Flash Flood Warning 16, NWS Norman, OK

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE NORMAN OK
947 PM CDT SAT AUG 13 2005

.UPDATE...
SHWRS/TSTMS WILL CONT OVERNITE. HOWEVER WITH THE LOSS OF
HEATING... THE SEVERE POTENTIAL IS VERY LOW. LOCALLY HEAVY
RAINFALL WILL BE THE MAIN CONCERN. HAVE ADJUSTED POPS AND ADDED
HEAVY RAIN WORDING. HAVE ALSO DECREASED TEMPS IN SEVERAL LOCATIONS
THAT THE FORECASTED MIN WAS AT OR ABOVE CURRENT TEMPS WHICH HAVE
DECREASED RAPIDLY DUE TO RAIN COOLED AIR. TWEAKED HOURLY GRIDS AND
SKY COVER TO SHOW CURRENT TRENDS. WILL SEND UPDATE SHORTLY.

MAXWELL

&&

.PREV DISCUSSION... (ISSUED 258 PM CDT SAT AUG 13 2005)

DISCUSSION...
TONIGHT THROUGH MONDAY - THINGS GOING MUCH ACCORDING TO PLAN
OVERALL...AT LEAST IN TERMS OF LARGER-SCALE FEATURES. MUCH-NEEDED
RAINFALL ON TAP FOR A LARGE PART OF THE CWA. SFC FRONT CURRENTLY
ACROSS NW OK WILL MOVE SE TONIGHT...BUT EVENTUAL POSITION OF
EFFECTIVE SFC BOUNDARY WILL LIKELY BE REDIRECTED BY EFFECTS OF
CONVECTION. STORMS AT THE MOMENT ARE BEHAVING MORE OR LESS AS
EXPECTED...MORE NUMEROUS CLOSER TO FRONTAL CONVERGENCE ZONE OVER NW
OK...AND THIS SHOULD BE THE CASE FOR THE NEXT COUPLE DAYS WITH
RAIN/SHOWERS/TSTORMS MORE NUMEROUS NEAR AND N OF THE SFC BOUNDARY.
POPS ARE RAISED AND EXPANDED BASED ON LATEST MODEL QPFS...BUT STILL
FIND IT HARD TO GO MUCH OVER 70PCT LOCALLY DUE TO PREVAILING
CONVECTIVE NATURE OF THE PRECIP. EXCEPTION IS TONIGHT ACROSS N OK
WHERE MODELS HAVE BEEN MOST CONSISTENT IN PAINTING HEAVIER
AMOUNTS...WHICH ARE SUPPORTED BY ONGOING ACTIVITY AND WARRANT A
SRIPE OF CATEGORICAL POPS THAT FITS IN WELL WITH NEIGHBORING GRIDS.
12Z ETA RUN-TOTAL QPF CONTINUES TO DEPICT WIDESPREAD 1-3 INCH TOTALS
BY LATE MON ACROSS THE NW HALF OF OK...SUPPORTED BY POOLING OF
MOISTURE AND PRECIPITABLE H20 VALUES OVER 2 INCHES. WILL CONTINUE TO
MENTION LOCALLY HEAVY RAIN...WHICH SHOULD BE SOAKED UP WELL IN MOST
AREAS DUE TO RECENT DRY WX BUT STILL COULD CAUSE LOCALIZED DRAINAGE
PROBLEMS WHEREVER TRAINING RESULTS IN TOO MUCH RAIN TOO FAST. TEMPS
MAY BE THE TOUGHEST PART OF THIS FCST AS CLOUDS AND PRECIP ARE
LIKELY TO HOLD SOME AREAS IN THE 70S FOR HIGHS. ALTHOUGH EFFECTIVE
FRONT REMAINS LIKELY TO SAG S TO NEAR THE RED RIVER BY SUN
NIGHT...ETA LIFTS IT BACK N INTO CENTRAL OK ROUGHLY NEAR I-40 ON MON
AND SHIFTS THE PRECIP AXIS UP INTO N OK. HARD TO SEE THIS HAPPENING
IF CONVECTION PERSISTS N OF THE FRONT...BUT FOR NOW WILL KEEP MUCH
OF OUR S/SE IN CHANCE-TYPE POPS ON MONDAY.

TUE THROUGH SAT - GRADUAL DECREASE IN POPS AND INCREASE IN DAYTIME
HIGHS THRU THU AS FRONTAL ZONE WEAKENS AND LEE TROFING BRINGS BACK A
MORE GENERAL S WIND AT LOW LEVELS. NEW CHALLENGE FOR LATE WEEK IS
ARRIVAL OF ANOTHER COLD FRONT...AS ALLUDED TO YESTERDAY BY THE
ECMWF. MOST OF THE OTHER MODELS HAVE NOW TRENDED THIS WAY...BUT
SPECIFIC DETAILS STILL VARY QUITE A BIT FROM MODEL TO MODEL AND RUN
TO RUN. THERE IS ENOUGH AGREEMENT IN GENERAL TO BACK OFF ON TEMPS
AND CONTINUE WITH SOME LOW POPS BEGINNING THU NIGHT AND CONTINUING
INTO DAY 7/SATURDAY. GFS WOULD SUPPORT EVEN HIGHER POPS AND COOLER
MAXES ON FRI-SAT THAN WE HAVE...BUT WOULD RATHER BEGIN A TREND AT
THIS POINT AND NOT MAKE DRASTIC CHANGES THAT FAR OUT.

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&

25/02

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NORMAN OK
1155 AM CDT SAT AUG 13 2005

OKZ004>048-050>052-TXZ083>090-141200-

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

.DAY ONE...THIS AFTERNOON AND TONIGHT...

THUNDERSTORM OUTLOOK...
STRONG THUNDERSTORMS ARE POSSIBLE...BUT NO ORGANIZED AREAS OF SEVERE
THUNDERSTORMS ARE EXPECTED THROUGH TONIGHT.

DISCUSSION...
SOUTH WINDS IN THE LOW LEVELS OF THE ATMOSPHERE CONTINUE TO
TRANSPORT MOIST AIR INTO THE AREA. THIS MOISTURE COMBINED WITH
NUMEROUS OUTFLOW BOUNDARIES PRODUCED BY THUNDERSTORMS OVERNIGHT AND
THIS MORNING ALONG WITH WARM AFTERNOON TEMPERATURES WILL AID IN
ADDITIONAL THUNDERSTORM DEVELOPMENT THIS AFTERNOON.  A COLD FRONT
WILL MOVE INTO NORTHERN OKLAHOMA THIS EVENING...PROVIDING ANOTHER
FOCUS FOR CONTINUED THUNDERSTORM DEVELOPMENT OVERNIGHT.

THE ATMOSPHERE WILL BE MARGINALLY SUPPORTIVE OF STRONG THUNDERSTORMS
THIS AFTERNOON AND EVENING... ALTHOUGH ORGANIZED SEVERE WEATHER IS
NOT ANTICIPATED.

PROBABILITY TABLE...
VALID THROUGH 700 AM CDT SUNDAY AUG 14.
PROBABILITY OF THUNDERSTORMS OCCURRING IN THE
              NWS NORMAN COUNTY WARNING AREA...100 PERCENT.
PROBABILITY OF SEVERE STORMS IF STORMS OCCUR...30 PERCENT.

OTHER HAZARDOUS WEATHER...
LOCALLY HEAVY RAINFALL WILL BE POSSIBLE THIS AFTERNOON AND
TONIGHT... ESPECIALLY NEAR THE COLD FRONT THAT WILL MOVE INTO
NORTHERN OKLAHOMA.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY...

THUNDERSTORM OUTLOOK...
THUNDERSTORMS REMAIN LIKELY SUNDAY AND SUNDAY NIGHT...WITH AT LEAST
SLIGHT CHANCES OF THUNDERSTORMS CONTINUING IN THE FORECAST THROUGH
WEDNESDAY... AND AGAIN LATE NEXT WEEK.

OTHER HAZARDOUS WEATHER...
THE POSSIBILITY OF LOCALLY HEAVY RAINFALL AND POTENTIAL FLASH
FLOODING WILL CONTINUE INTO MONDAY.

THE NEXT SCHEDULED HAZARDOUS WEATHER OUTLOOK WILL BE ISSUED AT 7 AM
SUNDAY.