Severe Thunderstorm Warning 429, NWS Norman, OK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
330 PM CDT SAT SEP 23 2000

FOR THE FIRST TIME SINCE JULY, WE CAN SAY IT LOOKS WET FOR PARTS OF
THE CWA. STRONG SURFACE FRONT EXPECTED TO STALL FROM W CENTRAL TX TO
NEAR SE CORNER OF OK TONIGHT AS SOUTHERLY 850 FLOW STRENGTHENS IN
RESPONSE TO STRONG UPPER SYSTEM MOVING OUT OF ROCKIES. FORCING WILL
CONCENTRATE IN 2 AREAS AS THIS SYSTEM MOVES INTO KS TONITE/SUN - ONE
AT LOW LEVELS ALONG THE STRONG BAROCLINIC ZONE NEAR AND N OF THE
SURFACE FRONT, AND ONE AT MID LEVELS AHEAD OF THE UPPER LOW. LATTER
AREA WILL STAY MAINLY N OF AREA, BUT FORMER AREA WILL POSITION
ITSELF DIRECTLY OVER AREA TONITE, AND LIKELY WILL BE ENHANCED AT MID
LEVELS BY LEADING IMPULSE EJECTING NE FROM REMNANTS OF TC NORMAN.
WITH MID LEVEL MOISTURE FROM REMNANTS OF NORMAN SURGING NE TOWARD
AREA, AND RICH LOW LEVEL MOISTURE LIFTING N INTO FRONTAL ZONE,
MOISTURE WILL NOT BE A PROBLEM. THIS IS ALSO THE FIRST TIME SINCE
JULY WE CAN SAY THAT.

WE WILL MAINTAIN HIGH POPS TONIGHT, AND RAISE THEM TO CATEGORICAL
ACROSS SE HALF OF AREA. SURFACE-BASED INSTABILITY WILL BE SUFFICIENT
FOR SEVERE POTENTIAL ALONG FRONT IN SE THIS EVENING, WHILE ELEVATED
INSTABILITY AND ABUNDANT MOISTURE SUGGEST POTENTIAL FOR SOME HAILERS
IN ANY ELEVATED CONVECTION OVERNIGHT MAINLY SE HALF. IMPRESSIVE
PRECIPITABLE WATER PROGGED IN 2-2.5 INCH RANGE, INDICATING PARTS OF
AREA MAY WELL GO FROM FAMINE TO FEAST. WE WILL MENTION POSSIBLE
HEAVY RAIN ACROSS S AND E TONIGHT. SITUATION LOOKS SIMILAR TO MADDOX
FRONTAL- TYPE EVENT, SO FLASH FLOOD WATCH MAY BE NEEDED LATER THIS
EVENING ONCE CONVECTION BEGINS TO DEVELOP/ORGANIZE. PLACEMENT OF MAX
POTENTIAL IS PRESENTLY UNCERTAIN, AS EVENING CONVECTION MAY NUDGE
THE FOCUS FARTHER S INTO TX. QPF WILL BE A BLEND OF THE MODEL AND
HPC GUIDANCE, ALL OF WHICH ARE REASONABLY CLOSE. BASIN AVERAGES OF
1-2 INCHES EASILY POSSIBLE IN SE, WITH LOCAL TOTALS >3 POSSIBLE.

FRONT WILL BEGIN MOVING S AGAIN BY LATE SUN AS SURFACE LOW
REDEVELOPS OVER NE TX AND MOVES INTO AR IN RESPONSE TO THE
APPROACHING UPPER SYSTEM. STILL ENOUGH MOISTURE AND LIFT AROUND FOR
PRECIP, BUT IT SHOULD BE LIGHT EXCEPT IN SE WHERE HEAVIER CONVECTION
MAY LINGER INTO EARLY SUN. STRENGTHENING N WINDS SHOULD MAKE FOR A
BLUSTERY COOL EARLY AUTUMN DAY. WILL TAPER OFF THE POPS SUN NIGHT
AND REMOVE THEM ON MON AS UPPER LOW MOVES INTO MO AND SUBSIDENCE
OVERSPREADS AREA.

TEMPS WILL BE A BEAR, BUT IN GENERAL EXPECT LIMITED DIURNAL RANGE
THRU SUN DUE TO CLOUDS/PRECIP. DIURNAL RANGE SHOULD OPEN UP SUN
NIGHT INTO MON AS CLOUDS MOVE OUT. WILL STAY SOMEWHERE BETWEEN THE
WARMER FWC AND COOLER FAN NUMBERS.

TUE-THU WILL LIKELY BE DOMINATED BY DRY NW FLOW ALOFT AND A WARMING
TREND AS UPPER RIDGE MAINTAINS IN SOME FORM OVER THE W, AND COOL
SURFACE HIGH WEAKENS AND MODIFIES.

NUMBERS TO FOLLOW SHORTLY...

24

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

OKZ004>048-050>052-TXZ083>090-232030-

THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE NORMAN OK
1230 PM CDT SAT SEP 23 2000

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
TONIGHT OVER PARTS OF WESTERN NORTH TEXAS... AND SOUTH CENTRAL AND
SOUTHEAST OKLAHOMA.  THE RISK AREA IS GENERALLY SOUTH OF A LINE FROM
SEYMOUR AND VERNON TEXAS... TO DUNCAN... TO HOLDENVILLE OKLAHOMA.

.DISCUSSION...A COLD FRONT MOVING SLOWLY SOUTHEAST ACROSS OKLAHOMA
AND NORTH TEXAS EARLY THIS AFTERNOON... WILL BECOME NEARLY
STATIONARY THIS EVENING OVER NORTH TEXAS. AHEAD OF THE FRONT THE
ATMOSPHERE WILL BECOME INCREASINGLY UNSTABLE... WITH SCATTERED
THUNDERSTORMS EXPECTED TO DEVELOP ALONG THE FRONT BY LATE THIS
AFTERNOON. SUFFICIENT INSTABILITY AND MODERATELY STRONG WINDS ALOFT
WILL ALLOW A FEW OF THESE STORMS TO PRODUCE DAMAGING WIND GUSTS AND
LARGE HAIL.

THIS EVENING AND OVERNIGHT... AN UPPER LEVEL DISTURBANCE IS EXPECTED
TO MOVE ACROSS THE ROCKIES... AIDING IN THE DEVELOPMENT OF
ADDITIONAL THUNDERSTORMS NORTH OF THE FRONT... AFFECTING WESTERN
NORTH TEXAS... AND MUCH OF SOUTHERN AND CENTRAL OKLAHOMA. THESE
STORMS MAY PRODUCE LARGE HAIL AND HEAVY tRAINFALL.

EMERGENCY MANAGERS AND STORM SPOTTER GROUPS SHOULD REMAIN ALERT TO
THE POSSIBILITY OF SEVERE WEATHER ACROSS THE SLIGHT RISK AREA LATE
THIS AFTERNOON AND TONIGHT.

CMS

LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
513 PM CDT SAT SEP 23 2000

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

0510 PM    5 MNW CENTRAHOMA           OK   .75 INCH HAIL
09/23/00   COAL                           REPORTED BY PUBLIC

TL