Severe Thunderstorm Warning 245, NWS Norman, OK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
235 PM CDT MON MAY 27 2002

UPPER LOW EXPECTED TO DRIFT SLOWLY OVER THE AREA TONIGHT...THEN
PERHAPS STALL. ALTHOUGH THE LOCAL AIRMASS REMAINS MOIST WITH
PRECIPITABLE WATER NEAR 1.5 INCHES AND MODEST LIFT OCCURRING...THE
LACK OF WIDESPREAD ANTECEDENT RAINFALL AND IDENTIFIABLE LOW LEVEL
BOUNDARIES MAKES THE TASK OF CONFIDENTLY DETERMINING AREAS MOST
LIKELY TO EXPERIENCE FLASH FLOODING PROBLEMS TONIGHT/TUESDAY VERY
DIFFICULT. OTHER THAN ISOLATED LOCATIONS WITHIN THE AREA THAT HAVE
RECEIVED SEVERAL INCHES OF RAIN THIS WEEK...MOST OF THE AREA HAS
EXPERIENCED WELL BELOW NORMAL RAIN FOR THE LAST MONTH. BELIEVE
MOST AREAS CAN ABSORB ANOTHER SEVERAL INCHES OF RAIN BEFORE THE RISK
OF FLASH FLOODING BECOMES SIGNIFICANT. THIS MAY VERY WELL OCCUR
OVERNIGHT BUT THE HIGH AMOUNTS MAY BE SO ISOLATED THAT ISSUING A
FLASH FLOOD WATCH FOR THE ENTIRE AREA OR AT LEAST A LARGE PART OF IT
SEEMS LESS APPROPRIATE THAN SIMPLY HIGHLIGHTING LOCALLY HEAVY RAIN
IN THE ZONES AND DEFERRING THE FLASH FLOOD WATCH DECISION UNTIL THIS
EVENING/OVERNIGHT WHEN THE POTENTIAL BECOMES MORE CLEAR.

BELIEVE 80 POPS OR HIGHER ARE NEEDED BOTH TONIGHT/TUESDAY BEFORE
RAIN CHANCES SLOWLY DIMINISH OVER WESTERN AREAS TUESDAY
NIGHT/WEDNESDAY AND FINALLY OVER SOUTHEAST OKLAHOMA THURSDAY NIGHT.
MEDIUM RANGE MODELS SUGGEST A VARIETY OF LONG WAVE PATTERNS MAY
INFLUENCE THE AREA BY NEXT WEEKEND AND EARLY NEXT WEEK...BUT THERE
APPEARS TO BE SOME AGREEMENT THAT AN EAST COAST/WEST COAST TROUGH
WILL FORM WITH A RIDGE OVER THE CENTRAL US. THIS SUPPORTS A DRY
FORECAST FOR THE WEEKEND EXCEPT FOR LATE SUNDAY OVER WEST
CENTRAL/NORTHWEST OKLAHOMA WHICH COULD EXPERIENCE THUNDERSTORMS
ADVECTING EAST FROM A TEXAS PANHANDLE DRYLINE. NOT CONFIDENT THE
PATTERN WILL PERSIST HOWEVER WITH THE POTENTIAL FOR EASTWARD
MOVEMENT OF THE WEST COAST TROUGH. THIS TROUGH MOVEMENT AND
CLIMATOLOGY SUPPORT SLIGHT CHANCE POPS FOR THE AREA NEXT MONDAY.

OKC   65  71  65  73 /  80  80  70  40
HBR   64  72  62  83 /  80  80  70  30
SPS   65  71  63  79 /  80  80  70  40
GAG   63  74  61  86 /  80  80  40  20
PNC   65  71  65  73 /  80  80  70  40
DUA   66  71  66  71 /  80  80  70  60

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

OKZ004>048-050>052-TXZ083>090-281830-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NORMAN OK
1200 PM CDT MON MAY 27 2002

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

LOCATION...
THE SLIGHT RISK AREA INCLUDES ALL OF WESTERN AND CENTRAL OKLAHOMA
AND WESTERN NORTH TEXAS.

TIMING...
STORMS SCATTERED THROUGHOUT THE AREA THIS AFTERNOON WILL BE CAPABLE
OF PRODUCING HAIL GREATER THAN 1 INCH DIAMETER AND HEAVY RAINFALL.
LARGER HAIL AND SLOW-MOVING...HEAVY RAIN PRODUCING STORMS ARE MORE
LIKELY LATE THIS AFTERNOON AND THROUGH THE EVENING.

IMPACTS...
HAIL UP TO 2 INCHES DIAMETER ALONG WITH HEAVY RAINFALL WILL BE THE
MAIN THREATS THROUGH TONIGHT.

RECOMMENDED ACTIONS...
STORM SPOTTER GROUPS AND EMERGENCY MANAGEMENT PERSONNEL ACROSS THE
RISK AREA SHOULD PLAN FOR SEVERE WEATHER OPERATIONS LATE THIS
AFTERNOON AND EVENING.

DISCUSSION...
ADDITIONAL STORMS WILL LIKELY FORM IN THE EASTERN TEXAS PANHANDLE
LATER THIS AFTERNOON WHERE CLOUDS HAVE DISSIPATED AND A SURFACE
BOUNDARY EXISTS FROM STORMS EARLIER THIS MORNING. THE SLOW EAST MOVEMENT OF
THE UPPER LOW ACROSS NORTHEAST NEW MEXICO AND THE NORTHERN TEXAS
PANHANDLE WILL GRADUALLY SHIFT STORM DEVELOPMENT/MOVEMENT INTO
WESTERN OKLAHOMA THIS EVENING.

THREAT TABLE...
VALID THROUGH 700 AM CDT TUE MAY 28.
PROBABILITY OF THUNDERSTORMS OCCURRING IN THE
              NWS NORMAN COUNTY WARNING AREA...100 PERCENT.
PROBABILITY OF SEVERE STORMS IF STORMS OCCUR...60 PERCENT.

OTHER HAZARDOUS WEATHER...
ASIDE FROM THE SEVERE WEATHER THREAT AND HEAVY RAINFALL POTENTIAL...NO OTHER
HAZARDOUS WEATHER IS EXPECTED THROUGH TONIGHT.