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

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FXUS64 KFWD 310241 AAB
AFDFWD

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
941 PM CDT WED JUL 30 2014

.UPDATE...
SHOWERS AND STORMS ARE NOW INCREASING IN COVERAGE ACROSS SOUTHERN
OKLAHOMA NORTH OF THE STATIONARY BOUNDARY DRAPED FROM GAINESVILLE
SOUTHEAST TOWARD EMORY. IN ADDITION...AS ONE SHORTWAVE DISTURBANCE
MOVES SOUTHEAST TOWARD THE ARKLATEX...ANOTHER SHORTWAVE CAN BE
SEEN ON WATER VAPOR IMAGERY MOVING SLOWLY SOUTHEAST ACROSS THE
HIGH PLAINS OF EASTERN COLORADO AND WESTERN KANSAS. STRONG TO
SEVERE STORMS ARE BETWEEN DUNCAN AND ARDMORE OKLAHOMA AND WILL
MOVE SOUTHEAST TOWARD THE GAINESVILLE/SHERMAN AREAS AFTER 10 PM
CDT. THE POTENTIAL IS THERE FOR FOR VERY GUSTY WINDS...BRIEF HEAVY
RAINFALL...FREQUENT LIGHTNING WITH THESE STRONGER STORMS.
MEANWHILE FURTHER SOUTHWEST AWAY FROM THE BETTER UPPER LEVEL
FORCING...SCATTERED SHOWERS WERE WEAKENING AND LIKELY BECOMING
ELEVATED IN THE DRIER LOW LEVEL AIRMASS WHICH SHOULD CONTINUE
COOLING READILY OVERNIGHT.

THOUGH A BRIEF REPRIEVE MAY OCCUR AFTER MIDNIGHT...THE APPROACH OF
THE SECOND SHORTWAVE DISTURBANCE AND THE PRESENCE OF AN INCREASING
30-35 KT LLJ WILL LIKELY INCREASE COVERAGE OF SHOWERS AND A FEW
THUNDERSTORMS CONTAINING LOCALIZED HEAVIER RAINS ACROSS THE
NORTHEAST COUNTIES...NEAR AND NORTH OF THE STATIONARY FRONT.
DETERMINING TOTAL RAINFALL IS VERY DIFFICULT WITH SO MANY PLAYERS
IN THE GAME...BUT WHAT WE DO KNOW IS THE HEAVIEST RAINS WILL
LIKELY OCCUR ALONG AND NORTHEAST OF A GAINESVILLE...DALLAS/MCKINNEY...
CANTON/ATHENS LINE. IF ANY TRAINING OCCURS EARLY THURSDAY
MORNING...SOME LOCALIZED FLASH FLOODING WILL BE POSSIBLE. AT THIS
TIME...WILL NOT ISSUE A FLASH FLOOD WATCH WITH ANTECEDENT SOIL
CONDITIONS NOT BEING CONDUCIVE FOR WIDESPREAD FLASH FLOODING AND A
RELATIVELY PROGRESSIVE DISTURBANCE ALOFT. ONCE THE SECOND
SHORTWAVE ARRIVES BY DAYBREAK...THE SURFACE LOW AND ASSOCIATED
COLD FRONT WILL MOVE EAST-SOUTHEAST ACROSS THE AREA WITH A DRY
SLOT QUICKLY MOVING SOUTHEAST ACROSS THE AREA LATER THURSDAY
MORNING AND THURSDAY AFTERNOON. SOME LOCALIZED HEAVIER RAINS WILL
REMAIN POSSIBLE ACROSS THE EASTERN COUNTIES AHEAD OF THE FRONT AND
WITHIN THE BETTER AXIS OF MOISTURE WHERE PWATS WILL AVERAGE
BETWEEN 1.75 AND 2.00 UNTIL THE COLD FRONT PASSES THROUGH.

05/

&&

.AVIATION...
/ISSUED 643 PM CDT WED JUL 30 2014/
/00Z TAFS/

CONCERNS...POTENTIAL FOR THUNDERSTORMS AT THE METROPLEX AIRPORTS
OVERNIGHT AND THEN AT WACO LATE THURSDAY MORNING WITH A COLD FRONT
BRINGING NORTH WINDS TO THE REGION.

SOUTHEAST WINDS AND VFR CONDITIONS WILL PREVAIL THIS EVENING AHEAD
OF AN APPROACHING COLD FRONT. SHOWERS AND THUNDERSTORMS ARE
ALREADY DEVELOPING ALONG THE FRONT LOCATED NEAR A LINE FROM
FREDERICK OK TO MIDLAND TEXAS. THE FRONT WILL MAKE SLOW BUT STEADY
PROGRESS OVERNIGHT REACHING THE METROPLEX BY 14Z AND WACO AROUND
16Z THURSDAY MORNING. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
DEVELOP NEAR THE METROPLEX...AHEAD OF THE FRONT...BEGINNING AROUND
05Z AS LIFT OCCURS AHEAD OF AN ATTENDANT SHORTWAVE. LIGHTNING AND
HEAVY RAINFALL WILL BE POSSIBLE WITH ANY CONVECTION OVERNIGHT.
WILL CONTINUE WITH THE VCSH/VCTS MENTION OVERNIGHT AND LIKELY
INCLUDE A TEMPO FOR -TSRA AT THE METROPLEX AIRPORTS WITH A LATER
TAF ISSUANCE. BEST GUESS RIGHT NOW FOR STORMS IN THE METROPLEX
MAY BE 09-13Z BUT WILL WATCH THE EVOLUTION AND ATTEMPT TO PINPOINT
A BETTER TIMING. SHOWERS AND THUNDERSTORMS WILL IMPACT WACO IN A
MUCH SHORTER WINDOW BETWEEN 16-19Z.

NORTHWEST WINDS BEHIND THE FRONT WILL BECOME MORE NORTHERLY
THURSDAY AFTERNOON. MVFR CIGS ARE EXPECTED TO DEVELOP OVERNIGHT
TONIGHT AND IMPACT ALL TAF SITES BUT CONDITIONS WILL IMPROVE TO
VFR BEHIND THE FRONT EARLY FRIDAY AFTERNOON.

82/JLD


&&



.PREV DISCUSSION... /ISSUED 355 PM CDT WED JUL 30 2014/
OUR FIRST ROUND OF PRECIPITATION HAS MOVED INTO NORTHEAST TEXAS.
WITH THE BACK EDGE OF THE EXITING IMPULSE CLEARLY EVIDENT ON
WATER VAPOR IMAGERY APPROACHING FROM THE WEST...IT APPEARS
SUBSIDENCE WILL DOMINATE THE NEXT SEVERAL HOURS. WILL KEEP THE
MENTION OF THUNDER IN THE FORECAST...BUT THE CONVECTIVE MODE WILL
BE PREDOMINANTLY LIGHT SHOWER ACTIVITY THROUGH AT LEAST MID-
EVENING.

THE EXITING SYSTEM HAS HELPED GIVE A PUSH TO A COLD FRONT...WHICH
IS NOW PLOWING SOUTH THROUGH THE HIGH PLAINS OF WEST TEXAS. THE
BULK OF BOUNDARY IS FREE OF STORMS AT THIS TIME...BUT AS IT PEELS
UP THE UNSTABLE AIR TO THE EAST...THE NEXT SHORTWAVE WILL ADD
SIGNIFICANT LIFT IN THE MID-LEVELS TO AID IN NOCTURNAL CONVECTIVE
INITIATION. THE NEXT IMPULSE HAS BEGUN TO INITIATE CONVECTION
ACROSS THE NEW MEXICO HIGHLANDS AND THE COLORADO ROCKIES. THIS
DISTURBANCE WILL SPREAD LARGE-SCALE LIFT EASTWARD THIS EVENING AS
A 30-KT LLJ ENSUES. THIS MOISTURE FLUX WILL SURGE PW VALUES ABOVE
2 INCHES...RESULTING IN PRECIPITATION EFFICIENCIES OF TROPICAL
PROPORTIONS. AS A RESULT...HAVE INTRODUCED HEAVY RAIN INTO THE
WEATHER GRIDS IN NORTHERN AND NORTHEASTERN ZONES. WHILE THIS MAY
APPEAR TO HAVE THE MAKINGS OF A FLASH FLOOD EVENT...THERE ARE A
FEW MITIGATING FACTORS. (1) UNSEASONABLY STRONG WINDS IN THE MID-
LEVELS WILL BEGIN VEERING DURING THE EVENT...BOTH ENHANCING THE
SPEED OF INDIVIDUAL CELLS AND REDUCING THE LIKELIHOOD OF TRAINING
ECHOES. (2) GUIDANCE SUGGESTS THIS VEERING WILL LEAD TO A
SIGNIFICANT INTRUSION OF DRY MID-LEVEL AIR THAT WILL CUT OFF THE
PRECIPITATION PROCESSES FROM WEST TO EAST BETWEEN SUNRISE AND
MIDDAY. (3) IF THE INITIAL CONVECTION IS INTENSE ENOUGH FOR
SIGNIFICANT HEAVY RAIN DURING THE EARLY MORNING...THE RESULTING
COLD POOL MAY PUSH THE EFFECTIVE SURFACE BOUNDARY MUCH FARTHER
SOUTH THAN GUIDANCE CURRENTLY SUGGESTS. SUBSEQUENT ACTIVITY WOULD
THEN BE CONFINED TO THE SOUTHERN ZONES THURSDAY AFTERNOON.

LOW-LEVEL COLD ADVECTION AND LINGERING CLOUD COVER THURSDAY AND
FRIDAY MAY KEEP HIGH TEMPERATURES IN THE 80S BOTH DAYS...AND
PERSISTENT NORTHERLY FLOW WILL MEAN A SLOW WARMING TREND THIS
WEEKEND. THE MILD AIR WILL GRADUALLY MODERATE...BUT TEMPERATURES
WILL REMAIN BELOW NORMAL INTO NEXT WEEK WHEN THE GULF FINALLY
REOPENS.

25



&&


.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  74  83  70  87  72 /  40  40  10   5   5
WACO, TX              74  89  70  89  70 /  20  30  20  10   5
PARIS, TX             68  78  65  83  68 /  80  50  20  10   5
DENTON, TX            72  83  67  87  68 /  50  40  10   5   5
MCKINNEY, TX          71  83  66  85  67 /  60  50  10   5   5
DALLAS, TX            74  83  70  86  73 /  40  40  10   5   5
TERRELL, TX           72  83  69  85  69 /  50  50  20  10   5
CORSICANA, TX         72  87  70  87  70 /  30  40  20  10   5
TEMPLE, TX            72  92  70  90  70 /  10  40  20  10   5
MINERAL WELLS, TX     70  84  67  89  68 /  30  20  10   5   5

&&

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

&&

$$

82/05





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