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

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FXUS64 KFWD 281639
AFDFWD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
1139 AM CDT THU MAY 28 2015

.UPDATE...
THE CONVECTIVE COMPLEX THAT MOVED ACROSS THE RED RIVER COUNTIES
OVERNIGHT/THIS MORNING HAD LIFTED NORTHEAST LATE THIS MORNING.
THE DEPARTING COMPLEX LEFT A WEAK OUTFLOW BOUNDARY DRAPED ACROSS
THE NORTHERN ZONES...GENERALLY NORTH OF THE INTERSTATE 20
CORRIDOR. THIS BOUNDARY WILL MOST LIKELY BECOME A FOCUS FOR
ADDITIONAL CONVECTION THIS AFTERNOON. THE ATMOSPHERE ACROSS NORTH
TEXAS IS MOIST AND UNSTABLE. WE HAVE DECIDED TO PUT UP AN 18Z
SOUNDING TO ASSESS THE AFFECTS OF THE MORNING STORM COMPLEX ON THE
ATMOSPHERE ACROSS THE REGION. WE ANTICIPATE THAT STORMS WILL BE
MORE NUMEROUS THIS AFTERNOON/EVENING THAN THEY WERE YESTERDAY. WE
ARE ALSO CONCERNED THAT A SECOND ROUND OF CONVECTION...CURRENTLY
DEVELOPING ACROSS WEST TEXAS...WILL ORGANIZE THROUGH THE
AFTERNOON AND MOVE ACROSS NORTH TEXAS OVERNIGHT AS A SHORT WAVE
EJECTS FROM THE DESERT SOUTHWEST. STORMS THIS AFTERNOON AND
TONIGHT WILL BE CAPABLE OF THE FULL ARRAY OF SEVERE WEATHER
THREATS AND WILL ALSO BE HEAVY RAIN PRODUCERS. THEREFORE...WE WILL
LEAVE THE FLASH FLOOD WATCH IN EFFECT FROM THIS EVENING THROUGH
SATURDAY MORNING.

THE CURRENT FORECAST IS IN GOOD SHAPE AND NO UPDATE IS NEEDED AT
THIS TIME.

79

&&

.AVIATION...
/ISSUED 714 AM CDT THU MAY 28 2015/
/12Z TAFS/

SHORT TERM CONCERNS...THUNDER POTENTIAL AND OUTFLOW WIND SHIFT.

THUNDERSTORMS WILL DISRUPT NORTH DEPARTURES DURING THE MORNING
PUSH...BUT IT APPEARS ONLY SHOWERY CELLS ON THE TAIL END OF THE
LINE WILL IMPACT ANY METROPLEX AIRPORTS THIS MORNING. NEW CELLS IN
ADVANCE OF THE LINE HAVE DISRUPTED THE OUTFLOW...AND LIGHT
SOUTHERLY WINDS MAY PREVAIL THIS MORNING ACROSS THE METROPLEX. AT
THIS POINT...ANY NORTHERLY OUTFLOW SHOULD BE LIGHT...THUS DO NOT
ANTICIPATE A NEED TO SWITCH FLOW.

AFTER THE MORNING CONVECTION ENDS...WHAT WEAK OUTFLOW BOUNDARY
REMAINS MAY BE OBLITERATED BY BREEZY SOUTHERLY WINDS. ALTHOUGH
CONSIDERABLE INSTABILITY WILL BE AVAILABLE AGAIN TODAY...
UNCERTAINTY ABOUT FORCING AND A FOCUS FOR INITIATION MEANS
CONFIDENCE IS TOO LOW TO INCLUDE MENTION IN THE TAFS AT THIS TIME.
THE MOST LIKELY TIME FRAME FOR THUNDERSTORMS WILL BE LATE TONIGHT
INTO EARLY FRIDAY MORNING. WILL MAINTAIN VCTS UNTIL MESOSCALE
GUIDANCE CAN BETTER CAPTURE THE EVENT.

25


&&



.PREV DISCUSSION... /ISSUED 417 AM CDT THU MAY 28 2015/
WE CONTINUE TO WATCH YET ANOTHER MCS MOVING ACROSS NW TX/SW OK
THIS MORNING...THOUGH THERE ARE SIGNS VIA REGIONAL RADAR THAT IT
IS BECOMING OUTFLOW DRIVEN. THIS SYSTEM WILL LIKELY ARRIVE INTO
OUR NORTHWEST COUNTIES JUST BEFORE OR BY SUNRISE BUT WEAKEN AS
OUTFLOW OUTRUNS IT AND THE LLJ VEERS AND WEAKENS AROUND SUNRISE.
WILL CARRY LIKELY CHANCES ACROSS THE FAR NW COUNTIES THIS MORNING
AND EXPECT A RESIDUAL OUTFLOW BOUNDARY TO SET UP SOMEWHERE NORTH
OF I-20 AND EITHER SIDE OF I-35 DEPENDING ON STRENGTH OF THE
OUTFLOW MOVING OUT AHEAD OF THIS SYSTEM. DURING THE MORNING
HOURS...WE EXPECT THE ATMOSPHERE TO RECHARGE WITH PLENTY OF COLUMN
MOISTURE AVAILABLE PER PWAT VALUES AT OR ABOVE 1.5 INCHES. ANOTHER
SHORTWAVE DISTURBANCE WITHIN THE PROGRESSIVE WNW FLOW ALOFT WILL
TRIGGER MORE STORMS ACROSS THE HIGH PLAINS BY MIDDAY AND THIS
AFTERNOON AND MOVE WITH THE MEAN STEERING CURRENT ALOFT TOWARD
WESTERN NORTH TEXAS LATER THIS AFTERNOON INTO TONIGHT. THOUGH
DISCRETE STORMS ARE POSSIBLE EARLY IN STORM EVOLUTION...A
NOCTURNAL LLJ WILL LIKELY RESULT IN YET ANOTHER LINEAR MCS MOVING
ACROSS OVERNIGHT AND INTO FRIDAY. CAPE VALUES BETWEEN 2500-3500
J/KG... MID LVL LAPSE RATES HOVERING BETWEEN 7-8 DEG/C AND DEEP
LAYER SHEAR INCREASING TO BETWEEN 30-35 KTS ALL POINT TO MORE
SEVERE WEATHER FOR AT LEAST THE NW HALF OF THE CWA BY THIS
EVENING...BEFORE LOCALIZED HEAVY RAIN AND MORE FLOODING BECOME A
CONCERN AT NIGHT AND INTO FRIDAY MORNING. SOILS ARE SATURATED AND
RUN OFF IS LIKELY TO OCCUR QUICKLY FOR FLASH FLOODING AND FOR
AGGRAVATING THE ONGOING FLOODING ALREADY OCCURRING WITH SWOLLEN
RIVERS...LAKES AND CREEKS ACROSS THE AREA.

A BRIEF REPRIEVE MAY OCCUR LATE FRIDAY INTO FRIDAY EVENING...BEFORE
MORE STORMS WITH HEAVY RAIN FORM OFF A COLD FRONT MOVING THROUGH
THE TX PANHANDLE AND OK DURING THE AFTERNOON AND EVENING. THIS
ACTIVITY IS BEING ADVERTISED TO FORM INTO YET ANOTHER MCS AND
LIKELY CROSS THE RED RIVER AFTER MIDNIGHT FRIDAY NIGHT AND TRACK
INTO AT LEAST THE NORTHWEST HALF OF CWA THROUGH SATURDAY MORNING.
A FLASH FLOOD WATCH HAS BEEN POSTED STARTING THIS EVENING AND
LASTING THROUGH MIDDAY SATURDAY FOR AREAS GENERALLY NORTH OF A
GOLDTHWAITE-HILLSBORO-ATHENS LINE PER PROJECTIONS OF WIDESPREAD
1-3 INCHES OF RAIN WITH LOCALIZED HIGHER AMOUNTS. WE DECIDED TO
LEAVE OUT CENTRAL TEXAS AREAS FURTHER TO THE SOUTH DUE TO LOWER
TOTAL RAINFALL PROJECTIONS DURING THIS TIME PERIOD. HOWEVER...IF
STORMS SYSTEMS TRACK FURTHER SOUTH THAN EXPECTED...THEN IT/S
HIGHLY PROBABLE THE FLASH FLOOD WATCH WOULD NEED TO BE EXTENDED
SOUTH AND INCLUDE OUR ENTIRE CWA. AS FOR THE THREAT FOR SEVERE
WEATHER BEYOND TONIGHT...CONFIDENCE IS LOW ON PINPOINTING THE
HIGHER RISK AREAS. THAT SAID...LOCALIZED SEVERE STORMS ARE
POSSIBLE JUST ABOUT ANYWHERE ACROSS THE AREA WITH INSTABILITY
DURING THE DAYTIME HOURS REMAINING IMPRESSIVE DESPITE THE RELATIVE
WEAK BULK SHEAR BELOW 30 KTS.

THE MAIN SHORTWAVE TROUGH AND ASSOCIATED COLD FRONT ARE EXPECTED
TO TRACK ACROSS THE SOUTHERN PLAINS LATE SATURDAY INTO SATURDAY
NIGHT PUSHING THE HIGHER RISK FOR SEVERE STORMS AND ANY FLOODING
TO AREAS SOUTH OF THE I-20 CORRIDOR. WEAK NNW FLOW ALOFT WILL
PREVAIL OVERHEAD SUNDAY INTO EARLY NEXT WEEK...AS MEDIUM RANGE
MODELS STALL AN UPPER TROUGH /OR LOW/ TO OUR EAST...WITH THE
EUROPEAN AND CANADIAN MODELS MORE OPEN...WEAKER AND FURTHER EAST
THAN THE GFS. AN UPPER RIDGE WILL BUILD INTO WEST TEXAS. THIS
SHOULD FINALLY BRING AN END TO THE ROUNDS OF SEVERE WEATHER AND
WIDESPREAD RAINS...THOUGH CERTAINLY ISOLATED DIURNAL CONVECTION
COULD OCCUR EAST OF I-35 WHERE THE RICHEST COLUMN MOISTURE WILL
RESIDE. TEMPERATURES THROUGH SATURDAY WILL LIKELY BE 5-10 DEGREES
BELOW CLIMATOLOGICAL NORMALS...RETURNING TO NEAR NORMAL VALUES
EARLY NEXT WEEK IN THE MID 80S.

05/



&&


.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  85  70  83  68  81 /  40  70  60  60  60
WACO, TX              86  71  84  67  83 /  20  50  60  30  50
PARIS, TX             82  70  81  67  79 /  30  50  60  60  60
DENTON, TX            84  70  81  67  81 /  40  70  60  60  60
MCKINNEY, TX          84  69  82  67  80 /  40  60  60  60  60
DALLAS, TX            85  71  83  69  82 /  30  60  60  60  60
TERRELL, TX           84  71  84  68  81 /  20  50  60  50  60
CORSICANA, TX         84  71  84  68  82 /  20  40  60  30  50
TEMPLE, TX            87  71  85  67  83 /  30  40  50  30  40
MINERAL WELLS, TX     83  68  82  66  80 /  50  70  40  60  60

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH FROM 6 PM CDT THIS EVENING THROUGH SATURDAY
MORNING FOR TXZ091>095-100>107-115>123-129>135-141>146.


&&

$$

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