Severe Thunderstorm Warning 216, NWS North Platte, NE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1020 AM CDT MON AUG 26 2002

HAVE UPDATED THE ZONES TO REFLECT THE CURRENT PRECIP TRENDS.  MCS
FROM LAST NIGHT CONTINUES TO HANG ON.  MORNING SOUNDING SHOWS VERY
STEEP LAPSE RATES ABOVE THE NOCTURNAL INVERSION.  MCK PROFILER
CONTINUES TO SHOW 25 KNOT SSW WINDS CONTINUING TO FEED THE MCS WITH
15C DEWPOINTS AT H8.  AS WE FURTHER MIX OUT THIS MORNING EXPECT THE
LLJ TO WEAKEN AND MCS TO BEGIN TO FALL APART THIS AFTERNOON...BUT
WITH PLENTY OF INSTABILITY...WIND SHEAR...AND BOUNDARIES
GALORE...MORE CONVECTION SHOULD FIRE UP/RE-INTENSIFY LATER THIS
AFTERNOON.

IZZI/POWER

PREVIOUS DISCUSSION FOLLOWS...

...FORECAST CONCERN WILL BE POPS OVER THE NEXT SEVERAL DAYS...

S/W AND ASSOC SPEED MAX SEEN IN H2O MOVED ACROSS HIGH PLANS INTO
NORTH CENTRAL NE SPARKING TSRA ACROSS MAINLY CHERRY COUNTY. S/W IS
MOVING IN FAST WESTERLY FLOW BETWEEN H5 RIDGE OVER THE DESERT
SOUTHWEST AND H5 TROF OVER NW CONUS. MRRN PROF SHOWING THIS SPEED
MAX WITH GOOD VEERING/WAA THROUGH 500 MB...IN ADDITION H25 JET AXIS
ARCING OVER ROCKIES INTO WESTERN NE/NE KANSAS. OTHER CONERN IS MCS
OVER WESTERN SOUTH DAKOTA WHICH NEW ETA SHOWS BUILDING SOUTHWARD
INTO CWA ALONG THETA-E AXIS. SURFACE MAP SHOWING TROF ALONG FRONT
RANGE OF ROCKIES...BUT CAN NOT REALLY PICK OUT THE BOUNDARY ON WHICH
THE TSRA IS FORMING ALONG...EXECPT THIS IS AREA OF TIGHTER DPNT
GRADIENT.

FIRST BIG CHALLENGE TODAY IS WHERE WILL DAKOTA MCS MIGRATE TO THIS
MORNING...WILL KEEP AN EYE ON THROUGH FORECAST ISSUANCE. LOOKS LIKE
NORTHEAST CWA IS UNDER THE GUN. CORFIDI VECTORS SUPPORT THE
SOUTHEAST TO SOUTHWARD MOVEMENT. AVN DOESNT HAVE A GOOD HANDLE ON
IT A 06Z AND BY 12Z-18Z MOVES AREA OF PRECIP EASTWARD THROUGH SOUTH
DAKOTA. CURRENT THINKING IS TO PLACE CHC POPS NORTH AND WEST WITH
SLGHT CHC SOUTHEAST TODAY. HOWEVER IT WORKS OUT...BEST INSTABILITY
AS IN THE PAST FEW DAYS WILL BE IN THE WEST WHERE
SOUTH/SOUTHEASTERLY UPSLOPE FLOW WILL CONTINUE TO KEEP BEST
SHEAR...AND THETA E RIDGE IN PLACE. TEMPS TODAY WILL ALSO DEPEND ON
WHERE SYSTEM TRACK...IF SOUTHWARD WOULD EXPECT MORE CLOUD COVER AND
COOLER TEMPS.

H5 TROF OFF THE WESTERN COAST WILL MOVE INLAND TODAY AND INTO GREAT
BASIN AREA TONIGHT AND PHASE WITH NORTHERN LOW OVER MT. THIS WILL
PUSH THE UPPER JET FARTHER SOUTH AND MID LEVEL FLOW WEAKENS SOMEWHAT
OVER THE WESTERN CWA TONIGHT...BUT UPSLOPE FLOW WILL CONTINUE TO
KEEP GOOD SHEAR ACROSS WESTERN HIGH PLAINS. LVL JET EVOLVES AGAIN
TONIGHT WITH THE STRONGEST ELEVATED INSTABILITY OVER THE WEST WILL
KEEP CHC POPS WEST OF HIGHWAY 83 WITH SLIGHT CHC EAST.

WILL KEEP POPS IN FOR TUESDAY AFTERNOON OVERNIGHT WITH CHC
WEST...SLGHT CHC EAST. PATTERN REMAINS SIMILAR WITH UPPER LOW OVER
THE GREAT BASIN THROWING S/WAVES INTO PLAINS IN SOUTHWEST FLOW.
UPSLOPE SOUTHEASTERLY FLOW CONTINUES WITH WAA ADVECTION REGIME
REMAINING PLANTED OVER HIGH PLAINS.

CONFIDENCE LOW ABOUT PATTERN CHANGE WEDNESDAY THROUGH WEEKEND.
H5 LOW IN GREAT BASIN EJECTS IN RESPONSE TO JET ROUNDING THE
BASE OF LOW ON LATE WEDNESDAY INTO THURS MORN...AS STRONGER WAVE
APPROACHES THE WEST COAST. WILL LEAVE REMAINDER OF FORECAST MOSTLY
AS IS WITH A FEW SLIGHT CHANGES.

.LBF...NONE.

DP

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORTH PLATTE, NE
918 AM CDT MON AUG 26 2002

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0910 AM    MILBURN                   NE   .75 INCH HAIL
08/26/02   CUSTER

IZZI

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORTH PLATTE, NE
924 AM CDT MON AUG 26 2002

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0920 AM    1 W TAYLOR                NE   .75 INCH HAIL
08/26/02   LOUP

IZZI

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORTH PLATTE, NE
934 AM CDT MON AUG 26 2002

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0930 AM    BREWSTER                  NE   1.00 INCH HAIL
08/26/02   BLAINE

IZZI

NEZ004>010-022>029-035>038-056>059-069>071-094-262045-

HAZARDOUS WEATHER OUTLOOK FOR WESTERN AND NORTH CENTRAL NEBRASKA
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1035 AM CDT MON AUG 26 2002

...STORM SPOTTER WILL BE REQUIRED ACROSS PORTIONS OF WESTERN AND
NORTH CENTRAL NEBRASKA TODAY...

THUNDERSTORMS WILL CONTINUE ACROSS PORTIONS OF WESTERN AND NORTH
CENTRAL NEBRASKA THIS MORNING.  SOME OF THESE THUNDERSTORMS WILL
REMAIN SEVERE INTO THE NOON HOUR.  LARGE HAIL AND STRONG DAMAGING
WINDS WILL BE THE PRIMARY THREAT WITH THESE THUNDERSTORMS THIS
MORNING.

AN UNSTABLE MOIST ATMOSPHERE WILL PERSIST ACROSS THE OUTLOOK AREA
THIS AFTERNOON. A LEE SIDE TROUGH REMAINS STATIONARY FROM EASTERN
COLORADO INTO THE NEBRASKA PANHANDLE.  IN ADDITION...THUNDERSTORMS
THIS MORNING WILL LAY DOWN FURTHER SURFACE BOUNDARIES TO FOCUS
ADDITIONAL THUNDERSTORM DEVELOPMENT THIS AFTERNOON AS TEMPERATURES
RISE...AND AN UPPER LEVEL DISTURBANCE ENTERS THE REGION.  THE
ATMOSPHERE WILL SUFFICIENTLY DESTABILIZE TO BRING US ANOTHER ROUND
OF SEVERE THUNDERSTORMS LATER THIS AFTERNOON INTO TONIGHT.  LARGE
HAIL AND DAMAGING WINDS WILL BE THE PRIMARY THREAT THIS AFTERNOON.

THE GREATEST THREAT OF SEVERE WEATHER THIS MORNING IS NORTH AND EAST
OF A LINE FROM THEDFORD IN THOMAS COUNTY TO BROKEN BOW IN
CUSTER COUNTY.

SEVERE WEATHER IS POSSIBLE ACROSS MOST OF WESTERN AND NORTH CENTRAL
NEBRASKA THIS AFTERNOON INTO TONIGHT...WITH THE GREATEST THREAT TO
THE WEST OF A LINE FROM VALENTINE TO NORTH PLATTE.

NEZ004>010-022>029-035>038-056>059-069>071-094-262045-

HAZARDOUS WEATHER OUTLOOK FOR WESTERN AND NORTH CENTRAL NEBRASKA
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1200 PM CDT MON AUG 26 2002

...STORM SPOTTER ACTIVATION WILL BE REQUIRED ACROSS WESTERN AND NORTH
CENTRAL NEBRASKA THIS AFTERNOON AND TONIGHT...

AN UNSTABLE MOIST ATMOSPHERE WILL PERSIST ACROSS THE OUTLOOK AREA
THIS AFTERNOON INTO TONIGHT. A LEE SIDE TROUGH REMAINS STATIONARY
FROM EASTERN COLORADO INTO THE NEBRASKA PANHANDLE.  IN ADDITION...
THUNDERSTORMS WHICH OCCURRED THIS MORNING OVER NORTH CENTRAL
NEBRASKA LAID DOWN FURTHER SURFACE BOUNDARIES TO FOCUS ADDITIONAL
THUNDERSTORM DEVELOPMENT THIS AFTERNOON AS TEMPERATURES RISE...AND AN
UPPER LEVEL DISTURBANCE ENTERS THE REGION.  THE ATMOSPHERE WILL
SUFFICIENTLY DESTABILIZE TO BRING US ANOTHER ROUND OF SEVERE
THUNDERSTORMS LATER THIS AFTERNOON INTO TONIGHT. LARGE HAIL AND
DAMAGING STRAIGHT LINE WINDS WILL BE THE PRIMARY THREAT THIS
AFTERNOON AND TONIGHT.

SEVERE WEATHER IS POSSIBLE ACROSS ALL OF WESTERN AND NORTH CENTRAL
NEBRASKA THIS AFTERNOON INTO TONIGHT.

NEZ004>010-022>029-035>038-056>059-069>071-094-262045-

HAZARDOUS WEATHER OUTLOOK FOR WESTERN AND NORTH CENTRAL NEBRASKA
NATIONAL WEATHER SERVICE NORTH PLATTE NE
345 PM CDT MON AUG 26 2002

...STORM SPOTTER ACTIVATION WILL BE REQUIRED ACROSS WESTERN AND NORTH
CENTRAL NEBRASKA THIS AFTERNOON AND TONIGHT...

AN UNSTABLE MOIST ATMOSPHERE WILL PERSIST ACROSS THE OUTLOOK AREA
THIS AFTERNOON INTO TONIGHT. A LEE SIDE TROUGH REMAINS STATIONARY
FROM EASTERN COLORADO INTO THE NEBRASKA PANHANDLE.  IN ADDITION...
THUNDERSTORMS WHICH OCCURRED THIS MORNING OVER NORTH CENTRAL
NEBRASKA LAID DOWN FURTHER SURFACE BOUNDARIES TO FOCUS ADDITIONAL
THUNDERSTORM DEVELOPMENT THIS AFTERNOON AS TEMPERATURES RISE...AND AN
UPPER LEVEL DISTURBANCE ENTERS THE REGION.  THE ATMOSPHERE WILL
SUFFICIENTLY DESTABILIZE TO BRING US ANOTHER ROUND OF SEVERE
THUNDERSTORMS LATER THIS AFTERNOON INTO TONIGHT. LARGE HAIL AND
DAMAGING STRAIGHT LINE WINDS WILL BE THE PRIMARY THREAT THIS
AFTERNOON AND TONIGHT.

SEVERE WEATHER IS POSSIBLE ACROSS ALL OF WESTERN AND NORTH CENTRAL
NEBRASKA THIS AFTERNOON INTO TONIGHT.