Severe Thunderstorm Warning 448, NWS Norman, OK

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE NORMAN OK
741 PM CDT FRI MAY 23 2003

DEVELOPING MCS IN PROGRESS BETWEEN AMA AND LBB WILL CONTINUE TO
PROGRESS SOUTHEASTWARD AND COULD MOVE INTO SOUTHWEST PARTS OF THE
AREA WITHIN THE NEXT FEW HOURS. CONTINUING TO MONITOR THUNDERSTORMS
DEVELOPING OVER NORTHWEST NEBRASKA...NEAR A COLD FRONT. THESE
THUNDERSTORMS STAND A GOOD CHANCE OF ALSO EVOLVING INTO A LARGER
THUNDERSTORM COMPLEX AS THE LOW LEVEL JET STRENGTHENS AND ADDITIONAL
LIFT BECOMES AVAILABLE THROUGH ISENTROPIC UPGLIDE IN THE 300K - 310K
LAYER. RECENTLY UPDATED THE HAZARDOUS WEATHER OUTLOOK TO HIGHLIGHT
TWO MAIN AREAS OF SLIGHT RISK OF SVR FOR TONIGHT...THE FIRST BEING
FAR SOUTHWEST AREAS BETWEEN 9 PM AND 1 AM...AND THE OTHER BEING THE
NORTHERN ONE THIRD OF THE AREA TOWARD MORNING. ZONES WERE ALSO
UPDATED TO REFLECT THIS THINKING. ALL POPS WERE REMOVED FROM
SOUTHEAST OKLAHOMA.

JAMES

-------------------------
323 PM CDT FRI MAY 23 2003

BOTH AVN AND ETA INDICATE TWO POSSIBLE AREAS WHERE ADDITIONAL STORM
MAY DEVELOP THIS AFTERNOON INTO THE OVERNIGHT PERIOD.  FIRST AND
MAYBE MOST LIKELY SCENARIO IS FOR STORMS TO DEVELOP ACROSS CENTRAL
HIGH PLAINS (SW NE...NW KS) THIS EVENING THEN MOVE SOUTHEAST TOWARD
FA OVERNIGHT INTO SATURDAY MORNING AS MCS.  OTHER AREA APPEARS TO BE
ACROSS TEXAS PANHANDLE AS SOUTH TO SOUTHEAST FLOW INCREASES ALONG
WITH DAYTIME HEATING.  WOULD ALSO EXPECT THAT SCATTERED STORMS
ACROSS NORTH CENTRAL AREA THIS AFTERNOON WILL CONTINUE TO DECREASE
IN COVERAGE.

FORECAST IN SHORT TERM WILL BE VERY DEPENDENT ON MCS DEVELOPMENT
TONIGHT OVER CENTRAL HIGH PLAINS.  LOOKS LIKE BEST CHANCE FOR STORMS
WILL OCCUR OVER NORTHERN PARTS OF FA AFTER MIDNIGHT WITH LOWER
CHANCES SOUTHEAST INTO WESTERN PARTS (CAP).  ALONG WITH THE SEVERE
CONCERNS WILL BE HEAVY RAIN THREAT...ESPECIALLY ON WESTERN EDGE OF
COMPLEX WHERE STRONGER STORMS WILL OCCUR.

WOULD EXPECT COVERAGE OF SHOWERS AND STORMS ASSOCIATED WITH MCS
WILL GRADUALLY DECREASE DURING THE MORNING WITH ASSOCIATED
BOUNDARIES/COLD FRONT BECOMING FOCUS FOR ADDITIONAL STORMS
SATURDAY AFTERNOON AND EVENING.  AT THIS TIME...APPEARS BEST
CHANCE FOR ADDITIONAL STORMS WILL BE ACROSS SOUTHERN PARTS OF
FA WHERE BETTER CONVERGENCE AND INSTABILITY ARE EXPECTED TO
BE.  INSTABILITY AND SHEAR WILL BE SUFFICIENT FOR
SEVERE STORMS WITH POTENTIAL FOR ANOTHER MCS DEVELOPING
OVERNIGHT ACROSS SOUTHERN ZONES AND HEAVY RAIN BECOMING
ANOTHER CONCERN.

WILL MAINTAIN CHANCES FOR TSRA...ESPECIALLY ACROSS SOUTHERN
ZONES ON SUNDAY WHERE ELEVATED FRONTAL BOUNDARY WILL PROVIDE FOCUS
FOR STORMS.

MEDIUM RANGE MODEL INDICATE THAT BETTER CHANCE OF TSRA WILL
BE CONFINED TO MAINLY WESTERN ZONES GOING INTO THE EARLY
AND MID PART OF NEXT WEEK AND FLOW ALOFT BECOMING MORE
NORTHERLY.

WAS PLANNING ON ISSUING SPS TO HIGHLIGHT SEVERE AND HEAVY RAIN
POTENTIAL OVER THE WEEKEND BUT THIS WILL INTERFERE WITH
SIGNIFICANT WEATHER ADVISORY WHICH IS ALSO ISSUED UNDER SPS
PIL.  WILL THEREFORE OUTLINE THESE HAZARDS IN THE HWO PRODUCT.

FCSTID = SIX

OKC  64 78 61 74 /  50 60 60 40
HBR  65 83 60 74 /  40 60 70 40
SPS  65 85 62 74 /  30 60 70 50
GAG  62 78 57 73 /  40 60 60 30
PNC  62 74 58 73 /  60 60 60 30
DUA  64 79 62 74 /  30 60 70 60

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

OKZ004>048-050>052-TXZ083>090-241200-

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE NORMAN OK
650 PM CDT FRI MAY 23 2003

THIS HAZARDOUS WEATHER OUTLOOK COVERS NORTHERN...WESTERN...
CENTRAL...AND SOUTHERN OKLAHOMA...AND WESTERN NORTH TEXAS.

.DAY ONE...THIS EVENING AND OVERNIGHT...

THUNDERSTORM OUTLOOK...
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TONIGHT ACROSS
PORTIONS OF NORTHERN...AND SOUTHERN OKLAHOMA...AND WESTERN NORTH
TEXAS.

LOCATION...
THERE ARE TWO SLIGHT RISK AREAS. THE FIRST AREA IS WEST OF A LINE
FROM ELK CITY...TO ALTUS...TO ARCHER CITY. THE SECOND AREA IS NORTH
OF A LINE FROM ARNETT...TO WATONGA...TO STILLWATER.

TIMING...
SEVERE THUNDERSTORMS ARE MOST LIKELY BETWEEN 9 PM AND 1 AM...
ACROSS THE SOUTHERN SLIGHT RISK AREA...AND BETWEEN 4 AND 7
AM...ACROSS THE NORTHERN SLIGHT RISK AREA.

IMPACTS...
LARGE HAIL IS THE PRIMARY THREAT.

RECOMMENDED ACTIONS...
STORM SPOTTER GROUPS AND EMERGENCY MANAGEMENT PERSONNEL ACROSS THE
RISK AREA SHOULD BE PREPARED FOR SEVERE WEATHER OPERATIONS.

DISCUSSION...
AS OF EARLY EVENING...SCATTERED THUNDERSTORMS HAD DEVELOPED ACROSS
THE HIGHER TERRAIN OF NEW MEXICO AND THE WESTERN TEXAS PANHANDLE.
THESE THUNDERSTORMS ARE EXPECTED TO CONTINUE MOVING SOUTHEASTWARD
THIS EVENING...AND EXPAND IN AREAL COVERAGE AS THE LOW LEVEL JET
STRENGTHENS. IF THIS TREND CONTINUES...THESE THUNDERSTORMS COULD
MOVE INTO PORTIONS OF SOUTHWEST OKLAHOMA...AND WESTERN NORTH TEXAS
DURING THE MID AND LATE EVENING.

THUNDERSTORMS ARE ALSO EXPECTED TO CONTINUE DEVELOPING THIS EVENING
OVER NEBRASKA...ALONG A COLD FRONT. AS THE FRONT MOVES SOUTHWARD
OVERNIGHT...THUNDERSTORMS DEVELOPING IN THIS AREA WILL ALSO MOVE
SOUTHWARD...AND EXPAND IN AREAL COVERAGE...AS THE LOW LEVEL JET
STRENGTHENS. THESE THUNDERSTORMS COULD MOVE INTO PORTIONS OF
NORTHERN OKLAHOMA LATE IN THE NIGHT.

PROBABILITY TABLE...
VALID THROUGH 700 AM CDT SATURDAY MAY 24.
PROBABILITY OF THUNDERSTORMS OCCURRING IN THE
              NWS NORMAN COUNTY WARNING AREA...60 PERCENT.
PROBABILITY OF SEVERE STORMS IF STORMS OCCUR...40 PERCENT.

OTHER HAZARDOUS WEATHER...
NONE.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY...

THUNDERSTORM OUTLOOK...
A SIMILAR NORTHWEST FLOW WEATHER PATTERN WILL PERSIST THROUGH AT
LEAST SATURDAY...RESULTING IN A CONTINUED CHANCE OF THUNDERSTORMS
AND A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE FORECAST
AREA THROUGH SATURDAY AND SATURDAY NIGHT. OUTFLOW BOUNDARIES FROM
ANY STORMS TONIGHT COULD PROVIDE A FOCUS FOR SEVERE STORM
REDEVELOPMENT IN THE AREA ON SATURDAY AFTERNOON. ADDITIONAL
NIGHTTIME THUNDERSTORM COMPLEXES MAY AFFECT THE AREA SATURDAY
NIGHT...WITH A CONTINUING POSSIBILITY OF SEVERE WEATHER.

OTHER HAZARDOUS WEATHER...
HEAVY RAIN AND POSSIBLE FLOODING WILL BE A CONCERN WITH
THUNDERSTORMS SATURDAY AND SATURDAY NIGHT.

A GRAPHICAL OUTLOOK CAN BE FOUND ON THE WEB AT WWW.SRH.NOAA.GOV/OUN.

JAMES