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

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FXUS64 KFWD 071152 AAA
AFDFWD

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
652 AM CDT TUE JUL 7 2015

.AVIATION...
/12Z TAFS/

CONCERNS...MVFR CEILINGS AND THUNDER POTENTIAL.

SHOWERS AND THUNDERSTORMS ACROSS WESTERN NORTH TEXAS WILL DIMINISH
IN INTENSITY THIS MORNING...BUT OUTFLOW FROM THE ONGOING ACTIVITY
MAY AID IN ADDITIONAL DEVELOPMENT CLOSER TO THE METROPLEX AT PEAK
HEATING THIS AFTERNOON.

AS A SHORTWAVE APPROACHES TONIGHT...A VIGOROUS LLJ WILL ENSUE...
INITIATING WIDESPREAD SHOWERS AND THUNDERSTORMS IN THE VICINITY OF
A NEARLY STATIONARY FRONTAL BOUNDARY. AT THIS TIME...IT APPEARS
THIS ACTIVITY WOULD STILL BE NORTHWEST OF METROPLEX TAF SITES
DURING THE OVERNIGHT LULL IN TRAFFIC. BUT AS THE IMPULSE ALOFT
MOVES EAST...THE ACTIVITY MAY EASE INTO THE METROPLEX DURING THE
MORNING PUSH.

25

&&


.PREV DISCUSSION... /ISSUED 411 AM CDT TUE JUL 7 2015/
LATEST UPPER AIR ANALYSIS INDICATED A WEAKNESS IN THE MID LEVEL
HEIGHT FIELDS THAT RESIDES ALONG A LINE FROM THE BIG BEND OF
TEXAS...THROUGH CENTRAL OKLAHOMA AND NORTHEAST INTO THE MIDWEST.
AT THE SURFACE A COLD FRONT WAS LOCATED IN THE VICINITY OF THE
MID LEVEL WEAKNESS...AND AS OF NOW WAS LOCATED FROM JUST NORTH OF
MIDLAND TO NEAR VERNON AND INTO THE OKLAHOMA CITY METRO. THE FRONT
WAS EFFECTIVELY STATIONARY BUT IT DID MAKE SOME SOUTHEASTWARD
PROGRESS LAST NIGHT AS A RESULT OF RAIN COOLED OUTFLOWS FROM
EXTENSIVE CONVECTIVE ACTIVITY.

ALSO OF NOTE IN THE UPPER LEVEL ANALYSIS WAS AN UPPER LEVEL RIDGE
AXIS AT 250MB THAT WAS SUPERIMPOSED ABOVE THE MID LEVEL WEAKNESS
AND COLD FRONT. CONVECTION DEVELOPING WITHIN A HIGH ALTITUDE RIDGE
IS AN INTERESTING OCCURRENCE FOR OUR REGION...AS IT IS USUALLY
SOMETHING THAT OCCURS IN THE TROPICS. HAVING THIS UPPER RIDGE OVER
THE AREA MEANS THAT THE TROPOPAUSE IS UNUSUALLY HIGH OVER THE
REGION...WHICH ALLOWS FOR VERY DEEP AND TALL CONVECTION. THE
CONVECTION NORTHWEST OF THE REGION LAST NIGHT AND THIS MORNING
HAD CLOUD TOPS OF -80C TO -85C. THIS IS INDICATIVE OF CONVECTION
THAT IS CAPABLE OF HEAVY DOWNPOURS SINCE THERE IS SO MUCH MORE
VERTICAL SPACE FOR HYDROMETEORS TO DEVELOP IN A THUNDERSTORM
WHICH OFTEN RESULTS IN VERY HIGH RAINFALL RATES. THE THREAT FOR
HEAVY RAINFALL EXISTS WITH THIS SYNOPTIC SET UP DESPITE THE
RELATIVELY DRY AIR AND LOWISH HUMIDITY SEEN ON THE REGIONAL
SOUNDINGS LAST NIGHT.

THE FORECAST CHALLENGE IS DETERMINING WHERE THIS DEEP CONVECTION
WILL OCCUR DUE TO THE RISK FOR HEAVY RAINFALL. ALL OF THE LATEST
MODEL GUIDANCE HAS SHIFTED THE LOCATION OF THE FRONTAL BOUNDARY
AND QPF AXIS FARTHER TO THE SOUTHEAST THAN THE PREVIOUS MODEL
RUNS. THIS IS ALSO CONFIRMED IN THE SHORT-TERM HIGH-RES MODEL
GUIDANCE. EXPECT THE FRONT TO REMAIN STATIONARY TODAY...BUT IT
SHOULD BEGIN TO MOVE SOUTHEAST BY LATE AFTERNOON AND EARLY
EVENING AS DIFFERENTIAL HEATING OCCURS. THE FRONT SHOULD MOVE
INTO THE NORTHWESTERN ZONES BY THIS EVENING...WHERE IT WILL BECOME
A FOCUS FOR SLOW MOVING STORMS TO DEVELOP AND TRACK ALONG. IN
ADDITION TO THE FRONT...A SLOW MOVING SHORTWAVE TROUGH THAT IS
CURRENTLY MOVING INTO WEST TEXAS WILL TRACK SLOWLY EAST-NORTHEAST
WITH DYNAMIC LIFT INCREASING OVER THE REGION LATER TODAY AND INTO
TONIGHT. HAVE BUMPED UP THE RAIN CHANCES OVER THE ENTIRE
REGION...BUT THE NORTHWEST ZONES WILL SEE THE GREATEST COVERAGE
OF RAIN WHERE POPS OF 60-80 PERCENT ARE NOW FORECAST. GIVEN THE
POTENTIAL FOR SLOW MOVING STORMS PRODUCING OVER 2 INCHES PER HOUR
RAINFALL RATES ALONG THE FRONT...WE ARE ALSO HIGHLIGHTING A
POTENTIAL FOR FLASH FLOODING OVER THE NORTHWESTERN ZONES WHERE A
FLASH FLOOD WATCH HAS BEEN ISSUED THROUGH NOON WEDNESDAY.

FOR TODAY...THE CURRENT CONVECTIVE COMPLEX ACROSS WEST TEXAS
SHOULD MAKE SLOW AND STEADY PROGRESS EASTWARD THROUGH THE MORNING
HOURS...LIKELY IMPACTING THE WESTERN ZONES THROUGH MIDDAY. AFTER
MIDDAY...EXPECT THE COMPLEX TO BECOME MORE DISORGANIZED AND
POSSIBLY DISSIPATE...BUT IT SHOULD SEND OUT AN OUTFLOW BOUNDARY
TO HELP KICK OFF ADDITIONAL ISOLATED TO SCATTERED SHOWERS AND
STORMS OVER THE CENTRAL AND EASTERN ZONES. POPS ARE NEAR 20-30
PERCENT SOUTHEAST OF A GOLDTHWAITE TO DFW TO SHERMAN LINE...WITH
THE LIKELY POPS RESERVED FOR THE NORTHWEST ZONES. TEMPERATURES
TODAY ARE TRICKY...BUT GENERALLY HAVE FORECAST LOW TO MID 80S IN
THE NORTHWEST WHERE CLOUDS/RAIN SHOULD KEEP TEMPS COOL...WITH
LOWER 90S OVER THE CENTRAL AND EASTERN ZONES.

BELIEVE THE GREATEST THREAT FOR HEAVY RAIN AND FLOODING WILL COME
TONIGHT NORTHWEST OF A SHERMAN TO FORT WORTH TO COMANCHE LINE.
CONVECTION SHOULD BLOSSOM THIS EVENING AND OVERNIGHT AS A
NOCTURNAL LOW LEVEL JET ENHANCES CONVERGENCE NEAR THE FRONT AND
LIFT FROM THE SHORTWAVE TROUGH REACHES ITS MAXIMUM. THIS COULD
RESULT IN A TRAINING BAND OF SLOW MOVING STORMS WITH MULTI-INCH
RAINFALL POSSIBLE IN THE WATCH AREA. POPS WILL RANGE FROM 80
PERCENT IN THE NORTHWEST...RAPIDLY DECREASING OFF TO THE
SOUTHEAST. THIS ROUND OF RAIN AND STORMS WILL CONTINUE INTO
WEDNESDAY MORNING...BUT SHOULD END BY THE AFTERNOON AS THE
SHORTWAVE LIFTS NORTHEAST AND THE FRONTAL BOUNDARY ALSO RETREATS
NORTH DUE TO INCREASING SOUTHERLY LOW LEVEL FLOW.

THE REMAINDER OF THE FORECAST IS PRETTY SIMPLE. AN UPPER LEVEL
HIGH WILL BUILD INTO THE REGION FROM THE EAST DURING THE MID-LATE
WEEK PERIOD WITH TEMPERATURES BEGINNING A SLOW CLIMB. HIGHS SHOULD
REACH THE UPPER 90S IN MOST AREAS BY EARLY NEXT WEEK. GUIDANCE HAS
COME IN A LITTLE COOLER WITH TEMPS EARLY NEXT WEEK AS IT IS LESS
ENTHUSIASTIC ABOUT BRINGING THE LOW LEVEL WINDS AROUND TO THE
WEST AND KEEPING THEM MORE SOUTHERLY. THIS MAY BE ENOUGH TO WARD
OFF DFW AND WACO/S FIRST 100 DEGREE READING THROUGH THIS 7 DAY
FORECAST PERIOD. REGARDLESS...IT IS CERTAINLY GOING TO BE HOT AND
DRY WELL INTO NEXT WEEK.

TR.92

&&



.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  91  74  90  75  93 /  30  50  30   5   5
WACO, TX              91  76  93  75  93 /  20  10   5   0   5
PARIS, TX             91  75  89  72  91 /  20  40  20   5   5
DENTON, TX            87  71  87  73  92 /  40  70  40  10   5
MCKINNEY, TX          90  74  90  74  92 /  30  50  30   5   5
DALLAS, TX            92  76  91  75  93 /  30  40  20   5   5
TERRELL, TX           92  75  92  73  92 /  20  20  10   5   5
CORSICANA, TX         92  76  92  74  92 /  20  10   5   0   5
TEMPLE, TX            91  76  92  74  92 /  20  10   5   0   5
MINERAL WELLS, TX     84  70  90  72  92 /  60  80  40  10   5

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH WEDNESDAY MORNING FOR TXZ091-092-
100>102-115-116-129.


&&

$$

25/92


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