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

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000
FXUS64 KFWD 192320
AFDFWD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
620 PM CDT SAT JUL 19 2014

.AVIATION...
VFR CONDITIONS WILL PREVAIL THROUGH 06Z MONDAY. VISIBLE SATELLITE
IMAGERY SHOWS THAT THE VFR CEILINGS ACROSS THE METROPLEX ARE
SHIFTING EAST. WILL START OVER THE KAFW...KFTW...AND KGKY TAFS AS
SCT040 AND LEAVE BKN035 AT KDFW AND KDAL TIL 01Z THEN SHOW
SCT040. THE STRATUS HAD ALREADY MOVED THE EAST OF WACO BY 22Z
TODAY...SO WILL JUST START THEM OFF SKC. LIGHT EAST SOUTHEAST
WINDS WILL BECOME SOUTHEASTERLY OVERNIGHT AND SOUTHERLY DURING
THE DAY SUNDAY AT LESS THAN 10 KNOTS AS A SURFACE RIDGE CONTINUES
TO MOVE EAST.

58

&&


.PREV DISCUSSION... /ISSUED 332 PM CDT SAT JUL 19 2014/

EARLY AFTERNOON VISIBLE SATELLITE IMAGERY SHOWED A RELATIVELY
THICK PLUME OF LOW-LEVEL CLOUDS HOLDING IN PLACE FOR LOCATIONS
GENERALLY ALONG AND EAST OF THE INTERSTATE 35/35W CORRIDOR. THIS
CLOUD COVER HAS KEPT TEMPERATURES ANYWHERE FROM 5 TO 10 DEGREES
COOLER THAN WHAT WE WOULD HAVE REACHED IN FULL SUNSHINE AS OF 2 PM
CDT. AS A RESULT...WENT AHEAD AND BUMPED DOWN TEMPERATURES FOR
THIS AFTERNOON INTO THE UPPER 70S TO LOWER 80S FOR HIGH
TEMPERATURES EAST OF I-35. TO THE WEST...MOST CLOUD COVER HAD
ERODED AS OF 2 PM WHERE TEMPERATURES WERE ALREADY IN THE MID TO
UPPER 80S.

EARLY AFTERNOON WATER VAPOR SATELLITE IMAGERY DEPICTED WEAK
RIDGING ALOFT OVER THE REGION. THIS CONTINUES TO SUPPORT LARGE
SCALE FORCING FOR SUBSIDENCE OVER MOST OF TEXAS. THE 12Z FWD RAOB
WAS ALREADY VERY WARM AND DRY IN THE MIDDLE TROPOSPHERE...SO
ADDITIONAL SUBSIDENCE WILL ONLY REINFORCE THIS THROUGH THE
WEEKEND. WITH SUBSIDENCE REPRESENTING THE DOMINANT LARGE SCALE
FORCING MECHANISM...MODELS CONTINUE TO SHOW LOW-LEVEL CLOUD COVER
CLEARING OUT ACROSS THE CWA FROM WEST TO EAST LATE THIS AFTERNOON
THROUGH THIS EVENING. THIS WAS STARTING TO OCCUR RIGHT ALONG THE
INTERSTATE 35 CORRIDOR AT 2 PM CDT WHERE LOW CLOUDS WERE SLOWLY
ERODING. HOWEVER...MODELS SEEM TO BE LARGELY MISSING THE LOW-
LEVEL FLOW THAT APPEARS TO BE REINFORCING THE STRATUS DECK FROM
THE EAST-NORTHEAST.

REGARDLESS...ALL GUIDANCE INDICATES THAT A SURFACE RIDGE WILL
MOVE EAST OVER LOUISIANA BY MIDNIGHT TONIGHT...CAUSING THE LOW-
LEVEL FLOW TO VEER AROUND TO THE SOUTHEAST. THIS SHOULD ALLOW THE
LOW-LEVEL CLOUD COVER TO SCATTER OUT FINALLY...BUT WE WILL HAVE
TO WAIT AND SEE HOW QUICKLY THIS WORKS WITHOUT THE AID OF DAYTIME
HEATING TO ENTRAIN DRIER AIR INTO THE CLOUDS. ASSUMING CLOUDS DO
CLEAR OUT BY MIDNIGHT...WE WILL BE LOOKING AT ANOTHER NEAR RECORD
COLD NIGHT ACROSS MOST OF NORTH AND CENTRAL TEXAS. OUR CURRENT
FORECAST LOWS ARE JUST A DEGREE OR TWO ABOVE RECORD LOWS FOR JULY
20TH. IF FOR SOME REASON SKIES CLEAR OUT RAPIDLY AROUND
SUNSET...WE MAY HAVE A CHANCE TO REACH THESE RECORD LOWS AT DFW
AND WACO WITH A FULL NIGHT OF IDEAL RADIATIONAL COOLING. WITH
CLOUDS BEING VERY SLOW TO CLEAR OUT DURING THE PEAK HEATING HOURS
OF THE DAY HERE IN MID-LATE JULY...SOME OF THESE CLOUDS WILL
PROBABLY HANG ROUND THROUGH THIS EVENING AND RADIATE BACK ENOUGH
HEAT TO PREVENT US FROM DIPPING BELOW RECORD LOWS TOMORROW
MORNING. EITHER WAY...IT LOOKS TO BE AN UNSEASONABLY COOL AND VERY
COMFORTABLE START TO THE DAY TOMORROW.

REGARDING TEMPERATURES SUNDAY THROUGH FRIDAY...MODELS INDICATE
THAT UPPER LEVEL RIDGING WILL BEGIN TO BUILD UP OVER THE
CENTRAL/SOUTHERN CONUS ROCKIES THROUGH EARLY NEXT WEEK. THIS WILL
LIKELY RESULT IN SOME VERY HOT WEATHER FOR THE CENTRAL
PLAINS...BUT FORTUNATELY IT LOOKS LIKE NORTH TEXAS WILL MISS OUT
ON THE MAIN AXIS OF HEAT THROUGH THE MIDDLE OF NEXT WEEK.
TEMPERATURES WILL SLOWLY CLIMB...BUT THAT IS MAINLY BECAUSE WE
ARE SO COOL RIGHT NOW AND SHOULD BE MOSTLY SUNNY THROUGH NEXT
WEEK. WE SHOULD WARM BACK UP TO SEASONAL NORMAL HIGH TEMPERATURES
BY MONDAY...WHICH WILL PRETTY MUCH HOLD STEADY THROUGH MUCH OF THE
WEEK AHEAD.

THE PRIMARY FACTOR THAT WILL LIKELY PREVENT US FROM CLIMBING
ABOVE 100 DEGREES FOR SEVERAL DAYS IS WEAK COLD AIR ADVECTION IN
THE LOWER ATMOSPHERE. COLD AIR ADVECTION SOUNDS REALLY STRANGE
WHILE WE ARE WARMING UP...BUT IT IS EXPECTED TO BE THAT COMPONENT
THAT PREVENTS US FROM GETTING INTO OUR OWN SUMMER HEAT WAVE HERE
LOCALLY. WITH VERY WARM WEATHER OFF TO OUR NORTHWEST...AND WEAK
LEE SIDE CYCLOGENESIS OVER THE HIGH PLAINS...OUR LOWER LEVEL WINDS
WILL GENERALLY BE OUT OF THE SOUTHEAST OR SOUTH THROUGH THE MIDDLE
OF NEXT WEEK. THIS WILL KEEP A STEADY SUPPLY OF SLIGHTLY COOLER
AIR ADVECTING OVER THE REGION AND SHOULD HELP TO KEEP HIGHS IN THE
UPPER 90S...OR NEAR NORMAL...FOR MOST OF THE WEEK AHEAD.

THIS MAY CHANGE BY THE END OF THE WEEK HEADED INTO NEXT WEEKEND AS
MODELS CONTINUE TO SHOW THE UPPER RIDGE TO OUR NORTHWEST
WEAKENING...BUT UNFORTUNATELY REORIENTING ITSELF RIGHT ON TOP OF
US. IF THE RIDGE DOES SET UP RIGHT ON US BY THE END OF THE
WEEK...WE WILL LOSE OUR LOW-LEVEL COLD AIR ADVECTION AND
TEMPERATURES WILL LIKELY CLIMB ABOVE THE CENTURY MARK WHILE THE
UPPER RIDGE HOLDS IN PLACE. THE UPPER RIDGE IS EXPECTED TO BE
MUCH WEAKER THOUGH...SO JUST HAVE ABOVE NORMAL TEMPERATURES IN THE
LATTER PORTION OF THE FORECAST AT THIS TIME. NOTHING CLOSE TO
RECORD HIGHS OR A MAJOR HEAT WAVE IS INDICATED AT THIS POINT.

REGARDING PRECIPITATION CHANCES IN THE WEEK AHEAD...WITH THE
RIDGE OFF TO THE NORTHWEST...A SOMEWHAT RARE NORTHEAST FLOW REGIME
WILL SET UP IN THE UPPER LEVELS OF THE ATMOSPHERE OVER NORTH
TEXAS. IN THIS TYPE OF FLOW REGIME WE WILL BE LOOKING
UPSTREAM...TO OUR NORTHEAST...FOR SHORTWAVE TROUGHS THAT MAY PLAY
A ROLE IN SPREADING SOME LIFT OVER THE REGION FOR ANY THUNDERSTORM
CHANCES EARLY NEXT WEEK. THE ECMWF CONTINUES TO SHOW A SHORTWAVE
TROUGH...CURRENTLY OVER THE BAJA/CALIFORNIA BORDER...MAKING ITS
WAY AROUND THE UPPER RIDGE AND SWEEPING BACK TO THE SOUTHWEST OVER
NORTH TEXAS ON WEDNESDAY. WITH UPPER RIDGING OFF TO OUR WEST AND
SOME PERSISTENT...ALBEIT WEAK...POSITIVE MOISTURE ADVECTION
LEADING UP TO WEDNESDAY...IT IS POSSIBLE THAT THIS TROUGH WILL
PROVIDE ENOUGH LIFT FOR ISOLATED STORMS ACROSS THE AREA WEDNESDAY
AFTERNOON. MAINTAINED THE BROAD BRUSHED 20 POPS FROM THE PREVIOUS
FORECAST AS A RESULT.

OTHERWISE...LEFT POPS IN THE FORECAST FOR POSSIBLE SEA-BREEZE
ACTIVITY TUESDAY AFTERNOON. IF THE SEA-BREEZE MAKES IT NORTHWEST
OF COLLEGE STATION...IT STILL LOOKS LIKE THE COVERAGE OF STORMS
WOULD BE ISOLATED AT BEST...SO JUST KEPT POPS IN THE 10 TO 20
PERCENT RANGE FOR NOW. THE NAM AND NAM4KM FORECAST SOUNDINGS BOTH
ADVERTISE ISOLATED THUNDERSTORMS ACROSS NORTH TEXAS MONDAY
AFTERNOON. THE FORECAST SOUNDINGS SHOW THAT THIS IS LARGELY DUE TO
STRONG POSITIVE MOISTURE ADVECTION COMBINED WITH STRONG HEATING
DURING THE DAY ON MONDAY. AT THIS POINT LEFT POPS OUT OF THE
FORECAST ON MONDAY BECAUSE THERE IS NO OBVIOUS FORCING FOR ASCENT
TO HELP REMOVE THE CAP OVER THE REGION ON MONDAY. THE GFS FORECAST
SOUNDINGS LOOK MUCH MORE REALISTIC AT THIS POINT AS THE GFS MIXES
OUT THE LOW-LEVEL MOISTURE DURING THE PEAK HEATING HOURS OF THE
DAY. WILL KEEP AN EYE ON MONDAY JUST IN CASE MOISTURE ADVECTION IS
STRONG LIKE THE NAM ADVERTISES...BUT CONFIDENCE IS MUCH HIGHER IN
THE GFS SOLUTION AT THIS TIME. ASSUMING THE RIDGE IS IN PLACE OVER
THE REGION LATE IN THE WEEK AHEAD...PRECIPITATION CHANCES SHOULD
BE VERY LOW AS SUBSIDENCE DOMINATES.

CAVANAUGH

&&



.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  68  93  74  96  76 /   0   0   0  10  10
WACO, TX              69  93  73  96  73 /   0   0   0  10  10
PARIS, TX             66  89  68  93  72 /   0   0   0  10  10
DENTON, TX            67  93  71  96  73 /   0   0   0  10  10
MCKINNEY, TX          66  92  70  94  73 /   0   0   0  10  10
DALLAS, TX            69  93  75  96  77 /   0   0   0  10  10
TERRELL, TX           69  92  73  95  74 /   0   0   0  10  10
CORSICANA, TX         70  93  73  95  74 /   0   0   0  10  10
TEMPLE, TX            69  94  72  95  72 /   0   0   0  10  10
MINERAL WELLS, TX     68  94  71  97  72 /   0   0   0  10  10

&&

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

&&

$$

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