Severe Thunderstorm Warning 214, NWS Tulsa, OK

EASTERN OKLAHOMA/NORTHWEST ARKANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
330 PM CDT WED MAY 24 2000

PLAYING THE WAITING GAME NOW. FRONTAL BOUNDARY HAS STALLED FROM FAR
NORTHWEST ARKANSAS TO TULSA TO OKLAHOMA CITY. EXTREME INSTABILITY IN
PLACE BUT MONSTER CAP REMAINS PER SPECIAL 20Z NORMAN SOUNDING. A
QUICK PEEK AT THE 18Z ETA DELAYS CONVECTIVE INITIATION UNTIL RIGHT
AT 00Z AND THE LATEST STORM PREDICTION CENTER HOURLY ANALYSIS FIELDS
SEEM TO CONFIRM THIS WITH VERY WARM 700 MILLIBAR TEMPERATURES STILL
UP NEAR THE KANSAS STATE LINE. STILL EXPECT RAPID SEVERE
THUNDERSTORM DEVELOPMENT ACROSS AT LEAST THE NORTHERN TIER OF
OKLAHOMA COUNTIES PRIOR TO SUNSET AND POSSIBLY INTO THE SECOND TIER
OF COUNTIES AS STRONG LIFT ERODES THE CAP. IMPROVING WIND PROFILES
SUPPORT SUPERCELLS AND THE POSSIBILITY OF TORNADIC
STORMS...PARTICULARLY WEST AND NORTH OF TULSA THIS EVENING.

STORMS EXPECTED TO EVOLVE INTO A LARGE COMPLEX OVERNIGHT AND MOVE
EAST WITH SOME PROPAGATION TO THE SOUTH DUE TO NEW DEVELOPMENT ON
THE OUTFLOW. SOUTHERN EXTENT OF ACTIVITY WILL BE LIMITED BY THE CAP
SO WILL HAVE A WIDE RANGE OF POPS OVERNIGHT FROM CATEGORICAL UP
NORTH TO SLIGHT CHANCE NEAR THE RED RIVER. WILL MENTION SEVERE
STORMS AND HEAVY RAINFALL IN THE NORTH BUT WILL HOLD OFF ON A FLASH
FLOOD WATCH DUE TO UNCERTAINTIES IN THE BEHAVIOR OF THE COMPLEX
LATER TONIGHT. FLASH FLOOD GUIDANCE VALUES ARE ALSO RATHER HIGH AS
WE HAVE HAD A CHANCE TO DRY OUT SINCE THE EXCESSIVE RAINS EARLIER
THIS MONTH.

FORECAST BEYOND TONIGHT IS CLOUDED IN UNCERTAINTY SINCE CONVECTION
TONIGHT WILL DETERMINE WHAT OCCURS LATER. WILL OPT TO KEEP THE
SURFACE BOUNDARY IN THE SOUTHERN PART OF THE AREA THURSDAY AND THEN
MOVE IT NORTH FRIDAY. THE BEST CHANCES FOR ORGANIZED CONVECTION
THURSDAY NIGHT LOOK TO BE TO OUR NORTH ALONG THE RETREATING 850
MILLIBAR BOUNDARY BUT COULD SEE SOME DEVELOPMENT ANYWHERE NORTH OF
THE WARM FRONT. THUS WILL KEEP CHANCE POPS GOING IN ALL PERIODS
BEYOND TONIGHT. CAP MAY BE A PROBLEM AGAIN IN MOST AREAS FRIDAY BUT
COOLING ALOFT BEGINS TO OVERSPREAD THE AREA LATE IN THE DAY SO
CANNOT RULE OUT DEVELOPMENT AT THAT TIME. BETTER CHANCES MAY COME
FRIDAY NIGHT THOUGH AS COLD FRONT APPROACHES.

THE HOLIDAY WEEKEND LOOKS NICER AS COLD FRONT PASSES SATURDAY ENDING
THE CHANCES OF CONVECTION. SHOULD BE MOSTLY SUNNY SUNDAY AND MONDAY
WITH NEAR SEASONAL TEMPERATURES BEFORE A WARMUP BEGINS AGAIN JUST
BEYOND THE SCOPE OF THIS FORECAST.

STAYED CLOSE TO GUIDANCE TEMPERATURES BUT DID GO A BIT WARMER FRIDAY.
COORDINATED WITH NORMAN ON FLASH FLOOD POTENTIAL TONIGHT.

FCSTID = 5
TUL   67  82  72  89 /  70  40  40  30
FSM   70  87  71  91 /  40  40  30  30
MLC   72  87  73  91 /  30  30  30  30
BVO   65  79  70  88 /  80  40  40  30
FYV   65  77  68  86 /  70  50  40  30
BYV   65  77  68  86 /  70  50  40  30
MIO   65  77  70  87 /  80  50  40  30
MKO   69  85  72  90 /  50  30  30  30
F10   69  85  72  90 /  50  30  30  30
HHW   73  90  74  91 /  20  20  20  20

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

PLATE

ARZ001-002-010-011-019-020-029-OKZ049-053>076-251200-

EASTERN OKLAHOMA/NORTHWEST ARKANSAS HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TULSA OK
115 PM CDT WED MAY 24 2000

...A FEW SEVERE THUNDERSTORMS EXPECTED MAINLY NORTH OF AN OKMULGEE
TO FAYETTEVILLE LINE THIS AFTERNOON AND EVENING...

.SYNOPSIS...
A COLD FRONT EXTENDED FROM OKLAHOMA CITY TO JUST SOUTH OF TULSA TO
NEAR FAYETTEVILLE ARKANSAS EARLY THIS AFTERNOON. THIS COLD FRONT IS
EXPECTED TO MOVE SOUTH AND BE THE FOCUS FOR SEVERE THUNDERSTORMS
LATER THIS AFTERNOON AND EVENING ACROSS PORTIONS OF NORTHEAST
OKLAHOMA INTO NORTHWEST ARKANSAS.

.PRIMARY HAZARD...
A FEW SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP AFTER 4
PM...MAINLY ALONG AND NORTH OF AN OKMULGEE TO TULSA TO FAYETTEVILLE
LINE. SUPERCELL THUNDERSTORMS WILL LIKELY DEVELOP INITIALLY ALONG AN
ADVANCING COLD FRONT THIS AFTERNOON...WITH THE MAIN THREAT BEING
ISOLATED TORNADOES AND LARGE HAIL. LATER IN THE EVENING...THE
THUNDERSTORMS WILL EVOLVE INTO MORE OF A COMPLEX...WITH THE MAIN
THREAT SHIFTING TO LARGE HAIL...AND DAMAGING STRAIGHT-LINE WINDS.
FLASH FLOODING MAY BECOME POSSIBLE ACROSS NORTHEAST OKLAHOMA DURING
THE OVERNIGHT HOURS AS WELL.

.DISCUSSION...
THE SURFACE COLD FRONT HAS MOVED INTO NORTHEAST OKLAHOMA AS OF EARLY
THIS AFTERNOON...AND WILL NOW PROVIDE THE FOCUS FOR CONVECTIVE
INITIATION. THE AIR MASS IS EXTREMELY UNSTABLE WITH SURFACE
DEWPOINTS IN THE LOWER TO MIDDLE 70S...AND CAPE VALUES EXCEEDING
2000 J/KG. THE SURFACE WINDS HAVE BECOME EASTERLY BEHIND THE
FRONT...WHICH WILL INCREASE THE POTENTIAL FOR SUPERCELL
THUNDERSTORMS. IN ADDITION...AN APPROACHING UPPER LEVEL DISTURBANCE
WILL INCREASE THE WINDS ALOFT...WHICH WILL FURTHER INCREASE SHEAR.
THE ATMOSPHERE REMAINS CAPPED HOWEVER...WITH WARM TEMPERATURES
ALOFT. HOWEVER...MID LEVEL COOLING WILL TAKE PLACE NORTH OF THE
BOUNDARY ACROSS NORTHEAST OKLAHOMA AND NORTHWEST ARKANSAS THIS
AFTERNOON. GIVEN THE SURFACE BASED INSTABILITY...THUNDERSTORMS
SHOULD DEVELOP AFTER 4 PM THIS AFTERNOON...AND RAPIDLY BECOME
SEVERE. SOUTH OF THE BOUNDARY...THUNDERSTORMS WILL NOT DEVELOP
BECAUSE OF THE STRONG CAP...UNTIL THE BOUNDARY PUSHES INTO THE AREA
LATER THIS EVENING.

THUNDERSTORMS WHICH DEVELOP ALONG AND NORTH OF THE BOUNDARY WILL
HAVE THE POTENTIAL FOR ISOLATED TORNADOES...LARGE HAIL AND DAMAGING
WINDS. THE THUNDERSTORMS WILL LIKELY DEVELOP ALONG AN EAST-WEST LINE
ALONG THE FRONT AND THUS THE POTENTIAL FOR REDEVELOPMENT EXISTS. AS
THE THUNDERSTORMS EVOLVE INTO A COMPLEX...THE THREAT WILL SHIFT TO
MAINLY LARGE HAIL AND STRAIGHT-LINE WINDS. HEAVY RAINS MAY BECOME A
PROBLEM AFTER MIDNIGHT...IF STORMS CONTINUE TO DEVELOP IN THE SAME
AREA. THE THREAT FOR FLASH FLOODING WILL MAINLY BE CONFINED TO THE
NORTHEAST CORNER OF OKLAHOMA.

.EMERGENCY AGENCY AND SPOTTER ACTIVATION...
SPOTTER ACTIVATION WILL LIKELY BECOME NECESSARY LATER THIS
AFTERNOON...SO EMERGENCY MANAGERS SHOULD BE PREPARED.

ARZ001-002-010-011-019-020-029-OKZ049-053>076-251200-

EASTERN OKLAHOMA/NORTHWEST ARKANSAS HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TULSA OK
625 PM CDT WED MAY 24 2000

...A FEW SEVERE THUNDERSTORMS EXPECTED MAINLY NORTH OF AN EUFAULA TO
OZARK LINE LATER THIS EVENING AND TONIGHT...

.SYNOPSIS...
SURFACE LOW PRESSURE WAS LOCATED IN THE TEXAS PANHANDLE THIS
EVENING SOUTHEAST OF AMARILLO. A FRONTAL BOUNDARY EXTENDED
NORTHEAST FROM THE SURFACE LOW INTO NORTHWEST AND NORTH-CENTRAL
OKLAHOMA. THE FRONT WILL DRIFT SLOWLY SOUTHEAST TONIGHT AND BE THE
FOCUSING MECHANISM FOR SEVERE THUNDERSTORMS LATER EVENING THROUGH
THE OVERNIGHT HOURS ACROSS NORTHEAST OKLAHOMA AND NORTHWEST
ARKANSAS.

.PRIMARY HAZARD...
A FEW SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP BETWEEN 700 AND
1000 PM OVER NORTHEAST OKLAHOMA. THE MAIN THREAT WITH THESE STORMS
WILL BE LARGE HAIL AND DAMAGING DOWNBURST WINDS. ISOLATED TORNADOES
WILL ALSO BE POSSIBLE. THE MAIN THREAT AREA WILL BE OVER
NORTHEASTERN OKLAHOMA...ALONG THE OKLAHOMA...KANSAS BORDER. FLASH
FLOODING MAY ALSO BECOME POSSIBLE ACROSS THIS AREA LATER TONIGHT.

.DISCUSSION...
THE COLD FRONT HAS BECOME QUASI-STATIONARY THIS EVENING ACROSS
NORTHWEST AND NORTH-CENTRAL OKLAHOMA.  MOISTURE CONVERGENCE
CONTINUES ALONG THE BOUNDARY WITH DEWPOINTS IN THE MID TO UPPER 70S.
THIS IN COMBINATION WITH DAYTIME HEATING HAS CREATED A VERY UNSTABLE
ATMOSPHERE WITH CAPE VALUES APPROACHING 5000 J/KG.  UPPER LEVEL
SPEED MAX IS FORECAST TO MOVE INTO NORTHWEST OKLAHOMA LATER THIS
EVENING WITH STRONG UPPER LEVEL DIVERGENCE FORECAST OVER NORTHEAST
OKLAHOMA BY MIDNIGHT. SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP
OVER NORTHEAST OKLAHOMA LATER THIS EVENING.

ALTHOUGH 0-6 KM SPEED SHEAR WILL BE MARGINAL...WITH THE HIGH
INSTABILITIES IN PLACE...ISOLATED SUPERCELLS WILL BE POSSIBLE ALONG
THE SOUTHERN EDGE OF THE THUNDERSTORM ACTIVITY...MAINLY BEFORE
MIDNIGHT.  FLOODING MAY ALSO BECOME A PROBLEM ALONG THE KANSAS...
OKLAHOMA BORDER LATER TONIGHT DUE TO THE SLOW PROGRESSION OF THE
OVERALL SYSTEM. THE THUNDERSTORM ACTIVITY IS FORECAST TO MOVE INTO
NORTHWEST ARKANSAS AFTER MIDNIGHT.

.EMERGENCY AGENCY AND SPOTTER ACTIVATION...
SPOTTER ACTIVATION WILL BE NECESSARY THIS EVENING.