Tornado Warning 9, NWS Norman, OK

OKLAHOMA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE OKLAHOMA CITY OK
1220 PM CDT SAT JUN 13 1987

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND THIS
EVENING OVER PARTS OF NORTH CENTRAL AND NORTHEASTERN OKLAHOMA GENERALLY
EAST OF A LINE FROM ALVA TO WATONGA AND NORTH OF A LINE FROM WATONGA TO
SALLISAW. WIDELY SCATTERED THUNDERSTORMS MAY DEVELOP THROUGHOUT ALL OF
OKLAHOMA EXCEPT THE PANHANDLE THIS AFTERNOON AND TONIGHT.

UPPER LEVEL HIGH PRESSURE HAS CONTINUED TO BUILD OVER THE ROCKY
MOUNTAINS DURING THE PAST 24 HOURS...AND THE UPPER LEVEL FLOW OVER
OKLAHOMA HAS BECOME NORTHERLY. THE VERY RICH AND DEEP TROPICAL MOISTURE
WHICH WAS OVER OKLAHOMA EARLIER THIS WEEK HAS SHIFTED SOUTHWARD...
HOWEVER...RESIDUAL LOW LEVEL MOISTURE REMAINS ABUNDANT OVER MOST
OF OKLAHOMA. A WEAK TROUGH OF LOW PRESSURE WHICH EXTENDS FROM NORTHERN
MISSOURI TO EASTERN COLORADO WILL MOVE INTO NORTHERN OKLAHOMA LATER
THIS AFTERNOON AND WILL AID IN THE DEVELOPMENT OF THUNDERSTORMS...A
FEW OF WHICH MAY BECOME SEVERE.
THUNDERSTORMS WHICH FORMED FRIDAY AFTERNOON OVER EASTERN
NEBRASKA MOVED INTO MISSOURI DURING THE NIGHT. ALTHOUGH THE STORMS
HAVE DISSIPATED...AN OLD OUTFLOW BOUNDARY EXTENDS FROM EXTREME
NORTHEASTERN OKLAHOMA TO A LOW PRESSURE SYSTEM EAST OF SALINA
KANSAS. A WIND SHIFT EXTENDS FROM THE SALINA LOW SOUTHWESTWARD
TO THE EASTERN TEXAS PANHANDLE. WITH MOSTLY CLEAR SKIES...TEMPERATURES
ARE RISING RAPIDLY OVER OKLAHOMA AND KANSAS. THE RELATIVELY
COOL AIR ALOFT AND WEAK LIFTING WITH THE UPPER LEVEL TROUGH WILL
FURTHER DESTABILIZE THE ATMOSPHERE DURING THE AFTERNOON. THE
OLD OUTFLOW BOUNDARY AND WINDSHIFT LINE WILL ACT AS FOCUSING
MECHANISMS FOR THUNDERSTORM DEVELOPMENT NORTH OF OKLHOMA THIS
AFTERNOON...AND THE STORMS WILL DRIFT SOUTH INTO OKLAHOMA LATE
THIS AFTERNOON AND THIS EVENING.

THE WEAKNESS OF THE LOW LEVEL FLOW OVER OKLAHOMA WILL WORK AGAINST
MAINTAINING THE THUNDERSTORMS MORE THAN A FEW HOURS AFTER SUNSET.
THE THUNDERSTORMS COULD FORM INTO A LARGE ENOUGH COMPLEX TO BUILD A
LARGE RAIN-COOLED AREA OF HIGH PRESSURE WHICH WOULD MOVE SOUTHWARD
FAST ENOUGH TO MAINTAIN STRONG STORMS MUCH OF THE NIGHT. AT THIS TIME...
THE ACTIVITY IS EXPECTED TO REMAIN SOMEWHAT DISORGANIZED WITH THE
SEVERE THREAT ONLY OVER NORTHERN OKLAHOMA.

OKLAHOMA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE OKLAHOMA CITY OK
315 PM CDT SAT JUN 13 1987

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND THIS
EVENING OVER PARTS OF NORTHERN AND NORTHEASTERN OKLAHOMA GENERALLY
EAST OF A LINE FROM MANCHESTER TO ANADARKO AND NORTH OF A LINE FROM
ANADARKO TO SALLISAW. OUTSIDE THE SEVERE THREAT AREA...WIDELY
SCATTERED THUNDERSTORMS MAY BE EXPECTED TO FORM DURING THE AFTERNOON
AND EARLY EVENING...BUT THESE ARE NOT EXPECTED TO BECOME SEVERE.
GUSTY WINDS MAY ACCOMPANY THE STRONGER STORMS...HOWEVER.

A LOW PRESSURE SYSTEM IS CENTERED OVER NORTHEASTERN KANSAS...AND A
TROUGH OF LOW PRESSURE EXTENDS FROM THE LOW TO SOUTHWESTERN OKLAHOMA
THIS AFTERNOON. RICH LOW LEVEL MOISTURE CONTINUES OVER MOST OF
OKLAHOMA IN ADVANCE OF THE TROUGH LINE...ALTHOUGH SOME DRYING HAS
OCCURRED OVER THE NORTHWESTERN PART OF THE STATE. MOSTLY CLEAR
SKIES HAVE ENABLED STRONG SURFACE HEATING TO OCCUR...AND TEMPERATURES
HAVE RISEN INTO THE LOWER 90S OVER MUCH OF OKLAHOMA. THE ATMOSPHERE
IS RELATIVELY COOL ALOFT...AND THE LOW LEVEL WARMING HAS RESULTED
IN CONSIDERABLE INSTABILITY.

THUNDERSTORMS ARE LIKELY TO DEVELOP DURING THE NEXT ONE TO TWO HOURS
ALONG THE TROUGH LINE AND MAY BECOME SEVERE. OTHER THUNDERSTORMS ARE
LIKELY TO DEVELOP NORTH OF THE OKLAHOMA BORDER AND TO MOVE SOUTHWARD
INTO OKLAHOMA THIS EVENING. THESE ALSO MAY BE SEVERE. SINCE THE LOW
LEVELS OF THE ATMOSPHERE HAVE BECOME VERY WARM...DAMAGING OUTFLOW WINDS
LIKELY WILL ACCOMPANY SOME OF THE STORMS AND MAY REPRESENT THE GREATEST
SEVERE WEATHER THREAT.

THE SEVERE WEATHER THREAT WILL DIMINISH A FEW HOURS AFTER SUNSET...
ALTHOUGH THE THUNDERSTORMS MAY CONTINUE MUCH OF THE NIGHT. THE KEY
TO MAINTAINING THE STORMS IS THE DEVELOPMENT OF A LARGE RAIN-COOLED
HIGH PRESSURE SYSTEM BEHIND THEM AS THEY MOVE TOWARD THE SOUTH.
IF THE STORMS FORM INTO A LARGE COMPLEX THIS AFTERNOON...SUBSEQUENT
DEVELOPMENT WILL OCCUR ALONG THE
SOUTHERN BOUNDARY OF THE RAIN-COOLED
AIR WELL INTO THE NIGHT. THE OUTLOOK AREA MAY HAVE TO BE ADJUSTED
SOUTHWARD IF THIS OCCURS.