000
FXUS64 KFWD 191718 AAC
AFDFWD

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
1218 PM CDT SUN MAY 19 2013

.AVIATION...

CONCERNS...WIND GUSTS NEAR OR EXCEEDING 34 KNOTS THIS AFTERNOON.

STRONG AND GUSTY SOUTH WINDS WILL PREVAIL THROUGH THE AFTERNOON
AND AGAIN ON MONDAY. CURRENTLY FEEL THAT MOST GUSTS WILL BE 34
KNOTS OR LESS BUT COULD SEE A FEW AIRPORTS REPORT 35 KNOTS OFF AND
ON DURING THE AFTERNOON. IF THEY GO HIGHER....THEN WE WILL LIKELY
ISSUE AND AWW FOR KDFW. THE WINDS WILL DIMINISH SOMEWHAT FOR THE
EVENING HOURS BUT COULD CRANK UP AND BECOME GUSTY AFTER 06Z AS THE LLJ
STRENGTHENS.

WITH ANOTHER NIGHT OF STRONG SOUTHERLY LLJ...MVFR CIGS SHOULD
RETURN AROUND 10Z AT KACT AND BY 11Z ACROSS THE METROPLEX.
BURN-OFF TIME SHOULD AGAIN BE 16-17Z.

THE DRYLINE OUT WEST IS NOW PUSHING EASTWARD AND WE DO EXPECT SOME
ISOLATED SUPERCELLS TO DEVELOP BY LATE AFTERNOON. HOWEVER...WE
EXPECT THE STORMS TO REMAIN WEST OF ALL TAF SITES THROUGH MID
EVENING HOURS...THEN DIE OFF.   75

&&

.UPDATE...
DRYLINE IS MAKING STEADY PROGRESS TO THE EAST TODAY AS MID LEVEL
WINDS HAVE BECOME MORE WESTERLY ACROSS WEST TEXAS IN THE WAKE OF
THE SHORTWAVE TROUGH THAT MOVED THROUGH THE SOUTHERN PLAINS LAST
NIGHT. ALL MODEL GUIDANCE IS IN AGREEMENT THAT THE DRYLINE WILL
ENTER THE WESTERN CWA THIS AFTERNOON. BECAUSE THE DRYLINE WILL BE
IN THE CWA...THE ONLY CHALLENGE IN THIS FORECAST IS DETERMINING
WHETHER CONVECTIVE INITIATION WILL OCCUR...AND IF IT DOES...THE
EXTENT OF THE COVERAGE. 12Z FWD SOUNDING SHOWS THAT CAPPING HAS
WEAKENED DURING THE LAST 24 HOURS...LIKELY DUE TO LIFT FROM
YESTERDAY/S SHORTWAVE. STRONG SOUTHERLY WINDS WILL KEEP LOW LEVEL
MOIST ADVECTION IN PLACE TODAY AND DEWPOINTS WILL LIKELY HOLD IN
THE 63 TO 66 DEGREE RANGE LATE THIS AFTERNOON TO THE EAST OF THE
DRYLINE. THE THERMODYNAMIC PROFILE LOOKS MORE FAVORABLE FOR SEVERE
CONVECTION IN THE CWA TODAY. HOWEVER MANY MORE MODELS ARE FAILING
TO SHOW CONVECTIVE INITIATION THIS FAR SOUTH TODAY. YESTERDAY
INITIATION WAS VERY LIMITED SOUTH OF THE RED RIVER WHEN THE
GUIDANCE WAS SPLIT ROUGHLY IN HALF BETWEEN ALL CLEAR AND STORMS.
TODAY THAT DROPS TO LESS THAN A FIFTH OF MODELS SHOWING CONVECTIVE
INITIATION.

PART OF THE ISSUE TODAY IS THE LACK OF A SHORTWAVE TO HELP ENHANCE
THE LIFT AT PEAK HEATING. HOWEVER Q-VECTOR CONVERGENCE IS
PRESENT...LIKELY DUE TO THE IMPACTS OF CYCLONIC CURVATURE IN THE
MID-LEVEL HEIGHT FIELDS...WHICH DOES CONTRIBUTE TO VERY SLIGHT
HEIGHT FALLS BETWEEN 18 AND 0Z. WHAT I SUSPECT IS THE MORE LIKELY
ISSUE TODAY ARE THE STRONGER WIND SPEEDS BELOW 700MB WHICH CAUSES
MORE DRY AIR ENTRAINMENT INTO INFANT UPDRAFTS AND TENDS TO CAUSE
TOWERING CUMULUS TO LEAN OVER AND STRUGGLE TO GROW INTO STORMS.
BECAUSE ANY UPDRAFT THAT DOES MANAGE TO OVERCOME THIS IMPEDANCE
WILL LIKELY BECOME A SEVERE SUPERCELL WITH THE POTENTIAL TO
PRODUCE SIGNIFICANT SEVERE WEATHER...WILL ERR ON THE SIDE OF
CAUTION AND KEEP POPS IN THE 20-30 PERCENT RANGE EVEN IF THIS
PROBABILITY IS TECHNICALLY TOO HIGH FOR THIS SITUATION.

THE HRRR/RUC/GFS ARE THE MODELS MOST AGGRESSIVE WITH CONVECTION
THIS AFTERNOON...AND THEY SHOW ACTIVITY AS FAR SOUTH AS SAN
SABA. THUS WILL UPDATE TO STRETCH THE LOW POPS DOWN INTO THE SW
CWA. FURTHERMORE...ANY SUPERCELL STORM THAT DOES GET GOING WILL
HAVE LESS CIN TO COMPETE WITH AS THEY HEAD EAST TODAY...AND WILL
STRETCH THE LOW POPS AND MENTION OF SEVERE WX A COUNTY OR SO
FARTHER EAST. THIS MEANS THE WESTERN PORTIONS OF THE METROPLEX
COULD BE UNDER THE GUN FOR SEVERE WEATHER SHOULD A SUPERCELL
DEVELOP FAR ENOUGH TO THE SOUTH. THE MAIN THREATS TODAY ARE VERY
LARGE HAIL AND DAMAGING WINDS...BUT AN ISOLATED TORNADO WILL BE
POSSIBLE ESPECIALLY BETWEEN 6PM AND 8PM WHEN LOW LEVEL HODOGRAPHS
BEGIN TO ENLARGE JUST BEFORE SURFACE BASED CIN BECOMES TOO HIGH
DUE TO LOSS OF HEATING.      TR.92

&&

.PREV DISCUSSION... /ISSUED 336 AM CDT SUN MAY 19 2013/
CONVECTION CONTINUES ACROSS THE PLAINS EARLY THIS MORNING IN THE
ACTIVE REGION OF A BROAD UPPER TROUGH OVER THE WEST-CENTRAL CONUS.
SHOWERS AND THUNDERSTORMS SHOULD REMAIN WELL NORTH OF THE RED
RIVER THIS MORNING BEFORE REDEVELOPING FARTHER SOUTH INTO TEXAS
ONCE AGAIN LATE THIS AFTERNOON. FOR THE SHORT TERM...THE MAIN
CONCERN WOULD BE THE GUSTY SOUTH WINDS TODAY DUE TO A FAIRLY TIGHT
PRESSURE GRADIENT. WINDS MAY GUST AT TIMES TO AT OR ABOVE 30
MPH...BUT AT THIS TIME IT APPEARS THAT CONDITIONS SHOULD REMAIN
BELOW ADVISORY CRITERIA TODAY.

LATER TODAY...STORMS WILL MOST LIKELY INITIATE WEST OF THE REGION
ALONG THE DRYLINE...WHICH IS FORECAST TO ADVANCE EAST TO WITHIN
20-40 MILES OF THE WESTERN-MOST COUNTIES OF THE CWA BY LATE
AFTERNOON. STORM MOTION WOULD BRING ISOLATED ACTIVITY INTO THE
WESTERN AND NORTHWESTERN COUNTIES OF NORTH TEXAS DURING THE LATE
AFTERNOON AND EVENING HOURS BEFORE THE LOSS OF SURFACE HEATING
CAUSES THE STORMS TO DIMINISH TONIGHT. COVERAGE WILL LIKELY REMAIN
SPARSE ONCE AGAIN IN TEXAS WITH HIGHER COVERAGE EXPECTED NORTH OF
THE RED RIVER IN CLOSER PROXIMITY OF THE UPPER TROUGH. WILL GO
WITH 20 POPS THIS EVENING ACROSS ROUGHLY THE NORTHWESTERN HALF OF
THE REGION WITH A SMALL AREA OF 30 POPS NEAR THE RED RIVER. A FEW
STORMS COULD BE SEVERE WITH LARGE HAIL AND DAMAGING WINDS.
INSTABILITY WILL REMAIN SUFFICIENT FOR A FEW SEVERE STORMS OVER
THE NORTHWESTERN COUNTIES AGAIN ON MONDAY. POPS WILL BE SIMILAR ON
MONDAY AS TODAY WITH THE BEST CHANCE OF STORMS GENERALLY NORTH OF
I-20 AND WEST OF I-35.

RAIN CHANCES WILL INCREASE AREA-WIDE TUESDAY THROUGH TUESDAY
NIGHT AS A SHORTWAVE TROUGH SWINGS SOUTHEASTWARD FROM THE GREAT
BASIN INTO THE SOUTHERN PLAINS. SHOWERS AND THUNDERSTORMS MAY BE
ONGOING NORTH OF THE REGION TUESDAY MORNING ALONG A COLD FRONT.
THE FRONT SHOULD REMAIN JUST NORTH OF THE AREA...BUT OUTFLOW FROM
ONGOING ACTIVITY TO THE NORTH...AND THE ADVANCING DRYLINE FROM THE
WEST...SHOULD PROVIDE FOCUS FOR ADDITIONAL DEVELOPMENT DURING THE
AFTERNOON HOURS. THIS ACTIVITY SHOULD SPREAD EAST AND SOUTHEAST
ACROSS NORTH TEXAS TUESDAY EVENING. THE SHORTWAVE WILL CONTINUE TO
PROPAGATE EASTWARD INTO THE SOUTHEASTERN U.S....ALLOWING RAIN
CHANCES TO END FROM NORTHWEST TO SOUTHEAST ON WEDNESDAY. THE
POTENTIAL FOR SEVERE WEATHER WILL REMAIN HIGHEST OVER THE
NORTHWEST COUNTIES...WITH DECREASING POTENTIAL FARTHER SOUTH AND
EAST DUE IN LARGE PART TO TIME OF DAY. THIS SYSTEM WILL BE QUICKLY
REPLACED WITH AN UPPER RIDGE OVER THE CENTRAL AND SOUTHERN PLAINS
LATE IN THE WEEK...WHICH WOULD BRING ABOVE NORMAL TEMPERATURES AND
LOW RAIN CHANCES FOR THE EXTENDED PORTION OF THE FORECAST.    30

&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  92  72  89  72  89 /  10  20  10  20  40
WACO, TX              92  73  90  73  92 /   5  10   5  10  20
PARIS, TX             89  70  87  70  83 /  10  20  10  40  40
DENTON, TX            92  71  89  70  87 /  10  30  20  30  40
MCKINNEY, TX          91  71  88  71  86 /  10  20  10  30  40
DALLAS, TX            92  74  90  74  91 /  10  10  10  20  40
TERRELL, TX           91  71  89  73  90 /   5  10  10  20  30
CORSICANA, TX         91  72  89  73  91 /   5   5   5  10  20
TEMPLE, TX            91  73  90  73  92 /   5   5   5  10  20
MINERAL WELLS, TX     96  70  92  71  92 /  20  20  20  20  30

&&

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

&&

$$

75/