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

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FXUS64 KFWD 171404
AFDFWD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
904 AM CDT SUN AUG 17 2014

.UPDATE...
CONVECTION DEVELOPED OVERNIGHT NEAR YESTERDAY/S MCV LEADING TO AN
AREA OF RAIN AND STORMS GENERALLY NEAR THE METROPLEX. THE MORNING
BALLOON SHOWS PRECIPITABLE WATER IS WELL ABOVE 2 INCHES...BUT
THERE IS A LAYER OF DRIER AIR IN THE LOW LEVELS THAT IS KEEPING
THE HEAVY RAINFALL THREAT LOCALIZED BENEATH THE STRONGER
THUNDERSTORM CORES. OUTSIDE OF STORMS...A LOT OF THE PRECIPITATION
IS EVAPORATING BEFORE REACHING THE GROUND WHICH IS LIMITING
RAINFALL RATES AND AMOUNTS. THIS CONVECTIVE COMPLEX WILL CONTINUE
OVER THE CENTRAL PARTS OF THE CWA THROUGH THE NEXT FEW
HOURS...BUT WILL LIKELY DIMINISH IN COVERAGE AND INTENSITY EARLY
THIS AFTERNOON. HOWEVER ADDITIONAL CONVECTION SHOULD POP UP OVER
MAINLY THE SOUTHERN ZONES THIS AFTERNOON WHERE STRONGER DAYTIME
HEATING WILL OCCUR. HAVE UPDATED TO LOWER HIGH TEMPS WHERE
RAINFALL WILL BE MOST PREVALENT THIS MORNING...AND HAVE AMENDED
SHORT TERM POPS TO ALIGN WITH RADAR TRENDS AND THE EXPECTED DECAY
AND GENERAL SOUTHWARD TRANSITION OF CONVECTIVE ACTIVITY BY
AFTERNOON. TR.92

&&

.AVIATION...
/ISSUED 642 AM CDT SUN AUG 17 2014/
/12Z TAFS/

CONCERNS...THUNDER AT THE AIRPORTS THE NEXT 24 HOURS.

THE CONVECTIVE TRENDS OVER THE NEXT 24 HOURS IS QUITE A CHALLENGE
AND DEPENDS ON SEVERAL SMALL SCALE AND LARGER SCALE FEATURES.
THUNDERSTORMS ARE CURRENTLY MOVING THROUGH THE METROPLEX WITH
SCATTERED SHOWERS STARTING TO DEVELOP NORTH AND WEST OF THE KACT
AIRPORT. HIGH MOISTURE CONTENT IN THE ATMOSPHERE THIS MORNING IS
ALLOWING FOR THE SHOWERS AND STORMS TO PRODUCE HIGH RAINFALL RATES
RESULTING IN PERIODS OF HEAVY RAIN AND REDUCED VISIBILITIES. SHORT
TERM MODELS INDICATE THERE COULD BE A SHORT BREAK IN THE SHOWERS
AND STORMS THIS MORNING...BUT THERE ALSO MAY CONTINUE TO BE
ISOLATED ACTIVITY THROUGH THE MORNING AS LARGE SCALE LIFT FROM AN
APPROACHING SHORTWAVE SPREADS OVER THE REGION. WILL CONTINUE WITH
A VCTS MENTION IN THE METROPLEX AND A VCSH MENTION THROUGH THE
MORNING HOURS. BETTER CHANCES FOR RAIN/STORMS ARE EXPECTED AGAIN
THIS AFTERNOON AND WILL CARRY VCTS INTO THE AFTERNOON HOURS FOR
ALL THE TAF SITES. WILL ALSO TEMPO FOR THUNDER FOR MUCH OF THE
AFTERNOON AND EARLY EVENING HOURS. ANY THUNDERSTORMS THIS
AFTERNOON OR EVENING COULD PRODUCE STRONG WINDS OR DAMAGING
DOWNBURSTS AND THE TEMPOS MAY HAVE TO BE UPDATED TO REFLECT THIS.

RAIN CHANCES OVERNIGHT WILL SHIFT TO AREAS SOUTH OF INTERSTATE 20
AND WILL CONTINUE WITH A VCSH MENTION OVERNIGHT AT KACT BUT REMOVE
THE PRECIPITATION FROM THE METROPLEX TAF SITES. IT IS POSSIBLE
THUNDERSTORMS MAY OCCUR OVERNIGHT AROUND KACT BUT THEY SHOULD BE
MORE ISOLATED IN NATURE.

82/JLD


&&



.PREV DISCUSSION... /ISSUED 346 AM CDT SUN AUG 17 2014/
MORE CHALLENGES LIE AHEAD TODAY INTO MONDAY AS NORTH TEXAS
REMAINS UNDERNEATH WEAK DIFFLUENT MID LEVEL FLOW ALOFT. THERE ARE
MANY FEATURES ALOFT TO NOTE. AN UPPER HIGH CONTINUED TO BE
CENTERED OVER ARIZONA WHILE A STRONG SHORTWAVE WAS MOVING
SOUTHEAST OVER THE MID MISSISSIPPI VALLEY. A VORTICITY AXIS
TRAILED SOUTHWEST FROM THIS DISTURBANCE INTO OKLAHOMA AND THE
TEXAS PANHANDLE. IN ADDITION...A TUTT LOW REMAINED OVER THE
WESTERN GULF OF MEXICO. MEANWHILE...THE ENVIRONMENT REMAINS VERY
MOIST WITH PWATS EXPECTED TO BE BETWEEN 1.8 AND 2.2 INCHES THROUGH
MONDAY. AT THE SURFACE THERE WAS A WEAK LOW NEAR THROCKMORTON WITH
AN OUTFLOW BOUNDARY SLIDING SOUTHEAST ACROSS OUR WESTERN COUNTIES.
ALSO...A MESOSCALE VORTEX /MCV/ WAS NOTED ON REGIONAL RADARS TRACKING
EAST ACROSS THE RED RIVER VALLEY EARLY THIS MORNING. HOW EACH OF
THESE FEATURES AFFECTS THE FORECAST THROUGH TONIGHT IS
UNCERTAIN...BUT WE CERTAINLY HAVE TO ACCOUNT FOR ALL OF THEM.

PER CURRENT WEATHER TRENDS...IT APPEARS THE HRRR/RAP AND WRF EAST
MODELS HAVE THE BEST HANDLE ON THINGS WITH THE TX TECH WRF A
PLAUSIBLE SECONDARY OPTION. THE CONVECTIVELY-INDUCED MCV ALONG THE
RED RIVER VALLEY WILL BE THE MAIN FOCUS THIS MORNING AND WILL
CARRY LIKELY RAIN CHANCES FROM DFW NORTHEAST TOWARD PARIS. THIS
AFTERNOON WILL BE MORE CHALLENGING REGARDING HOW THINGS PLAY OUT.
DAYTIME HEATING...OUTFLOW BOUNDARIES...SUBSIDENCE BEHIND THE
MORNING MCV AND THE VORTICITY AXIS ALL COULD PLAY ROLES ON
CONVECTIVE EVOLUTION. WE HAVE PLACED HIGHEST RAIN CHANCES ALONG
AND JUST SOUTH OF I-20 FOR THIS AFTERNOON AS THE OUTFLOW BOUNDARY
STALLS. SUBSIDENCE BEHIND THE MORNING MCV SHOULD BE MORE
NEGLIGIBLE ACROSS THESE AREAS AS WELL. ACQUIRED POPS WERE LOWERED
INTO THE CHANCE CATEGORY DUE TO THE AFOREMENTIONED UNCERTAINTY.

CURRENT THINKING IS THE OUTFLOW BOUNDARY SETS UP THIS AFTERNOON
JUST SOUTH OF I-20. SHOWERS AND STORMS THAT DEVELOP WILL BE SLOW
MOVERS WITH ONLY WEAK WEST-NORTHWEST FLOW ALOFT. LOCALIZED VERY
HEAVY RAINFALL AND FLOODING IS HIGHLY POSSIBLE DUE TO THE VERY
MOIST ATMOSPHERE IN PLACE. THE BULK OF THE RICHER MOISTURE WILL
BE ELEVATED...THOUGH LOW LEVELS ARE SLIGHTLY MORE MOIST TODAY
VERSUS YESTERDAY. ENOUGH DRY AIR ALOFT WILL EXIST FOR PRECIPITATION
LOADING AND LOCALIZED DOWNBURST WINDS ONCE AGAIN WITH STRONGER
STORMS. WE WILL FOCUS BEST RAIN CHANCES SOUTH OF I-20 TONIGHT INTO
MONDAY AS THE VORT AXIS PROGRESSES THROUGH THE AREA AND WHERE
SURFACE BOUNDARIES ARE LIKELY TO SET UP. LOCALLY HEAVY RAINFALL
AND FLOODING WILL CONTINUE TO BE A CONCERN. AT THIS TIME...HEAVIER
RAINS ARE NOT EXPECTED TO BE WIDESPREAD AND WE DO NOT ANTICIPATE
ISSUING ANY FLOOD OR FLASH FLOOD WATCHES.

SUBSIDENCE BEGINS TAKING HOLD LATER MONDAY NIGHT INTO TUESDAY...AS
THE VORT AXIS SLIDES OVER AND EVENTUALLY EXITS THE AREA. ENOUGH
RESIDUAL MOISTURE WILL RESIDE FOR ISOLATED AFTERNOON/EVENING
STORMS ON TUESDAY AND HAVE LET THAT RIDE IN THE FORECAST. BY
WEDNESDAY...THE UPPER HIGH SLIDES EAST IN RESPONSE TO AN UPPER LEVEL
TROUGH DEEPENING OVER THE FAR WESTERN U.S. THE UPPER HIGH WILL
STRENGTHEN AND ANCHOR OVER THE SOUTHEAST U.S FOR THE LATTER HALF
OF THE WEEK INTO NEXT WEEKEND. NORTH TEXAS WILL BE UNDERNEATH THE
WESTERN SIDE OF THE UPPER HIGH. HIGH TEMPERATURES WILL HEAT UP
AND REACH THE CENTURY MARK ONCE AGAIN ACROSS PARTS OF THE AREA.
THE UPPER HIGH APPEARS STRONGER OVER OUR AREA VERSUS YESTERDAY/S
MODEL RUNS WHICH MEANS SUBSIDENCE WILL BE STRONGER AS WELL. HAVE
LEFT THE ENTIRE CWA RAIN FREE THE LATTER HALF OF THE WEEK INTO
NEXT WEEKEND.

05/



&&


.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  90  77  99  78 100 /  60  20  20  10  10
WACO, TX              91  75  99  76  99 /  40  40  30  10  10
PARIS, TX             88  72  96  73  96 /  90  20  10  10  10
DENTON, TX            92  75  99  75 100 /  40  20  10  10  10
MCKINNEY, TX          90  74  98  74  99 /  90  20  10  10  10
DALLAS, TX            90  78  99  79  99 /  80  20  20  10  10
TERRELL, TX           88  75  98  75  99 /  90  20  30  10  10
CORSICANA, TX         89  75  97  75  98 /  40  40  30  10  10
TEMPLE, TX            94  75  98  74  99 /  40  40  20  10  10
MINERAL WELLS, TX     94  73  99  73 101 /  30  20  20  10  10

&&

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

&&

$$

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