000
FXUS64 KFWD 200018
AFDFWD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
718 PM CDT SUN MAY 19 2013

.AVIATION...

FOR THE 00Z TAFS...THUNDERSTORM CHANCES AND TIMING THE ONSET OF
MVFR STRATUS ARE THE PRIMARY FORECAST CONCERNS THROUGH THE VALID
FORECAST PERIOD.

THUNDERSTORM CHANCES...WENT AHEAD AND LEFT THUNDERSTORMS OUT OF
THE METROPLEX AREA TAFS FOR THIS EVENING BASED LARGELY ON
SATELLITE OBSERVATIONS. THE LATEST RAP FORECAST SOUNDINGS
INDICATED THAT THE CAP OVER THE DFW AREA WOULD ERODE BY 02Z
POSSIBLY RESULTING IN THUNDERSTORMS NEAR AREA TAF SITES. VISIBLE
SATELLITE IMAGERY INDICATES FLAT CUMULUS CLOUDS WHILE IR SATELLITE
IMAGES SHOW CLOUD TOP TEMPERATURES HOLDING STEADY AT THE TIME OF
THIS DISCUSSION. EARLY RESULTS FROM THE 00Z FWD RAOB INDICATE A
SUBSTANTIAL CAP REMAINS IN PLACE OVER THE METROPLEX...HOWEVER AN
AIRCRAFT SOUNDING TAKING OFF FROM KDAL DID INDICATE A WEAKER CAP.
EITHER WAY...A CAP REMAINS IN PLACE AND IN THE ABSENCE OF STRONG
LIFT...DO NOT SEE A REASON FOR STORMS TO INITIATE NEAR AREA TAF
SITES THIS EVENING OR OVERNIGHT.

FOR TOMORROW...AN UPPER LEVEL DISTURBANCE OVER UTAH IS EXPECTED TO
MOVE TOWARDS THE REGION OVER THE NEXT 24 TO 36 HRS. THIS WILL
RESULT IN BETTER UPPER LEVEL SUPPORT AND LIFT ALONG THE DRYLINE BY
LATE TOMORROW AFTERNOON RESULTING IN A HIGHER CONFIDENCE FORECAST
FOR THUNDERSTORMS. STORMS THAT DEVELOP ALONG THE DRYLINE WOULD
LIKELY NOT REACH THE METROPLEX UNTIL AFTER 23Z OR 6 PM CDT. WENT
AHEAD WITH A MENTION OF VCTS IN ALL METROPLEX AREA TAFS AFTER THIS
TIME DUE TO THE HIGHER CONFIDENCE IN THE CLOSE PROXIMITY OF
STORMS. A CAPPING INVERSION IS EXPECTED TO REMAIN IN PLACE OVER
THE METROPLEX TOMORROW AFTERNOON...SO ITS DIFFICULT TO KNOW
WHETHER STORMS WILL BE ABLE TO OVERCOME THIS CAP OR NOT TO MOVE
DIRECTLY OVER AREA TAF SITES. EITHER WAY...THE STORMS ARE EXPECTED
TO BE CLOSE ENOUGH TO CAUSE TRAFFIC HEADACHES AT AREA AIRPORTS SO
THE VCTS IS IN THE FORECAST FOR PLANNING PURPOSES MORE THAN
ANYTHING ELSE AT THIS POINT.

MVFR STRATUS...NO CHANGES MADE TO THE PREVIOUS FORECAST. WE WILL
ONCE AGAIN HAVE A STRONG LOW-LEVEL JET OF 50 KTS OR GREATER OVER
NORTH TX TONIGHT. THIS SHOULD RESULT IN A SIMILAR STRATUS TIMING
TO THIS MORNING WHERE STRATUS BUILT OVER METROPLEX TAF SITES AFTER
11Z. STRATUS SHOULD SCATTER OUT OR LIFT TO VFR LEVELS QUICKLY WITH
DRIER AIR ABOVE THE STRATUS DECK ABOVE THE CAP.

CAVANAUGH


&&


.PREV DISCUSSION... /ISSUED 328 PM CDT SUN MAY 19 2013/
THE DRYLINE HAS REACHED A LINE FROM WICHITA FALLS TO GRAHAM TO
BROWNWOOD WHERE IT WILL LIKELY STALL BEFORE RETREATING WEST THIS
EVENING. THE MAIN FORECAST CONCERN THROUGH THIS EVENING IS
WHETHER STORMS WILL INITIATE ALONG THE DRYLINE AND THE AMOUNT OF
COVERAGE. AS DISCUSSED IN THE MORNING UPDATE...MOST OF THE MODEL
GUIDANCE IS NOT INITIATING ANY CONVECTION IN OUR REGION THIS
EVENING DESPITE CIN BECOMING ALMOST NEGLIGIBLE ACROSS THE WESTERN
ZONES. HOWEVER THE RUC/HRRR/GFS HAVE NOT WAVERED AND ONE OF THE
HI-RES WRFS AT 12Z HAS NOW JOINED THE INITIATION CAMP. THE ISSUE
AT HAND IS LIKELY THAT TODAY/S STRONG WINDS AND DRY AIR ALOFT WILL
MAKE IT TOUGH FOR AN INFANT UPDRAFT TO BECOME ESTABLISHED AND
GROW INTO A SUPERCELL WITHOUT A SHORTWAVE TO AID IN LIFT. RIGHT
NOW THE BEST GUESS IS THAT 1 TO 3 STORMS WILL MANAGE TO DEVELOP
OVER THE WESTERN CWA BY EARLY EVENING...AND WILL CONTINUE THE
FORECAST OF 20-30 POPS WEST OF A LINE FROM SHERMAN TO DFW TO
LAMPASAS. LOCAL OBJECTIVE ANALYSIS INDICATES CAPE VALUES ARE FROM
2000-3000 J/KG OVER THE CWA AND AMPLE DEEP LAYER SHEAR EXISTS TO
SUPPORT VERY LARGE HAIL AND DAMAGING WINDS. AN ISOLATED TORNADO
WILL BE POSSIBLE BETWEEN 6 AND 8 PM WHEN LOW LEVEL WIND SHEAR
RAMPS UP JUST BEFORE THE SURFACE AIRMASS BECOMES TOO NEGATIVELY
BUOYANT WITH LOSS OF HEATING. STORMS MAY HOLD TOGETHER LONG ENOUGH
TO AFFECT LOCATIONS FARTHER TO THE EAST BY MID-LATE
EVENING...ESPECIALLY NORTH OF I-20...BUT SEVERE WEATHER POTENTIAL
WILL BE DIMINISHING. OTHERWISE A BREEZY AND MUGGY NIGHT IS IN
STORE FOR THE REGION.

THE STORM THREAT FOR MONDAY IS LOOKING GREATER ACROSS A LARGER
PART OF NORTH TEXAS. THE CIN WILL BE EVEN WEAKER THAN TODAY AND
ALMOST ALL OF THE MODELS ARE INDICATING STORM INITIATION IN THE
CWA. THE DRYLINE WILL BE ROUGHLY IN THE SAME LOCATION AS IT IS
TODAY. THE GFS AND NAM ARE MOST AGGRESSIVE WITH HEIGHT FALLS AND
CONVECTION ACROSS THE NW CWA...WHICH RAISES CONFIDENCE THAT THIS
AREA WILL LIKELY SEE SUPERCELL STORMS AND SEVERE WEATHER. EXPECT
SEVERAL SUPERCELLS TO DEVELOP ACROSS THE WESTERN ZONES...INCLUDING
SOME ISOLATED CELLS ACROSS THE SW ZONES. VERY HIGH INSTABILITY
AND AMPLE DEEP LAYER SHEAR WILL SUPPORT A THREAT OF SIGNIFICANT
SEVERE WEATHER INCLUDING GIANT HAIL...DAMAGING WINDS AND A FEW
TORNADOES. LOW LEVEL WIND SHEAR GETS STRONGER AFTER 7PM WITH 0-3KM
SRH VALUES ABOVE 300 M2/S2. SINCE THERE IS LESS CIN THERE IS MORE
TIME FOR EVENING SUPERCELLS TO TAP INTO THIS INSTABILITY AFTER
DARK WHICH IS WHAT IS RAISING OUR CONCERN FOR TORNADOES. HAVE
BUMPED UP POPS TO 30-50 PERCENT IN THE WESTERN ZONES...AND
RAISED THEM FOR THE CENTRAL AND NORTHEAST ZONES AS WELL...AS
SUPERCELLS WILL HEAD EASTWARD AND HOLD TOGETHER LONGER.

ON TUESDAY A WEAK COLD FRONT WILL BECOME DRAPED ACROSS THE CWA
FROM ROUGHLY PARIS TO DFW TO EASTLAND. HIGH TEMPS WILL BE A LITTLE
COOLER THIS DAY...BUT INSTABILITY WILL STILL BE VERY HIGH
ESPECIALLY ACROSS THE SOUTHERN ZONES. ALL MODEL GUIDANCE SHOWS
STRONG UPPER LEVEL FORCING OVER NORTH TEXAS TUESDAY AFTERNOON AS
THE TROUGH AXIS SWINGS THROUGH THE AREA. THIS WILL SET THE STAGE
FOR SCATTERED TO NUMEROUS SHOWERS AND STORMS THAT WILL LIKELY
DEVELOP ALONG THE FRONT TUESDAY AFTERNOON AND MOVE EAST AND
SOUTHEAST INTO THE NIGHTTIME HOURS. SINCE LOW LEVEL WIND FIELDS
RELAX A BIT...THESE STORMS MAY TEND TO ORGANIZE INTO A MCS/SQUALL
LINE OVER THE CENTRAL ZONES. OBVIOUSLY A SEVERE WEATHER THREAT
WILL EXIST WITH THIS CONVECTIVE EPISODE AS WELL. RAINFALL WILL
RANGE FROM A TRACE IN THE NW TO 1.5 INCHES IN THE SOUTHEAST ZONES.
EXPECT THIS CONVECTIVE EPISODE TO FINALLY EXHAUST THE ATMOSPHERE
AND PUSH THE BEST MOISTURE AND INSTABILITY SOUTHEAST OF THE AREA
BY WEDNESDAY MORNING. WILL KEEP WEDNESDAY DRY.

WEAK RIDGING SETS UP OVER THE AREA WEDNESDAY AND INTO NEXT
WEEKEND. SOUTHEAST WINDS WILL CONTINUE WHICH WILL KEEP LOW TEMPS
IN THE MID 60S TO NEAR 70...AND HIGHS IN THE MID 80S TO NEAR 90
EACH DAY. CONVECTION IS EXPECTED TO OCCUR OVER THE HIGH PLAINS
THURSDAY AND FRIDAY...AND WITH A SOUTHEASTERLY FLOW IN THE LOWEST
800MB WE WILL NEED TO KEEP AN EYE ON SOME OF THIS ACTIVITY MAKING
A RUN AT THE CWA DURING THE OVERNIGHT HOURS. SINCE THERE IS A LACK
OF STRONG NORTHWEST FLOW ALOFT IN THE MID LEVELS...BELIEVE
CONVECTION WILL DISSIPATE BEFORE REACHING MOST OF THE AREA...BUT
HAVE INSERTED A SLIGHT CHANCE IN THE NW ZONES THURSDAY AND FRIDAY
NIGHTS. WILL KEEP THE REMAINDER OF THE FORECAST DRY.

TR.92

&&



.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  71  90  71  88  67 /  10  20  40  50  50
WACO, TX              72  90  72  91  68 /   5  10  20  40  60
PARIS, TX             70  87  69  83  65 /  10  10  60  50  50
DENTON, TX            70  89  69  86  64 /  10  30  40  40  40
MCKINNEY, TX          70  89  70  85  65 /  10  20  40  50  50
DALLAS, TX            73  91  73  89  69 /  10  20  40  50  50
TERRELL, TX           70  89  71  87  68 /  10  10  30  50  60
CORSICANA, TX         71  89  72  88  69 /   5  10  20  40  60
TEMPLE, TX            71  90  72  92  69 /   5  10  20  40  60
MINERAL WELLS, TX     70  94  68  88  65 /  20  30  30  40  40

&&

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

&&

$$