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

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000
FXUS64 KFWD 271129
AFDFWD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
629 AM CDT SUN JUL 27 2014

.AVIATION...
FORECAST FOR THE NEXT 24 HOURS APPEAR TO BE RELATIVELY QUIET. VFR
CONDITIONS WILL PREVAIL AT THE TERMINALS...DESPITE A FEW AREAS OF
MVFR CEILINGS TO THE EAST AND SOUTHEAST OF OUR AREAS OBSERVATION
SITE. KCLL HAS BEEN REPORTED MVFR CEILINGS FOR MOST OF THE
EVENING...WITH OVC011 REPORTED AT 11Z. SATELLITE IMAGERY SHOWS
NARROW BANDS OF LOW CLOUDS/FOG IN THE HILL COUNTRY...AND IN A
NARROW BAND FROM NEAR JACKSONVILLE...TO COLLEGE STATION...TO
HONDO. AT THIS POINT...AM NOT ANTICIPATING ANYTHING OTHER THAN A
FEW TO SCATTERED CLOUDS AROUND 080 THIS AFTERNOON...MUCH LIKE
YESTERDAY.

ATTENTION THEN TURNS TO THE WIND SHIFT FOR EARLY MONDAY. LATEST
GUIDANCE AND HI RES MODEL SOLUTIONS SUGGEST THE WIND SHIFTING TO
THE NORTH AND NORTHEAST SOMETIME BETWEEN 15 AND 17Z MONDAY...AT
THE METROPLEX TAF SITES.

FOX

&&


.PREV DISCUSSION... /ISSUED 420 AM CDT SUN JUL 27 2014/

00Z UPPER AIR ANALYSIS INDICATED THAT AN UPPER LEVEL RIDGE
REMAINED IN PLACE OVER THE SOUTHERN PLAINS...AND HAD ACTUALLY
STRENGTHENED OVER THE PAST 24 HRS. THE 00Z FWD RAOB SHOWED THAT
PRECIPITABLE WATER HAD INCREASED ABOUT A QUARTER OF AN INCH FROM
24 HRS AGO...A TREND THAT IS LIKELY TO CONTINUE OWING TO SOUTH
WINDS FROM THE SURFACE TO 750 MB. EARLY MORNING WATER VAPOR
SATELLITE IMAGERY SHOWED A STRONG UPPER LOW OVER NORTHERN
MINNESOTA MOVING SOUTHEAST TOWARDS THE GREAT LAKES STATES. IN ITS
WAKE...EARLY MORNING SURFACE OBSERVATIONS SHOWED A COLD FRONT
MOVING SOUTH ACROSS THE CENTRAL PLAINS. 08Z SURFACE OBSERVATIONS
SHOWED THE FRONT NEAR A LINE EXTENDING FROM KANSAS CITY SOUTHWEST
TO DODGE CITY CONTINUING INTO FAR SOUTHEAST COLORADO.

FOR TODAY...EXPECT ANOTHER HOT DAY WITH SUNNY SKIES AND UPPER
LEVEL RIDGING DOMINATING OUR LOCAL WEATHER PATTERN. THE CENTRAL
PLAINS COLD FRONT WILL CONTINUE TO SINK SOUTH THROUGHOUT THE DAY
TODAY...BUT IS EXPECTED TO MOVE VERY SLOWLY AS GUIDANCE TAKES THE
FRONT FROM ITS EARLY MORNING POSITION OVER KANSAS...TO THE RED
RIVER BY LATE TONIGHT. SOUTH OF THE FRONT...A LOW-LEVEL THERMAL
RIDGE WILL EXTEND EASTWARD OFF THE HIGH PLAINS. THIS THERMAL RIDGE
IS EXPECTED TO REMAIN JUST NORTHWEST OF THE CWA TODAY...RESULTING
IN 850 MB TEMPERATURES THAT ARE ALMOST IDENTICAL TO YESTERDAY.

AS A RESULT...THINK THAT MOST LOCATIONS WILL SEE HIGHS TOP OUT
NEAR OR JUST ABOVE 100 DEGREES TODAY...APPROACHING 105 DEGREES
AROUND GRAHAM AND BRECKENRIDGE CLOSER TO THE THERMAL RIDGE. THE
FAR EASTERN CWA WILL LIKELY SEE A SLIGHT UPTICK IN AFTERNOON
TEMPERATURES...ALTHOUGH 100 DEGREES IS UNLIKELY AS THESE LOCATIONS
ONLY CLIMBED INTO THE LOWER 90S YESTERDAY OWING TO DEEPER MOISTURE
IN PLACE. DEEPER MOISTURE MEETS 100 DEGREE TEMPERATURES AROUND THE
INTERSTATE 35 CORRIDOR TODAY...AND THIS IS WHERE HEAT INDICES ARE
LIKELY TO CLIMB TO 105 OR SLIGHTLY ABOVE THIS AFTERNOON. NO HEAT
ADVISORY WILL BE ISSUED AT THIS TIME BECAUSE TOMORROW IS EXPECTED
TO BE MUCH COOLER WITH THE FRONT PUSHING ACROSS THE CWA.

MAINTAINED A DRY FORECAST FOR TODAY DUE TO THE STRONG UPPER LEVEL
RIDGE IN PLACE OVER THE REGION. WILL HAVE TO WATCH THE
SOUTHEASTERN CWA FOR ANY POTENTIAL LATE AFTERNOON ISOLATED
THUNDERSTORM ACTIVITY ASSOCIATED WITH THE SEA-BREEZE BOUNDARY.
THERE WAS LITTLE ACTIVITY YESTERDAY...BUT MOISTURE WILL BE A BIT
DEEPER THIS AFTERNOON. WILL ALSO HAVE TO KEEP A CLOSE EYE ON THE
FRONT. IF IT MOVES QUICKER THAN FORECAST AND GETS TO THE RED RIVER
BEFORE SUNSET...LATE AFTERNOON THUNDERSTORMS MAY BE POSSIBLE ALONG
THE RED RIVER AS WELL.

ON MONDAY...THE COLD FRONT IS EXPECTED TO SINK SOUTH OF THE RED
RIVER AROUND OR JUST BEFORE SUNRISE TOMORROW MORNING. WITH THE
FRONT COMING INTO THE CWA SO EARLY IN THE MORNING...SURFACE BASED
STORMS...AND THEREFORE STORMS RIGHT ALONG THE LEADING EDGE OF THE
FRONT...ARE UNLIKELY. FORECAST SOUNDINGS DO SHOW SOME MEAGER MID-
LEVEL CAPE...ON THE ORDER OF 250 J/KG...SO MAINTAINED 20 TO 30
POPS PRIMARILY BEHIND THE LEADING EDGE OF THE FRONT MENTIONING
SHOWERS WITH ISOLATED THUNDERSTORMS POSSIBLE.

THE FRONT IS EXPECTED TO BE IN CENTRAL TEXAS...MOVING VERY SLOWLY
TO THE SOUTH...BY TOMORROW AFTERNOON. WHEREVER THE FRONT IS DURING
THE PEAK HEATING HOURS OF THE DAY...THERE WILL BE A CHANCE FOR
SOME ISOLATED TO SCATTERED SURFACE BASED STORMS ALONG AND SOUTH
OF THE FRONTAL BOUNDARY. FORECAST SOUNDINGS SHOW A DEEP MIXED
LAYER UNDERNEATH MID-LEVEL MOISTURE...OR A CLASSIC INVERTED-V TYPE
SOUNDING. CAPE VALUES REMAIN MEAGER...BUT ANY STORMS THAT DEVELOP
WILL BE CAPABLE OF PRODUCING SOME LOCALIZED STRONG WIND GUSTS
DURING THE PEAK HEATING HOURS OF THE DAY. THE BEST CHANCE OF
RAINFALL IS EXPECTED TO REMAIN BEHIND THE SURFACE FRONT WHERE LIFT
IS STRONGER AND INTERACTS DIRECTLY WITH MID-LEVEL MOISTURE.
MICROBURST CHANCES ARE MUCH LOWER BEHIND THE FRONTAL BOUNDARY DUE
TO WEAKER LOW-LEVEL LAPSE RATES.

BY LATE MONDAY EVENING...GUIDANCE SUGGESTS THAT THE SURFACE FRONT
WILL STALL OUT OVER THE HILL COUNTRY...OR JUST SOUTH OF THE CWA.
ONCE STALLED OUT...ATTENTION TURNS TO TRACKING THE DEEPER COOL AND
DRY AIR BEHIND THE FRONT ADVECTING SOUTH INTO THE CWA FROM THE
NORTHEAST. THIS IS EASIEST TO TRACK IN MODEL GUIDANCE BY LOOKING
AT THE 850 MB REFLECTION OF THE COLD FRONT. THE GFS AND NAM BOTH
STALL OUT THE 850 MB FRONT OVER THE CWA MONDAY NIGHT INTO TUESDAY
MORNING...AND ACTUALLY VEER THE LOW-LEVEL FLOW TO THE SOUTHWEST OF
THE FRONT RESULTING IN SOME SHORT-LIVED...BUT GOOD...LOW-LEVEL
CONVERGENCE BEFORE SUNRISE ON TUESDAY. THE ECMWF AND CANADIAN ARE
MORE AGGRESSIVE WITH THE ADVECTION OF COOLER AND DRIER AIR INTO
THE REGION AND NEVER REALLY STALL OUT THE SURFACE OR 850 MB FRONT
MONDAY NIGHT INTO TUESDAY MORNING.

BECAUSE MODELS YESTERDAY WERE GENERALLY IN BETTER AGREEMENT WITH
THE ECMWF AND CANADIAN IN THE MORE AGGRESSIVE ADVECTION OF COOL
DRY AIR OVER NORTH AND CENTRAL TEXAS BEHIND THE FRONT...KEPT THE
FORECAST MORE OR LESS IN LINE WITH THIS SOLUTION. MAINTAINED 20 TO
30 POPS OVER THE SOUTHWESTERN HALF OF THE CWA TUESDAY MORNING TO
AT LEAST ACCOUNT FOR PERSISTENT RAIN CHANCES ASSOCIATED WITH A
VERY SLOW MOVING FRONT. KEPT QPF VALUES LOW AT THIS TIME HOWEVER
ASSUMING THAT SOME MOVEMENT OF THE FRONT WOULD CONTINUE TUESDAY
MORNING. IF THE H850 FRONT DOES END UP STALLING OUT EARLY TUESDAY
MORNING FOR SEVERAL HOURS...THIS FORECAST WILL NEED TO BE
CHANGED...POSSIBLY QUITE A BIT.

IF THE 850 MB FRONT STALLS OUT...THE NAM AND GFS PARAMETERS FOR
A SHORT-LIVED HEAVY RAINFALL EVENT ARE QUITE HIGH. PWATS IN BOTH
OF THESE MODELS INCREASE OVER 2 INCHES NEAR THE STALLED OUT 850
MB FRONT AND CORFIDI VECTORS ARE ORIENTED PARALLEL TO THE
FRONT...MEANING STORMS AND STORM MOTION FAVORS TRAINING UNTIL THE
FRONT STARTS TO MOVE AGAIN. THIS DOES NOT LOOK LIKELY TO OCCUR
YET...WHICH IS WHY IT IS NOT IN THE OFFICIAL FORECAST...HOWEVER
THIS IS AN ALTERNATIVE SOLUTION WE WILL BE WATCHING CLOSELY OVER
THE NEXT 24 TO 36 HRS. IF THIS ENDS UP BECOMING THE MOST PLAUSIBLE
SOLUTION...POPS AND QPF WILL NEED TO BE INCREASED QUITE A BIT NEAR
THE STALLED OUT 850 MB FRONT EARLY TUESDAY MORNING.

TUESDAY AND WEDNESDAY...REGARDLESS OF WHAT SOLUTION VERIFIES
MONDAY NIGHT INTO TUESDAY MORNING WITH REGARDS TO THE FRONT...ALL
GUIDANCE SHOWS COOL AND DRY AIR PUSHING SOUTHWEST OVER MOST OF
NORTH AND CENTRAL TEXAS BY TUESDAY AFTERNOON. WHENEVER THIS
COOL...DRY AIR ARRIVES...PRECIPITATION CHANCES WILL BE VERY LOW.
THE FRONT ITSELF LOOKS TO BECOME RE-ORIENTED FROM THE TEXAS
PANHANDLE TO THE SOUTH-SOUTHEAST ACROSS WEST CENTRAL TX...NEAR OUR
WESTERN CWA BORDER...WEDNESDAY MORNING. MODELS SHOW A FAIRLY
STRONG 850 MB BAROCLINIC ZONE SETTING UP OVER THE TEXAS PANHANDLE
ON WEDNESDAY...WHICH SHOULD RESULT IN LOW-LEVEL CYCLOGENESIS BY
WEDNESDAY AFTERNOON. MOST MODELS SHOW A WELL DEFINED SURFACE LOW
ALONG THE TEXAS/NEW MEXICO BORDER BY EARLY WEDNESDAY AFTERNOON.
HOW THIS SURFACE LOW EVOLVES THROUGH THURSDAY AFTERNOON WILL HAVE
A LARGE IMPACT ON THE TIMING AND PLACEMENT OF THE HEAVIEST
PRECIPITATION THROUGH THURSDAY. FOR NOW...LEFT 20 POPS OVER THE
NORTHWESTERN CWA ON WEDNESDAY...CLOSEST TO THE REORGANIZING
FRONTAL BOUNDARY.

WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...MODELS ARE SHOWING TWO
POSSIBLE SOLUTIONS WITH REGARDS TO THE EVOLUTION OF THE SURFACE
LOW THAT DEVELOPS WEDNESDAY AFTERNOON. ONE SOLUTION MOVES THE
SURFACE LOW ALMOST DUE SOUTH INTO THE BIG BEND AREA. THE OTHER
MOVES THE SURFACE LOW TO THE EAST...OVER NORTH TEXAS ON THURSDAY.
THE BIGGEST DIFFERENCE IN THESE SOLUTIONS IS THAT THE SURFACE LOW
MOVING EAST DELAYS THE PASSAGE OF THE COLD FRONT ACROSS THE AREA
BY ABOUT 12 HOURS. AT THIS TIME THE FORECAST FAVORS THE FASTER
FRONTAL SOLUTION WITH OUR BEST CHANCE OF SHOWERS AND THUNDERSTORMS
OVER THE CWA FROM WEDNESDAY NIGHT THROUGH THURSDAY. IF THE OTHER
SOLUTION VERIFIES...OUR BEST PRECIPITATION CHANCES WILL LIKELY
OCCUR FROM THURSDAY LATE AFTERNOON THROUGH THURSDAY NIGHT WITH THE
SLOWER PASSAGE OF THE COLD FRONT.

EITHER WAY...AT LEAST ONE ROUND OF GOOD THUNDERSTORM CHANCES
SHOULD MOVE THROUGH THE CWA WITH THIS SECOND SYSTEM. THE TIMING
AND EVOLUTION OF THIS SYSTEM WILL BE BETTER REFINED IN LATER
FORECASTS. IN EITHER CASE...MODELS CONTINUE TO SHOW THAT AN MCS
MAY DEVELOP ALONG THE NEARLY STATIONARY FRONT WEDNESDAY NIGHT AND
MOVE SOUTHEAST OVER THE RED RIVER EARLY THURSDAY MORNING. AS A
RESULT...THE NORTHERN CWA IS MORE LIKELY THAN THE SOUTHERN CWA TO
SEE SOME LOCALLY HEAVY RAINFALL ASSOCIATED WITH THIS SYSTEM.

LEFT BROAD BRUSHED 20 POPS IN THE FORECAST FOR FRIDAY WITH A GREAT
DEAL OF UNCERTAINTY REGARDING THE POSITION OF THE COLD FRONT...AND
ANY REMNANT OUTFLOW BOUNDARIES FROM CONVECTION ON THURSDAY. THURSDAY
OR FRIDAY ARE LIKELY TO BE THE COOLEST DAYS OF THE WEEK AS MOSTLY
CLOUDY SKIES ARE LIKELY DURING THIS PERIOD.

NEXT WEEKEND...GUIDANCE IS FAIRLY CONSISTENT THAT DRIER AIR WILL
ADVECT OVER THE CWA BY SATURDAY...BRINGING AN END TO OUR
PRECIPITATION CHANCES. UPPER TROUGHING IS EXPECTED TO NUDGE WEST
TOWARDS THE CWA...SO DESPITE DRIER CONDITIONS AND A RETURN TO
MOSTLY SUNNY SKIES...TEMPERATURES SHOULD REMAIN BELOW NORMAL NEXT
WEEKEND. THE SUN ANGLE IS STILL HIGH...SO IF CLOUDS CLEAR OUT
HIGHS WILL STILL CLIMB INTO THE 90S...HOWEVER HIGHS IN THE LOWER
90S ARE MOST LIKELY WHICH WOULD RESULT IN A FAIRLY NICE WEEKEND TO
GET OUTDOORS.

CAVANAUGH

&&



.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 102  79  93  73  92 /   0  10  30  30  10
WACO, TX             100  75  98  73  92 /   0   5  30  30  20
PARIS, TX             96  75  89  69  89 /   0  20  40  10   0
DENTON, TX           100  76  90  71  90 /   0  20  40  30  10
MCKINNEY, TX         101  76  91  70  91 /   0  20  40  20  10
DALLAS, TX           101  81  93  75  92 /   0  10  30  30  10
TERRELL, TX           98  77  94  73  92 /   0  10  30  30  10
CORSICANA, TX         98  76  96  73  91 /   0   5  30  30  10
TEMPLE, TX            99  73  97  73  92 /   0   5  30  30  20
MINERAL WELLS, TX    102  74  93  70  91 /   0  10  30  30  20

&&

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

&&

$$

14/69





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