Flash Flooding and Hail in Oklahoma, May 16 to 17, 2002

EASTERN OKLAHOMA/NORTHWEST ARKANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
753 PM CDT THU MAY 16 2002

COMPLICATED SFC PATTERN THIS EVENING WITH MULTIPLE BOUNDARIES ACROSS
AREA.  COLD FRONT LOCATED NEAR MCI EXTENDING SW INTO OK PANHANDLE.
FURTHER SOUTH INVERTED SFC TROUGH OVER NW OK AND SECONDARY WEAKER
BOUNDARY ACROSS SE OK.  ELEVATED CONVECTION HAS DEVELOP OVER
SOUTH-CENTRAL OK/NORTH TEXAS IN RESPONSE TO WEAK UPPER WAVE THAT
MOVED OUT OF MEXICO EARLIER TODAY.  ELEVATED INSTABILITIES WILL
REMAIN MARGINAL THIS EVENING...BUT STRONGER CELLS COULD BRIEFLY
APPROACH SEVERE LIMITS AS ACTIVITY MOVES EAST ACROSS SE OK THIS
EVENING.

STRONGER CONVECTION WILL LIKELY DEVELOP AFTER MIDNIGHT AS MAIN UPPER
DISTURBANCE MOVES OUT INTO THE CENTRAL PLAINS. SCT TSTMS COULD
DEVELOP LATER THIS EVENING ALONG INVERTED SFC TROUGH OVER
NORTH-CENTRAL/ NORTHEAST OK...BECOMING MORE WIDESPREAD AS COLD FRONT
PUSHES SOUTH INTO FA LATE TONIGHT.  THE HEAVIEST PRECIP EXPECTED
AFTER 300 AM... CONTINUING THROUGH THE MORNING HOURS BEFORE PUSHING
EAST OF FA BY MID AFTERNOON FRIDAY.

FLASH FLOOD WATCH STILL LOOKS GOOD AS WIDESPREAD 2-3 INCH RAINFALL
AMOUNTS WILL BE POSSIBLE OVER PORTIONS OF FA THROUGH FRIDAY
AFTERNOON. WILL UPDATE TO TWEAK CURRENT FORECAST GIVEN LATEST
TRENDS...OTHERWISE NO SIGNIFICANT CHANGES ANTICIPATED THIS EVENING.

FCSTID = 12

.TSA...
AR...FLASH FLOOD WATCH  UNTIL NOON CDT FRIDAY FOR ZONES
ARZ001>002...ARZ010>011...ARZ019>020...ARZ029.

OK...FLASH FLOOD WATCH FROM UNTIL NOON CDT FRIDAY FOR ZONES
OKZ054>076.

ARZ001-002-010-011-019-020-029-OKZ049-053>065-066>076-171100-

EASTERN OKLAHOMA / NORTHWEST ARKANSAS HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TULSA OK
856 PM CDT THU MAY 16 2002

...A CHANCE OF SEVERE THUNDERSTORMS LATE TONIGHT...

THUNDERSTORMS DEVELOPING ACROSS WESTERN OKLAHOMA AND TEXAS THIS
EVENING WILL FORM INTO A THUNDERSTORM COMPLEX AND PUSH INTO EASTERN
OKLAHOMA AND NORTHWEST ARKANSAS LATE TONIGHT. MOST OF THE
THUNDERSTORM ACTIVITY IS EXPECTED TO TAKE PLACE AFTER 3 AM FRIDAY
MORNING. SOME OF THESE STORMS COULD BECOME SEVERE WITH THE LARGE
HAIL THE PRIMARY THREAT.

.SPOTTER ACTIVATION...
SPOTTER ACTIVATION MAY BE REQUIRED AFTER MIDNIGHT ACROSS NORTHEAST
OKLAHOMA AND NORTHWEST ARKANSAS.

.DISCUSSION...
THUNDERSTORMS ARE DEVELOPING THIS EVENING ACROSS EASTERN COLORADO...
WESTERN OKLAHOMA AND WESTERN TEXAS AS A STRONG MID LEVEL SHORTWAVE
MOVES OUT OF THE ROCKIES AND ACROSS THE PLAINS. THESE THUNDERSTORMS
WILL FORM INTO A MESOSCALE CONVECTIVE SYSTEM AS THE LOW LEVEL
JET INCREASES TO 40 KTS ACROSS WESTERN OKLAHOMA LATE THIS EVENING.
THIS THUNDERSTORM COMPLEX WILL THEN PUSH EAST INTO EASTERN OKLAHOMA
AND NORTHWEST ARKANSAS LATE TONIGHT. THE PRIMARY THREAT FROM THESE
THUNDERSTORMS WILL BE LARGE HAIL. DAMAGING WINDS WILL BE POSSIBLE
IF SOME OF THE THUNDERSTORMS CAN GET ROOTED IN THE BOUNDARY LAYER
WHICH WILL BE POSSIBLE IN THE VICINITY OF THE COLD FRONT THAT WILL
MOVE INTO THE AREA LATE TONIGHT.

THREAT TABLE
VALID THROUGH 1200 UTC FRIDAY

AREA 1...ALL OF EASTERN OKLAHOMA AND NORTHWEST ARKANSAS
THUNDERSTORM PROBABILITY...100
SEVERE PROBABILITY IF STORMS OCCUR...50
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 GOLFBALL SIZE HAIL OR LARGER.

.OTHER HAZARDS...
A FLASH FLOOD WATCH IS ALSO IN EFFECT THOUGH NOON FRIDAY FOR MUCH OF
EASTERN OKLAHOMA AND NORTHWEST ARKANSAS. PLEASE REFER TO THE LATEST
STATEMENT (OKCFFATUL) ISSUED BY THE NATIONAL WEATHER SERVICE IN
TULSA FOR ADDITIONAL INFORMATION.

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