Severe Thunderstorm Warning 424, NWS Fort Worth, TX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
1200 AM CDT FRI AUG 21 2009

.AVIATION...
/12Z TAFS/

TRAINING ACTIVITY ALONG THE RED RIVER IS MAKING MINIMAL PROGRESS
SOUTHWARD. ALTHOUGH ERODING GROUND CLUTTER IN FANNIN COUNTY IS
EVIDENCE OF OUTFLOW...INFLOW REMAINS MEAGER...AND COLD POOL
PROPAGATION WILL BE NEGLIGIBLE. 00Z GFS HAS THE ONLY REASONABLE
REPRESENTATION OF ONGOING CONVECTION...AND IT BRINGS CONVECTION
INTO TAF SITES. WILL BEAR WATCHING...BUT EXPECT TERMINALS TO
REMAIN RAIN-FREE.

25

&&

.UPDATE...
WATCH FOR NE THIRD OF NORTH TX(NOT INCLUDING IMMEDIATE DALLAS/FORT WORTH
AREA) CONTINUES UNTIL 4 AM. HAVE RAISED POPS INCREMENTALLY ACROSS THE
NE COUNTIES TO HIGH CHANCE/LIKELY DURING THE OVERNIGHT...DUE TO SOME
BACKBUILDING AND SLOW SSE PROPAGATION OF STORMS.

OTHERWISE...JUST ADJUSTED SOME TRENDS A BIT.

05/

&&

.PREV DISCUSSION... /ISSUED 330 PM CDT THU AUG 20 2009/
TOWERING CU HAS DEVELOPED ALONG THE OLD OUTFLOW BOUNDARY
EXTENDING FROM YOUNG COUNTY EASTWARD INTO LAMAR COUNTY. EXPECT
THESE CU TO CONTINUE TO DEVELOP IN THE VERY UNSTABLE ENVIRONMENT.
CAPE VALUES EXCEED 3000 J/KG AND SHEAR VALUES HAVE ACTUALLY
IMPROVED TO 30 KNOTS ALONG THE RED RIVER. SEVERE STORM WATCH HAS BEEN
ISSUED UNTIL 03Z OR 10 PM FOR AREAS NORTH OF A YOUNG TO DENTON TO
HOPKINS/RAINS COUNTY LINE. EXPECTING LARGE HAIL AND DAMAGING WINDS
TO BE THE MAIN THREATS FOR SEVERE WEATHER. STORMS SHOULD CONTINUE
TO SLOWLY SAG SOUTHWARD AS THE FRONT/BOUNDARY CONTINUE TO PROGRESS
SOUTH THROUGH THE EVENING HOURS.

FRONT WILL LOSE ITS STEAM OVER NIGHT AND STALL OUT SOMEWHERE
AROUND CENTRAL TEXAS. POPS WILL CONTINUE ALONG THE FRONTAL
BOUNDARY BUT SEVERE POTENTIAL SHOULD DIMINISH AS THE NIGHT
PROGRESSES AS AIRMASS BECOMES MORE STABLE.

DRIER AIR WILL FILTER IN BEHIND THE FRONT WITH DEW POINTS UNDER 60
TOMORROW AFTERNOON FOR AREAS GENERALLY NORTH OF INTERSTATE 20.
THIS WILL BRING COOLER NIGHTS AND LESS HUMIDITY THROUGH THE WEEKEND.

INTERESTING SYNOPTIC PATTERN SHAPING UP FOR NEXT WEEK. MONDAY...A
DOMINANT RIDGE WILL BE CENTERED OVER THE TEXAS PANHANDLE WITH DEEP
TROUGHS ON EITHER SIDE. THE WESTERN TROUGH NUDGES THE HIGH EAST WHICH
CAUSES THE EASTERN TROUGH TO CUT OFF UNDERNEATH THE RIDGE. STILL
ALOT OF UNCERTAINTY WITH THIS SCENARIO WITH THE 12Z GFS BRINGING
THE LOW INTO TEXAS AND THE ECMWF KEEPING IT OVER FLORIDA...SO WILL
KEEP 10 POPS FOR THE EXTENDED.

85/NH

&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  73  96  73  95  73 /  40  10  10   5  10
WACO, TX              77 100  73 101  75 /  20  10  10   5  10
PARIS, TX             68  92  65  90  63 /  70   5  10   5   5
DENTON, TX            71  95  67  94  68 /  30   5  10   5   5
MCKINNEY, TX          70  94  66  95  66 /  50  10  10   5   5
DALLAS, TX            75  96  73  96  74 /  40  10  10   5  10
TERRELL, TX           73  96  69  96  68 /  50  10  10   5   5
CORSICANA, TX         74  96  71  96  71 /  30  20  10   5  10
TEMPLE, TX            76  99  72 100  72 /  10  10  10   5  10

&&

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

&&

25/05

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
838 PM CDT THU AUG 20 2009

TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175-211200-
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-
838 PM CDT THU AUG 20 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH TEXAS.

.DAY ONE...TONIGHT.
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EAST OF A SHERMAN...
DALLAS...HILLSBORO...FAIRFIELD AND PALESTINE LINE OVERNIGHT. DAMAGING
WINDS...LARGE HAIL...BRIEF HEAVY RAINFALL...AND POSSIBLY A BRIEF TORNADO
WILL BE THE MAIN THREATS...AS SCATTERED STORMS MOVE THROUGH THE SLIGHT
RISK AREA.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.
THUNDERSTORMS REMAIN POSSIBLE FRIDAY SOUTHEAST OF A TEMPLE...CORSICANA...
SULPHUR SPRINGS LINE. CLOUD TO GROUND LIGHTNING AND BRIEF HEAVY RAIN
MAY ACCOMPANY THE STORMS.

.SPOTTER INFORMATION STATEMENT...
LIMITED SPOTTER ACTIVATION MAY BE REQUESTED ACROSS EASTERN NORTH TEXAS.

05/

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE FORT WORTH TX
1029 PM CDT THU AUG 20 2009

TXZ095-210400-
LAMAR TX-
1029 PM CDT THU AUG 20 2009

...SIGNIFICANT WEATHER ADVISORY FOR...
  LAMAR COUNTY

AT 1029 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM 5 MILES NORTH OF PARIS...MOVING SOUTHEAST AT 15
MPH.

CITIES IN THE PATH OF THIS STORM INCLUDE BLOSSOM...DEPORT AND PARIS.

TORRENTIAL RAINFALL AND WIND GUSTS TO 50 MPH ARE LIKELY WITH THIS STORM.

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

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 400 AM CDT FRIDAY
MORNING FOR NORTHEASTERN TEXAS.

LAT...LON 3386 9545 3387 9533 3390 9533 3389 9530
      3338 9530 3338 9531 3343 9542 3368 9585
      3384 9585 3386 9581 3385 9577 3390 9575
      3390 9568 3395 9561
TIME...MOT...LOC 0329Z 307DEG 13KT 3373 9557

DUNN

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE FORT WORTH TX
1148 PM CDT THU AUG 20 2009

TXZ094-095-106-210515-
LAMAR TX-FANNIN TX-DELTA TX-
1148 PM CDT THU AUG 20 2009

...SIGNIFICANT WEATHER ADVISORY FOR...
  FANNIN COUNTY
  DELTA COUNTY
  LAMAR COUNTY

AT 1147 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
CLUSTER OF STRONG THUNDERSTORMS EXTENDING FROM NEAR HONEY GROVE
ACROSS SOUTHERN LAMAR COUNTY AND INTO DELTA COUNTY.

THESE STORMS WILL PRODUCE VERY HEAVY RAINFALL...NEARLY CONTINUOUS
LIGHTNING AND GUSTY WINDS.  FLOODING OF LOW LYING AREAS WILL BE
POSSIBLE.  A FLASH FLOOD WARNING IS IN EFFECT FOR LAMAR COUNTY.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 400 AM CDT FRIDAY
MORNING FOR NORTHEASTERN TEXAS.

LAT...LON 3386 9545 3388 9530 3337 9531 3335 9559
      3323 9585 3341 9586 3335 9637 3373 9637
      3370 9631 3377 9628 3376 9619 3382 9614
      3382 9618 3383 9617 3389 9595 3385 9577
      3390 9575 3395 9561
TIME...MOT...LOC 0447Z 326DEG 14KT 3354 9581

DUNN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FORT WORTH TX
1157 PM CDT THU AUG 20 2009

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

1130 PM     FLASH FLOOD      PARIS                   33.67N  95.55W
08/20/2009                   LAMAR              TX   LAW ENFORCEMENT

            URBAN FLOODING OF STREETS IN PARIS