Severe Thunderstorm Warning 259, NWS Norman, OK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
1055 AM CDT SUN MAY 27 2001

MINOR CHANGES TO TEMPS AND POPS FIRST PERIOD...OTHERWISE NO SIGNIFICANT
CHANGES MADE. SURFACE PATTERN IS VERY COMPLEX WITH WEAK PRESSURE
GRADIENT AND RESIDUAL OUTFLOW BOUNDARIES. DEW POINTS ARE HIGHER
ACROSS OKLAHOMA AND NORTH TEXAS TODAY THAN YESTERDAY WITH DEWPOINTS
AT OR ABOVE 60F AS FAR NW AS AMA AND DDC. EXPECT SURFACE WINDS TO
BECOME MORE ORGANIZED AND SOUTHEASTERLY BY LATE AFTERNOON BENEATH
MODERATELY STRONG NORTHWEST FLOW ALOFT. MID LEVEL TEMPS APPEAR WARM
ENOUGH TO HOLD OFF CONVECTIVE INITIATION UNTIL LATE AFTERNOON WHEN
CAPE VALUES WILL BE >3K J/KG.  STORMS SHOULD DEVELOP MOST ANYWHERE
FROM EASTERN TEXAS PANHANDLE NORTH INTO WESTERN KANSAS...THEN MOVE
SOUTHEAST ALONG INSTABILITY AXIS EXPECTED TO LIE COINCIDENT WITH SPC
MDT RISK AREA.  IN ADDITION TO SEVERE RISK...HEAVY RAINFALL IS A
CONCERN FOR POTENTIAL FLOODINNG. GIVEN RELATIVELY HIGH FLASH FLOOD
GUIDANCE VALUES...40 KNOT MID LEVEL WINDS...AND AMBIGUITY OF
MESOSCALE DETAILS WE HAVE ELECTED NOT TO ISSUE FLASH FLOOD WATCH AT
THIS TIME.  ..16..

.OUN...
OK...NONE.
TX...NONE.

OKZ004>048-050>052-TXZ083>090-272000-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NORMAN OK
100 PM CDT SUN MAY 27 2001

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
TONIGHT ACROSS ALL OF WESTERN...CENTRAL...AND SOUTHERN OKLAHOMA.
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON
AND TONIGHT ACROSS WESTERN NORTH TEXAS. DAMAGING WIND AND LARGE
HAIL WILL BE THE PRIMARY SEVERE WEATHER THREATS...WITH ISOLATED
TORNADOES POSSIBLE IN THE MODERATE RISK AREA LATE THIS AFTERNOON AND
EVENING. IN ADDITION...HEAVY RAINFALL MAY CAUSE FLOODING OVERNIGHT.

THUNDERSTORMS ARE EXPECTED TO DEVELOP BY MID TO LATE AFTERNOON
ACROSS THE EASTERN OKLAHOMA AND TEXAS PANHANDLES...KANSAS
...AND WESTERN OKLAHOMA. RELATIVELY STRONG NORTHWEST WINDS ALOFT
WILL RESULT IN STRONG WIND SHEAR AND CARRY THE STORMS SOUTHEAST
ACROSS OKLAHOMA AND EVENTUALLY PORTIONS OF NORTH TEXAS. AS THE
STORMS MOVE INTO INCREASINGLY UNSTABLE AIR THEY WILL BECOME SEVERE
PRODUCING LARGE HAIL AND DAMAGING WINDS. A FEW SUPERCELL
THUNDERSTORMS...CAPABLE OF PRODUCING ISOLATED TORNADOES...WILL BE
POSSIBLE...ESPECIALLY DURING THE AFTERNOON AND EVENING ACROSS
NORTHWEST OKLAHOMA. AS THE STORMS MOVE SOUTHEAST OVERNIGHT THE RISK
FOR TORNADOES WILL TEND TO DECREASE...WHILE THE THREAT OF DAMAGING
WINDS AND FLOODING RAINFALL WILL INCREASE.

EMERGENCY MANAGER GROUPS ACROSS OKLAHOMA AND NORTH TEXAS SHOULD BE
PREPARED FOR ACTIVATION THIS AFTERNOON AND EVENING.

..16..