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

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FXUS64 KFWD 250449 AAC
AFDFWD

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
1149 PM CDT SUN AUG 24 2014

.AVIATION...
VFR CONDITIONS ARE EXPECTED TO PREVAIL AT THE TAF SITES THROUGH
12Z TUESDAY AS AN UPPER LEVEL RIDGE CENTERED TO OUR EAST THAT HAS
DOMINATED THE WEATHER ACROSS NORTH AND CENTRAL TEXAS ONLY SLOWLY
WEAKENS. SOME HIGH CLOUDS WILL MOVE ACROSS THE REGION BRINGING
SCT-BKN300. SOME CUMULUS...SCT050-060...WILL OCCUR MONDAY
AFTERNOON. SOUTHEAST WINDS AROUND 10 KNOTS AT 04Z MONDAY WILL
BECOME SOUTHERLY BY 09Z...AND SOUTH-SOUTHWEST BY 14Z. WINDS WILL
BACK AROUND TO THE SOUTHEAST AFTER 20Z.

58

&&

.UPDATE...
A QUIET NIGHT WILL PREVAIL ACROSS THE REGION. THUNDERSTORMS TO THE
WEST OF THE AREA WILL NOT MAKE IT INTO NORTH TEXAS BUT WILL SPREAD
SOME HIGH CLOUD COVER OVER THE WESTERN COUNTIES.
OTHERWISE...TEMPERATURES WILL BE VERY NEAR OR SLIGHTLY WARMER THAN
THIS MORNING/S LOW TEMPERATURES.

82/JLD

&&

.PREV DISCUSSION... /ISSUED 322 PM CDT SUN AUG 24 2014/

12Z UPPER AIR ANALYSIS INDICATED THAT THE UPPER LEVEL RIDGE THAT
HAS BEEN CENTERED JUST TO THE EAST OF THE CWA THE PAST COUPLE OF
DAYS HAS STEADILY WEAKENED OVER THE PAST 24 HRS. 500 MB HEIGHT
RISES WERE FOUND FROM THE UPPER MIDWEST TO THE NORTHEASTERN CONUS
BUT 24 HOUR HEIGHT FALLS OF 2-4 DM WERE FOUND ALL ALONG THE GULF
COAST WHERE THE RIDGE HAS BEEN CENTERED AND STRONGEST. A TRUE
CENTER OF THE UPPER RIDGE WAS A BIT DIFFICULT TO LOCATE...BUT IT
WAS PROBABLY LOCATED SOMEWHERE OVER THE OK/AR BORDER...NEAR THE
CENTER OF THE ANTICYCLONIC STREAMLINES AT THE 500 MB LEVEL. WATER
VAPOR SATELLITE IMAGERY CONTINUED TO SHOW A TUTT LOW OVER THE
EASTERN GULF OF MEXICO MOVING SLOWLY TO THE WEST. A LARGE UPPER
LOW WAS OBSERVED OVER THE WESTERN DAKOTAS WHILE A STRONG SHORTWAVE
TROUGH COULD BE SEEN DIGGING INTO THE BACK OF THE UPPER LOW OVER
THE CASCADES OF WA/OR. A WEAK UPPER LEVEL DISTURBANCE WAS ALSO
OBSERVED OVER THE TX PANHANDLE...MOVING VERY SLOWLY TO THE
NORTHEAST EARLY THIS AFTERNOON.

THROUGH MONDAY...THE UPPER LEVEL RIDGE IS EXPECTED TO RE-ESTABLISH
ITSELF OFF TO THE NORTHEAST OF THE REGION ALLOWING EASTERLY FLOW
ALOFT TO BUILD OVER THE GULF COAST AND NORTH CENTRAL TEXAS. EVEN
THOUGH THE RIDGE WILL BE MOVING AWAY FROM US DURING THIS TIME...WE
WILL STILL BE LARGELY UNDER ITS INFLUENCE WITH FORCING DOMINATED
BY LARGE SCALE SUBSIDENCE. AS A RESULT...MOSTLY CLEAR SKIES AND
HOT AND DRY CONDITIONS WILL CONTINUE FOR THE NEXT 36 HOURS. WE
WILL KEEP A CLOSE EYE ON THE TEXAS PANHANDLE UPPER LEVEL
DISTURBANCE AS IT HAS ALREADY CAUSED SCATTERED THUNDERSTORMS TO
DEVELOP EARLY THIS AFTERNOON. HOWEVER THE ANTI-CYCLONIC FLOW ALOFT
SHOULD SHUNT THIS FEATURE OFF TO THE NORTHEAST OF NORTH TEXAS
TONIGHT.

BY TUESDAY...THE TUTT LOW IS EXPECTED TO MOVE WESTWARD OVER
TX...LIKELY SPREADING SOME WEAK LARGE SCALE FORCING FOR ASCENT
OVER PART OF EAST TEXAS...THE TX GULF COAST...AND THE EASTERN
PORTIONS OF CENTRAL TEXAS. LOW-LEVEL FLOW IS EXPECTED TO BECOME
EASTERLY FROM THE CWA OVER ALONG THE GULF COAST BY THIS
TIME...ALLOWING FOR SLIGHTLY COOLER CONDITIONS AND POSITIVE
MOISTURE ADVECTION. ON TUESDAY...THE LARGE SCALE LIFT ASSOCIATED
WITH THE TUTT LOW APPEARS TO REMAIN MOSTLY SOUTHEAST OF THE CWA.
HOWEVER PWATS ARE EXPECTED TO CLIMB TO AROUND 2 INCHES FOR
LOCATIONS ALONG AND SOUTHEAST OF A LINE FROM ATHENS TO
ROCKDALE...SO MAINTAINED 30 POPS TUESDAY AFTERNOON FOR THESE
LOCATIONS. KEPT 20 POPS TO THE NORTHWEST OF THIS LINE...BUT LEFT
MOST LOCATIONS WEST OF INTERSTATE 35 DRY AS THE RETURN OF DEEP
TROPICAL MOISTURE LOOKS LIKE IT WILL BE DELAYED BY ABOUT 12 HOURS
FROM PREVIOUS MODEL RUNS.

LOW-LEVEL EASTERLY FLOW WILL SPREAD WEAK COLD AIR ADVECTION AND
MAINTAIN POSITIVE MOISTURE ADVECTION INTO THE AREA THROUGH THROUGH
MID-WEEK. TEMPERATURES WILL STILL BE SEASONABLY WARM/HOT...BUT ARE
MORE LIKELY TO STAY UNDER 100 DEGREES AND SHOULD SLOWLY COOL TO
SEASONAL NORMALS BY THE END OF THE WEEK.

WITH TROPICAL MOISTURE SLOWLY RETURNING TO THE REGION...PWATS
SHOULD CLIMB INTO THE 1.75 TO 2 INCH RANGE FOR MOST LOCATIONS
ACROSS NORTH AND CENTRAL TEXAS BY WEDNESDAY AFTERNOON. JUST LIKE
THE PREVIOUS FORECAST DISCUSSION MENTIONED...MODELS CONTINUE TO
STRUGGLE ON A SOLUTION REGARDING THE EVOLUTION OF THE CASCADES
SHORTWAVE TROUGH OVER THE REGION LATE WEEK. WHAT ALL MODELS DO
SHOW IS A LACK OF ANY STRONG LIFT OR SUBSIDENCE OVER NORTH TEXAS
FOR WEDNESDAY AND THURSDAY.

WITH DEEP MOISTURE IN PLACE...AND NEUTRAL OR NO SIGNIFICANT
FORCING TO SPEAK OF...WENT AHEAD AND JUST CHANGED POPS FROM BROAD
BRUSHED 20S TO BROAD BRUSHED 20S ONLY DURING THE AFTERNOON AND
EVENING HOURS OF THE DAY. IN THE ABSENCE OF ORGANIZED FORCING BUT
DEEP...TROPICAL MOISTURE IN PLACE...THE ASSUMPTION IS THAT
HEATING/BUOYANCY WILL PROVIDE UNORGANIZED/CHAOTIC FORCING LEADING
TO AFTERNOON "POPCORN THUNDERSTORM" ACTIVITY ACROSS ALL OF NORTH
AND CENTRAL TEXAS. AS WE GET CLOSER TO MID-WEEK...THERE MAY BE
SMALLER SCALE FORECAST DETAILS THAT POINT TO A FOCUS FOR
THUNDERSTORM DEVELOPMENT...BUT NO SUCH FEATURE IS EVIDENT AT THIS
TIME.

BY FRIDAY...MOST MODEL GUIDANCE INDICATES THAT THE CASCADES
SHORTWAVE TROUGH WILL MOVE OVER THE SOUTH PLAINS...SPREADING SOME
LARGE SCALE FORCING FOR ASCENT OVER THE REGION. WHILE ALL MODELS
MOVE THIS UPPER TROUGH OVER THE REGION SOMETIME BETWEEN LATE ON
THURSDAY THROUGH SOMETIME ON SUNDAY...THERE IS STILL QUITE A BIT
OF DISPARITY REGARDING THE DETAILS OF THIS UPPER LEVEL SYSTEM FROM
MODEL TO MODEL. THE CANADIAN IS THE ONLY MODEL THAT REALLY BRINGS
A WELL DEFINED FRONT THROUGH THE AREA NOW...AND IS ALSO THE
FASTEST WITH THE UPPER TROUGH. THE GFS BACKED WAY OFF ON THE SPEED
OF THE UPPER TROUGH...BUT NOW PROCEEDS TO CAMP THE UPPER TROUGH
OVER WEST CENTRAL TEXAS ALL WEEKEND RESULTING IN A WET WEEKEND FOR
MOST FOLKS. THE ECMWF SEEMS TO BE MAINTAINING THE MOST RUN TO RUN
CONSISTENCY SHOWING THE UPPER TROUGH MOVING SLOWLY OVER THE REGION
FROM FRIDAY THROUGH SATURDAY.

WHILE CONSISTENCY IS NO GUARANTEE OF ACCURACY...WENT AHEAD AND
SIDED WITH THE ECMWF SOLUTION AT THIS TIME. HOPEFULLY MODEL TO
MODEL CONSISTENCY WILL IMPROVE HERE IN THE NEXT COUPLE OF DAYS
ALLOWING BROAD BRUSHED LOW POPS TO BE REFINED INTO A MORE NARROW
WINDOW OF TIME FOR LATE THIS WEEK HEADED INTO NEXT WEEKEND. THE
ENTIRE PERIOD IS VERY UNLIKELY TO BE A WASH-OUT...BUT IT IS VERY
DIFFICULT TO PIN DOWN THE MOST LIKELY TIME FOR THUNDERSTORMS UNTIL
MODEL CONSISTENCY IMPROVES. ALL MODELS SHOW TEMPERATURES HOLDING
NEAR NORMAL DURING THIS TIME FRAME AS EVEN THOSE SOLUTIONS THAT PUSH
THE TROUGH THROUGH QUICKLY MAINTAIN ZONAL FLOW ALOFT AND DO NOT
REBUILD AN UPPER LEVEL RIDGE OVER US AT THIS TIME.

CAVANAUGH



&&


.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  79 101  79  99  79 /   0   0   0  10  10
WACO, TX              76 101  75  99  76 /   0   0   0  10  20
PARIS, TX             76  98  74  94  73 /   0   0   5  10  20
DENTON, TX            75 101  75  98  76 /   0   0   0  10  10
MCKINNEY, TX          75  99  75  97  75 /   0   0   0  10  10
DALLAS, TX            79 100  80  99  79 /   0   0   0  10  10
TERRELL, TX           77 100  78  98  75 /   0   0   0  10  20
CORSICANA, TX         75 100  78  99  75 /   0   0   5  20  20
TEMPLE, TX            75 100  75  99  74 /   0   0   0  20  20
MINERAL WELLS, TX     76 103  74  99  73 /   0   0   0  10  10

&&

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

&&

$$

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