Tornado Warning 43, NWS Fort Worth, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
315 PM CDT SAT OCT 23 2010

.DISCUSSION...

AT FORECAST TIME A WELL DEFINED OUTFLOW BOUNDARY WAS LOCATED FROM
ROUGHLY THE CITY OF DALLAS SOUTHWESTWARD TO JUST NORTH OF
GOLDTHWAITE. 1930Z WATER VAPOR IMAGERY INDICATED THAT THE BASE OF
A SHORTWAVE TROUGH WAS ROTATING NORTHEAST MOVING TOWARDS AREAS
JUST SOUTH OF WACO.  LARGE SCALE FORCING FOR ASCENT WAS AIDING IN
THE DEVELOPMENT OF WIDESPREAD THUNDERSTORMS OVER MUCH OF NORTH
TEXAS THIS AFTERNOON. FOR THE REMAINDER OF THE AFTERNOON...THE
BIGGEST SEVERE THUNDERSTORM THREAT WOULD APPEAR TO EXIST FOR AREAS
SOUTHEAST OF THE CURRENT LOCATION OF THE OUTFLOW
BOUNDARY...GENERALLY SOUTHEAST OF A DALLAS TO GOLDTHWAITE LINE.
LOCALLY CALCULATED ENVIRONMENTAL PARAMETERS INDICATE THAT THIS
ENVIRONMENT IS CHARACTERIZED BY 1500 J/KG OF MIXED LAYER CAPE...50
KTS OF 0-6 KM BULK SHEAR AND 30 KTS OF 0-1 KM BULK SHEAR. BETWEEN
THE STRONG FORCING FOR ASCENT ASSOCIATED WITH THE SHORTWAVE TROUGH
AND OUT AHEAD OF THE OUTFLOW BOUNDARY THINKING IS THAT STORM MODE
WILL BE LARGELY QUASI-LINEAR. THE CAPE AND SHEAR PARAMETERS
COMBINED SUGGEST THAT SUPERCELL STRUCTURES WILL LIKELY BE EMBEDDED
WITHIN THESE QUASI-LINEAR STRUCTURES. DAMAGING OUTFLOW WINDS AND
LARGE HAIL ARE THE PRIMARY SEVERE WEATHER HAZARDS...HOWEVER
TORNADOES ARE POSSIBLE THRU THE EARLY EVENING HOURS AS WELL.

TORNADO POTENTIAL...SOUTHEAST OF THE OUTFLOW BOUNDARY THE LARGE
SCALE FORCING FOR ASCENT HAS CAUSED PRESSURE FALLS ON THE ORDER OF
1 MB/HR. WINDS HAD BACKED A BIT WHERE PRESSURE FALLS WERE
OCCURRING WHICH WAS BRINGING 0-1 KM STORM RELATIVE HELICITY VALUES
UP ABOVE 300 M2/S2. WITH SOME BREAKS IN THE CLOUD COVER 0-3 KM
CAPE VALUES HAVE CLIMBED TO NEAR 100 J/KG OVER THE SAME AREA.
THINKING IS THAT STORMS THAT DEVELOP SOUTHEAST OF THE OUTFLOW
BOUNDARY AND CAN REMAIN DISCRETE THE LONGEST WILL BE THE MOST
LIKELY TO PRODUCE TORNADOES THROUGH THIS EVENING. ANY QLCS
ACTIVITY MAY ALSO PRODUCE BRIEF TORNADOES IN THIS HIGHLY SHEARED
LOW LEVEL ENVIRONMENT.

FLASH FLOODING POTENTIAL...PWATS HAVE CLIMBED TO NEAR 1.5 INCHES
ACROSS MUCH OF THE FORECAST AREA. WHILE THE REGION HAS BEEN WELL
BELOW NORMAL IN TERMS OF PRECIPITATION FOR THE MONTH OF
OCTOBER...RAINFALL RATES OF 1.5 TO 2 INCHES PER HOUR REMAIN
POSSIBLE THRU LATE THIS EVENING. ANY LOCATIONS THAT SEE MULTIPLE
ROUNDS OF THUNDERSTORMS WILL LIKELY SEE SOME LOCALIZED FLOODING
PROBLEMS.

TONIGHT...LATE THIS EVENING THE SHORTWAVE TROUGH IS EXPECTED TO
MOVE NORTHEAST INTO EASTERN OK SPREADING LARGE SCALE FORCING FOR
SUBSIDENCE OVER NORTH TX. THE LOSS OF DAYTIME HEATING COUPLED WITH
FORCING FOR SUBSIDENCE IS EXPECTED TO BRING A QUICK END TO TSTM
ACTIVITY A FEW HRS AFTER SUNSET.

SUNDAY...A STRONG SHORTWAVE TROUGH CURRENTLY MOVING SOUTHEAST
THRU NV IS EXPECTED TO MOVE INTO THE SOUTHERN PLAINS SUNDAY
AFTERNOON. THE REMNANT OUTFLOW BOUNDARY AND DRYLINE ARE EXPECTED
TO BE DRAPED OVER THE CWA TOMORROW AFTERNOON. THE LATEST MODEL
CONSENSUS HAS THIS BOUNDARY EXTENDING FROM A SHERMAN TO DFW TO
HAMILTON LINE AT 18Z EARLY SUNDAY AFTERNOON. ASSUMING THIS
BOUNDARY POSITION IS ACCURATE WE WILL LIKELY SEE ANOTHER ROUND OF
STRONG THUNDERSTORMS DEVELOP SUNDAY AFTERNOON. CAPE VALUES ARE
ONCE AGAIN EXPECTED TO CLIMB TO 1500 J/GK WHILE DEEP LAYER SHEAR
VALUES REMAIN AROUND 50 TO 55 KTS. ONCE AGAIN SUPERCELL
THUNDERSTORMS WILL BE POSSIBLE IN THIS ENVIRONMENT. LARGE HAIL MAY
BE A BIGGER THREAT TOMORROW AFTERNOON AS MID LEVEL LAPSE RATES
LOOK TO BE STEEPER THAN THEY ARE TODAY. THE NEAR SURFACE WINDS
APPEAR TO BE SLIGHTLY WEAKER AND MORE VEERED ALONG THE FRONT
TOMORROW...SO THE TORNADO THREAT MAY BE A BIT LOWER...HOWEVER
ISOLATED TORNADOES WILL REMAIN POSSIBLE.

THE REMAINDER OF THE FORECAST REMAINS LARGELY UNCHANGED AT THIS
TIME WITH THE FOCUS OF THE FORECAST PACKAGE ON THE NEXT 24 TO 48
HRS.

CAVANAUGH

&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  65  84  63  88  59 /  60  20  20   5  10
WACO, TX              67  86  64  88  63 /  50  30  30   5  10
PARIS, TX             64  83  62  83  59 /  60  40  40  10  20
DENTON, TX            64  84  59  87  56 /  50  20  10   5  10
MCKINNEY, TX          65  84  60  86  56 /  60  30  30  10  20
DALLAS, TX            66  84  62  87  60 /  60  30  20  10  10
TERRELL, TX           67  84  64  86  62 /  60  40  30  10  10
CORSICANA, TX         67  84  65  85  64 /  60  40  40   5  10
TEMPLE, TX            67  85  63  88  63 /  50  30  30   5  10
MINERAL WELLS, TX     60  85  54  90  53 /  20  10  10   5  10

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FORT WORTH TX
401 PM CDT SAT OCT 23 2010

TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175-241115-
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-
401 PM CDT SAT OCT 23 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH TEXAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT.
NUMEROUS THUNDERSTORMS WILL AFFECT NORTH TEXAS LATE THIS AFTERNOON
AND EVENING. SEVERE THUNDERSTORMS WITH LARGE HAIL AND DAMAGING
WINDS WILL BE POSSIBLE...PRIMARILY EAST OF THE I-35 CORRIDOR.
ISOLATED TORNADOES MAY ALSO OCCUR...AND VERY HEAVY RAIN MAY CAUSE
FLASH FLOODING. THUNDERSTORM COVERAGE AND INTENSITY WILL DIMINISH
FROM WEST TO EAST THIS EVENING...BUT SOME STORMS MAY LINGER IN
EAST TEXAS AFTER MIDNIGHT.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.
SEVERE THUNDERSTORMS WILL BE POSSIBLE ON SUNDAY...MAINLY EAST OF
THE I-35 CORRIDOR. LARGE HAIL...DAMAGING WINDS...AND ISOLATED
TORNADOES WILL BE POSSIBLE.

WIDELY SCATTERED THUNDERSTORMS ARE EXPECTED ACROSS NORTHEAST TEXAS
MONDAY NIGHT AS A COLD FRONT MOVES THROUGH THE AREA. SEVERE
WEATHER IS NOT EXPECTED.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION WILL LIKELY BE REQUESTED THIS AFTERNOON AND
EVENING...PARTICULARLY EAST OF THE I-35 CORRIDOR.

25

PRELIMINARY LOCAL STORM REPORT...RETRANSMITTED
NATIONAL WEATHER SERVICE FORT WORTH TX
241 PM CDT SAT OCT 23 2010

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

1255 PM     TSTM WND DMG     2 SSE NORTH RICHLAND HILLS 32.80N  97.24W
10/23/2010                   TARRANT            TX   TRAINED SPOTTER

            A RESIDENCE ROOF WAS PARTIALLY BLOWN OFF NEAR BOWSPIRIT
            LANE. TIME ESTIMATED.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE FORT WORTH TX
246 PM CDT SAT OCT 23 2010

TXZ159-232015-
MCLENNAN TX-
246 PM CDT SAT OCT 23 2010

...SIGNIFICANT WEATHER ADVISORY FOR...
  MCLENNAN COUNTY

AT 247 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM 5 MILES SOUTHWEST OF WOODWAY...MOVING NORTHEAST
AT 30 MPH.

CITIES IN THE PATH OF THIS STORM INCLUDE BELLMEAD...BEVERLY HILLS...
HALLSBURG...HEWITT...LACY-LAKEVIEW...MART...NORTHCREST...ROBINSON...
WACO...WEST AND WOODWAY.

PENNY-SIZED HAIL AND WIND GUSTS TO 50 MPH CAN BE EXPECTED FROM THIS
STORM.

HEAVY RAINFALL MAY RESULT IN FLOODING OF LOW LYING AREAS SUCH AS
DITCHES AND UNDERPASSES. AVOID THESE AREAS AND DO NOT CROSS FLOODED
ROADS AS THEY MAY BE WASHED OUT.

IF THIS STORM INTENSIFIES...A SEVERE WEATHER WARNING MAY BE NEEDED.

LAT...LON 3158 9743 3185 9705 3154 9681 3137 9730
TIME...MOT...LOC 1947Z 231DEG 26KT 3148 9727

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE FORT WORTH TX
351 PM CDT SAT OCT 23 2010

TXZ160-232115-
FALLS TX-
351 PM CDT SAT OCT 23 2010

...SIGNIFICANT WEATHER ADVISORY FOR...
  FALLS COUNTY

AT 345 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM 16 MILES SOUTHWEST OF MARLIN...MOVING NORTHEAST
AT 35 MPH.

CITIES IN THE PATH OF THIS STORM INCLUDE LOTT...MARLIN AND ROSEBUD.

NICKEL-SIZED HAIL AND WIND GUSTS TO 50 MPH CAN BE EXPECTED FROM THIS
STORM.

IF THIS STORM INTENSIFIES...A SEVERE WEATHER WARNING MAY BE NEEDED.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 800 PM CDT SATURDAY EVENING
FOR EASTERN TEXAS.

LAT...LON 3117 9714 3147 9676 3123 9660 3111 9682
      3112 9683 3100 9708
TIME...MOT...LOC 2045Z 225DEG 31KT 3113 9697

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