Severe Thunderstorm Warning 223, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
255 PM CDT TUE JUL 7 2009

.DISCUSSION...
THE SEVERE WEATHER SITUATION IS SLOWLY EVOLVING THIS AFTN ACROSS ERN
SD. A SFC LOW IS EXPECTED TO DROP DUE SOUTH THROUGH WRN NEB THIS
AFTN AND EVENING POOLING MOISTURE AND INSTABILITY ALONG AN INVERTED
TROF. THE SMART GUESS FOR SUPER CELL INITIATION AND PROPAGATION
IS ACROSS SCNTL SD LATE THIS AFTN VCNTY KICR. STRONG LINEAR SHEAR
ALOFT AND HELP FROM THE NAM12 AND RUC MODELS SUGGEST A LARGE SINGLE
CELL OR COMPACT CLUSTER OF STRONG TO SEVERE STORMS WILL FORM AND DROP
DUE SOUTH ALONG HIGHWAY 183...BUT PERHAPS FARTHER EAST ALONG 283 OR
FARTHER WEST ALONG HIGHWAY 83 DEPENDING ON THE INSTABILITY GRADIENT
WHICH IS YET TO FORM. AS INDICATED BY SPC VERY LARGE HAIL COULD
OCCUR IF THE DEVELOPMENT REALLY GETS GOING.

OTHER MORE ISOLATED STRONG STORMS COULD FORM FARTHER WEST IN A DEEPER
MIXED LAYER ACROSS WRN NEB AS A WEAK COLD FRONT DRIFTS SOUTH.

FOR WEDNESDAY...THE COLD FRONT WILL QUICKLY LIFT BACK NORTH INTO THE
DAKOTAS. CAPE IS EXPECTED TO SOAR BUT A VERY STRONG CAP WILL BE IN
PLACE. THE NAM SUGGESTED AN ISOLATED THUNDERSTORM COULD FROM OFF THE
BLACK HILLS AND MOVE TOWARD OR INTO NORTHERN NEBRASKA LATE IN THE
DAY. IT IS ALSO POSSIBLE REMNANTS OF A MCS ACROSS THE NRN PLAINS
COULD DRIFT THROUGH NRN NEBRASKA WEDNESDAY MORNING OR LATE
WEDNESDAY NIGHT. A COLD FRONT WILL ALSO BE MOVING SOUTH THROUGH THE
FCST AREA AFTER MIDNIGHT. SO BASICALLY A THUNDERSTORM COULD FROM AT
ANY TIME IF THE CAP WEAKENS SUFFICIENTLY WHICH IS MOST LIKELY ACROSS
NRN NEB.

THURSDAY...A COLD FRONT SWEEPS INTO KS. PRODUCING MOSTLY SUNNY SKIES
AND SLIGHTLY COOLER WEATHER.

FRIDAY...THE FRONT IS EXPECTED TO LIFT NORTH INTO SRN NEB. NRN NEB
MAY BE BRUSHED BY THE REMNANTS OF A MCS MOVING THROUGH SD. OTHERWISE
ISOLATED THUNDERSTORMS COULD DEVELOP FRIDAY NIGHT ACROSS WRN AND SRN
NEB AS A DISTURBANCE MOVES THROUGH SRN WY AND COLO.

SATURDAY AND SUNDAY...HIGH CAPE WILL CONTINUE ACROSS WRN AND SRN
PTNS OF THE FCST AREA AS A STATIONARY FRONT LIFTS SLOWLY NORTH.
WINDS ALOFT WILL REMAIN QUITE STRONG AND THE GFS AND ECMWF ARE FAIRLY
CLOSE WITH THE FRONTAL POSITION. ANY DISTURBANCES WHICH MOVE OUT OF
WY COULD PRODUCE ISOLATED THUNDERSTORMS.

MONDAY AND TUESDAY...A WARM FRONT WILL LIFT NORTH MONDAY PROVIDING
FOCUS FOR ISOLATED THUNDERSTORM DEVELOPMENT AND A COLD FRONT TO
FOLLOW MONDAY NIGHT LEAVING TUESDAY SLIGHTLY COOLER BUT DRY.

TEMPERATURES ARE A BLEND OF THE NAM AND GUIDANCE THROUGH FRIDAY.
HPC PROVIDED TEMPERATURES FOR THE EXTENDED FCST. THE ECMWF IS
COOLER THAN THE GFS. HPC PREFERRED THE WARMER GFS. THUS THERE IS A
CHANCE MAX TEMPERATURES MAY HAVE TO BE MARKED DOWN A CATEGORY OR
TWO. LESS THAN AN INCH OF RAIN IS EXPECTED DURING THE NEXT 7 DAYS.
ALL MODELS FOCUS THE HEAVIEST RAIN ACROSS THE DAKOTAS AND THE UPPER
MIDWEST.

&&

.AVIATION...
THUNDERSTORM CHANCES NEAR AND EAST OF KVTN AND KLBF ARE THE PRIMARY
AVIATION CONCERN.  THE ATMOSPHERE OVER CENTRAL NEBRASKA WILL BE
VERY UNSTABLE THIS AFTERNOON AND EVENING AND THUNDERSTORMS ARE IN
BOTH AFOREMENTIONED TAF SITES.  STRONG TO SEVERE THUNDERSTORMS ARE
POSSIBLE NEAR AND EAST OF KVTN ACROSS NORTH CENTRAL NEBRASKA AND
THIS IS REFLECTED IN THE KVTN TAF.  OUTSIDE OF THUNDERSTORMS AND
AFTER 6Z TONIGHT...VFR CONDITIONS ARE EXPECTED.
&&

.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&

CDC/HIRSCH

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE NORTH PLATTE NE
803 PM CDT TUE JUL 7 2009

NEZ004>010-022>029-035>038-056>059-069>071-094-090115-
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-
803 PM CDT TUE JUL 7 2009 /703 PM MDT TUE JUL 7 2009/

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

.DAY ONE...TONIGHT.

THERE REMAINS A CHANCE OF THUNDERSTORMS THIS EVENING...ACROSS
NORTH CENTRAL NEBRASKA. ANY STORMS WHICH DEVELOP COULD CONTAIN
GUSTY WINDS AND SMALL HAIL.

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

THUNDERSTORMS ARE POSSIBLE ARE AGAIN POSSIBLE ON WEDNESDAY NIGHT AND
AGAIN FRIDAY NIGHT THROUGH MONDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED THROUGH TONIGHT.

&&

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

KAR