Tornadoes and Hail in Nebraska, June 11, 2003

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
149 PM CDT WED JUN 11 2003

MAIN FOCUS TONIGHT WILL BE FRONTAL POSITION AND SEVERE THREAT AS
ATMOSPHERE DESTABILIZES LATE THIS AFTERNOON.

CU FORMING ALONG THE NORTH PLATTE RIVER VALLEY WEST OF OGA AT 130 PM
CDT AND VIEWABLE AS VISIBLE SATELLITE SHOW INCREASING SC
FORMATION OVER THE NORTH CENTRAL. WATER VAPOR LOOP SHOWING WEAKER
BRANCH OF MID-LEVEL JET STREAK LIFTING NORTHEAST INTO THE
NORTHWEST PANHANDLE WHILE STRONGER JETSTREAM AXIS SHOWN OVER SOUTHERN
IDAHO...AND APPROACHING THE NORTHWEST PANHANDLE NOW. WILL USE
BLEND OF WSETA AND MESOETA WITH FRONTAL BOUNDARY EXPECTED TO SLOW
WHILE MOVING SOUTHEAST ACROSS THE PANHANDLE. AS DEFORMATION FIELD
FORMS. AREA SEEN AS GREATEST POTENTIAL SEVERE WEATHER TO BE EAST OF A
MERRIMAN TO OGA LINE AND POTENTIAL SUPERCELLS POSSIBLE BETWEEN 23Z TO
06Z. THIS AFTERNOON SURFACE CONVERGENCE TO INCREASE OVER THE
NORTHWEST WITH SOUTH WINDS TO PUSH DEWPOINTS TO A 60-65 RANGE THROUGH
NORTH CENTRAL AND OBSERVATIONS SHOW MID 60S AS FAR NORTH AS BBW.
FORECASTS SOUNDING SHOWS UNIDIRECTIONAL SHEAR BUT H85 WINDS ONLY
MODERATE AS WINDS TO 20-25 KTS THIS EVENING THEN H85 JETLET
INCREASING OVER NORTHWEST KANSAS TO 40 KTS TOWARD MIDNIGHT FOR
POTENTIAL ELEVATED THUNDERSTORMS FORMING IN THE SOUTHWEST
FOR THE OVERNIGHT HOURS.

THIS EVENING FORECAST SOUNDING SHOW INDICES WITH THE POTENTIAL FOR A
FEW TORNADIC STORMS AS THUNDERSTORMS RAPIDLY DEVELOP BEYOND 4 PM CDT
AND TRACK SOUTHEAST ACROSS THE NORTH CENTRAL. MAIN FRONTAL BOUNDARY
WILL KICK EAST AFTER 09Z AS STRONGER H5 WAVE MOVES EAST.

THURSDAY THE FRONT BACKS WEST TO THE FRONT RANGE TILL SATURDAY WITH
SCHC OF THUNDERSTORMS DAILY AS EMBEDDED WAVES MOVE DOWNSTREAM.
SATURDAY THE UPPER RIDGE WILL STRENGTHEN AND RIDGE NORTH ON THE HIGH
PLAINS WITH A CONTINUE CHANCE OF STORMS UNTIL THE UPPER RIDGE BUILDS
EAST SATURDAY NIGHT.

BLEND OF ECMWF AND GFS USED IN THE EXTENDED. MAIN THREAT SEEN FOR
CONVECTION IS IN THE NORTHWEST AS POSITIVE TILTED RIDGE AXIS
EXTENDS NORTH NORTHEAST ACROSS WESTERN NEB. SURFACE FRONT WILL BE TO
THE NORTHWEST WITH CONVECTION FORMING ON THE HIGH PLAINS AND
WEAKENING WHILE MOVING EAST ACROSS WESTERN NEB.

.LBF...NONE.

KECK

NEZ004>010-022>029-035>038-056>059-069>071-094-121045-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1159 AM CDT WED JUN 11 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND NORTH CENTRAL
NEBRASKA.

.DAY ONE...TODAY

THERE IS A CHANCE FOR THE DEVELOPMENT OF SEVERE THUNDERSTORMS LATER
THIS AFTERNOON ACROSS PORTIONS OF WESTERN AND NORTH CENTRAL
NEBRASKA. THE AREA OF GREATEST CONCERN INITIALLY IS IN AN AREA
BOUNDED BY A LINE FROM MERRIMAN...TO OGALLALA...TO THEDFORD TO
AINSWORTH.

WARM...MOIST...UNSTABLE AIR WILL BE IN PLACE ACROSS THE PREVIOUSLY
MENTIONED AREA...AND FURTHER EAST. A BOUNDARY SEPARATING THE
WARM...MOIST AIR FROM DRYER AIR TO THE WEST...OR DRYLINE...WILL
PROGRESS ACROSS THE EASTERN PANHANDLE THIS AFTERNOON. AS THIS
BOUNDARY ENCOUNTERS THE UNSTABLE AIR...AND AN UPPER LEVEL
DISTURBANCE...THUNDERSTORMS ARE EXPECTED TO DEVELOP QUICKLY IN OR
CLOSE TO THE AREA OF GREATEST CONCERN. DEVELOPMENT IS EXPECTED TO
OCCUR AFTER 2 PM CDT (1 PM MDT). ALTHOUGH THE MAIN SEVERE WEATHER
THREAT WILL BE LARGE HAIL AND DAMAGING WINDS...WIND PROFILES ALOFT
WILL BE FAVORABLE FOR THE DEVELOPMENT OF ISOLATED TORNADOES AS WELL.

LATER TONIGHT...THUNDERSTORM DEVELOPMENT IS EXPECTED TO BECOME MORE
WIDESPREAD ACROSS WESTERN AND NORTH CENTRAL NEBRASKA...WITH SEVERE
THUNDERSTORMS POSSIBLE EAST OF A LINE FROM MERRIMAN TO OGALLALA AS
THE THUNDERSTORM COMPLEX MOVES EAST. IN ADDITION...FURTHER
THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE LATE TONIGHT...GENERALLY
AFTER MIDNIGHT ACROSS SOUTHWEST NEBRASKA...AS A COLD FRONT PUSHES
INTO THE AREA.

THOSE PLANNING OUTDOOR ACTIVITIES TODAY AND TONIGHT ACROSS WESTERN
AND NORTH CENTRAL NEBRASKA SHOULD MONITOR NOAA WEATHER RADIO AND
LOCAL MEDIA BROADCASTS TO KEEP AWARE OF THE POTENTIAL FOR SEVERE
WEATHER DEVELOPMENT.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

ADDITIONAL SEVERE THUNDERSTORM DEVELOPMENT IS POSSIBLE AGAIN
THURSDAY AFTERNOON AND EVENING...ACROSS PORTIONS OF THE SOUTHEAST
NEBRASKA PANHANDLE AND SOUTHWEST NEBRASKA.

ALSO...FRIDAY HOLDS YET ANOTHER CHANCE FOR SEVERE THUNDERSTORM
DEVELOPMENT...MAINLY ACROSS WESTERN NEBRASKA.

.SPOTTER INFORMATION STATEMENT...
SPOTTERS WILL LIKELY BE NEEDED ACROSS NORTH CENTRAL NEBRASKA THIS
AFTERNOON...AND ACROSS MOST OF THE OUTLOOK AREA THIS EVENING AND
TONIGHT. SPOTTERS MAY ALSO BE NEEDED IN THE SOUTHWEST PORTION OF THE
OUTLOOK AREA ON THURSDAY.

JWS