Severe Thunderstorm Warning 248, NWS Norman, OK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
300 PM CDT THU MAY 18 2000

TRICKY FORECAST FOR THE SOUTHERN PLAINS FOR THE NEXT SEVERAL DAYS.
ONE UPPER WAVE ACROSS CENTRAL PLAINS WILL CONT TO SLOWLY FILL AND
MOVE OFF TOWARD THE NORTHEAST TONIGHT. SFC FRONT WILL ALSO CONT TO
MOVE SOUTHEAST INTO N TX. PRECIP CHANCES TONIGHT IF ANY WILL BE
CONFINED TO THE SOUTH AND SOUTHEAST AND WILL TAKE A LATE LOOK TO TRY
TO DETERMINE THOSE. CHANCES INCREASE AREA WIDE BY TOMORROW AFTN THRU
TOMORROW NIGHT AS MOISTURE WORKS ITS WAY BACK NORTH ACROSS THE STATE
AND UPPER WAVE SEEN ON WATER VAPOR MOVING ACROSS N ARIZONA
APPROACHES AREA. UPPER WAVE AND MOISTURE WORK THEIR WAY EAST EARLY
SATURDAY. WILL KEEP LOW POPS EARLY SATURDAY...OTHERWISE MOST AREAS
BECMG PC.

EXTENDED...UPPER PATTERN SHIFTS TO A MORE NORTHWEST FLOW BY SUNDAY
AS RIDGE BUILDS ACROSS SOUTHWEST US. A COUPLE OF WEAK WAVES MOVE
SOUTHEAST ACROSS AREA SUNDAY AND MONDAY WITH SURFACE BOUNDARY MOVING
THROUGH PARTS OF AREA AND CAPPING INVERSION NOT YET REESTABLISHED.
WILL KEEP CHANCE OF SHOWERS AND THUNDERSTORMS GOING THROUGH MONDAY.
UPPER RIDGE BEGINS TO BUILD EAST INTO PLAINS BY TUESDAY SO WILL GO
PARTLY CLOUDY AND WARMER FOR LAST DAY OF EXTENDED.

FCSTID = 30
OKC   56  73  57  78 /  10  30  40  20
HBR   54  74  56  79 /  10  30  30  10
SPS   60  76  58  80 /  10  40  40  20
GAG   48  71  50  79 /  10  20  20  10
PNC   54  72  54  78 /  10  20  20  20
DUA   60  75  60  80 /  30  30  40  40

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

OKZ004>048-050>052-TXZ083>090-181900-

THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE NORMAN OK
1230 PM CDT THU MAY 18 2000

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING OVER PARTS OF SOUTHEAST OKLAHOMA...SOUTHEAST OF A LINE FROM
COALGATE TO MARIETTA. WHILE LARGE HAIL AND DAMAGING WINDS WILL BE
THE MAIN SEVERE WEATHER THREATS... AN ISOLATED TORNADO WILL ALSO BE
POSSIBLE.

DISCUSSION...A COLD FRONT THAT EXTENDED FROM CALVIN... TO ADA... TO
ARDMORE AT MIDDAY WILL CONTINUE MOVING SOUTHEAST THROUGH THE
AFTERNOON. THE FRONT IS EXPECTED TO REACH SOUTHEAST BRYAN COUNTY BY
EARLY EVENING. THE MOIST AIRMASS AHEAD OF THE FRONT IN SOUTHEAST
OKLAHOMA WILL BECOME VERY UNSTABLE DURING THE AFTERNOON AS
TEMPERATURES CONTINUE TO WARM. MEANWHILE... AREAS NORTHWEST OF THE
FRONT WILL EXPERIENCE A DRIER AND MORE STABLE AIRMASS.

WARM TEMPERATURES ALOFT WERE INHIBITING THUNDERSTORM DEVELOPMENT AT
MIDDAY. HOWEVER... THOSE TEMPERATURES WILL BE COOLING DURING THE
AFTERNOON. THUNDERSTORMS...SOME OF THEM SEVERE... ARE EXPECTED TO
DEVELOP IN SOUTHEAST OKLAHOMA ALONG AND AHEAD OF THE FRONT BY MID
AFTERNOON. LOCALLY HEAVY RAINFALL WILL ALSO BE POSSIBLE.

THE THREAT OF SEVERE WEATHER IN SOUTHEAST OKLAHOMA WILL GRADUALLY
DIMINISH DURING THE EVENING AS THE COLD FRONT MOVES SOUTHEAST OUT OF
THE AREA. HOWEVER... SHOWERS AND THUNDERSTORMS... SOME WITH HEAVY
RAIN... COULD PERSIST LONGER INTO THE NIGHT.

ISOLATED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE SOME DISTANCE
NORTH OF THE FRONT... HOWEVER... ANY STORMS THAT DEVELOP SHOULD
REMAIN BELOW SEVERE LEVELS.

SPOTTER GROUPS IN SOUTHEAST OKLAHOMA SHOULD BE READY iFOR POSSIBLE
ACTIVATION THIS AFTERNOON AND EVENING.

CJS