Severe Thunderstorm Warning 115, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
347 PM CDT TUE JUN 3 2008

.DISCUSSION...
TONIGHT THROUGH NOON WEDNESDAY...
A DISTURBANCE WILL EXIT THE COLO ROCKIES THIS AFTN AND MOVE THROUGH
PARTS OF WRN AND NCNTL NEB THIS EVENING AND OVERNIGHT. AN MCS IS
SUGGESTED BY THE NGM...GFS AND NAM12 OVER PARTS OF SWRN AND NCNTL
NEB. A SECOND MCS COULD DEVELOP OFF THE BLACK HILLS THIS EVENING
AFFECTING NRN ZONES. THE MODELS SUGGEST A THIRD MCS MAY SPLIT OFF
NORTHWARD FROM THE ONE MOVING THROUGH SWRN NEB AND CROSS CUSTER
COUNTY AND ADJOINING AREAS TO THE NORTH. MOISTURE ADVECTION IS
SOMEWHAT LIMITED SO THESE SYSTEMS WILL LIKELY BE OPERATING ON
RESIDUAL MOISTURE SWEPT EAST FROM A WEAK COLD FRONT WHICH MOVED
THROUGH THIS MORNING. THUS THE STAGE IS SET FOR A FAIRLY WIDESPREAD
ROUND OF THUNDERSTORMS BUT FLOODING POTENTIAL IS SOMEWHAT LIMITED.
THE FLASH FLOOD WATCH WILL CONTINUE TONIGHT ACROSS THE NORTHEASTERN
ZONES WHERE 3 HOUR FLASH FLOOD GUIDANCE IS VERY LOW. ACROSS THE
SOUTHWEST...HPC PROVIDED NO GUIDANCE ON THIS AREA ALTHOUGH THE NGM...
GFS AND NAM12 SUGGESTED CLOSE TO AN INCH OF RAIN TONIGHT. THE 12Z
ECMWF WAS SILENT ACROSS ALL OF WRN AND NCNTL NEB. THE 18Z NAM12
SUGGESTS THE NORTH AND SOUTH CONVECTIVE COMPLEXES WILL CONGEAL ACROSS
CUSTER AND ADJOINING PARTS OF NCNTL NEB BETWEEN 06Z AND 12Z THIS
EVENING. THIS IS VERY SIMILAR TO THE 12Z GFS. THE NAM12 PUTS DOWN
1 TO 2.5 INCHES OF RAINFALL FROM INTERSTATE 80 NORTHWARD TO THE SD
BORDER TONIGHT.

THE WRN 3/4 OF THE FCST IS OUTLOOKED FOR SEVERE WEATHER TONIGHT...
THIS IS THE AREA WHICH COVERS ALL BUT THE NORTHEAST ZONES. LARGE HAIL
AND ISOLATED TORNADOES ARE THE MAIN CONCERN. WINDS ALOFT REMAIN
QUITE STRONG AND THE PARAMETERS FOR ISOLATED TORNADO DEVELOPMENT ARE
MOST FAVORED ACROSS SWRN NEB AND DECREASE NORTH AND EAST TO NEB
HIGHWAY 2. ARRIVAL TIMES FOR THE STORMS ARE 00Z FOR PERKINS AND CHASE
COUNTIES...LINCOLN 03Z AND CUSTER COUNTY 06Z BASED ON A 25 MPH
FORWARD MOTION OBSERVED IN THE COLO SYSTEM UNDERWAY THIS AFTN.
CONVECTIVE INITIATION WITHIN THE FCST SEEMS UNLIKELY GIVEN THE LACK
OF UA FORCING. ACROSS THE NORTH...MCS DEVELOPMENT AND PROPAGATION IS
MORE UNCERTAIN AS THE FORCING IS WEAK. ALL OF THIS CONVECTION SHOULD
EXIT THE FCST AREA BY AROUND NOON WEDNESDAY.

WEDNESDAY AFTERNOON THROUGH THURSDAY MORNING...
THE NAM12 AND GFS SUGGEST ANOTHER POWERFUL DISTURBANCE WILL EXIT THE
CNTL ROCKIES AND TRAVERSE WRN NEB. THE NAM12 IS SPREADING THE
THUNDERSTORMS FARTHER EAST INTO MUCH OF NCNTL NEB WHILE THE GFS HOLDS
THE ACTIVITY MOSTLY WEST. THE GFS IS SIMILAR TO THE 12Z ECMWF. THUS
IT IS QUITE LIKELY THE FLASH FLOOD WATCH FOR THE NORTHEASTERN CORNER
OF THE FCST AREA WILL NEED TO BE REISSUED FOR WEDNESDAY NIGHT AND
THURSDAY.

THURSDAY AFTN THROUGH FRIDAY MORNING...
THE LAST MAJOR SURGE OF ENERGY FROM THE WRN U.S LONG WAVE TROF WILL
LIFT THROUGH THE CNTL PLAINS. THE 12Z ECMWF IS TRENDING DANGEROUSLY
WESTWARD SUCH THAT THE SFC LOW AND ATTENDANT WARM FRONT WOULD LIFT
THROUGH NCNTL NEB ALONG AND EAST OF HIGHWAY 83. IF THIS VERIFIES A
TORNADO OUTBREAK COULD DEVELOP ACROSS THE AFOREMENTIONED AREA. THE
NAM12 AND GFS ARE FARTHER EAST AND SPARE NCNTL NEB SUGGESTING THE
TORNADOES WILL FORM ACROSS JUST ERN NEB. THIS IS CLOSE TO THE SPC
DAY 3 OUTLOOK WHICH CALLS FOR A MAJOR SEVERE WEATHER EVENT FROM
ROUGHLY EAST OF A LINE FROM GRAND ISLAND TO SIOUX CITY WITH LESSER
RISK OF SEVERE WEATHER TO THE WEST AND NORTH.

FLOODING CONCERNS ARE EXPECTED TO GRADUALLY INCREASE TONIGHT THROUGH
THURSDAY NIGHT AS ALL GUIDANCE INDICATES CHANCE TO LIKELY POPS
THROUGHOUT THIS TIME FRAME AND MODEL QPF TOTALS GENERALLY RANGE
FROM 1 TO 2 INCHES SOUTH AND 2 OT 3 INCHES NORTH.

FRIDAY AND SATURDAY...BOTH THE ECMWF AND GFS SETTLE DOWN AND DEVELOP
A WARMING TREND. BOTH MODELS ARE CONSISTENT DROPPING A COLD FRONT
THROUGH SOMETIME LATE SATURDAY. THIS FRONT IS EXPECTED TO HANG UP
OVER KANSAS AND BECOME ORIENTED MORE OR LESS PARALLEL TO THE H5
FLOW SW TO NE ACROSS WRN KS AND ERN NEB. THE ECMWF SUGGESTS
SIGNIFICANT RAINFALL WILL REDEVELOP SUNDAY NIGHT AS A DEEPENING
WRN U.S. TROF DEVELOPS AND ENERGY EJECTS NORTHEASTWARD FROM THE
SYSTEM. THE GFS IS DRIER AND NOT NEARLY AS AMPLIFIED. THE HPC FCST IS
FOR CHC/SLGHT CHC POPS SATURDAY NIGHT THROUGH MONDAY MORNING. THE
TEMPERATURE FCST FOR SATURDAY LOOKS REASONABLE WITH 80S FOR HIGHS.
70S TO NEAR 80 IS FCST FOR SUNDAY AND MONDAY. LATER FCSTS MAY NEED TO
ADJUST THESE HIGHS DOWN SLIGHTLY TO ACCOMMODATE INCREASED CLOUDINESS
AND RAINFALL.

TUESDAY...TEMPERATURES REBOUND INTO THE 80S. WINDS ALOFT ARE
EXPECTED TO REMAIN QUITE STRONG BUT NO SIGNIFICANT DISTURBANCES ARE
ANTICIPATED AT THIS TIME SO THE FCST IS DRY.

&&

.AVIATION...
WEAK HIGH PRESSURE RESIDES ACROSS WESTERN NEBRASKA...WHICH WILL
FAVOR LIGHT AND VARIABLE WINDS AT KLBF/KVTN THROUGH TUESDAY
AFTERNOON. THE ATMOSPHERE IS EXPECTED TO DESTABILIZE OVER THE HIGH
PLAINS BY MID AFTERNOON...RESULTING IN SHOWER AND THUNDERSTORM
DEVELOPMENT. ALTHOUGH THERE IS A SLIGHT CHANCE OF A STORM AFFECTING
THE KLBF TAF SITE DURING THE LATE AFTERNOON...THE MORE LIKELY
SCENARIO IS FOR THUNDERSTORM ACTIVITY TO BECOME MORE WIDESPREAD
DURING THE OVERNIGHT HOURS AS LOW LVL WARM AIR ADVECTION INCREASES.
THESE STORM ARE THEN EXPECTED TO AFFECT BOTH KLBF AND KVTN AFTER
04Z...POSSIBLY PERSISTING AFTER SUNRISE WEDNESDAY.
&&

.LBF WATCHES/WARNINGS/ADVISORIES...FLASH FLOOD WATCH TONIGHT
THROUGH EARLY WEDNESDAY AFTERNOON ZONES 006-007-009-010-029.
&&

CDC/JG

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE NORTH PLATTE NE
412 PM CDT TUE JUN 3 2008

NEZ004>010-022>029-035>038-056>059-069>071-094-042115-
SHERIDAN-EASTERN CHERRY-KEYA PAHA-BOYD-BROWN-ROCK-HOLT-GARDEN-
GRANT-HOOKER-THOMAS-BLAINE-LOUP-GARFIELD-WHEELER-ARTHUR-MCPHERSON-
LOGAN-CUSTER-DEUEL-KEITH-PERKINS-LINCOLN-CHASE-HAYES-FRONTIER-
WESTERN CHERRY-
412 PM CDT TUE JUN 3 2008 /312 PM MDT TUE JUN 3 2008/

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

.DAY ONE...TONIGHT.

SEVERE THUNDERSTORMS ARE POSSIBLE ACROSS PORTIONS OF WESTERN AND
NORTH CENTRAL NEBRASKA. THE STRONGEST ACTIVITY WILL INITIALLY
DEVELOP WEST OF HIGHWAY 61 AS STORMS SPREAD EAST OUT OF NORTHEAST
COLORADO AND THE NEBRASKA PANHANDLE. THESE STORMS ARE THEN
EXPECTED TO EXPAND IN COVERAGE AS THEY ENTER WESTERN NEBRASKA.
ADDITIONAL...MORE ISOLATED ACTIVITY...MAY MOVE SOUTHEAST OUT OF
SOUTH DAKOTA AND INTO NORTH CENTRAL NEBRASKA. THE COMBINATION OF
MODERATE INSTABILITY AND VERTICAL WIND SHEAR WILL FAVOR THE
DEVELOPMENT OF STRONG MULTICELLS AS WELL AS A FEW
SUPERCELLS...CAPABLE OF PRODUCING LARGE HAIL.

IN ADDITION TO THE SEVERE WEATHER THREAT...HEAVY RAIN IS POSSIBLE
OVERNIGHT...AND MAY LEAD TO FLASH FLOODING...PARTICULARLY IN NORTH
CENTRAL AND NORTHEASTERN NEBRASKA DUE TO SATURATED GROUND
CONDITIONS. A FLASH FLOOD WATCH IS IN EFFECT EAST OF A LINE FROM
SPRINGVIEW...TO AMELIA...TO BARTLETT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

THE THREAT FOR SEVERE THUNDERSTORMS CONTINUES ON WEDNESDAY ACROSS
ALL OF WESTERN AND NORTH CENTRAL NEBRASKA. AN AREA OF LOW PRESSURE
IS EXPECTED TO MATERIALIZE OVER EASTERN COLORADO AND WESTERN
KANSAS DURING WEDNESDAY AFTERNOON. NORTH OF THE LOW...SURFACE
WINDS WILL BE EASTERLY ACROSS MOST OF WESTERN NEBRASKA...WHICH
WILL DRAW A MOIST LOW LEVEL AIRMASS WEST INTO THE REGION. AS A
POTENT UPPER LEVEL DISTURBANCE EJECTS EAST ACROSS THE CENTRAL
UNITED STATES...THUNDERSTORMS ARE EXPECTED TO RAPIDLY DEVELOP
ACROSS MUCH OF THE PLAINS. UNCERTAINTY EXISTS REGARDING HOW MUCH
SURFACE HEATING WILL OCCUR...WHICH WILL IMPACT THE TORNADO
THREAT...BUT THE PRESENCE OF STRONG VERTICAL WIND SHEAR WILL FAVOR
THE DEVELOPMENT OF SUPERCELLS PRODUCING LARGE HAIL AND DAMAGING
WINDS.

ON THURSDAY...SEVERE THUNDERSTORMS ARE AGAIN POSSIBLE EAST OF A
BARTLETT TO HAYES CENTER LINE.

ALTHOUGH THUNDERSTORMS ARE POSSIBLE SATURDAY NIGHT AND
SUNDAY...SEVERE WEATHER IS NOT EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED TONIGHT.

&&

THIS PRODUCT IS NOW AVAILABLE...ALONG WITH OTHER WEATHER...
HYDROLOGICAL AND CLIMATOLOGICAL INFORMATION...AT
HTTP://WWW.WEATHER.GOV/NORTHPLATTE

GARNER

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORTH PLATTE NE
600 PM CDT TUE JUN 03 2008

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0535 PM     TSTM WND GST     4 N MERRIMAN            42.98N 101.70W
06/03/2008  E60 MPH          CHERRY             NE   PUBLIC

&&

13

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