Severe Thunderstorm Warning 157, NWS Norman, OK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
949 PM CDT WED APR 19 2000

A NORTHWESTWARD MOVING DRY LINE SEPARATING A VERY UNSTABLE AIRMASS
FROM A STABLE ONE WILL SOON BE INTERSECTED BY A STRONG AND FAST
MOVING COLD FRONT. WHERE THESE BOUNDARIES COLLIDE WILL LIKELY BE
WHERE THUNDERSTORMS DEVELOP OVERNIGHT. NOT MUCH TIME TO GET INTO
DETAILS AS NUMEROUS FORECAST UPDATES HAVE BEEN REQUIRED.
BASICALLY...COVERAGE OF MODERATE RISK AREA WAS LEFT ALONE...HOWEVER
THE NORTHWESTWARD RETREAT OF THE DRYLINE HAS RESULTED IN A WESTWARD
SHIFT OF THE SLIGHT RISK AREA...AND THE INCLUSION OF POPS FARTHER
WEST.

COLD FRONT IS ONLY AN HOUR OR TWO AWAY FROM COLLIDING WITH THIS
UNSTABLE AIRMASS. A LINE FROM PERRY...TO KINGFISHER...TO ANADARKO...
TO LAWTON MAY BE WHERE STORMS FIRST INITIATE.

WIND SPEEDS ARE WELL ABOVE WIND ADVISORY CRITERIA BEHIND COLD FRONT
ACROSS NORTHWEST OKLAHOMA...AND RECENT RUC GUIDANCE SUGGESTS THIS
WILL CONTINUE OVERNIGHT. THE BUFFALO MESONET IN HARPER COUNTY GUSTED
TO 65 MPH EARLIER. HAVE ALREADY ISSUED A WIND ADVISORY OVERNIGHT FOR
PORTIONS OF NORTHWEST AND WEST CENTRAL OKLAHOMA. ONE THUNDERSTORM
CELL HAS JUST DEVELOPED SOUTH OF LAWTON...SO NEED TO GO.

.OUN...
OK...WIND ADVISORY OVERNIGHT OKZ004-005-009-010-014-015-021
TX...NONE.
JAMES

OKZ004>048-050>052-TXZ083>090-200409-

THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE NORMAN OK
909 PM CDT WED APR 19 2000

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THROUGH THE
EARLY MORNING HOURS ACROSS PORTIONS OF CENTRAL OKLAHOMA...MAINLY
ALONG AND EAST OF A LINE FROM STILLWATER...TO OKLAHOMA CITY...TO ADA.
A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDS THE MODERATE RISK
AREA...AND EXTENDS ALONG AND EAST OF A LINE FROM PONCA CITY...TO
WATONGA...TO LAWTON...TO WALTERS.

DISCUSSION...VERY WARM AND UNSTABLE AIR REMAINS AHEAD OF A DRYLINE...
WHICH CURRENTLY EXTENDS FROM NEAR STILLWATER...TO CHICKASHA...TO
LAWTON. THE DRYLINE HAS MOVED NORTHWESTWARD THIS EVENING AND WILL BE
INTERSECTED BY A FAST MOVING COLD TOWARD MIDNIGHT. ALTHOUGH
THUNDERSTORM DEVELOPMENT IS POSSIBLE ANYTIME THIS EVENING ALONG THE
DRYLINE...IT IS MORE PROBABLE THAT DEVELOPMENT WILL BE DELAYED UNTIL
THE COLD FRONT CATCHES UP WITH THE DRYLINE...WHICH WILL MOST LIKELY
OCCUR DURING THE LATE EVENING HOURS ACROSS NORTH CENTRAL OKLAHOMA...
AND SHORTLY AFTER MIDNIGHT ACROSS SOUTHERN OKLAHOMA. AFTER THE COLD
FRONT PASSES...THE THREAT FOR SEVERE THUNDERSTORMS WILL GREATLY
DIMINISH.

DUE TO A LARGE AMOUNT OF INSTABILITY AND STRENGTHENING WINDS
ALOFT...THE PRIMARY CONCERNS WILL BE FOR LARGE HAIL AND DAMAGING
THUNDERSTORM WIND GUSTS. ISOLATED TORNADOES WILL ALSO BE POSSIBLE...
ESPECIALLY ACROSS THE MODERATE RISK AREA. EMERGENCY MANAGERS AND
STORM SPOTTER GROUPS SHOULD REMAIN ALERT THIS EVENING FOR THE
POSSIBILITY OF FUTURE WATCHES AND OR WARNINGS.

JAMES