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

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FXUS64 KFWD 141541
AFDFWD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
1041 AM CDT MON APR 14 2014

.UPDATE...
GRIDS HAVE BEEN UPDATED TO INCLUDE SEVERE THUNDERSTORM WATCH 80
FOR AREAS GENERALLY ALONG AND SOUTHEAST OF A LINE FROM KILLEEN TO
ATHENS. STORMS CONTINUE TO DEVELOP IN THESE AREAS WITH
ELEVATED CORES OCCASIONALLY PRODUCING QUARTER SIZED HAIL.
THUNDERSTORMS WILL GRADUALLY SHIFT EAST OF NORTH TEXAS ALONG WITH
THE 850MB FRONT AND THE PRIMARY UPPER TROUGH AXIS. THE WATCH IS IN
EFFECT UNTIL 5 PM CDT...BUT WE SHOULD BE ABLE TO CLEAR COUNTIES FROM
WEST TO EAST AS WARRANTED BY TRENDS.

30

&&

.AVIATION...
/12Z TAFS/

MVFR CONDITIONS WILL PREVAIL THROUGH THE MORNING WITH GUSTY NORTH
WINDS EXPECTED MOST OF THE DAY. EXTENSIVE CLOUDINESS WILL BEGIN TO
SCATTER OUT THIS AFTERNOON AS DRIER AIR MIXES DOWN. VFR CONDITIONS
EXPECTED LATER TODAY THROUGH TUESDAY. WINDS WILL DIMINISH THIS
EVENING BECOMING LGT/VAR BY EARLY TUESDAY...THEN SOUTHERLY AROUND
10KTS TUESDAY AFTERNOON.

DUNN


&&


.PREV UPDATE...
.UPDATE...
ELEVATED CONVECTION NEAR WAXAHACHIE...HILLSBORO...CORSICANA AND
SURROUNDING AREAS WILL CONTINUE TO LIFT NORTHEAST AS AN UPPER
TROUGH DIGS SOUTHEAST ACROSS THE CENTRAL AND SOUTHERN PLAINS. WE
DID A QUICK UPDATE TO INCLUDE POPS THIS MORNING FOR AREAS
IMMEDIATELY EAST AND SOUTH OF DALLAS. ACTIVITY WILL SHIFT EAST OF
THE AREA BY EARLY AFTERNOON ALONG WITH THE TROUGH AXIS. OTHERWISE
STRONG NORTH WINDS WILL CONTINUE THROUGH THE AFTERNOON. CLOUDS AND
COLD ADVECTION WILL KEEP A LID ON TEMPERATURES...WILL KEEP AN EYE
ON TRENDS TO SEE IF AFTERNOON HIGHS NEED TO BE LOWERED AT ALL.
RECORD LOW MAX AT DFW IS 55 FOR TODAY...AND 56 AT WACO SO IT WILL
BE CLOSE.

30

&&


.PREV DISCUSSION... /ISSUED 417 AM CDT MON APR 14 2014/

08Z SURFACE ANALYSIS INDICATED A STRONG COLD FRONT MOVING
SOUTHEAST ACROSS THE CWA...LOCATED NEAR A LINE FROM ATHENS TO
WACO TO LAMPASAS. JUST TO THE NORTHWEST OF THIS FRONT...A LINE OF
SCATTERED SHOWERS AND THUNDERSTORMS WAS OBSERVED...LIKELY
ASSOCIATED WITH THE 850 MB REFLECTION OF THE COLD FRONT. AT
0830Z...NONE OF THIS ACTIVITY WAS STRONG IN NATURE...AND AS
ALLUDED TO ABOVE...IT IS ALL ELEVATED IN NATURE OVER THE FRONTAL
INVERSION. REGIONAL SURFACE OBSERVATIONS INDICATE UNSEASONABLY
COLD AIR BEHIND THE FRONT...WITH TEMPERATURES IN THE LOWER 40S
LOCATED OVER WICHITA FALLS. NORTH WINDS WERE ALREADY RELATIVELY
STRONG BEHIND THE FRONT...WITH MANY LOCATIONS OBSERVING WINDS IN
THE 20 TO 25 MPH RANGE EARLY THIS MORNING.

THIS MORNING...WENT AHEAD AND CANCELLED THE SEVERE THUNDERSTORM
WATCH IN COORDINATION WITH THE SPC AND WFO SHV AS THE COLD FRONT
HAD UNDERCUT ALL ONGOING CONVECTION. THIS DOES NOT MEAN IT/S
IMPOSSIBLE TO GET STRONG STORMS THIS MORNING...HOWEVER THE ONLY
STRONG TO MARGINALLY SEVERE STORM HAZARD ASSOCIATED WITH ELEVATED
STORMS IS GOING TO BE IN THE FORM OF HAIL. RAP FORECAST SOUNDINGS
INDICATE THE PRESENCE OF 1000-1500 J/KG OF MUCAPE AVAILABLE FOR
THESE ELEVATED STORMS. DEEP LAYER SHEAR VALUES LOOK
IMPRESSIVE...BUT ARE NOT REALLY RELEVANT FOR THIS ACTIVITY AS THE
BULK OF THE CONTRIBUTION TO THE HIGHER SHEAR VALUES OCCURS BELOW
THE FRONTAL INVERSION. DEEP LAYER BULK SHEAR CALCULATIONS INDICATE
ABOUT 60 KTS OF SHEAR...WHILE EFFECTIVE BULK SHEAR IS MORE
REALISTICALLY AROUND 25 KTS. AS A RESULT...STRONG...BUT LIKELY
UNORGANIZED ELEVATED CONVECTION IS POSSIBLE THIS MORNING. BASED ON
THE RADAR PRESENTATION OF STORMS SO FAR EARLY THIS
MORNING...CHANCES ARE NO LARGE HAIL WILL FALL ACROSS THE
CWA...HOWEVER IF IT DOES OCCUR...HAIL WILL LIKELY BE CLOSE TO 1
INCH OR QUARTER SIZE IN DIAMETER.

REMAINDER OF TODAY...THE 850 MB FRONT WILL SLIDE SOUTHEAST OF THE
CWA BY LATE THIS MORNING...TAKING ALL THUNDERSTORM CHANCES
SOUTHEAST OUT OF THE AREA IN ITS WAKE. RELATIVELY STRONG ISENTROPIC
DOWNGLIDE/COLD AIR ADVECTION WILL DOMINATE THE LOWER TROPOSPHERE
IN THE WAKE OF THIS FRONT. A STRONG UPPER LEVEL LOW PRESSURE
SYSTEM WILL MOVE FROM WEST TO EAST OVER THE SOUTH PLAINS
TODAY...WHICH WILL SPREAD SOME STRONG LARGE SCALE FORCING FOR
ASCENT OVER THE CWA THIS AFTERNOON. HOWEVER...THE LARGE SCALE
FORCING FOR ASCENT ASSOCIATED WITH THIS UPPER LOW IS NOT EXPECTED
TO PENETRATE MUCH DEEPER THAN THE MIDDLE TROPOSPHERE TODAY BECAUSE
THE MIDDLE TO LOW TROPOSPHERE WILL BE DEFINED BY HIGH STATIC
STABILITY. A THERMODYNAMICALLY STABLE LAYER RESISTS VERTICAL
MOTIONS...AND THEREFORE SHOULD PREVENT ANY ADDITIONAL
PRECIPITATION FROM DEVELOPING OVER THE CWA TODAY ASSOCIATED WITH
THIS UPPER LOW. THIS IS SUCH A STRONG UPPER TROUGH THAT IT WOULD
BE A HUGE SURPRISE TO SEE SOME WEAK RADAR RETURNS DEVELOP OVER THE
CWA EARLY THIS AFTERNOON...BUT THE COLD FRONT PUSHING THROUGH THE
AREA JUST LOOKS TOO STRONG AND COLD TO ALLOW FOR MUCH LIFT TO
OCCUR WHERE WE WOULD NEED IT TO GET RAIN SHOWERS...THAT BEING THE
MID TO LOWER TROPOSPHERE.

ASIDE FROM PRECIPITATION CONCERNS...BEHIND THE FRONT WE SHOULD
JUST SEE STRONG NORTH WINDS AND COLD AIR ADVECTION THROUGHOUT THE
DAY TODAY. TEMPERATURES ARE EXPECTED TO INCREASE INTO THE LOWER TO
MID 50S BY LATE THIS AFTERNOON DESPITE THE STRONG COLD AIR
ADVECTION AS SKIES CLEAR OUT RAPIDLY BEHIND THE PASSAGE OF THE
UPPER TROUGH. EVEN THOUGH THE AIR BEHIND THE FRONT WILL REMAIN
COLD...THE SUN ANGLE IS GETTING TOO HIGH FOR US NOT TO HEAT UP A
BIT EVEN WITH JUST A FEW HOURS OF SUNSHINE. A WIND ADVISORY
REMAINS IN EFFECT FOR THE ENTIRE AREA TODAY DUE TO NORTH WINDS OF
25 TO 30 MPH BEHIND THE FRONT. WINDS SHOULD DIMINISH AN HOUR OR
TWO AFTER SUNSET AS HIGH PRESSURE BEGINS TO MOVE INTO THE REGION.

TONIGHT...HIGH PRESSURE IS EXPECTED TO SLIDE SOUTH-SOUTHEAST
ACROSS TEXAS FROM THE TX PANHANDLE TONIGHT. THIS WILL RESULT IN
NEARLY CALM WINDS ACROSS WEST CENTRAL TEXAS...AND LIGHT NORTHERLY
WINDS TO THE EAST. LIGHT WINDS AND CLEAR SKIES WILL MAKE FOR AN
IDEAL RADIATIONAL COOLING ENVIRONMENT RESULTING IN TEMPERATURES
FALLING INTO THE UPPER 20S TO MID 30S ACROSS THE CWA. YES...YOU
READ THAT CORRECTLY...PARTS OF NORTH AND CENTRAL TEXAS ARE
EXPECTED TO FALL BELOW FREEZING TONIGHT INTO TUESDAY MORNING. THIS
IS PUSHING RECORD TERRITORY FOR A LATE FREEZE WHICH IS QUITE
REMARKABLE CONSIDERING RECORDS HAVE BEEN KEPT SINCE THE LATE 1800S
TO EARLY 1900S...SO WE ARE LOOKING AT AN EVENT THAT HAS A RETURN
INTERVAL OF OVER 100 YEARS...FOR NORTH AND CENTRAL TEXAS AT LEAST.
AS A RESULT...THIS FREEZE...ASSUMING IT OCCURS AS FORECAST...HAS
THE POTENTIAL TO DO QUITE A BIT OF DAMAGE TO OUTDOOR PLANTS AS
MOST FOLKS WOULD NOT HAVE WAITED THIS LONG TO GET THEIR SPRING
PLANTING TAKEN CARE OF. AT ANY RATE...THIS IS WHY FREEZE WARNINGS
ARE ISSUED...TO GIVE FOLKS A CHANCE TO PROTECT THEIR PLANTS.

A FREEZE WARNING IS IN EFFECT FROM 1 AM TO 10 AM TONIGHT/TUESDAY
MORNING FOR LOCATIONS ALONG AND NORTHWEST OF A LINE FROM SULPHUR
SPRINGS TO KELLER TO WACO TO LAMPASAS. LOCATIONS JUST SOUTHEAST OF
THIS LINE GENERALLY HAVE FORECAST LOWS AT 33 DEGREES...SO THIS
WARNING MAY BE EXPANDED BASED ON HOW WARM WE GET THIS AFTERNOON
AND BASED ON NEW MODEL GUIDANCE THROUGHOUT THE DAY.
FORTUNATELY...MOST LOCATIONS IN THE FREEZE WARNING SHOULD SEE LOWS
FALL JUST BELOW FREEZING...GENERALLY 30 TO 32 DEGREES.
TEMPERATURES FALLING INTO THE UPPER 20S IS MORE LIKELY NORTH OF
INTERSTATE 30...NEAR THE RED RIVER.

TEMPERATURES ARE MORE LIKELY TO FALL BELOW FREEZING IN RURAL AREAS
MORE SO THAN URBAN AREAS. THE URBAN HEAT ISLAND EFFECT WILL KEEP
MOST OF THE CONCRETED AREAS OF THE METROPLEX ABOVE FREEZING.
TARRANT COUNTY IS INCLUDED IN THE FREEZE WARNING ANYWAYS BECAUSE
THE FAR NORTH AND WESTERN PORTIONS OF THE COUNTY...OUTSIDE OF THE
820 LOOP...ARE MORE LIKELY TO SEE FREEZING TEMPERATURES.
TEMPERATURES ARE EXPECTED TO CLIMB ABOVE FREEZING AREA WIDE AFTER
10 AM TUESDAY MORNING.

FROST IS POSSIBLE IN AREAS NOT INCLUDED IN THE FREEZE WARNING...SO
EVEN IF YOU ARE NOT IN THE FREEZE WARNING AT THIS TIME...IT MAY BE
PRUDENT TO PROTECT YOUR PLANTS ANYWAYS AS A PRECAUTION. THE AIR IS
EXPECTED TO BE VERY DRY...SO WIDESPREAD FROST IS NOT LIKELY...BUT
IT MAY BE BETTER TO BE SAFE THAN SORRY.

REMAINDER OF THE FORECAST...WE WILL WARM UP AFTER TUESDAY...WITH
NO MORE POTENTIAL FROSTS OR FREEZES IN THE FORECAST THROUGH NEXT
WEEKEND. TUESDAY NIGHTS LOWS WILL BE WELL BELOW NORMAL AGAIN...BUT
SHOULD FALL INTO THE MID TO UPPER 30S AT WORST. BY
WEDNESDAY...SOUTH WINDS WILL HELP BRING DEW POINTS BACK UP INTO
THE MID TO UPPER 40S...BRINGING ABOUT A RETURN TO MORE SEASONAL
TEMPERATURES DURING THE DAYTIME AND OVERNIGHT.

OUR NEXT CHANCE OF RAIN STILL LOOKS TO BE THURSDAY...ASSOCIATED
WITH AN UPPER LEVEL TROUGH PROGGED TO MOVE OVER THE SOUTHERN
PLAINS THURSDAY AFTERNOON. HOWEVER...THE ECMWF AND GFS BOTH KEEP
THE BULK OF THE UPPER LEVEL FORCING FOR ASCENT ASSOCIATED WITH
THIS TROUGH NORTH OF THE CWA. ASSUMING THIS VERIFIES...THIS DOES
NOT USUALLY BODE WELL FOR PRECIPITATION CHANCES...EVEN WITH A WEAK
COLD FRONT PUSHING SOUTHEAST ACROSS THE CWA THURSDAY
AFTERNOON/EVENING. THE LOSS OF UPPER LEVEL DYNAMICS USUALLY MAKES
PRECIPITATION ALONG COLD FRONTS ISOLATED AT BEST. THE CANADIAN IS
FURTHER SOUTH WITH THIS UPPER TROUGH...AND THEREFORE HAS MUCH MORE
PRECIPITATION FOR THE CWA. WILL CONTINUE TO MONITOR THE EVOLUTION
OF THIS TROUGH IN FUTURE FORECASTS...HOWEVER FOR NOW JUST KEPT
POPS IN THE 20 TO 30 PERCENT RANGE IN LINE WITH THE GFS/ECMWF
SOLUTION.

AFTER THURSDAY...OUR NEXT SHOT AT RAIN LOOKS TO BE SATURDAY NIGHT
INTO SUNDAY...AS ALL GUIDANCE INDICATES AN UPPER LEVEL TROUGH WILL
MOVE OVER THE SOUTHWESTERN CONUS AND TOWARDS NORTH TX AT THAT
TIME. THE GFS IS THE MOST AGGRESSIVE WITH TAPPING INTO SOME
TROPICAL PACIFIC MOISTURE IN THE UPPER TROPOSPHERE COURTESY OF THE
SUB-TROPICAL JET. AS A RESULT THE GFS GIVES THE CWA A
GOOD...WIDESPREAD ONE HALF TO ONE INCH OF RAINFALL FROM SATURDAY
NIGHT THROUGH SUNDAY. WILL NOT BITE OFF ON THIS SOLUTION QUITE
YET...BUT IT IS A GOOD SIGN THAT AT LEAST ALL MODELS HAVE SOME
VERSION OF THIS TROUGH OVER THE SOUTHWESTERN CONUS. IF THIS
CONSISTENT CONTINUES...POPS WILL BE INCREASED AREA WIDE FOR
SATURDAY NIGHT INTO SUNDAY. THIS DOES NOT LOOK TO BE A GOOD SEVERE
WEATHER SET UP FOR NOW...SO A GOOD WIDESPREAD RAINFALL WITH
EMBEDDED THUNDERSTORMS IS WHAT IS EXPECTED AT THIS TIME. WE WILL
SEE HOW THINGS CHANGE AS WE GET CLOSER TO NEXT WEEKEND OF COURSE.

CAVANAUGH



&&


.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  55  34  63  42  66 /  10   5   0   0   0
WACO, TX              56  33  63  36  67 /  30   0   0   0   0
PARIS, TX             51  30  59  36  64 /  20   5   0   0   0
DENTON, TX            53  29  62  38  66 /  10   5   0   0   0
MCKINNEY, TX          53  30  62  38  65 /  10   5   0   0   0
DALLAS, TX            56  35  63  42  66 /  10   5   0   0   0
TERRELL, TX           55  33  62  37  65 /  20   5   0   0   0
CORSICANA, TX         54  33  61  38  66 /  30   5   0   0   0
TEMPLE, TX            58  33  64  36  68 /  30   0   0   0   0
MINERAL WELLS, TX     55  32  63  37  69 /  10   0   0   0   0

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING FROM 1 AM TO 10 AM CDT TUESDAY FOR TXZ091>095-
100>107-115>118-129>133-141>145-156-157-159.

WIND ADVISORY UNTIL 9 PM CDT THIS EVENING FOR TXZ091>095-100>107-
115>123-129>135-141>148-156>162-174-175.


&&

$$

58/30





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