Severe Thunderstorm Warning 253, NWS Tulsa, OK

EASTERN OKLAHOMA/NORTHWEST ARKANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
950 AM CDT WED JUN 13 2001

WILL BE UPDATING FORECAST TO MODIFY CLOUD FORECAST FOR TODAY...LOOKS
LIKE STRATUS WILL BE FAIRLY THICK THIS MORNING WITH SOME CLEARING
BEFORE STORMS MOVE IN. MAY ALSO NEED TO TRIM DOWN MAXES A LITTLE.
POTENTIAL FOR SEVERE STORMS STILL LOOKS GOOD. BEST INSTABILITY AND
MOISTURE FLUX CONVERGENCE LOOKS LIKE IT WILL OCCUR ALONG AND JUST
SOUTH OF THE RED RIVER BY EARLY THIS AFTERNOON BUT WILL STILL BE
VERY UNSTABLE ACROSS ENTIRE CWA EVEN WITH THE CLOUDS. VERTICAL WIND
PROFILE ALSO SUPPORTS SEVERE STORMS...BUT BACKING FLOW ABOVE 500MB
CAUSING TOP PARTS AND ANVILS OF STORMS TO FLOW BACK OVER PREVIOUS
CONVECTION. HOT SPOT MAY BE ACROSS FAR SRN OK AND NRN TX WHERE SKIES
ARE MORE CLEAR AND STORMS ARE BUILDING SOUTH FROM WESTERN OK INTO NW
TX BUT A LOT COULD CHANGE IF SKIES OVER ERN OK CLEAR SOONER THAN
EXPECTED.

LOOK AT NEW MESOETA SHOWS MORNING CONVECTION DISSIPATING AND NEW
STORMS LATER THIS AFTERNOON ALONG FRONT AND CONTINUING OVERNIGHT
ACROSS THE ENTIRE. PATTERN OF CONVECTION AS FRONT SAGS SLOWLY SOUTH
INTO WSW-ESE ORIENTATION AND SLOW OVERALL MOVEMENT OF STORMS IMPLY
COULD SEE VERY HEAVY RAINFALL TONIGHT. MAY HAVE TO ISSUE FFA THIS
AFTERNOON. EXACT EVOLUTION LOOKS QUESTIONABLE ON THE MESOETA BUT
WILL CONTINUE TO MONITOR CURRENT RADAR AND SATELLITE IMAGES.

FCSTID = 26

.TSA...
AR...NONE.
OK...NONE.

ARZ001-002-010-011-019-020-029-OKZ049-053>076-151100-

EASTERN OKLAHOMA/NORTHWEST ARKANSAS HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TULSA OK
600 AM CDT THU JUN 14 2001

...NUMEROUS SEVERE THUNDERSTORMS EXPECTED ACROSS EASTERN OKLAHOMA
AND NORTHWEST ARKANSAS THIS AFTERNOON AND EVENING...

A COLD FRONT LOCATED FROM CENTRAL KANSAS INTO THE TEXAS PANHANDLE
THIS MORNING WILL CONTINUE TO SLOWLY MOVE SOUTHEAST TODAY.  BY
TONIGHT THIS FRONT WILL BE LOCATED FROM ST. LOUIS TO LITTLE ROCK.
AN UPPER LEVEL DISTURBANCE OVER THE ROCKIES THIS MORNING WILL MOVE
INTO THE PLAINS BY TONIGHT.  THE COMBINATION OF THE SURFACE COLD
FRONT AND UPPER LEVEL SYSTEM WILL ALLOW THUNDERSTORMS TO DEVELOP
ALONG AND AHEAD OF THE FRONT THIS AFTERNOON ACROSS NORTHEAST
OKLAHOMA.  THESE THUNDERSTORMS WILL THEN EVOLVE INTO A LARGER
CONVECTIVE SYSTEM AS THEY MOVE EAST TO SOUTHEAST ACROSS EASTERN
OKLAHOMA AND NORTHWEST ARKANSAS DURING THE EVENING.

.SPOTTER ACTIVATION...
SPOTTER ACTIVATION WILL LIKELY BE REQUIRED BY THIS AFTERNOON
INTO THIS EVENING ACROSS EASTERN OKLAHOMA AND NORTHWEST ARKANSAS.

.DISCUSSION...
A SURFACE COLD FRONT WILL CONTINUE TO PUSH SOUTHEAST THIS MORNING
INTO PORTIONS OF NORTHEAST OKLAHOMA BY THIS AFTERNOON.  TEMPERATURES
BY THIS TIME WILL ALREADY BE IN THE MID TO UPPER 80S WITH DEWPOINTS
IN THE LOWER TO MID 70S.  AN UPPER LEVEL DISTURBANCE WILL ALSO BE
MOVING INTO THE PLAINS TODAY WITH A 100 KT UPPER LEVEL JET
ASSOCIATED WITH IT.  AS THE UPPER SYSTEM MOVES EAST...TEMPERATURES
ALOFT WILL COOL ALLOWING THE ATMOSHPERE TO BECOME INCREASINGLY
UNSTABLE BY THIS AFTERNOON.

THE AIRMASS OVER NORTHEAST OKLAHOMA WILL BE MODERATELY UNSTABLE BY
THIS AFTERNOON AS LIFTED INDEX VALUES DROP TO -4 TO -6 DEGREES C
WITH CAPE VALUES FROM 2000 TO 3000 J/KG.  THUNDERSTORMS SHOULD BEGIN
TO DEVELOP ALONG OR AHEAD OF THE FRONT AROUND MIDDAY ACROSS OSAGE
AND PAWNEE COUNTIES AND SPREAD SOUTHEAST DURING THE AFTERNOON.  A
FEW SUPERCELLS WILL BE POSSIBLE WITH LARGE HAIL AND DAMAGING WINDS
ACROSS NORTHEAST OKLAHOMA.  MARGINAL VERTICAL WIND PROFILES WILL BE
IN PLACE SO AN ISOLATED TORNADO CAN NOT BE RULED OUT.  THE
THUNDERSTORMS SHOULD THEN EVOLVE INTO A LINE AS THEY MOVE INTO
NORTHWEST ARKANSAS AND SOUTHEAST OKLAHOMA THIS EVENING WITH DAMAGING
WINDS BECOMING THE PRIMARY THREAT.

THREAT TABLE
VALID THROUGH 6 AM FRIDAY

THREAT AREA 1...EASTERN OKLAHOMA AND NORTHWEST ARKANSAS
THUNDERSTORM PROBABILITY...90
SEVERE PROBABILITY IF STORMS OCCUR...90
SIGNIFICANT SEVERE PROBABILITY IF STORMS OCCUR...80

THREAT AREAS DEFINE THE GREATEST RISK. PROBABILITIES ARE IN PERCENT.
SIGNIFICANT SEVERE IS DEFINED AS F1 OR GREATER WIND/TORNADO DAMAGE
AND/OR GOLFBALL SIZE HAIL OR LARGER.

RELATED GRAPHICAL INFORMATION CAN BE FOUND AT...
WWW.SRH.NOAA.GOV/TULSA

AN UPDATED HAZARDOUS WEATHER OUTLOOK WILL BE ISSUED AROUND 1 PM
TODAY.