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

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FXUS64 KFWD 041735 AAB
AFDFWD

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
1235 PM CDT SAT JUL 4 2015

.AVIATION...

CONCERNS...AFTERNOON CONVECTION NEAR/EAST OF THE METROPLEX AND
MVFR CIGS.

MVFR CIGS CURRENTLY AT KACT SHOULD LIFT AND GIVE WAY TO VFR
CONDITIONS SOON...BUT ANOTHER BRIEF ROUND IS POSSIBLE SUNDAY
MORNING AT KACT AND ACROSS THE CENTRAL AND EASTERN PORTIONS OF THE
METROPLEX.

ISOLATED TO WIDELY SCATTERED AFTERNOON CONVECTION SHOULD DEVELOP
MAINLY EAST OF THE I-35/35E CORRIDOR THIS AFTERNOON.
HOWEVER...MORNING CONVECTION REVEALED AN AREA OF CONVERGENCE ALONG
AND JUST NORTH OF I-30...EAST OF KDFW...THAT MAY DEVELOP A FEW
CELLS AROUND THE METROPLEX MID TO LATE AFTERNOON. THUS HAVE
RETAINED THE VCTS FOR THE 21-00Z TIME PERIOD.

SOUTHERLY WINDS AT 10-15 KNOTS SHOULD CONTINUE THROUGH THE
FORECAST.   75

&&

.UPDATE...

UPDATED THE FORECAST TO LOWER POPS FOR MOST LOCATIONS ACROSS NORTH
AND CENTRAL TEXAS THROUGH TONIGHT.

12Z SUBJECTIVE UPPER AIR ANALYSIS SHOWED A SHORTWAVE TROUGH OVER
ARKLATEX. WATER VAPOR SATELLITE IMAGERY SHOWED THIS FEATURE MOVING
SOUTHEAST WHICH SHOULD FAVOR WEAK SUBSIDENCE OVER NORTH TEXAS IN
ITS WAKE. AT THE 850 MB LEVEL...DEW POINTS WERE STILL QUITE
HIGH...OBSERVED AROUND 15 DEG C ACROSS THE SOUTHERN
PLAINS...HOWEVER THE WIND FIELD WAS CHARACTERIZED BY DIVERGENT OR
ANTICYCLONIC FLOW. THE EARLY MORNING MCS ACTIVITY THAT WAS
EXPECTED TO IMPACT OUR NORTHEASTERN CWA OCCURRED...BUT WAS
DISPLACED 75 MILES TO THE EAST ALONG THE LOUISIANA/ARKANSAS
BORDER. LATE MORNING SURFACE ANALYSIS DID NOT IDENTIFY ANY OBVIOUS
SURFACE BOUNDARIES ACROSS THE CWA. TEMPERATURES HAD ALREADY
CLIMBED INTO THE MID TO UPPER 80S FOR MOST LOCATIONS...WHILE DEW
POINTS WERE HOLDING STEADY IN THE LOWER 70S.

THE WARM START TO THE DAY COMBINED WITH DEW POINTS NOT MIXING OUT
DOES RAISE A CONCERN FOR THE POTENTIAL FOR AIR MASS THUNDERSTORM
DEVELOPMENT DURING THE PEAK HEATING HOURS OF THE DAY TODAY. THE
MAIN REASON POPS WERE LOWERED FOR THIS AFTERNOON IS THAT DESPITE
THE WARM TEMPERATURES AND RELATIVELY HIGH DEW POINT VALUES ACROSS
THE CWA...VISIBLE SATELLITE IMAGERY INDICATED THAT THERE WAS NO
SURFACE BASED CUMULUS FIELD ACROSS NORTH TEXAS. WITH SIMILAR
SURFACE CONDITIONS OBSERVED ACROSS CENTRAL TEXAS WHICH HAD A
SURFACE BASED CUMULUS FIELD...THE ASSUMPTION IS THAT LARGE SCALE
SUBSIDENCE IS WORKING AGAINST SURFACE BASED CUMULUS FROM
CONDENSING/DEVELOPING LATE THIS MORNING.

ASSUMING SUBSIDENCE IS IN PLACE...WHICH MAKES SENSE BASED ON THE
CWA`S RELATIVE POSITION TO THE SHORTWAVE TROUGH...RAIN SHOWER AND
THUNDERSTORM CHANCES ARE LOOKING LESS LIKELY FOR THIS AFTERNOON
AND EVENING. DROPPED POPS BY 10 PERCENT PRETTY MUCH ACROSS THE
REGION...SO MOST LOCATIONS NOW HAVE A 10 PERCENT CHANCE OF STORMS
FOR THIS AFTERNOON AND EVENING. LEFT SOME 20 PERCENT POPS ACROSS
THE FAR EASTERN AND SOUTHEASTERN CWA WERE DEW POINTS WERE IN OR
CLOSER TO THE MID 70S AS "POP UP" AIR MASS THUNDERSTORMS APPEAR TO
BE MORE LIKELY IN THESE LOCATIONS.

WILL CONTINUE TO MONITOR SHORT TERM CONDITIONS AND WILL UPDATE THE
FORECAST IF IT LOOKS LIKE STORMS ARE MORE OF A THREAT TO
INDEPENDENCE DAY FESTIVITIES THIS AFTERNOON AND EVENING. AS IT
LOOKS RIGHT NOW...MOST LOCATIONS WILL REMAIN DRY THROUGH TONIGHT.

CAVANAUGH

&&

.PREV DISCUSSION... /ISSUED 300 AM CDT SAT JUL 4 2015/
A BROAD VIEW OF THE CONUS REVEALS AN UPPER TROUGH EXTENDING FROM
THE GREAT LAKES SOUTHWARD TO THE TENNESSEE VALLEY...WITH THE BASE
OF THE TROUGH TAILING WESTWARD INTO THE SOUTHERN PLAINS. A
COMBINATION OF LIFT ASSOCIATED WITH THE UPPER LEVEL FEATURE...A
STATIONARY FRONT...AND OUTFLOW FROM EARLIER SHOWERS AND
THUNDERSTORMS CONTINUES TO ALLOW NOCTURNAL CONVECTION TO PERSIST
ACROSS CENTRAL AND SOUTHEAST OKLAHOMA EARLY THIS MORNING. AS THESE
MESOSCALE BOUNDARIES PUSH SOUTH...WE WILL LIKELY SEE SHOWERS AND
STORMS DEVELOP ACROSS THE NORTHEASTERN QUADRANT OF NORTH TEXAS
LATE THIS MORNING AND INTO THE AFTERNOON.

SOME OF THE COMPUTER MODELS CONTINUE TO ADVERTISE MORE WIDESPREAD
CONVECTION ACROSS THE REST OF THE REGION...BUT THE MOST RECENT
TRENDS INDICATE OTHERWISE. IT IS POSSIBLE THAT THE VEERED WINDS AT
THE LOWER LEVELS MAY BE HINDERING DEVELOPMENT THE FARTHER SOUTH
AND WEST OF THE UPPER TROUGH YOU GO. WHATEVER THE CASE...A FEW
MODELS SUCH AS THE NAM12 AND THE TEXAS TECH WRF APPEAR TO BE
HANDLING THE CURRENT PATTERN PRETTY WELL AND WE WILL USE THEM AS A
STARTING POINT FOR TODAY/S POPS...WITH THE HIGHEST NEAR
PARIS...AND THE LOWEST NEAR LAMPASAS. IF OUTFLOW PUSHES FARTHER
SOUTHWEST THAN PLANNED WE WILL ADJUST POPS ACCORDINGLY.

ANYWAY...MOISTURE AND INSTABILITY WILL BE SUFFICIENT TO ALLOW A
FEW STORMS TO BECOME STRONG WITH GUSTY WINDS AND HEAVY RAIN.
FOR THE EVENING FESTIVITIES...CONVECTION SHOULD BEHAVE SIMILAR TO
LAST NIGHT WITH ACTIVITY DIMINISHING AROUND SUNSET AS SURFACE
HEATING WANES. ISOLATED STORMS MAY PERSIST INTO THE NIGHT ACROSS
THE EAST AND NORTHEAST COUNTIES WHERE LIFT FROM THE TROUGH WILL BE
STRONGEST.

MOST ACTIVITY WILL HAVE SHIFTED EAST OF THE REGION BY
SUNDAY...AND GENERALLY HOT AND DRY CONDITIONS ARE EXPECTED ON
MONDAY. FLOW BECOMES MORE ZONAL ON TUESDAY...AND A WEAK SHORTWAVE
IS PROGGED TO MOVE EAST ACROSS THE SOUTHERN PLAINS TUESDAY AND
WEDNESDAY. SCATTERED SHOWERS AND THUNDERSTORMS ASSOCIATED WITH
THE SHORTWAVE WILL AFFECT MAINLY THE NORTHERN HALF OF THE REGION
ON TUESDAY...WITH ISOLATED THUNDERSTORMS LINGERING WEDNESDAY AS
THE WEAK FEATURE EXITS TO THE EAST. A STRENGTHENING UPPER RIDGE
WILL PROVIDE SEASONABLY HOT AND RAIN-FREE CONDITIONS DURING THE
SECOND HALF OF NEXT WEEK AND INTO NEXT WEEKEND.

30



&&


.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  93  76  93  77  93 /  20  10  10   5   5
WACO, TX              90  75  92  75  92 /  10  10  10   5   5
PARIS, TX             89  73  88  74  90 /  40  20  20  10  10
DENTON, TX            91  75  92  76  93 /  20  10  10   5   5
MCKINNEY, TX          92  75  91  75  91 /  20  10  10   5   5
DALLAS, TX            93  76  94  77  93 /  20  10  10   5   5
TERRELL, TX           90  74  90  74  91 /  20  10  10   5   5
CORSICANA, TX         91  75  92  75  92 /  20  10  10   5   5
TEMPLE, TX            90  74  92  75  92 /  10  10  10   5   5
MINERAL WELLS, TX     91  74  93  74  93 /  10  10  10   5   5

&&

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

&&

$$

75


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