Severe Thunderstorm Warning 129, NWS Tulsa, OK

EASTERN OKLAHOMA/NORTHWEST ARKANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
1005 AM CDT SUN APR 21 1996

MAIN QUESTION TODAY IS HOW FAR N WARM FNT WILL BE ABLE TO MIX OUT
AND WHERE PCP WILL BREAK OUT. MID/UPPER 60S SFC DWPTS AND H85 DWPTS
> +10 OVERRIDDING WARM FNT THAT WAS STILL ALONG RED RIVER AT 14Z.
LOW CLDS HAVE THICKENED DURING THE MORNING OVER MOST OF FA. LATEST
VIS SAT PICS SHOW THINNER CLDS MOVING JUST N OF RED RIVER WITH
MESONET DWPTS CREEPING INTO THE LOWER 60S IN SE OK WITH RISING
DWPTS AS FAR N AS MLC. 3HR PRES FALLS CENTERED IN NC OK AND PRES
RISES S OF WARM FNT INDICATE BNDRY WILL MAKE PROGRESS N THIS
AFTERNOON INTO SE OK. NEW ETA 12 HR SFC PROG STILL HAS TROF FROM
LOW NEAR CDS ALONG RED RIVER. WILL PLAN ON FNT AT LEAST MIXING OUT
TO NEAR I-40...PUTTING SE ZNS IN WARM SECTOR LATE TODAY. SFC BASED
CAPES EXPECTED TO BE > 3000J/KG IN WARM SECTOR WITH WK CAP. AM
SURPRISED NO CONVECTION HAS YET DVLPED IN ISENTROPIC LIFT N OF WARM
FNT. ELEVATED CAPES (FROM H85) ARE PROGGED TO BE ARND 2000J/KG. NEW
12 HR ETA SHOWING IMPRESSIVE H7 UVV CENTERED OVER C OK WITH A LOBE
EXTENDING E N OF PROGGED SFC WARM FNT. SFC TROF/DRYLN WILL REMAIN
WELL W OF FA UNTIL TONIGHT.

EXPECT SCT TRW TO DVLP IN WARM SECTOR BY LATE AFTERNOON IN WEAKLY
CAPPED JUICY AIRMASS. CUD SEE SOME BRIEF L- JUST N OF WARM
FNT...BUT ALSO EXPECT SCT RW/TRW TO DVLP N OF WARM FNT BY LATE
AFTERNOON...AS NEXT H5 S/W NOW MOVING INTO SRN ROCKIES BEGINS
MOVING INTO TX/OK PH. MAIN SFC FOCUSING MECHS SHUD NOT ARRIVE IN FA
UNTIL TONIGHT AS SFC LOW/FNT MOVE E. WILL KEEP MENTION OF PSBL SVR
IN SRN ZNS THIS AFTERNOON AND UP TMPS INTO 80-85 DEG RANGE THERE.
NO SIG CHGS TO NRN ZNS FROM MID PACKAGE.

OTHER THING TO CONSIDER WILL BE CHC FOR HVY RAIN EVENT TONIGHT INTO
MONDAY OVER MUCH OF FA. THINGS HAVE BEEN VRY DRY LATELY...ESP IN NE
OK...SO EXPECT WE CUD HANDLE 3 OR 4 INCHES OF RAIN IN MOST
AREAS...BUT 3 HR FFG IS ONLY 2-3 INCHES SO MAY HAVE pFFA IN PM
PACKAGE.   /13

.TUL...
OK...NONE.
AR...NONE.

ARZ001-002-010-011-019-029-OKZ054>077-221100-

EASTERN OKLAHOMA/NORTHWEST ARKANSAS THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE TULSA OK
100 PM CDT SUN APR 21 1996

...STRONG POTENTIAL FOR SEVERE WEATHER AND TORNADOES THIS AFTERNOON
AND TONIGHT...

NUMEROUS SEVERE THUNDERSTORMS ARE EXPECTED OVER EASTERN OKLAHOMA
AND NORTHWEST ARKANSAS LATE THIS AFTERNOON AND TONIGHT.

AN UPPER-LEVEL SYSTEM WILL CONTINUE MOVING INTO THE CENTRAL AND
SOUTHERN PLAINS THIS AFTERNOON. MEANWHILE...LOW LEVEL MOISTURE HAS
INCREASED RAPIDLY ACROSS THE AREA RESULTING IN A LARGE AMOUNT OF
INSTABILITY...ESPECIALLY OVER SOUTHEAST OKLAHOMA.  THIS MOISTURE
WILL CONTINUE SPREADING NORTHWARD OVER ALL OF THE AREA BY LATE
AFTERNOON. AS THE SYSTEM APPROACHES A LOW PRESSURE AREA AT THE
SURFACE WILL FORM OVER NORTHWEST TEXAS NEAR WICHITA FALLS WITH A
COLD FRONT EXTENDING NORTHEASTWARD TOWARDS NORTHCENTRAL OKLAHOMA.

THUNDERSTORMS WILL DEVELOP LATER THIS AFTERNOON AND RAPIDLY BECOME
SEVERE. THE MOST LIKELY PLACES FOR SEVERE THUNDERSTORM FORMATION
THIS AFTERNOON WILL BE OVER THREE MAIN AREAS.

ONE AREA FOR THUNDERSTORM DEVELOPMENT WILL BE SOUTH OF THE SURFACE
LOW ALONG THE DRY-LINE IN NORTHWEST TEXAS NEAR WICHITA FALLS AND
ABILENE TEXAS. THESE THUNDERSTORMS WILL MOVE TOWARDS SOUTHERN
OKLAHOMA AND NORTH TEXAS THROUGH THE EVENING.

ANOTHER AREA WHERE THUNDERSTORMS WILL LIKELY DEVELOP IN THE LATE
AFTERNOON WILL BE ALONG A COLD FRONT WHICH WILL BE LOCATED ALONG A
PONCA CITY TO LAWTON LINE AROUND SUNSET. THESE STORMS WILL LIKELY
MOVE OVER MUCH OF NORTHEAST OKLAHOMA BETWEEN 6 AND MIDNIGHT
CONTINUING EASTWARD TOWARDS NORTHWEST ARKANSAS DURING THE NIGHT.

A THIRD AREA OF CONCERN IS ALONG AND SOUTH OF A NORTHWARD MOVING
WARM FRONT WHICH WAS LOCATED ACROSS SOUTHERN AND CENTRAL OKLAHOMA
EARLY THIS AFTERNOON. STRONG CONVERGENCE OR LIFTING WAS OBSERVED
SOUTH OF THE WARM FRONT NEAR THE RED RIVER. THIS AREA MAY BE A
FOCUS FOR SEVERE THUNDERSTORM DEVELOPMENT OVER SOUTHEAST AND
EASTCENTRAL OKLAHOMA THIS AFTERNOON.

IN ALL OF THESE AREAS...THE LARGE AMOUNT OF INSTABILITY SUGGESTS
THAT VERY LARGE HAIL AS WELL STRONG AND DAMAGING WINDS ARE LIKELY.
THE VERTICAL WIND SHEAR ALSO FAVORS THE DEVELOPMENT OF TORNADOES
WITH THESE STORMS. THE GREATEST THREAT FOR TORNADOES WILL BE ALONG
AND AHEAD OF THE DRY-LINE AFTER 5 PM...AND ALONG AND SOUTH OF THE
WARM FRONT AFTER 4 PM.

SEVERE WEATHER PREPARATION BY EMERGENCY MANAGEMENT AGENCIES AND
SPOTTER GR`OUPS SHOULD BE RUSHED TO COMPLETION AND SHOULD MAINTAIN
A HIGH STATE OF READINESS FOR LIKELY ACTIVATION LATE THIS AFTERNOON
THROUGH MOST OF THE NIGHT.