Areal Flood Warning 21, NWS Fort Worth, TX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
628 AM CDT SUN SEP 13 2009

.AVIATION...
33 OUT OF THE LAST 34 HOURS THERE HAS BEEN SOME SORT OF
PRECIPITATION FALLING FROM THE SKY AT DFW AND THERE LOOKS TO BE NO
END IN SIGHT ON RADAR. LOW PRESSURE SYSTEM RESPONSIBLE FOR THE
GLOOMY WEATHER HASNT MOVED MUCH FROM YESTERDAY...THUS THE PROLONGED
STREAK OF PRECIP. HAVE RAIN PREVAILING IN THE METRO TAFS UNTIL 6Z
TONIGHT. RAIN CHANCES WILL DECREASE FROM SOUTH TO NORTH...AND HAVE
ENDED IT AT 00Z FOR WACO. CIGS AND VIS WILL BOUNCE IN AND OUT OF
LIFR/IFR/MVFR WITH THE PERIODS OF HEAVY RAINFALL. NOT EXPECTING A
WHOLE LOT IN THE WAY OF THUNDER AS INSTABILITY REMAINS WEAK.

85/NH

&&

.PREV DISCUSSION... /ISSUED 539 AM CDT SUN SEP 13 2009/

ONGOING FLOODING ACROSS SOUTHERN PORTIONS OF THE METROPLEX AND
SHORT TERM FORECAST ARE THE PRIMARY FORECAST CONCERNS.

09Z WATER VAPOR IMAGERY DEPICTS CENTER OF LOW PRESSURE SYSTEM WEST
OF MILAM AND FALLS COUNTY. REGIONAL MOSAIC OF DOPPLER RADARS
INDICATES A CYCLONIC SWIRL IN THE LIGHT RAIN SHOWER ACTIVITY OVER
HOPKINS/HUNT/RAINS COUNTIES ASSOCIATED WITH A LOBE OF VORTICITY ON
THE OUTER PERIPHERY OF THE UPPER LOW MOVING SLOWLY NORTHWEST. 09Z
RUC TROPOPAUSE ANALYSIS INDICATES A POTENTIAL VORTICITY ANOMALY
ROTATING NORTHEAST TOWARDS THE SOUTHERN COUNTIES OF NORTH
TX...WHICH SEEMS TO BE PROVIDING THE FORCING FOR ASCENT THAT IS
DRIVING THE ONGOING CONVECTIVE DEVELOPMENT NEAR MILAM AND
ROBERTSON COUNTIES EARLY THIS MORNING. AS THIS VORT LOBE ROTATES
SLOWLY NORTHEAST DURING THE DAY TODAY...EXPECT THAT IT WILL AID IN
THE REGENERATION OF SHOWERS AND ISOLATED THUNDERSTORMS CAPABLE OF
PRODUCING HEAVY RAINFALL OVER MUCH OF THE FORECAST AREA THROUGH
THE AFTERNOON HRS.

PERHAPS MORE IMPORTANTLY...WITH THE CENTER OF THE UPPER LOW
HOLDING OVER SOUTHERN PORTIONS OF THE FORECAST AREA...LOW AND MID
LVL FLOW WILL REMAIN OUT OF THE EAST FOR MUCH OF THE DAYTIME
HRS...KEEPING AN AMPLE SUPPLY OF RICH MOISTURE INTO NORTH TX. KSHV
00Z SOUNDING HAD PWAT VALUE OF 2.20 INCHES WHICH IS HIGHER THAN
THE FWD SOUNDING OF RIGHT AROUND 2 INCHES. WITH A NEARLY SATURATED
TROPOSPHERE ALREADY IN PLACE AND SLIGHTLY HIGHER MOISTURE AMTS TO
THE EAST...DO NOT SEE MUCH HOPE FOR AN END TO RAINFALL UNTIL THE
UPPER LOW MOVES FAR ENOUGH NORTH TO CUT OFF THE EASTERLY TRANSPORT
OF RICH MOISTURE. 00Z GUIDANCE INDICATES THAT THE UPPER LOW WILL
DRIFT SLOWLY NORTH DURING THE DAY TODAY...BRINGING AN END TO
EASTERLY LOW TO MID LEVEL FLOW INTO THE FORECAST AREA DURING THE
EVENING HRS. EXPECT A GRADUAL DECREASE IN THE AMT OF RAINFALL THAT
FALLS AS THIS UPPER LOW MOVES NORTH...HOWEVER MUCH OF THE AREA
WILL LIKELY SEE AT LEAST LIGHT RAIN SHOWER ACTIVITY CONTINUE
THROUGH SUNDAY NIGHT AND POSSIBLY INTO MONDAY MORNING.

WITH LOW LVL FLOW BACKING AROUND TO THE NORTH AFTER 00Z...WILL NOT
EXPAND THE FLASH FLOOD WATCH AT THIS TIME. FEELING IS THAT AS
UPPER MOVES NORTHEAST...HEAVY RAINFALL WILL REMAIN NORTH AND EAST
OF NORTH TX...BUT LATER SHIFTS CAN EVALUATE SHORT TERM TRENDS AND
EXTEND WATCH IF NEEDED. WITH ON AND OFF PERIODS OF HEAVY RAINFALL
EXPECTED TODAY...KEPT TEMPERATURES IN THE MID 70S FOR MOST
LOCATIONS WITH LITTLE DIURNAL CHANGE IN TEMPERATURE EXPECTED
SIMILAR TO YESTERDAY.

MONDAY THROUGH WEDNESDAY...THE UPPER LOW LOOKS TO BE VERY SLOW TO
COMPLETELY EXIT THE REGION TO THE NORTHEAST. WITH THE UPPER LOW
LOOKING TO HOLD OVER EASTERN OK OR INTO AR...WILL SEE BEST
RAINFALL CHANCES OVER THE NORTHERN AND EASTERN PORTIONS OF NORTH
TX DURING THE PERIOD. GRADUALLY DIMINISHED POPS FROM WEST TO EAST
ACROSS THE AREA AS LOW LVL TRAJECTORIES DO BEGIN TO FEED DRIER AIR
INTO NORTH TX. WITH THE UPPER LOW REMAINING CLOSE TO THE FORECAST
AREA WILL LIKELY SEE SOME PIECES OF ENERGY DIVE SOUTH THROUGH THE
PLAINS AND CONTINUE TO GIVE US SOME CHANCE FOR SCATTERED OR
ISOLATED TSTM ACTIVITY. WITH MUCH OF THE FORECAST AREA RECEIVING
AMPLE AMOUNTS OF RAINFALL THIS WEEKEND...ANY BREAKS IN THE CLOUDS
COULD ALSO LEAD TO SOME AFTERNOON ISOLATED/LARGELY UNORGANIZED
TSTM ACTIVITY. WOULD EXPECT WITH NORTHERLY LOW LVL FLOW
TEMPERATURES WILL REMAIN BELOW NORMAL FOR LATE SUMMER...AND KEPT
HIGHS GENERALLY IN THE LOWER TO MID 80S.

THURSDAY THROUGH SUNDAY...ANOTHER UPPER LEVEL LOW PRESSURE SYSTEM
APPROACHES THE SOUTHERN PLAINS FROM THE WESTERN CONUS. GFS/ECMWF
GENERALLY CUT THIS FEATURE OFF AND KEEP IT CENTERED OVER WESTERN
TX OR INTO NEW MEXICO...BUT WITH THIS WEEKENDS UPPER LOW LOOKING
TO HOLD IN THE TN VALLEY...A WEAK DEFORMATION ZONE MAY SET UP OVER
THE SOUTHERN PLAINS DURING THE PERIOD. MEDIUM RANGE GUIDANCE ATM
INDICATES MUCH DRIER AIRMASS IN PLACE...SO WEAK FORCING FOR ASCENT
MAY NOT CAUSE MUCH MORE THAN MID TO HIGH LEVEL CLOUDINESS...BUT
THIS IS SOMETHING TO KEEP AN EYE ON AS THIS PERIOD APPROACHES. FOR
NOW JUST KEPT POPS AROUND 10 PERCENT...ALTHOUGH WOULD ANTICIPATE
ANY RAIN SHOWER OR TSTM ACTIVITY WOULD OCCUR DURING AFTERNOON HRS
WHERE WEAK FORCING MAY TAKE ADVANTAGE OF PEAK HEATING HRS TO
DEVELOP SOME CONVECTION AROUND THE AREA. EXPECT TEMPERATURES TO
REMAIN JUST BELOW NORMAL WITH WEAK NORTHERLY FLOW EXPECTED TO
CONTINUE.

CAVANAUGH

&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  75  68  78  68  81 /  90  60  40  30  30
WACO, TX              78  67  79  68  83 /  70  50  30  30  30
PARIS, TX             75  66  79  65  81 /  90  60  60  40  40
DENTON, TX            75  66  77  65  81 /  90  60  40  30  30
MCKINNEY, TX          75  68  76  66  80 /  90  60  50  30  30
DALLAS, TX            75  69  77  69  81 /  90  60  40  30  30
TERRELL, TX           76  68  77  67  81 /  80  60  50  30  30
CORSICANA, TX         79  67  78  67  81 /  70  60  40  30  40
TEMPLE, TX            79  67  80  66  84 /  70  30  30  20  30

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH THIS EVENING FOR TXZ091>095-100>107-
115>123-129>135-141>148-156>162-174-175.

&&

85/69

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FORT WORTH TX
502 AM CDT SUN SEP 13 2009

TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175-141100-
MONTAGUE-COOKE-GRAYSON-FANNIN-LAMAR-YOUNG-JACK-WISE-DENTON-COLLIN-
HUNT-DELTA-HOPKINS-STEPHENS-PALO PINTO-PARKER-TARRANT-DALLAS-
ROCKWALL-KAUFMAN-VAN ZANDT-RAINS-EASTLAND-ERATH-HOOD-SOMERVELL-
JOHNSON-ELLIS-HENDERSON-COMANCHE-MILLS-HAMILTON-BOSQUE-HILL-NAVARRO-
FREESTONE-ANDERSON-LAMPASAS-CORYELL-BELL-MCLENNAN-FALLS-LIMESTONE-
LEON-MILAM-ROBERTSON-
502 AM CDT SUN SEP 13 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH TEXAS.

.DAY ONE...TODAY AND TONIGHT.

A FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH THIS EVENING.

SHOWERS WITH ISOLATED THUNDERSTORMS CONTAINING HEAVIER RAINFALL
ARE EXPECTED TO CONTINUE OFF AND ON ACROSS ALL OF NORTH TEXAS
TODAY. RAINFALL AMOUNTS BETWEEN 1 AND 2 INCHES WILL OCCUR WITH
MOST ACTIVITY...HOWEVER LOCALIZED AMOUNTS UP TO 4 INCHES WILL BE
POSSIBLE MAINLY NORTH OF INTERSTATE 20 WHERE THE HIGHEST CHANCE
FOR LOCALIZED FLASH FLOODING WILL OCCUR.

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

RAINFALL CHANCES WILL BEGIN TO DECREASE MONDAY WITH ONLY A CHANCE OF
A SHOWER OR THUNDERSTORM BY WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

85/NH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FORT WORTH TX
340 AM CDT SUN SEP 13 2009

..TIME..    ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE..    ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0339 AM     FLASH FLOOD      ROCKDALE                30.65N  97.00W
09/13/2009                   MILAM              TX   LAW ENFORCEMENT

            WIDESPREAD FLOODING IN THE CITY OF ROCKDALE. NUMEROUS
            STREETS CLOSED AND HIGHWAY 79 IS CLOSED WEST OF ROCKDALE.

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FORT WORTH TX
546 AM CDT SUN SEP 13 2009

..TIME..    ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE..    ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0530 AM     FLASH FLOOD      GRAND PRAIRIE           32.75N  96.98W
09/13/2009                   DALLAS             TX   LAW ENFORCEMENT

            WATER OVER ROAD AT CARRIER AND 161...CARRIER AND JEN
            MCFALLS...CARRIER AND DICKEY AS WELL AS OTHER MAJOR ROADS

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