINDS WILL TRANSPORT
LOW LEVEL MOISTURE NORTHWARD INTO THE CENTRAL AND EASTERN PORTIONS OF
THE STATE. ALTHOUGH ABUNDANT SUNSHINE IS NOT EXPECTED ACROSS THE AREA
THROUGH THE DAY...WARM AIR JUST ABOVE THE SURFACE WILL ALSO BE
TRANSPORTED NORTHWARD WHICH WILL SERVE TO DESTABILIZE THE ATMOSPHERE
THROUGHOUT THE DAY. AN UPPER LEVEL DISTURBANCE WILL THEN MOVE INTO THE
AREA BY LATE IN THE DAY AND IS EXPECTED TO TRIGGER THUNDERSTORM
DEVELOPMENT EAST OF A LINE FROM AINSWORTH TO OGALLALA BY
EVENING...HOWEVER THE TIMING OF THIS FEATURE IS UNCERTAIN AND
THUNDERSTORM DEVELOPMENT MAY BE POSSIBLE BY LATE AFTERNOON.

THE MAIN SEVERE WEATHER THREAT WILL BE LARGE HAIL AND DAMAGING
WINDS...WITH THE BEST CHANCES COMING DURING THE EVENING AND OVERNIGHT
HOURS.

SINCE THIS IS AN UNUSUAL OCCURRENCE FOR THIS AREA FOR THIS TIME
OF YEAR...STAY TUNED TO NOAA WEATHER RADIO FOR FURTHER UPDATES ON THIS
SITUATION.

THUNDERSTORMS MAY ALSO HAVE THE POTENTIAL TO PRODUCE SEVERE WEATHER ON
FRIDAY IN THE EASTERN PORTION OF THE OUTLOOK AREA.

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