Severe Thunderstorm Warning 82, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
236 AM CDT TUE JUN 26 2001

THE CHANCES OF PRECIPITATION AND TEMPERATURES ARE THE MAIN FORECAST
CHALLENGES THROUGH WEDNESDAY...

...06Z SYNOPSIS...
    ONGOING CONVECTION IN SOUTHWEST NEBRASKA HAS DRIFTED WEST AND
NORTHWEST AS RED WILLOW PROFILER WINDS ARE EAST AND SOUTHEAST IN THE
MID LEVELS. LOW LEVEL H85 JET OF 50 KTS IS SUSTAINING CONVECTION
WITH SEVERAL BOUNDARIES EVIDENT. VERY LITTLE FOCUS FOR CONVECTION SO
FAR ALONG THE SURFACE BOUNDARY GENERALLY RUNNING FROM PIR SD TO SNY
NEBR. WATER VAPOR IMAGERY INDICATES A WELL DEVELOPED WAVE IN
SOUTHERN CALIFORNIA. ACCORDING TO THE ETA/AVN OUTPUT...THIS FEATURE
WILL MOVE INTO THE CENTRAL AND SOUTHERN ROCKIES BY WEDNESDAY EVENING
AND INTO THE CENTRAL PLAINS ON THU INTO THU NIGHT. THIS COULD BE
MORE OF A PLAYER THAN THE MODELS CURRENTLY INDICATED AND WILL NEED
TO BE MONITORED.

 ...MODELS...
    THE ETA HAS PERFORMED BETTER THAN THE AVN AND NGM REGARDING
POSITIONING OF QPFS TONIGHT. THE AVN HOWEVER IS GENERATING QPFS IN
NORTHERN KS INTO SOUTHERN NEBRASKA WHICH LOOKS BETTER WITH ONGOING
CONVECTION MOST CONCENTRATED IN SOUTHWEST NEBRASKA. THE NGM
DISREGARDED AS ITS TOO BULLISH OVER AREAS OF SOUTHERN SD AND
NORTHERN NEBRASKA. WILL USE AND ETA AVN BLEND.

TODAY...FOCUS FOR THUNDERSTORMS WILL RESIDE ALONG THE SURFACE AND
H85 FRONT. THE ETA SHOWS THE SURFACE WARM FRONT ACROSS CENTRAL
NEBRASKA WITH THE 850 FRONT JUST TO THE NORTH OVER NORTH CENTRAL
NEBRASKA. STRONG SURFACE HEATING FROM KS INTO SOUTHERN NEBRASKA
SHOULD SUFFICIENTLY DESTABILIZE THE ATMOS AS WM AIR IS LIFTED NORTH
OF THE FRONT. SUFFICIENT SHEAR ACROSS THE NORTH CENTRAL FOR
SUPERCELLS AND LG HAIL. DEWPOINTS TO REACH THE MID 60S OVER NORTH
CENTRAL. ONGOING CONVECTION OVER MAINLY THE SOUTHWEST SHOULD SUBSIDE
BY MID MORNING AS H85 JET WEAKENS. BY AFTERNOON THE BEST POPS TO BE
ACROSS THE NORTH AND WILL LEAVE OUT POPS FAR SOUTHWESTERN COUNTIES.
WILL GO SLIGHTLY ABOVE THE WARMER FCC GUIDANCE IN THE SOUTHWEST WITH
MID 90S POSSIBLE FAR SOUTHWEST TO MID 80S NORTHCENTRAL WHERE NE
WINDS...HIGHER DWPTS AND MORE CLOUDINESS TO RESIDE.

TONIGHT...EVENING CONVECTION CONTINUES IN THE NORTH CENTRAL BUT WILL
DIMINISH AS H85 FRONTOGENESIS DROPS SOUTH AND WEAKENS AND SURFACE
WARM FRONT LIFTS NORTH INTO SOUTH DAKOTA. A 20 POP NEEDED FOR
EVENING IN THE SOUTHWEST AS H85 FRONTOGENESIS MOVES SOUTHWARD BUT
WEAKENS BY LATE EVENING.

WEDNESDAY...VERY WARM TEMPERATURES TO RETURN TO ALL OF CWFA AS WARM
FROM LIFTS NORTH INTO NORTH DAKOTA AND SURFACE TROUGH REMAINS ALONG
THE WESTERN HIGH PLAINS. WILL GO A CATEGORY OR TWO ABOVE GUIDANCE.
MOSTLY SUNNY AND DRY AS UPPER RIDGE BUILDS BACK TO THE WEST. CUTTOFF
LOW OVER SRN MO REMAINS WELL AWAY FROM AREA.

WEDNESDAY NIGHT...WHILE SURFACE TROUGH REMAINS OVER WESTERN NEBRASKA
THE WAVE CURRENTLY OVER SRN CA EJECTS AND ARRIVES OVER THE ROCKIES
WEDNESDAY NIGHT. STRONG DAYTIME HEATING SHOULD DEVELOP ISOLATED TSAR
TO OUR WEST BY LATE AFT AND MOVE AND DEVELOP EASTWARD. WITH TIMING
OF VORT MAX STILL UNCERTAIN WILL LIMIT TSRA CHANCES TO THE WESTERN
COUNTIES AND LEAVE THE EAST DRY.

IN THE EXTENDED...WILL CHECK THE LATEST MRF CONCERNING UPPER RIDGE
TRENDS AND ITS EFFECTS ON TEMPS AND PRECIP.

.LBF...NONE.

ROBERG

NEZ004>010-022>029-035>038-056>059-069>071-261630-

SEVERE WEATHER OUTLOOK FOR WESTERN AND NORTH CENTRAL NEBRASKA
NATIONAL WEATHER SERVICE NORTH PLATTE NE
532 AM CDT TUE JUN 26 2001

...STORM SPOTTER ACTIVATION MAY BE NEEDED LATE THIS AFTERNOON INTO
TONIGHT...

THERE IS A CHANCE OF THUNDERSTORMS THIS AFTERNOON NORTH OF A LINE
FROM MASON CITY...TO ANSELMO...TO ANTIOCH...WHILE TONIGHT THERE IS A
CHANCE OF THUNDERSTORMS THROUGHOUT WESTERN AND NORTH CENTRAL
NEBRASKA. THE GREATEST THREAT OF SEVERE THUNDERSTORMS WILL EXIST
ALONG AND TO THE NORTH OF A LINE FROM ERICSON TO ANTIOCH. LARGE HAIL
AND DAMAGING WINDS WILL BE THE PRIMARY THREAT.

A FRONT WILL REMAIN NEARLY STATIONARY ACROSS NORTHERN NEBRASKA
THIS AFTERNOON INTO TONIGHT. A VERY WARM...MOIST AND UNSTABLE
ENVIRONMENT WILL EXIST OVER SOUTHERN NEBRASKA INTO THE SOUTHERN
PLAINS. STEADY SOUTHERLY WINDS OVER THIS AREA WILL CONTINUOUSLY
FORCE THE UNSTABLE AIR OVER THE FRONT TODAY WITH INCREASED
POTENTIAL FOR THUNDERSTORM DEVELOPMENT ALONG AND NORTH OF THE FRONT.
ANY THUNDERSTORMS THAT DO DEVELOP COULD RAPIDLY REACH SEVERE LEVELS.
THE THUNDERSTORMS WILL ALSO EXHIBIT VERY LITTLE MOVEMENT AND HAVE THE
POTENTIAL TO PRODUCE HEAVY RAINFALL.

DJB