Flash Flood Warning 28, NWS Norman, OK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
406 AM CDT MON AUG 11 2008

.DISCUSSION...
CONVECTION INCREASING THIS MORNING ACROSS MUCH OF OK IN AREA OF
ENHANCED LOW-LEVEL WARM ADVECTION N OF SFC LOW AND FRONT ACROSS N
TX. HEAVY RAINFALL POSSIBLE WITHIN VERY MOIST AIRMASS... ESPECIALLY
NE OF THE SFC LOW WHERE LLJ WILL CONTINUE TO ENHANCE WAA/LOW LEVEL
FORCING INTO THE MORNING. MID-LEVEL SHORTWAVE MOVING ESE OUT OF
CO/NM LIKELY TO KEEP CONVECTION GOING AT SOME LEVEL THROUGH THE
DAY. FURTHER ENHANCEMENT LIKELY TO RESULT IN MORE WIDESPREAD/
CONCENTRATED CONVECTION OVER SE OK TONIGHT AS LLJ RESTRENGTHENS.
PW VALUES PROGGED AOA 2.5 INCHES N OF NEARLY-STATIONARY FRONT
ACROSS NE TX AND ARKLATEX TONIGHT. SETUP SUGGESTS A POSSIBLE
FRONTAL-TYPE FLASH FLOOD EVENT FROM SE OK ACROSS ARKLATEX AND
EASTWARD. WE WILL INCLUDE MENTION OF POTENTIAL HEAVY RAIN... AND
MONITOR FOR POSSIBLE NEED FOR A FLOOD WATCH OF SOME KIND. PRECIP
EXPECTED TO SHUT DOWN NW TO SE TONIGHT INTO TUE MORNING WITH
PASSAGE OF THE UPPER TROUGH. DEEP LAYER OF HIGH RH PROGGED TO
PERSIST OVER THE AREA RESULTING IN WIDESPREAD CLOUDS AND
UNSEASONABLY LOW DAYTIME TEMPS OVER MUCH OF THE AREA.

TREND WILL BE TOWARD WARMER/DRIER TUE-WED AS UPPER FLOW VEERS TO
MORE NNW. STILL WILL NEED TO WATCH FOR CONVECTION DEVELOPING OVER
HIGH PLAINS AND TURNING/ROLLING SE-S OVERNIGHT DURING THIS TIME.
TUESDAY NIGHT LOOKS RELATIVELY SAFE WITH RIDGING UPSTREAM AND MID-
LEVEL WINDS VEERED ALMOST TO NORTHERLY. BUT THERE IS STILL ENOUGH
OF A SIGNAL IN THE MODELS TO SUGGEST SOMETHING GETTING INTO OUR W
ZONES WED NIGHT INTO EARLY THU. GFS-MOS POPS REFLECT THIS AND
WILL BE FOLLOWED.

INTERESTING DEVELOPMENTS MAY BE IN STORE LATE IN THE WEEK AS THE
UPPER LOW NOW OVER ALBERTA TURNS S AND DIVES INTO/THROUGH THE
PLAINS. LATEST MODELS ARE ALL FAIRLY CONSISTENT - OR AT LEAST A
BIT MORE THAN THEY HAVE BEEN LATELY - IN BRINGING A CLOSED LOW AS
FAR S AS THE CENTRAL PLAINS BY THE END OF THE WEEK. SOUTHWARD
MIGRATION OF THIS SYSTEM SHOULD SUPPORT A FAIRLY STRONG LATE-
SUMMER OR EARLY-FALL TYPE FRONT INTO THE S PLAINS AROUND THURSDAY
NIGHT AND FRIDAY. SOUTH WINDS AT 850MB PROGGED TO INCREASE TO
30-40 KT AS COLD FRONT PUSHES INTO OK THU NIGHT. W-NW WINDS ALSO
STRENGTHEN TO 30-40 KT OR MORE AT AND ABOVE 500MB... SETTING UP
FAVORABLE DEEP-LAYER SHEAR FOR WIDESPREAD, ORGANIZED STRONG
CONVECTION WITH THE FRONT AS IT ENCOUNTERS INCREASING MOISTURE/
INSTABILITY. WE WILL INCREASE WHAT GUIDANCE IS GIVING US ON POPS
THU NIGHT INTO FRIDAY... AND IN FACT INCREASE THEM ON INTO
SATURDAY AS THERE ARE SIGHNS THE UPPER SYSTEM MAY REMAIN NEAR THE
AREA FOR AN EXTENDED PERIOD. TEMPS WILL BE TRENDED TOWARD THE LOW
END OF THE MEX ENSEMBLE GUIDANCE... AND EVEN THEY MAY BE TOO WARM
IF THE UPPER LOW PARKS OVER OR NEAR THE AREA. 24

&&

.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK  82  65  89  68 /  60  20  10  10
HOBART OK         85  66  92  71 /  40  20  10  10
WICHITA FALLS TX  86  69  94  71 /  60  30  10  10
GAGE OK           85  62  90  65 /  30  20  10  10
PONCA CITY OK     78  63  87  66 /  50  20  10  10
DURANT OK         81  68  86  68 /  80  60  20  10

&&

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

30/24

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE NORMAN OK
1025 PM CDT SUN AUG 10 2008

OKZ004>048-050>052-TXZ083>090-111200-
HARPER-WOODS-ALFALFA-GRANT-KAY-ELLIS-WOODWARD-MAJOR-GARFIELD-NOBLE-
ROGER MILLS-DEWEY-CUSTER-BLAINE-KINGFISHER-LOGAN-PAYNE-BECKHAM-
WASHITA-CADDO-CANADIAN-OKLAHOMA-LINCOLN-GRADY-MCCLAIN-CLEVELAND-
POTTAWATOMIE-SEMINOLE-HUGHES-HARMON-GREER-KIOWA-JACKSON-TILLMAN-
COMANCHE-STEPHENS-GARVIN-MURRAY-PONTOTOC-COAL-COTTON-JEFFERSON-
CARTER-JOHNSTON-ATOKA-LOVE-MARSHALL-BRYAN-HARDEMAN-FOARD-WILBARGER-
WICHITA-KNOX-BAYLOR-ARCHER-CLAY-
1025 PM CDT SUN AUG 10 2008

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

.DAY ONE...TONIGHT...

THUNDERSTORM OUTLOOK...
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO CONTINUE DURING THE NIGHT
ACROSS PARTS OF OKLAHOMA AND WESTERN NORTH TEXAS. HOWEVER... NO
SEVERE THUNDERSTORMS ARE EXPECTED.

DISCUSSION...
SHOWERS AND THUNDERSTORMS WILL CONTINUE OVERNIGHT WITH THE BEST
CHANCES BEING ACROSS SOUTHERN OKLAHOMA AND PARTS OF WESTERN NORTH
TEXAS. SHOWER AND THUNDERSTORM CHANCES WILL DECREASE AS YOU GO NORTH
FROM CENTRAL OKLAHOMA TO THE KANSAS BORDER. INCREASING SOUTHWEST
WINDS DURING THE NIGHT IS EXPECTED TO CONTINUE TO SUPPORT ONGOING
SHOWER AND THUNDERSTORM ACTIVITY ACROSS MAINLY SOUTHERN OKLAHOMA.
HOWEVER... INSTABILITIES AND VERTICAL WIND PROFILES ARE EXPECTED TO
BE INSUFFICIENT TO SUPPORT SEVERE STORMS. SINCE THE AIRMASS ACROSS
THE REGION IS VERY MOIST... SOME OF THE SHOWERS AND THUNDERSTORMS
COULD PRODUCE LOCALLY HEAVY RAINS... MAINLY ACROSS PARTS OF SOUTH
CENTRAL AND SOUTHEAST OKLAHOMA. SHOULD A LOW LEVEL BOUNDARY BECOME
ESTABLISHED OVERNIGHT AND FOCUS HEAVY RAINS IN A SMALLER AREA... THE
POSSIBILITY OF LOCALIZED FLOODING WOULD INCREASE.

PROBABILITY TABLE...
VALID THROUGH 700 AM CDT MONDAY AUG 11.
PROBABILITY OF THUNDERSTORMS OCCURRING IN THE
              NWS NORMAN COUNTY WARNING AREA...100 PERCENT.
PROBABILITY OF SEVERE STORMS IF STORMS OCCUR...10 PERCENT.

OTHER HAZARDOUS WEATHER...
NONE.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY...

THUNDERSTORM OUTLOOK...
THUNDERSTORM CHANCES WILL CONTINUE MONDAY AND MONDAY NIGHT AS A
STATIONARY REMAINS JUST SOUTH OF THE AREA. MEANWHILE... NORTHWEST
WINDS ALOFT WILL CONTINUE TO STEER DISTURBANCES ACROSS THE CENTRAL
AND SOUTHERN PLAINS FROM THE CENTRAL ROCKIES. THUNDERSTORM CHANCES
WILL RETURN ON WEDNESDAY AND CONTINUE INTO NEXT WEEKEND.

OTHER HAZARDOUS WEATHER...
NONE.

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

CJS

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NORMAN OK
253 AM CDT MON AUG 11 2008

OKZ024>026-030>032-110845-
LINCOLN OK-CANADIAN OK-OKLAHOMA OK-POTTAWATOMIE OK-SEMINOLE OK-
HUGHES OK-
253 AM CDT MON AUG 11 2008

...SIGNIFICANT WEATHER ADVISORY...

THIS SIGNIFICANT WEATHER ADVISORY IS FOR CANADIAN...HUGHES...
LINCOLN...OKLAHOMA...POTTAWATOMIE AND SEMINOLE COUNTIES.

AN AREA OF STRONG THUNDERSTORMS WAS LOCATED FROM THE OKLAHOMA CITY
METRO SOUTHEAST TO SHAWNEE... SEMINOLE AND HOLDENVILLE AT 253 AM
CDT...MOVING EAST AT 10 TO 15 MPH. THESE STORMS WILL PRODUCE VERY
HEAVY RAINFALL... WHICH WILL CAUSE SOME MINOR LOCALIZED FLOODING...
AS WELL AS PONDING ON AREA ROADWAYS AND REDUCED VISIBILITIES...
MAKING FOR TREACHEROUS DRIVING CONDITIONS.

PEOPLE IN CANADIAN...HUGHES...LINCOLN...OKLAHOMA...POTTAWATOMIE AND
SEMINOLE COUNTIES...INCLUDING THE CITIES OF DEL
CITY...EDMOND...MIDWEST CITY...OKLAHOMA CITY AND SHAWNEE...SHOULD
MONITOR THE WEATHER SITUATION CLOSELY. LISTEN FOR WARNINGS AND
REMAIN ALERT FOR THREATENING WEATHER CONDITIONS.