Severe Thunderstorm Warning 461, NWS Fort Worth, TX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
723 PM CDT MON SEP 21 2009

.AVIATION...
/00Z TAFS/

AN AIRPORT WEATHER WARNING IS IN EFFECT FROM 730-1100PM...
PRIMARILY FOR LIGHTNING...THOUGH GUSTY WEST WINDS AND SMALL HAIL
MAY ALSO ACCOMPANY THE STORMS IN THE METROPLEX THIS EVENING. THE
BROKEN LINE OF STORMS WILL MAKE SLOW EASTWARD PROGRESS...LINGERING
AT METRO TAF SITES MUCH OF THE EVENING.

CONVECTIVE WIND SHIFT MAY BE TEMPORARY AS EASTERLY OUTFLOW WINDS
ALREADY OBSERVED OUT THE BACK OF THE LINE. COLD FRONT IS NEAR SPS
AT 7 PM...AND WILL ARRIVE AT METRO TAF SITES AROUND MIDNIGHT.

MVFR CIGS WILL PREVAIL THEREAFTER...SHOULD STAY ABOVE ABOVE 1KFT.
SHOULD LIFT ABOVE ALTERNATE CATEGORY EARLY TUESDAY AFTERNOON...VFR
BY TUESDAY EVENING.

THE ORIENTATION OF THE SQUALL LINE WILL MEAN A MUCH LATER ARRIVAL
AT WACO. (A SIMILAR DELAY IN FROPA AND LIFTING OF CIGS ABOVE 2KFT.)

25

&&

.PREV DISCUSSION... /ISSUED 259 PM CDT MON SEP 21 2009/
OVERALL...LITTLE HAS CHANGED IN FORECAST THINKING FOR OUR EVENT
TONIGHT. CONVECTION ACROSS EASTERN OKLAHOMA CONTINUES TO BUILD
SOUTHWESTWARD INTO CENTRAL...AND EVENTUALLY SOUTHERN OKLAHOMA.

FRONTAL BOUNDARY IS CURRENTLY ACROSS NORTHWEST OKLAHOMA...WITH A
PREFRONTAL TROUGH DRAPED OVER MUCH OF CENTRAL OKLAHOMA. HERE IN
NORTH TEXAS...BREEZY SOUTH WINDS CONTINUE THE FLOW OF MOISTURE...
WITH SURFACE DEWPOINTS IN THE LOW 70S. DEEP MOISTURE WILL YIELD
AMPLE INSTABILITY...WITH 2000 J/KG OF ML CAPE STILL ACROSS NORTH
TEXAS AT 06Z TONIGHT. BULK SHEAR VALUES FROM 25-30 KTS WILL BE
SUFFICIENT FOR A STRONGLY FORCED LINE OF CONVECTION ALONG THE
FRONT THIS EVENING/TONIGHT. LARGE HAIL AND WINDS TO 70 MPH WILL BE
THE PRIMARY HAZARDS.

MODEL DATA IS FAIRLY CONSISTENT WITH DEVELOPING A SECONDARY AREA
OF CONVECTION BEHIND THE FRONT...MAINLY ACROSS THE DFW METRO AND
POINTS TO THE NORTHEAST. IF THIS COMES TO FRUITION...ADDITIONAL
HEAVY RAINFALL CAN BE EXPECTED. WITH SEVERAL ROUNDS OF HEAVY
RAINFALL POSSIBLE...AND THE ALREADY SATURATED GROUNDS...WE WILL
CONTINUE THE FLASH FLOOD WATCH AS IS THROUGH 6 AM.

THE PRECIP FORECAST REMAINS MESSY FOR THE REMAINDER OF THIS
WEEK...AS THE UPPER LEVEL LOW MEANDERS ACROSS THE ROCKIES. SUBTLE
UPPER LEVEL WAVES RIDING ALONG THE SOUTHERN PORTION OF THE UPPER
LOW...ALONG WITH A LINGERING SURFACE BOUNDARY IN OUR AREA AND
AMPLE MOISTURE...WILL KEEP THUNDERSTORMS IN THE FORECAST THROUGH
FRIDAY EVENING. HOWEVER...THE BEST CHANCE /ASIDE FROM TONIGHT/
APPEARS TO BE ON THURSDAY.

GIVEN THE PRECIP CHANCES AND ASSOCIATED CLOUD COVER...HAVE OPTED
TO STAY RATHER CLOSE TO GUIDANCE ON TEMPERATURES THIS WEEK.
GENERALLY EXPECT HIGHS IN THE MID 70S TO LOWER 80S FOR THE REST OF
THE WORK WEEK...WITH READINGS CLIMBING INTO THE UPPER 80S THIS WEEKEND.

SCHULTZ

&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  68  74  61  79  64 /  90  50  10  10  20
WACO, TX              71  78  61  79  65 /  70  70  20  20  30
PARIS, TX             68  76  61  79  63 /  90  50  20  20  20
DENTON, TX            66  75  58  79  61 /  90  50  10  10  20
MCKINNEY, TX          67  76  58  80  61 /  90  50  10  10  20
DALLAS, TX            69  76  62  80  67 /  90  60  10  10  20
TERRELL, TX           69  78  62  79  66 /  90  70  20  20  20
CORSICANA, TX         70  77  62  79  65 /  70  70  20  20  30
TEMPLE, TX            71  76  61  78  64 /  50  70  20  20  30

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 6 AM CDT TUESDAY FOR TXZ093>095-103>107-
118>123-131>135-144>146.

&&

25/58

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FORT WORTH TX
318 PM CDT MON SEP 21 2009

TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175-221145-
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-
318 PM CDT MON SEP 21 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH TEXAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

THUNDERSTORMS ARE EXPECTED TO DEVELOP NEAR A BOWIE TO BRECKENRIDGE
LINE LATE THIS AFTERNOON...AND THEN BECOME MORE NUMEROUS WHILE
MOVING SOUTHEAST DURING THE EVENING AND OVERNIGHT HOURS AS A COLD
FRONT MOVES THROUGH THE OUTLOOK AREA. ANY STORMS THAT DEVELOP THIS
AFTERNOON THROUGH THE OVERNIGHT HOURS WILL BE CAPABLE OF PRODUCING
DAMAGING WINDS IN EXCESS OF 60 MPH AND LARGE HAIL.

IN ADDITION TO ANY SEVERE WEATHER...HEAVY RAINFALL WILL BE
POSSIBLE AS THE FRONT MOVES THROUGH LEADING TO FLASH FLOODING. A
FLASH FLOOD WATCH IS IN EFFECT FOR AREAS NORTH AND EAST OF A
GAINESVILLE TO MERIDIAN TO ATHENS LINE THROUGH TONIGHT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

SHOWERS AND THUNDERSTORMS WILL CONTINUE MAINLY ACROSS THE
SOUTHEAST HALF OF NORTH TEXAS INTO TUESDAY. HEAVY RAINFALL WILL BE
THE MAIN THREAT DURING THIS TIME.

THE CHANCE FOR THUNDERSTORMS WILL CONTINUE FOR ALL OF NORTH TEXAS
THURSDAY AND FRIDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS LIKELY LATE THIS AFTERNOON AND INTO THE
EVENING HOURS FOR AREAS GENERALLY ALONG AND NORTH OF INTERSTATE
20. SPOTTER ACTIVATION MAY BE NEEDED ACROSS ALL OF NORTH TEXAS
DURING THE OVERNIGHT HOURS.

CAVANAUGH

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE FORT WORTH TX
856 PM CDT MON SEP 21 2009

TXZ104-119-120-220230-
COLLIN TX-DALLAS TX-ROCKWALL TX-
856 PM CDT MON SEP 21 2009

...SIGNIFICANT WEATHER ADVISORY FOR...
  SOUTHERN COLLIN COUNTY
  NORTHEASTERN DALLAS COUNTY
  ROCKWALL COUNTY

AT 856 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED
STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM PLANO TO 2 MILES
SOUTHEAST OF DALLAS...MOVING EAST AT 30 MPH.

CITIES IN THE PATH OF THESE STORMS INCLUDE ADDISON...DALLAS...FATE...
GARLAND...HEATH...HIGHLAND PARK...LUCAS...MESQUITE...MURPHY...
PARKER...PLANO...RICHARDSON...ROCKWALL...ROWLETT...ROYSE CITY...
SACHSE...SUNNYVALE...UNIVERSITY PARK AND WYLIE.

FREQUENT CLOUD TO GROUND LIGHTNING...VERY HEAVY RAINFALL...PEA-SIZED
HAIL...AND WIND GUSTS TO 50 MPH CAN BE EXPECTED FROM THESE STORMS.

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

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1100 PM CDT
MONDAY EVENING FOR NORTHEASTERN TEXAS.

LAT...LON 3282 9630 3282 9651 3276 9652 3276 9686
      3307 9684 3316 9630
TIME...MOT...LOC 0156Z 268DEG 27KT 3302 9674 3277 9673

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