Severe Thunderstorm Warning 69, NWS Tulsa, OK

EASTERN OKLAHOMA/NORTHWEST ARKANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
305 PM CDT SAT APR 14 2001

CONVECTION EXPECTED TO INCREASE ACROSS WESTERN OKLAHOMA NEXT FEW
HOURS AND ALSO ACROSS SOUTHERN AND EASTERN KANSAS THIS EVENING.
CURRENT THINKING IS THAT ACTIVITY WILL ORGANIZE INTO A MESOSCALE
CONVECTIVE SYSTEM SOMEHWERE IN NORTHWEST OKLAHOMA OR SOUTH CENTRAL
KANSAS THIS EVENING...MOVING EAST SOUTHEAST ACROSS NORTHEAST
OKLAHOMA AND NORTHWEST ARKANSAS LATE TONIGHT. WILL GO WITH LIKELY
POPS IN ALL ZONES TONIGHT...WITH BEST CHANCE FOR SEVERE STORMS
ACROSS NORTHEAST OKLAHOMA WHERE BETTER FORCING FOR STORMS PRESENT.
IF STORMS ORGANIZE ACROSS SOUTHEAST OKLAHOMA NEAR AND NORTH OF THE
WARM FRONT...THEN THERE WILL ALSO BE A THREAT FOR EXCESSIVE RAINS
GIVEN RELATIVELY LOW FLASH FLOOD GUIDANCE VALUES THAT AREA.

ANY REMAINING CONVECTION SHOULD QUICKLY MOVE EAST OF AREA SUNDAY
MORNING AS DRIER AIRMASS MOVES IN BEHIND PACIFIC FRONT. EXPECT
MOSTLY SUNNY SKIES AREA WIDE BY SUNDAY AFTERNOON...WITH TEMPERATURES
IN THE UPPER 70S AND LOWER 80S.

BIG WEATHER CHANGE IN STORE BEGINNING MONDAY AND LASTING UNTIL ABOUT
WEDNESDAY. EXPECT DRY WEATHER FOR NEARLY ALL OF THE COMING WORK
WEEK...AS UNSEASONABLY COLD UPPER LOW MOVES THROUGH GREAT LAKES
REGION AND HELPS BRING A CANADIAN AIRMASS SOUTH INTO PLAINS. CURRENT
TEMPERATURES IN THE TEENS AND 20S ACROSS PARTS OF ALBERTA AND
MANITOBA GIVE CREDENCE TO MODEL TRENDS OF BRINGING A VERY COOL
AIRMASS INTO THE AREA BEGINNING MONDAY. THERE WILL LIKELY BE SOME
FREEZE WARNINGS REQUIRED ACROSS NORTHERN ZONES EARLY IN THE WEEK.
WARMUP SHOULD COMMENCE BY LATE WEDNESDAY AS UPPER RIDGING MOVES INTO
CENTRAL U.S.

FCSTID = 9
TUL   61  79  48  64 /  70  10   0  10
FSM   61  83  49  72 /  60  20   0  10
MLC   63  81  50  70 /  60  20   0  10
BVO   60  78  46  62 /  70  10   0  10
FYV   61  77  45  67 /  70  20   0  10
BYV   61  77  45  67 /  70  20   0  10
MIO   61  78  45  64 /  70  10   0  10
MKO   63  81  50  70 /  60  20   0  10
F10   61  79  48  64 /  70  10   0  10
HHW   64  82  54  75 /  60  30   0  10

.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
120 PM CDT SAT APR 14 2001

...A FEW SEVERE STORMS POSSIBLE THROUGH TONIGHT IN NORTHEAST
OKLAHOMA AND FAR NORTHWEST ARKANSAS...MAINLY NORTH OF A TULSA TO
FAYETTEVILLE LINE...

SURFACE LOW PRESSURE WITH A WARM FRONT THAT EXTENDED FROM NORTHWEST
OKLAHOMA AND SOUTHERN KANSAS WILL CONTINUE TO LIFT NORTH IN CENTRAL
KANSAS THIS AFTERNOON. A SECOND SURFACE BOUNDARY WAS LOCATED JUST
SOUTH OF THE RED RIVER. AS AN UPPER LEVEL SYSTEM MOVES THROUGH THE
REGION TONIGHT... THE FRONT ACROSS KANSAS WILL MOVE SOUTHWARD AS A
COLD FRONT INTO OKLAHOMA. BY SUNDAY MORNING...THE SURFACE FRONT
WILL BE ACROSS ARKANSAS AND EXTENDING SOUTHWEST ACROSS NORTHERN
TEXAS.

THUNDERSTORMS HAVE CONTINUED TO DEVELOP AND MOVE EAST ACROSS
SOUTHEAST OKLAHOMA AND WEST CENTRAL ARKANSAS IN ASSOCIATION WITH THE
SURFACE BOUNDARY NEAR THE RED RIVER. THESE STORMS ARE EXPECTED TO
DECREASE IN AREAL COVERAGE THIS AFTERNOON.

THUNDERSTORMS ARE EXPECTED TO DEVELOP NEAR THE FRONT...FROM CENTRAL
KANSAS TO WESTERN OKLAHOMA LATE THIS AFTERNOON OR THIS EVENING. AS
THE FRONT SAGS SOUTHWARD...STRONG TO SEVERE STORMS MAY MOVE INTO
NORTHEAST OKLAHOMA NORTHWEST ARKANSAS TONIGHT. THE MAIN THREATS FROM
THE STORMS WILL BE LARGE HAIL AND DAMAGING WINDS. THE THREAT FOR
TORNADOES WOULD BE MAINLY IN KANSAS THIS EVENING.

.SPOTTER ACTIVATION...
SPOTTER ACTIVATION MAY BE NEEDED THROUGH TONIGHT IN NORTHEAST
OKLAHOMA AND NORTHWEST ARKANSAS.

.DISCUSSION...
SUPERCELL THUNDERSTORMS MAY DEVELOP WEST AND NORTHWEST OF THE AREA
THIS EVENING WHERE CAPES OF 2500-3000 J/KG AND STRONG VERTICAL WIND
SHEAR WILL BE IN PLACE. ANY STORMS THAT DEVELOP WILL TRACK TO THE
EAST OR SOUTHEAST TOWARDS NORTHEAST OKLAHOMA TONIGHT. HOWEVER...WITH
THE LOSS OF DAYTIME HEATING THE STORMS ARE EXPECTED TO LOSE SOME
INTENSITY WITH THE THREAT FOR SUPERCELLS DIMINSHING AS THEY APPROACH
NORTHEAST OKLAHOMA TONIGHT.

THREAT TABLE
NORTH OF A TULSA TO FAYETTEVILLE LINE TONIGHT.
THUNDERSTORM PROBABILITY...50
SEVERE PROBABILITY IF STORMS OCCUR...40
SIGNIFICANT SEVERE PROBABILITY IF STORMS OCCUR...20

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

ADDITIONAL WEATHER INFORMATION...INCLUDING RELATED GRAPHICS CAN BE
FOUND AT: WWW.SRH.NOAA.GOV/TULSA.

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

EASTERN OKLAHOMA/NORTHWEST ARKANSAS HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE TULSA OK
500 PM CDT SAT APR 14 2001

...ISOLATED SEVERE THUNDERSTORMS POSSIBLE IN FAR SOUTHEAST OKLAHOMA
THROUGH EARLY THIS EVENING...

...A FEW SEVERE STORMS POSSIBLE LATE THIS EVENING AND OVERNIGHT IN
NORTHEAST OKLAHOMA AND NORTHWEST ARKANSAS...MAINLY NORTH OF A BRISTOW
TO FORT SMITH LINE...

SURFACE LOW PRESSURE WAS CENTERED OVER THE OKLAHOMA PANHANDLE LATE
THIS AFTERNOON WITH A WARM FRONT EXTENDING SOUTH TO JUST WEST OF
WICHITA FALLS TEXAS AND THEN EAST ACROSS NORTHERN TEXAS INTO
NORTHERN LOUISIANA. A DEVELOPING FRONTAL BOUNDARY ACROSS KANSAS WILL
MOVE SOUTH AS A COLD FRONT LATER TONIGHT AND WILL ENTER NORTHEAST
OKLAHOMA BY SUNDAY MORNING.

THUNDERSTORMS NORTH OF THE WARM FRONT HAVE INTENSIFIED IN FAR
SOUTHEAST OKLAHOMA LATE THIS AFTERNOON AND A COUPLE OF STORMS HAVE
BECOME SEVERE. THE THREAT FOR ISOLATED SEVERE STORMS IN THIS AREA
WILL CONTINUE UNTIL AROUND SUNSET WITH LARGE HAIL BEING THE MAIN
THREAT.

THUNDERSTORMS ARE ORGANIZING IN CENTRAL KANSAS LATE THIS AFTERNOON
AND WILL BEGIN TO DEVELOP SOUTHEAST TOWARDS NORTHEAST OKLAHOMA THIS
EVENING. THE STORMS SHOULD ENTER NORTHEAST OKLAHOMA BY MIDNIGHT AND
NORTHWEST ARKANSAS AFTER 2 AM. A FEW OF THESE STORMS MAY BE SEVERE
WITH LARGE HAIL AND DAMAGING WINDS.

.SPOTTER ACTIVATION...
SPOTTER ACTIVATION MAY BE NEEDED THROUGH EARLY THIS EVENING IN FAR
SOUTHEAST OKLAHOMA AND LATER THIS EVENING AND OVERNIGHT IN NORTHEAST
OKLAHOMA AND NORTHWEST ARKANSAS.

.DISCUSSION...
A COUPLE STRONG TO SEVERE STORMS HAVE DEVELOPED IN FAR SOUTHEAST
OKLAHOMA LATE THIS AFTERNOON. INSTABILITY IS MARGINAL IN THIS AREA
AND WITH THE LOSS OF DAYTIME HEATING...THE THREAT OF SEVERE WEATHER
SHOULD DIMINISH IN SOUTHEAST OKLAHOMA EARLY THIS EVENING. SUPERCELL
STORMS IN SOUTHWEST AND SOUTH CENTRAL OKLAHOMA WILL WEAKEN BELOW
SEVERE LIMITS BEFORE REACHING SOUTHEAST OKLAHOMA.

A CLUSTER OF THUNDERSTORMS HAS DEVELOPED IN CENTRAL KANSAS. THESE
STORMS WILL LIKELY ORGANIZE INTO A LARGE COMPLEX OF STORMS THIS
EVENING WHICH WILL DEVELOP SOUTHEAST INTO NORTHEAST OKLAHOMA BY
MIDNIGHT AND INTO NORTHWEST ARKANSAS AFTER 2 AM. GREATER INSTABILITY
IN THIS AREA ALONG WITH LOW LEVEL CONVERGENCE ALONG THE DEVELOPING
FRONTAL BOUNDARY WILL SUPPORT THE THREAT OF LARGE HAIL AND DAMAGING
WINDS WITH THESE STORMS LATER TONIGHT.

THREAT TABLE
VALID THROUGH 6 AM SUNDAY

THREAT AREA 1...SOUTHWEST OF A MCALESTER TO TALIHINA LINE THROUGH
                EARLY THIS EVENING.
THUNDERSTORM PROBABILITY...20
SEVERE PROBABILITY IF STORMS OCCUR...20
SIGNIFICANT SEVERE PROBABILITY IF STORMS OCCUR...2

THREAT AREA 2...NORTH OF A BRISTOW TO FORT SMITH LINE TONIGHT.
THUNDERSTORM PROBABILITY...70
SEVERE PROBABILITY IF STORMS OCCUR...70
SIGNIFICANT SEVERE PROBABILITY IF STORMS OCCUR...30

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

AD<DITIONAL WEATHER INFORMATION...INCLUDING RELATED GRAPHICS CAN BE
FOUND AT: WWW.SRH.NOAA.GOV/TULSA.