Severe Thunderstorm Warning 556, NWS Norman, OK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
1103 AM CDT SUN OCT 4 1998

SEVERE WEATHER PARAMETERS APPEAR TO BE COMING TOGETHER OVER MOST OF
THE FORECAST AREA THIS AFTERNOON...ESPECIALLY IN NORTH CENTRAL AND
CENTRAL OKLAHMOA. 12Z SURFACE ANALYSIS INDICATED A DRY LINE IN THE
OKLAHOMA PANHANDLE WHICH SHOULD MAKE ONLY LITTLE PROGRESS EASTWARD
UNTIL LATER THIS AFTERNOON...WHILE UPPER AIR ANALYSES SHOWED THE
STRONGEST WIND SHEAR..850 MB TEMPERATURE RIDGE AND 850 MB MOISTURE
AXIS OVER WESTERN AND CENTRAL KANSAS...THE OKLAHOMA PANHANDLE AND
WESTERN TEXAS. WITH RECENT RUC2 AND ETA GUIDANCE INDICATING MOST OF
THESE PARAMETES MOVING EAST INTO CENTRAL KANSAS AND CENTRAL OKLAHOMA
BETWEEN 18Z AND 00Z...COINCIDING WITH THE TIME OF MAX HEATING...
EXPECT THE BEST SEVERE WEATHER THREAT TO BE OVER NORTH CENTRAL AND
CENTRAL OKLAHOMA. HOWEVER 70 DEGREE SURFACE DEWPOINTS ARE ALREADY
ADVECTING NORTHWARD FROM TEXAS INTO WESTERN OKLAHOMA. IF SUNSHINE
CAN WARM UP TEMPERATURES IN THE WEST BEFORE THE OTHER SEVERE WEATHER
PARAMETERS MOVE EAST...WESTERN AREAS WILL ALSO BE UNDER THE GUN.
PLAN TO ADD POPS IN THE SOUTHWEST WHERE WE HAVE NONE CURRENTLY.

.OUN...
OK...NONE.
TX...NONE.

FCSTID 20/JAMES

OKZ004>048-050>052-TXZ083>090-042100-

THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE NORMAN OK
1244 PM CDT SUN OCT 4 1998

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING ACROSS PORTIONS OF NORTH CENTRAL AND CENTRAL OKLAHOMA
NORTH AND EAST OF A LINE FROM ALVA TO WATONGA TO NORMAN TO
HOLDENVILLE. THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS
THE REMAINDER OF CENTRAL OKLAHOMA AS WELL AS ALL OF WESTERN OKLAHOMA
...AND WESTERN NORTH TEXAS. LARGE HAIL...DAMAGING WINDS AND ISOLATED
TORNADOES WILL ALL BE POSSIBLE THIS AFTERNOON AND EVENING...
ESPECIALLY ACROSS THE MODERATE RISK AREA.

DISCUSSION...SURFACE LOW PRESSURE WAS LOCATED IN EXTREME NORTHWEST
KANSAS EARLY THIS AFTERNOON WITH A DRY LINE EXTENDING SOUTH ACROSS
FAR WESTERN TEXAS WHILE STRONG LOW LEVEL WINDS WERE TRANSPORTING
ABUNDANT LOW LEVEL MOISTURE NORTHWARD ACROSS THE CENTRAL AND
SOUTHERN PLAINS. WITH HIGH TEMPERATURES EXPECTED TO REACH INTO THE
80S AND LOWER 90S THIS AFTERNOON...A VERY UNSTABLE ATMOSPHERE IS
EXPECTED TO DEVELOP OVER MUCH OF OKLAHOMA AND WESTERN NORTH TEXAS.

THE SURFACE LOW IS EXPECTED TO MOVE INTO NORTHERN KANSAS AND
SOUTHERN NEBRASKA LATE THIS AFTERNOON WITH A DRYLINE MOVING INTO
WESTERN...AND EVENTUALLY CENTRAL OKLAHOMA BY EARLY EVENING.
THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG AND AHEAD OF THE DRYLINE
THIS AFTERNOOON AS IT MOVES EAST. STRONG WINDS IN THE MIDDLE AND
UPPER LEVELS OF THE ATMOSPERE ARE EXPECTED TO FORM OVER MUCH OF THE
CENTRAL AND SOUTHERN PLAINS WHICH WILL HELP DEVELOPING THUNDERSTORMS
TO BECOME QUICKLY SEVERE WITH LARGE HAIL...DAMAGING WINDS AND
ISOLATED TORNADOES ALL POSSIBLE.

THE BEST CHANCE FOR SEVERE THUNDERSTORMS APPEARS TO BE OVER NORTH
CENTRAL AND CENTRAL OKLAHOMA WHERE THE BEST ATMOSPHERIC INSTABILITY
WILL COMBINE WITH THE STRONGEST WINDS ALOFT. HOWEVER IF TEMPERATURES
CAN WARM UP QUICKLY ENOUGH ACROSS THE REMAINDER OF CENTRAL AND
WESTERN OKLAHOMA...AND WESTERN PORTIONS OF NORTH TEXAS...BEFORE THE
STRONGEST WINDS ALOFT MOVE EAST...SEVERE THUNDERSTORMS MAY ALSO
DEVELOP HERE.

SCATTERED THUNDERSTORMS WILL ALSO DEVELOP OVER SOUTH CENTRAL
OKLAHOMA THIS AFTERNOON...HOWEVER THE CHANCES FOR SEVERE
THUNDERSTORMS ARE EXPECTED TO HOLD OFF UNTIL STRONGER WINDS ALOFT
APROACH THE AREA FROM THE WEST LATE THIS AFTERNOON AND EVENING.

SPOTTER GROUPS AND EMERGENCY MANAGERS SHOULD BE PREPARED FOR
ACTIVATION FROM EARLY AFTERNOON THROUGH TONIGHT.

JAMES

OKZ004>048-050>052-TXZ083>090-042100-

THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE NORMAN OK
1244 PM CDT SUN OCT 4 1998

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING ACROSS PORTIONS OF NORTH CENTRAL AND CENTRAL OKLAHOMA
NORTH AND EAST OF A LINE FROM ALVA TO WATONGA TO NORMAN TO
HOLDENVILLE. THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS
THE REMAINDER OF CENTRAL OKLAHOMA AS WELL AS ALL OF WESTERN OKLAHOMA
...AND WESTERN NORTH TEXAS. LARGE HAIL...DAMAGING WINDS AND ISOLATED
TORNADOES WILL ALL BE POSSIBLE THIS AFTERNOON AND EVENING...
ESPECIALLY ACROSS THE MODERATE RISK AREA.

DISCUSSION...SURFACE LOW PRESSURE WAS LOCATED IN EXTREME NORTHWEST
KANSAS EARLY THIS AFTERNOON WITH A DRY LINE EXTENDING SOUTH ACROSS
FAR WESTERN TEXAS WHILE STRONG LOW LEVEL WINDS WERE TRANSPORTING
ABUNDANT LOW LEVEL MOISTURE NORTHWARD ACROSS THE CENTRAL AND
SOUTHERN PLAINS. WITH HIGH TEMPERATURES EXPECTED TO REACH INTO THE
80S AND LOWER 90S THIS AFTERNOON...A VERY UNSTABLE ATMOSPHERE IS
EXPECTED TO DEVELOP OVER MUCH OF OKLAHOMA AND WESTERN NORTH TEXAS.

THE SURFACE LOW IS EXPECTED TO MOVE INTO NORTHERN KANSAS AND
SOUTHERN NEBRASKA LATE THIS AFTERNOON WITH A DRYLINE MOVING INTO
WESTERN...AND EVENTUALLY CENTRAL OKLAHOMA BY EARLY EVENING.
THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG AND AHEAD OF THE DRYLINE
THIS AFTERNOOON AS IT MOVES EAST. STRONG WINDS IN THE MIDDLE AND
UPPER LEVELS OF THE ATMOSPERE ARE EXPECTED TO FORM OVER MUCH OF THE
CENTRAL AND SOUTHERN PLAINS WHICH WILL HELP DEVELOPING THUNDERSTORMS
TO BECOME QUICKLY SEVERE WITH LARGE HAIL...DAMAGING WINDS AND
ISOLATED TORNADOES ALL POSSIBLE.

THE BEST CHANCE FOR SEVERE THUNDERSTORMS APPEARS TO BE OVER NORTH
CENTRAL AND CENTRAL OKLAHOMA WHERE THE BEST ATMOSPHERIC INSTABILITY
WILL COMBINE WITH THE STRONGEST WINDS ALOFT. HOWEVER IF TEMPERATURES
CAN WARM UP QUICKLY ENOUGH ACROSS THE REMAINDER OF CENTRAL AND
WESTERN OKLAHOMA...AND WESTERN PORTIONS OF NORTH TEXAS...BEFORE THE
STRONGEST WINDS ALOFT MOVE EAST...SEVERE THUNDERSTORMS MAY ALSO
DEVELOP HERE.

SCATTERED THUNDERSTORMS WILL ALSO DEVELOP OVER SOUTH CENTRAL
OKLAHOMA THIS AFTERNOON...HOWEVER THE CHANCES FOR SEVERE
THUNDERSTORMS ARE EXPECTED TO HOLD OFF UNTIL STRONGER WINDS ALOFT
APROACH THE AREA FROM THE WEST LATE THIS AFTERNOON AND EVENING.

SPOTTER GROUPS AND EMERGENCY MANAGERS SHOULD BE PREPARED FOR
ACTIVATION FROM EARLY AFTERNOON THROUGH TONIGHT.

JAMES