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

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000
FXUS64 KFWD 290452 AAC
AFDFWD

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
1152 PM CDT MON JUL 28 2014

.AVIATION...

A COLD FRONT CURRENTLY SOUTH OF THE KACT REGION WILL REMAIN NEARLY
STATIONARY OVERNIGHT...BUT THE WESTERN END SHOULD BEGIN TO LIFT
NORTHWARD ON TUESDAY. THIS WILL RESULT IN LIGHT NORTHERLY WINDS
OVERNIGHT AND TUESDAY MORNING THEN WINDS WILL GO EASTERLY 10 KNOTS
OR LESS AROUND MIDDAY AND THEN SOUTHEASTERLY IN THE LATE AFTERNOON.

OTHERWISE...THE TERMINALS WILL REMAIN VFR THROUGH THEM FORECAST
WITH SCATTERED CIGS AROUND 12 KFT POSSIBLE ACROSS THE METROPLEX AT
TIMES TONIGHT. AS FOR CONVECTION...IT SHOULD REMAIN WEST OF THE
TERMINALS TONIGHT. HOWEVER...WITH THE COLD FRONT SO CLOSE TO
KACT...THERE COULD BE SOME ISOLATED TO WIDELY SCATTERED ACTIVITY
LATE TONIGHT (08-12Z) AND ON TUESDAY. LOW CONFIDENCE IN THIS
OCCURRENCE PRECLUDES US FROM ADDING IT TO THE TAF. 75

&&

.UPDATE...
THE COLD FRONT...AS WELL AS THE PRECIPITATION...HAD EXITED THE CWA
AS OF 930 PM. WE EXPECT A QUIET REMAINDER OF THE EVENING WITH
DRIER AND COOLER AIR IN PLACE.

ALTHOUGH THE BEST ISENTROPIC LIFT WILL BE WEST OF THE REGION
OVERNIGHT...THERE SHOULD BE ENOUGH MOISTURE AND LIFT OVER THE
FRONTAL SURFACE ACROSS NORTH TEXAS TO GENERATE SCATTERED SHOWERS
AND A FEW THUNDERSTORMS. THEREFORE...WE WILL KEEP SOME LOW POPS IN
THE FORECAST OVERNIGHT/TUESDAY MORNING.

OTHER THAN REMOVING EVENING POPS...NO MAJOR CHANGES ARE NEEDED
WITH THIS UPDATE.

79

&&

.PREV DISCUSSION... /ISSUED 342 PM CDT MON JUL 28 2014/
A WEAK COLD FRONT ENTERED CENTRAL TEXAS THIS AFTERNOON BUT HAS
BECOME NEARLY STATIONARY...DESPITE INCREASING SURFACE WINDS BEHIND
THE BOUNDARY. THUNDERSTORMS HAVE DEVELOPED ALONG AND BEHIND THE
SURFACE BOUNDARY AS MEAGER MECHANICAL FORCING ABOVE THE FRONTAL
SLOPE IS HELPING VERY UNSTABLE AIR OVERCOME DEEP SUBSIDENCE. JULY
SUNSHINE AND STRONG SURFACE HEATING NORTH OF THE BOUNDARY HAS
ALLOWED POST-FRONTAL AIR TO MIX WITH THE AIR ABOVE THE FRONTAL
INVERSION...RESULTING IN THE UNUSUAL SITUATION OF SURFACE-BASED
CONVECTION BEHIND A FRONTAL BOUNDARY.

WITH CAPE VALUES EXCEEDING 2000J/KG WHERE CONVECTION IS ONGOING...
AND PW VALUES TOPPING 2 INCHES...STRONG UPDRAFTS WILL ALLOW FOR
SIGNIFICANT PRECIP LOADING. THE WEAK SHEAR IS RESULTING IN SLOW-
MOVING STORMS CAPABLE OF VERY HEAVY RAIN...BUT INDIVIDUAL UPDRAFTS
WILL GENERALLY BE TOO SHORT-LIVED FOR ANY FLOODING CONCERNS. RAIN-
COOLED AIR AND ASSOCIATED CLOUD COVER HAVE BEGUN TO NARROW DEW
POINT DEPRESSIONS AT THE SURFACE...BUT SOME CELLS WILL STILL BE
CAPABLE OF PRODUCING DOWNBURST WINDS IN EXCESS OF 50 MPH...
PARTICULARLY WITH COLLAPSING STORMS.

ALTHOUGH COOL/DRY ADVECTION BEHIND THE BOUNDARY HAS SO FAR BEEN
MODEST...THE 60-DEGREE ISODROSOTHERM IS EXPECTED TO SLIP SOUTH OF
THE RED RIVER TONIGHT. THE NORTHERN EXTENT OF THE ONGOING
CONVECTION...WHICH IS NOW FROM SHERMAN/DENISON TO NEAR LAKE
TAWAKONI...WILL DRIFT SOUTHWESTWARD AS DRIER AIR INVADES FROM THE
NORTHEAST. THE AXIS OF ELEVATED INSTABILITY...AND THE PRIMARY
FOCUS FOR ACTIVITY TONIGHT...WILL SET UP ACROSS THE SOUTHWESTERN
ZONES. THIS CONVECTION MAY PERSIST INTO THE LATE MORNING ON
TUESDAY. AN UNUSUAL GRADIENT BETWEEN DRY CONDITIONS IN EAST TEXAS
AND MARITIME TROPICAL AIR IN WESTERN NORTH TEXAS WILL KEEP THE
TUESDAY AFTERNOON ACTIVITY PRIMARILY WEST OF I-35.

THE FIRST OF A PAIR OF SHORTWAVES EMBEDDED IN NORTHWEST FLOW ALOFT
WILL SWING INTO OKLAHOMA ON WEDNESDAY...WITH ITS TRAILING FRIEND
EVENTUALLY GLIDING THROUGH NORTH TEXAS ON THURSDAY WITH AN
ASSOCIATED COLD FRONT. THE BEST CHANCES FOR PRECIPITATION
THROUGHOUT THE PERIOD WILL BE IN AREAS NORTH OF THE I-20 CORRIDOR
AND IN NORTHEAST TEXAS...BUT AREAS FARTHER SOUTH COULD SEE SOME
ACTIVITY THURSDAY AFTERNOON AS THE FRONT MOVES THROUGH THE REGION.
PORTIONS OF CENTRAL TEXAS COULD REACH THE CENTURY MARK WEDNESDAY
IF THE CLOUD COVER AND PRECIPITATION FAIL TO MAKE AN IMPACT
THERE...PARTICULARLY IN AREAS THAT MISS THE RAINFALL MONDAY AND
TUESDAY. THURSDAY TEMPERATURES ARE LARGELY DEPENDENT ON THE
EXTENT OF RAINFALL AND LINGERING CLOUD COVER...BUT EVEN CENTRAL
TEXAS WILL SEE MILDER AIR ARRIVE ON THURSDAY AND FRIDAY.

MID-SUMMER COLD FRONTS ARE ALWAYS DIFFICULT FOR GUIDANCE TO
HANDLE...BUT THE UPPER PATTERN SUGGESTS THAT THE BOUNDARY SHOULD
BE ABLE TO CLEAR THE CWA...BRINGING AN END TO RAIN CHANCES
THURSDAY NIGHT. HOWEVER...CHOSE TO LEAVE SOME LINGERING POPS IN
THE SOUTHEAST ON FRIDAY IN CASE THE FRONT IS NOT SO INCLINED.

NORTHWEST FLOW WILL CONTINUE INTO THE UPCOMING WEEKEND...AND NORTH
WINDS SHOULD PREVAIL AT THE SURFACE. ABUNDANT SUNSHINE WILL STILL
ALLOW TEMPERATURES TO REACH THE 90S...BUT THE HUMIDITY MAY BE A
BIT MORE TOLERABLE THAN IT USUALLY IS IN EARLY AUGUST.

25



&&


.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  74  95  74  95  74 /  20  20  10  20  40
WACO, TX              74  96  73  98  74 /  30  30  10  10  20
PARIS, TX             69  90  69  81  67 /  10  10  30  50  60
DENTON, TX            71  94  73  94  71 /  20  20  20  30  40
MCKINNEY, TX          70  92  71  93  72 /  20  20  20  40  50
DALLAS, TX            75  94  75  95  74 /  20  20  10  20  40
TERRELL, TX           71  94  71  94  73 /  20  20  10  30  40
CORSICANA, TX         73  94  72  96  72 /  20  20  10  10  30
TEMPLE, TX            73  96  72  98  74 /  30  30  20  10  20
MINERAL WELLS, TX     70  94  71  97  73 /  30  30  20  20  30

&&

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

&&

$$

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