223 
FXUS64 KFWD 191139 AAA
AFDFWD

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
639 AM CDT TUE MAR 19 2013

.AVIATION...
/12Z TAFS/

VFR CONDITIONS PREVAIL ACROSS NORTH TEXAS THIS MORNING WITH
SCT/BKN250 CIGS SPREADING OVERHEAD. CHANGES ON THE WAY BY LATER
THIS MORNING WITH RAPID MOISTURE ADVECTION EXPECTED ACROSS PARTS
OF THE HILL COUNTRY. MVFR CIGS EXPECTED TO DEVELOP BY MID MORNING
IN THESE AREAS AND WILL CONTINUE WITH BKN024 AT WACO BY 15Z. BY
THIS EVENING A STRONG DISTURBANCE WILL MOVE THROUGH THE REGION
WITH SCATTERED THUNDERSTORMS EXPECTED TO DEVELOP MAINLY SOUTHWEST
OF THE MAJOR AIRPORTS. HIGHEST POPS APPEAR TO BE JUST SOUTHWEST OF
WACO BUT WILL INCLUDE A FEW HOURS OF VCTS BY 20/02Z. PRECIP SHOULD
MOVE OUT BY EARLY WEDNESDAY MORNING WITH VFR CONDITIONS EXPECTED.

DUNN 

&&

.PREV DISCUSSION... /ISSUED 456 AM CDT TUE MAR 19 2013/
TODAY WILL START OF SUNNY AND BEAUTIFUL WITH SEASONABLE TEMPS BUT
RAPID CHANGES ARE EXPECTED AS A SHORTWAVE NOW LOCATED OVER THE
GREAT BASIN MOVES ACROSS CENTRAL TEXAS TONIGHT. MID AND HIGH
CLOUDS WILL INCREASE THIS AFTERNOON AHEAD OF THE DISTURBANCE AND
THE COLD FRONT THAT MOVED THROUGH YESTERDAY WILL RETREAT NORTHWARD
AND BECOME STATIONARY ALONG A LINE FROM ROUGHLY SWEETWATER TO
LAMPASAS TO COLLEGE STATION BY LATE AFTERNOON.

FRONTOGENETIC FORCING NEAR THE BOUNDARY AND DYNAMIC LIFT AHEAD OF
THE SHORTWAVE WILL RAPIDLY DESTABILIZE THE ATMOSPHERE WITH STEEP
LOW TO MID LEVEL LAPSE RATES DEVELOPING ACROSS THE SW HALF OF THE
CWA. MEANWHILE STRONG 850MB THETA-E ADVECTION NEAR AND JUST TO THE
NORTH OF THE STATIONARY FRONTAL BOUNDARY WILL PROVIDE THE MOISTURE
REQUIRED FOR CONVECTION. SB CAPE COULD APPROACH 1000 J/KG ACROSS
THE SW ZONES BY LATE AFTERNOON AND BULK SHEAR WILL BE OVER 50KT.
OBVIOUSLY THE POTENTIAL IS THERE FOR SEVERE STORMS AND PERHAPS
SUPERCELLS AFFECTING THE FAR SOUTHWESTERN AND SOUTHERN ZONES LATE
THIS AFTERNOON AND EARLY EVENING. LOW LEVEL DIRECTIONAL SHEAR WILL
BE ENHANCED NEAR AND JUST BEHIND THE FRONTAL BOUNDARY AND THUS LOW
LEVEL ROTATION WOULD BE POSSIBLE WITH ANY SUPERCELL. LIMITING THE
TORNADO THREAT ARE THE DEWPOINTS WHICH WILL ONLY BE IN THE MID TO
UPPER 50S...THUS LIMITING LOW LEVEL INSTABILITY AND RAISING LCLS.
NONETHELESS...WE WILL MENTION A RISK OF SEVERE STORMS SOUTH OF A
COMANCHE TO WACO TO CENTERVILLE LINE. MODELS OVER THE LAST 12
HOURS HAVE REALLY AMPED UP THE INSTABILITY AND THIS IS THE REASON
FOR THE BIG CHANGE IN THE FORECAST. CONFIDENCE IN CONVECTIVE
POTENTIAL IS FAIRLY HIGH AND HAVE ALSO BUMPED UP POPS TO 40-60
PERCENT ACROSS THE SOUTHERN CWA THIS EVENING...WHERE QPF WILL
AVERAGE A HALF INCH. FROM THE I-20 CORRIDOR AND NORTHWARD RAIN
POTENTIAL WILL BE MUCH LOWER AS THE BRUNT OF THE FORCING AND
DYNAMICS WILL REMAIN TOO FAR SOUTH AND HAVE KEPT JUST LOW POPS FOR
LIGHT RAIN. MOST OF THE RAIN ACTIVITY WILL EXIT THE CWA BY 3 AM.
TEMPS TONIGHT WILL BE HELD UP DUE TO THE CLOUD COVER ACROSS THE
CENTRAL AND NORTHERN ZONES...BUT WILL COOL TO WET BULBS IN THE
UPPER 40S ACROSS THE RAINY SOUTHERN ZONES.

SKIES WILL RAPIDLY CLEAR WEDNESDAY MORNING AND A NICE DAY IS
EXPECTED WITH LIGHT TO MODERATE NORTHEAST WINDS PROVIDING WEAK
COLD ADVECTION TO THE AREA. TEMPS WILL ONCE AGAIN TOP OUT IN THE
UPPER 60S TO LOW 70S. WINDS VEER TO THE SOUTHEAST WEDNESDAY NIGHT
AS THE NEXT UPPER LEVEL SHORTWAVE APPROACHES THE AREA. LOW CLOUDS
RETURN THURSDAY MORNING. BREEZY SOUTH WINDS AND WARM ADVECTION
WILL CONTINUE INTO THURSDAY AFTERNOON AND TEMPS WILL WARM INTO
THE UPPER 70S WEST...WHERE MORE SUNSHINE IS EXPECTED...TO NEAR 70
IN THE EAST WHERE CLOUDS WILL HANG IN ALL DAY. A DRY LINE/WEAK
FRONT WILL SET UP ACROSS NW TEXAS THURSDAY AFTERNOON AND BEGIN TO
PUSH INTO NORTHERN PARTS OF THE CWA THURSDAY EVENING. POPS WILL
INCREASE THURSDAY EVENING OVER MAINLY THE NORTHERN ZONES AS
CONVECTION FIRING OFF THE DRY LINE MOVES EAST ACROSS THE NORTHERN
CWA. SEVERE POTENTIAL LOOKS LOW DUE TO THE RATHER LIMITED
INSTABILITY...BUT WILL NEED TO BE MONITORED.

THE GFS CONTINUES TO BE VERY WEAK WITH THE THURSDAY NIGHT FRONT
AND NEVER MOVES IT INTO THE CWA. IT CONTINUES TO REMAIN THE OUTLIER
AND THERE IS OVERWHELMING SUPPORT FROM THE ECMWF/UKMET/GEM AND
EVEN THE LATEST 6Z NAM AND 3Z SREF THAT THE FRONT WILL SLOWLY MOVE
THROUGH THE CWA DURING THE DAY FRIDAY. WILL CONTINUE TO DISCOUNT
THE GFS SOLUTION FROM FRIDAY AND BEYOND. TEMPS FRIDAY WILL BE
DIFFICULT DUE TO THE SLOW MOVING FRONT BUT EXPECT MID 60S ACROSS
THE NORTH TO MID 70S IN THE SOUTH. HOWEVER THE SOUTHERN ZONES
COULD GET INTO THE LOW 80S IF THE FRONT IS SLOWER. WILL RETAIN LOW
POPS FRIDAY NEAR THE FRONT...BUT SHORTWAVE RIDGING WILL LIMIT ANY
UPPER LEVEL SUPPORT FOR ORGANIZED CONVECTION.

THE ECMWF/GEM/UKMET INDICATE THAT THE COLD FRONT SHOULD STALL NEAR
OR JUST SOUTH OF THE CWA FRIDAY EVENING. AS ANOTHER VERY STRONG
PIECE OF UPPER LEVEL ENERGY SWINGS DOWN THROUGH THE ROCKIES AND
INTO THE TEXAS PANHANDLE BY SATURDAY NIGHT...ISENTROPIC LIFT IS
EXPECTED TO INCREASE IN OUR AREA BEHIND THE FRONT. WILL RAISE POPS
FRIDAY NIGHT INTO SATURDAY TO ACCOUNT FOR THIS. RAIN COVERAGE
COULD BE SUBSTANTIAL...BUT HAVE KEPT POPS CONSERVATIVE SINCE THE
GFS IS NOT ON BOARD. THE ECMWF IS INDICATING ENOUGH ELEVATED
INSTABILITY FOR THUNDERSTORMS. THE FRONT MAY TRY TO LIFT NORTH
INTO PART OF THE CWA SATURDAY AFTERNOON...WHICH PLAYS HAVOC WITH
THE FORECAST HIGHS. IF IT RAINS ALL DAY...TEMPS WILL BE IN THE 50S
BUT SOUTHERN AND SOUTHWEST ZONES HAVE THE BEST SHOT AT SEEING WARM
FRONTAL PASSAGE AND THUS HEDGED THOSE HIGHS UP INTO THE 60S.

AS THE STRONG UPPER LEVEL LOW ROTATES THROUGH THE SOUTHERN PLAINS
SATURDAY NIGHT AND SUNDAY...A STRONG FRONT WILL BLAST THROUGH THE
AREA SATURDAY NIGHT. WINDS WILL BE QUITE BREEZY SUNDAY WITH STRONG
COLD ADVECTION AND CLEARING SKIES. SUNDAY NIGHT LOOKS TO BE THE
COLDEST WITH LOWS IN THE 30S. A SLOW MODERATING TREND IS EXPECTED
EARLY NEXT WEEK BUT TEMPS WILL REMAIN BELOW NORMAL.

TR.92

&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  71  48  71  51  74 /   5  10   0   0  10 
WACO, TX              72  47  71  51  76 /   5  50   5   0   5 
PARIS, TX             68  43  67  43  66 /   5  10   0   0  20 
DENTON, TX            69  45  68  48  73 /   5  10   0   0  20 
MCKINNEY, TX          69  44  68  47  72 /   5  10   0   0  20 
DALLAS, TX            71  49  71  53  74 /   5  10   0   0  10 
TERRELL, TX           71  46  70  48  73 /   5  10   0   0  10 
CORSICANA, TX         73  48  72  51  75 /   5  30   5   0  10 
TEMPLE, TX            74  47  71  50  76 /  10  60   5   0   5 
MINERAL WELLS, TX     71  46  71  49  79 /   5  20   0   0  10 

&&

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

&&

$$