Area Forecast Discussion
Issued by NWS Dallas/Fort Worth, TX

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FXUS64 KFWD 191158 AAB
AFDFWD

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
658 AM CDT TUE AUG 19 2014

.AVIATION...
/12Z TAFS/

CONCERNS...POTENTIAL FOR THUNDERSTORMS.

OUTFLOW FROM THE NORTH HAS INTRODUCED LIGHT NORTH AND EAST WINDS.
THESE WINDS ARE GENERALLY 5KTS OR LESS...WHICH SHOULD ALLOW THE
MORNING PUSH TO CONTINUE IN SOUTH FLOW. SOUTH WINDS WILL RETURN BY
MID-MORNING.

MONDAY AFTERNOON THUNDERSTORMS ACROSS THE HILL COUNTRY SENT AN
IMPULSE NORTHEAST...WHICH RESULTED IN SHOWERS AND THUNDERSTORMS
ACROSS NORTH TEXAS INTO THE EARLY MORNING HOURS TODAY. ALTHOUGH
THE MOST VIGOROUS CONVECTION IS DIVING SOUTH INTO THE RIO GRANDE
PLAINS OF SOUTH TEXAS...A WEAKNESS ALOFT REMAINS IN ITS WAKE...
EVIDENCED BY THE NOCTURNAL REDEVELOPMENT OF STORMS ACROSS THE BIG
COUNTRY AND CONCHO VALLEY. THIS HOLE IN THE RIDGE HAS SENT ANOTHER
LOBE OF VORTICITY IN OUR DIRECTION THIS MORNING. THIS APPROACHING
IMPULSE...THE LEADING EDGE OF WHICH IS AROUND HAMILTON AND CORYELL
COUNTIES...CAN BE TRACED ON BOTH RADAR AND WATER VAPOR IMAGERY.
EXTRAPOLATION PUTS THIS FEATURE OVER THE METROPLEX 18-19Z (1-2PM
CDT).

EXTENSIVE CONVECTIVE DEBRIS WILL LIMIT INSOLATION AND THE
DESTABILIZATION OF THE BOUNDARY LAYER...BUT WITH SIGNIFICANT
FORCING FOR ASCENT IN THE MID-LEVELS...ANTICIPATE SOME DEVELOPMENT
AROUND THE TIME THE IMPULSE TRACKS ACROSS THE METROPLEX. SURFACE
WINDS SHOULD BE INSUFFICIENT TO ERODE LINGERING OUTFLOW
BOUNDARIES...WHICH MAY SERVE TO FOCUS CONVECTIVE INVITATION. NEW
TEXAS TECH WRF IS NOW KEYING ON INITIATION IN THE 18-19Z TIME FRAME
AROUND THE METROPLEX...WITH THIS INITIAL ACTIVITY MOVING QUICKLY
OFF TO THE NORTH AND NORTHEAST. HAVE INTRODUCED VCTS 18-21Z (1-4PM
CDT) INTO METROPLEX TAFS. ADDITIONAL ACTIVITY MAY OCCUR ACROSS
WESTERN PORTIONS OF NORTH TEXAS LATER IN THE AFTERNOON.

UNLESS THE ACTIVITY IS BOTH WIDESPREAD AND INTENSE...WHICH IS
NOT ANTICIPATED...TODAY SHOULD BE THE LAST DAY WITH THE POTENTIAL
FOR THUNDERSTORMS THIS WEEK.

25

&&

.PREV DISCUSSION... /ISSUED 356 AM CDT TUE AUG 19 2014/
WESTERN PARTS OF NORTH AND CENTRAL TEXAS WILL CONTINUE TO SEE
OCCASIONAL UNSETTLED WEATHER THROUGH THIS EVENING. A SUBTLE MID
LEVEL DISTURBANCE IN THE VICINITY OF SAN ANGELO/BROWNWOOD WILL
ONCE AGAIN GENERATE ISOLATED TO SCATTERED SHOWERS AND STORMS
TODAY...MAINLY WEST OF THE I-35 CORRIDOR. CONSIDERING THE DRY AIR
LOCATED BETWEEN 900-650MB ON THE 00Z FWD SOUNDING...IT/S QUITE
SURPRISING THAT CONVECTION HAS LASTED THIS LONG AND QUITE A
DISTANCE FROM THE MID LEVEL DISTURBANCE TO THE SOUTHWEST.

AN EARLIER CLUSTER OF STORMS NEAR EAGLE MOUNTAIN LAKE COLLAPSED
AND PUT OUT A NORTHEAST PROPAGATING OUTFLOW BOUNDARY THAT MADE IT
ALL THE WAY TO THE RED RIVER. ANOTHER OUTFLOW BOUNDARY GENERATED
FROM ONGOING CONVECTION BETWEEN WEATHERFORD AND COMANCHE WAS
MOVING NORTHEAST THROUGH PARKER...TARRANT...WISE...DALLAS AND
DENTON COUNTIES. POTENTIAL WIND GUSTS BETWEEN 25 TO 35 MPH WERE
NOTED PER VELOCITY MEASUREMENTS FROM KFWS AND TDWR/S IN THE
IMMEDIATE DFW METRO AREA. MEANWHILE ON THE LARGER SCALE...THE UPPER
HIGH CENTER TO OUR WEST CONTINUES TO WEAKEN AND MIGRATE EASTWARD
IN RESPONSE TO AN UPPER LOW ENTERING CENTRAL CALIFORNIA. THESE
WEATHER FEATURES BOTH AT THE SYNOPTIC AND MESOSCALE LEVELS WILL
MAKE FOR A CHALLENGING FORECAST TODAY. THE MODELS AND ASSOCIATED
MOS GUIDANCE CONTINUE TO STRUGGLE WITH THE MID LEVEL FEATURE TO
THE SOUTHWEST AS IT REMAINS WITHIN THE UPPER RIDGE OVER EXPANDING
OVER THE SOUTHERN PLAINS. HIGH RESOLUTION MODELS HAVE DIFFERING
SOLUTIONS ON CONVECTIVE EVOLUTION TODAY...THOUGH THE HRRR...WRF
EAST AND SREF SEEMS TO BE CLOSEST TO REALITY. GIVEN ALL THE
OUTFLOW BOUNDARIES AND UNCERTAINTY WITH THE THERMODYNAMIC
ENVIRONMENT NOT ANY ONE MODEL CAN BE COMPLETELY TRUSTED THE NEXT
24 HRS.

THE WEST-CENTRAL TEXAS MID LEVEL DISTURBANCE IS FORECAST TO DRIFT
SLOWLY NORTH OR NORTHEAST LATER TODAY INTO THIS EVENING...AS THE
LARGE SCALE RIDGE TO OUR NORTHWEST CONTINUES BREAK DOWN. WEAK
SOUTHWESTERLIES ALOFT ARE EXPECTED TO LIFT THE DISTURBANCE NORTHEAST
NORTHEAST OUT OF THE AREA BY WEDNESDAY MORNING. HOWEVER UNTIL THAT
OCCURS...WE WILL ADVERTISE BETTER CHANCES FOR SHOWERS AND STORMS
ACROSS AREAS MAINLY WEST OF THE I-35/35W CORRIDORS. IF DRY AIR
ALOFT CONTINUES TO SHOW ON THIS MORNING/S SOUNDING...THEN GUSTY
DOWNBURST WINDS WILL CONTINUE TO BE AN ISSUE WITH COLLAPSING
ACTIVITY. ANY TRAINING OR SLOW-MOVING STORMS WILL ALSO PRODUCE
LOCALIZED HEAVY RAIN AND POSSIBLE FLOODING AS WELL ACROSS THE
WESTERN HALF OF THE AREA. ISOLATED CONVECTIVE CHANCES SHOULD
LINGER ACROSS THE NORTHERN COUNTIES THIS EVENING AS THE DISTURBANCE
LIFTS OUT AND AWAY FROM THE AREA. UNCERTAINTY ON EVOLUTION OF
FEATURES AND RESULTING CONVECTION THROUGH TONIGHT CANNOT BE
STRESSED ENOUGH. ADJUSTMENTS WILL LIKELY NEED TO BE MADE THROUGH
THE DAY ON REALITY VERSUS MODEL PROGNOSIS.

THE WESTERN U.S TROUGH WILL BE SLOW TO MOVE WITH AN INTENSIFYING
HIGH PRESSURE RIDGE OVER THE SOUTHEAST U.S FROM WEDNESDAY INTO THE
WEEKEND. NORTH AND CENTRAL TEXAS WILL BE UNDER THE WESTERN PORTION OF
THE UPPER HIGH WITH HOT AND BREEZY CONDITIONS EACH DAY. HIGH
TEMPERATURES WILL LIKELY TOP 100 DEGREES ACROSS A FEW AREAS BY
THURSDAY AND BEYOND. THE SOUTHERN PERIPERHY OF THE UPPER HIGH MAY
BE WEAK ENOUGH WEDNESDAY AND POSSIBLY THURSDAY AFTERNOONS TO
ALLOW FOR DIURNAL SEABREEZE FRONTS AND ISOLATED CONVECTION TO
COME CLOSE TO OUR FAR SOUTHEAST COUNTIES. CONFIDENCE HOWEVER IS
LOW AND WILL KEEP RAIN CHANCES OUT OF THE FORECAST. THE UPPER
RIDGE DOES SHOW SIGNS OF WEAKENING EARLY NEXT WEEK WITH A STRONG
DISTURBANCE MOVING ACROSS THE NORTHERN TIER STATES. THIS MAY HELP
WEAKEN THE STRENGTH OF THE UPPER HIGH WITH TEMPERATURES MODIFYING
TOWARD SEASONAL NORMALS. NO RAINFALL IS EXPECTED THIS COMING
WEEKEND OR EARLY NEXT WEEK AT THIS TIME.

05/



&&


.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  96  78  98  78 100 /  20  10   5   0   0
WACO, TX              97  75  97  77 100 /  20  10   5   5   5
PARIS, TX             96  72  97  75  98 /  20  20   5   0   0
DENTON, TX            96  74  98  77 100 /  30  20   5   0   0
MCKINNEY, TX          97  75  96  75  98 /  20  10   5   0   0
DALLAS, TX            96  78  97  78  99 /  20  10   5   0   0
TERRELL, TX           97  74  96  76  98 /  10  10   5   0   0
CORSICANA, TX         97  75  97  76  99 /  10  10   5   5   5
TEMPLE, TX            96  75  97  75  99 /  20  10   5   5   5
MINERAL WELLS, TX     96  71  98  73 100 /  40  20   5   0   0

&&

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

&&

$$

25/05




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