Tornado Warning 7, NWS Norman, OK

OKLAHOMA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE OKLAHOMA CITY OK
1200 PM CDT THU MAY 21 1987

A MODERATE RISK OF SEVERE THUNDERSTORMS EXISTS OVER PORTIONS OF
NORTHERN AND EASTERN OKLAHOMA THIS AFTERNOON AND TONIGHT. THE MODERATE
RISK AREA COVERS THAT PORTION OF OKLAHOMA NORTH AND EAST OF A PONCA
CITY...OKLAHOMA CITY...FORT SMITH AR LINE. THERE IS A SLIGHT RISK
OF SEVERE THUNDERSTORMS OVER PORTIONS OF SOUTHERN OKLAHOMA. THE SLIGHT
RISK AREA LIES EAST OF AN ALTUS...OKLAHOMA CITY LINE AND WEST OF A
DURANT...FORT SMITH AR LINE...AND BORDERS THE MODERATE RISK AREA TO THE
NORTH.

AT MIDDAY...A COLD FRONT HAS PUSHED ACROSS NORTHWEST PORTIONS OF
OKLAHOMA AND CURRENTLY LIES ALONG A PONCA CITY-HOLLIS LINE. THIS FRONT
CONTINUES TO PUSH SLOWLY SOUTHEASTWARD. A DRY LINE EXTENDS FROM THE
FRONT NEAR OKLAHOMA CITY SOUTHWARD INTO NORTH TEXAS TO THE WEST OF
ABILENE. THE LOCATION WHERE THE FRONT AND DRYLINE INTERSECT IS CALLED
A 'TRIPLE POINT' BY METEOROLOGISTS...AND IS OFTEN A FOCUS FOR SEVERE
WEATHER DEVELOPMENT. LOW LEVEL MOISTURE IS SURGING NORTHWARD AHEAD
OF THE FRONT AND DRYLINE...ACROSS THE SOUTHEASTERN TWO-THIRDS OF THE
STATE...WHERE THE AIRMASS IS EXTREMELY UNSTABLE.

THE POTENTIAL EXISTS FOR A SIGNIFICANT OUTBREAK OF SEVERE WEATHER OVER
PORTIONS OF THE STATE THIS AFTERNOON AND TONIGHT. THUNDERSTORM
DEVELOPMENT IS EXPECTED TO BEGIN BY MID-AFTERNOON...MOST LIKELY
ALONG THE FRONT AND/OR DRYLINE. THE TRIPLE POINT IS EXPECTED TO MOVE
SLOWLY NORTHEASTWARD ALONG THE FRONT...MOVING INTO NORTH CENTRAL
OR NORTHEAST OKLAHOMA BY LATE AFTERNOON. THE BEST CHANCE FOR SEVERE
WEATHER EXISTS NEAR THE TRIPLE POINT...BUT SEVERE ACTIVITY CANNOT
BE RULED OUT ANYWHERE IN OKLAHOMA NEA?R THE FRONT OR DRYLINE.

CIVIL DEFENSE AND STORM SPOTTER GROUPS IN THE OUTLOOK AREA SHOULD
REMAIN ALERT AND BE READY FOR ACTIVATION LATER THIS AFTERNOON.
LATER INFORMATION WILL BE INCLUDED IN THE UPDATED OUTLOOK TO BE ISSUED
AROUND 3 PM.

OKLAHOMA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE OKLAHOMA CITY OK
315 PM CDT THU MAY 21 1987

A MODERATE RISK OF SEVERE THUNDERSTORMS EXISTS OVER PORTIONS OF
NORTHERN AND EASTERN OKLAHOMA THIS AFTERNOON AND TONIGHT. THE MODERATE
RISK AREA COVERS THAT PORTION OF OKLAHOMA NORTH AND EAST OF A PONCA
CITY...OKLAHOMA CITY...FORT SMITH AR LINE. THERE IS A SLIGHT RISK
OF SEVERE THUNDERSTORMS OVER PORTIONS OF SOUTHERN OKLAHOMA. THE SLIGHT
RISK AREA LIES EAST OF AN ALTUS...OKLAHOMA CITY LINE AND WEST OF A
DURANT...FORT SMITH AR LINE...AND BORDERS THE MODERATE RISK AREA TO THE
NORTH.

AT MIDAFTERNOON...A STATIONARY FRONT EXTENDS ALONG A LINE FROM PONCA
CITY TO CHILDRESS TX. A DRY LINE EXTENDS FROM THE FRONT NEAR OKLAHOMA
CITY SOUTHWARD INTO NORTH TEXAS TO THE WEST OF ABILENE. THE LOCATION
WHERE THE FRONT AND DRYLINE INTERSECT IS CALLED A 'TRIPLE POINT' BY
METEOROLOGISTS...AND IS OFTEN A FOCUS FOR SEVERE WEATHER DEVELOPMENT.
LOW LEVEL MOISTURE COVERS THE SOUTHEASTERN TWO-THIRDS OF THE STATE AHEAD
OF THE FRONT AND DRYLINE.

UPPER AIR INFORMATION RECEIVED AROUND 2 PM FROM SOUTH CENTRAL
OKLAHOMA INDICATES THE ATMOSPHERE IS NOT QUITE AS EXPLOSIVELY
UNSTABLE AS IT WAS EARLIER TODAY. HOWEVER...THUNDERSTORM ACTIVITY
IS STARTING TO FIRE UP ALONG THE COLD FRONT TO OUR NORTHEAST IN
MISSOURI...AND TO OUR SOUTH IN TEXAS ALONG THE DRYLINE. SUFFICIENT
INSTABILITY STILL EXISTS OVER OKLAHOMA...AND THUNDERSTORMS ARE
EXPECTED TO DEVELOP ALONG THE COLD FRONT AND/OR DRYLINE BY 4 PM.

THE POTENTIAL REMAINS FOR A SIGNIFICANT OUTBREAK OF SEVERE
WEATHER OVER PORTIONS OF THE STATE THIS AFTERNOON AND TONIGHT.
THE BEST CHANCE FOR SEVERE WEATHER EXISTS NEAR THE TRIPLE POINT...BUT
SEVERE ACTuIVITY CANNOT BE RULED OUT ANYWHERE IN OKLAHOMA NEAR THE FRONT
OR DRYLINE.

CIVIL DEFENSE AND STORM SPOTTER GROUPS IN THE OUTLOOK AREA SHOULD
EXPECT TO BE ACTIVATED BY LATE AFTERNOON.