716  
FXUS64 KSHV 291451  
AFDSHV  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SHREVEPORT LA  
951 AM CDT WED MAR 29 2017  
   
UPDATE
 
 
RECENT RADAR TRENDS DISPLAYED THE LINE OF STORMS FROM EARLIER THIS  
MORNING HAS WEAKENED SUBSTANTIALLY, AND IN FACT, DOES NOT RESEMBLE  
A LINE AT ALL. THERE ARE ONLY SCATTERED SHOWERS AND THUNDERSTORMS  
NOTED ACROSS PORTIONS OF EAST TX, SOUTHWEST AR, NORTHERN LA AND  
DEEP EAST TX. ELECTED TO KEEP LIKELY POPS STRETCHED FROM DEEP EAST  
TX NORTHEAST TO SOUTHWEST AR DUE TO THE ACTIVITY AFFECTING DEEP  
EAST TX THAT IS ANTICIPATED TO MOVE EAST NORTHEAST WITH TIME.  
OTHERWISE, UPLOADED CURRENT OBS FOR TEMPS, RELATIVE HUMIDITY AND  
DEWPOINT TEMPS BUT WILL NEED TO SEE IF THE CLOUD COVER HANGS  
AROUND LONGER OR SHORTER THAN ANTICIPATED AS THAT WILL AFFECT THE  
AMOUNT OF WARMING.  
 
THE FORECAST IN THE SHORT TERM WILL BE A DIFFICULT ONE AS COMPUTER  
MODELS DID NOT HANDLE THE TIMING OF THIS MORNING LINE OF STORMS.  
MOST MODELS HAD THE PRECIPITATION WEST OF TYLER THIS MORNING WHICH  
OF COURSE WAS TOO SLOW. WE WILL NEED TO REMAIN VIGILANT TODAY AND  
MAKE UPDATES WHEN NECESSARY.  
 

 
   
PREV DISCUSSION
 
/ISSUED 718 AM CDT WED MAR 29 2017/  
 
AVIATION...  
FOR THE 29/12Z TAFS, A LINE OF CONVECTION IS MOVING ACROSS THE  
AREA, BUT WILL GRADUALLY DIMINISH DURING THE FIRST FEW HOURS OF  
THE TAF PERIOD. MORE STRONG CONVECTION WILL MOVE INTO THE AREA  
FROM THE SOUTHWEST, AND NEW DEVELOPMENT IS POSSIBLE DURING THE  
AFTERNOON, MAINLY EAST OF A LINE FROM KJSO TO KDEQ. SOME OF THE  
STORMS COULD BE SEVERE, ESPECIALLY THIS AFTERNOON THROUGH TONIGHT.  
CONVECTION WILL BE SLOW TO EXIT THE AREA AND MAY STILL BE  
AFFECTING KELD AND KMLU AT THE END OF THE PERIOD. FLIGHT  
CONDITIONS WILL BE QUITE VARIABLE DUE TO THE SHOWERS AND  
THUNDERSTORMS. HOWEVER, VFR CONDITIONS ARE EXPECTED LATE IN THE  
PERIOD IN LOCATIONS WHERE THE CONVECTION ENDS. SUSTAINED SOUTHERLY  
WINDS NEAR 15 KTS WITH GUSTS NEAR 25 KTS CAN BE EXPECTED ACROSS  
MUCH OF THE AREA. SPEEDS SHOULD DIMINISH AFTER SUNSET, AND WINDS  
WILL BECOME WESTERLY AFTER 30/06Z AS A PACIFIC COLD FRONT MOVES  
ACROSS THE REGION.  
 
CN  
 
PREV DISCUSSION... /ISSUED 601 AM CDT WED MAR 29 2017/  
 
DISCUSSION...  
THE SQUALL LINE OF ECNTRL TX/SE OK HAS FINALLY BEGUN TO WEAKEN AS IT  
ENTERS OUR WRN ZONES THIS MORNING, WITH WIND GUSTS OF 30-40KTS STILL  
BEING RECORDED ALONG THE LINE, MOST RECENTLY AT PSN AS OF 0935Z. THIS  
WEAKENING TREND SHOULD CONTINUE THIS MORNING AS THE CONVECTION MOVES  
INTO AN AREA OF LOWER INSTABILITY, AND FURTHER AWAY FROM LARGE SCALE  
FORCING ASSOCIATED AHEAD OF THE CLOSED LOW OVER CNTRL NM. THIS LOW  
WILL DRIFT INTO THE TX PANHANDLE LATER THIS MORNING BEFORE REACHING  
WRN OK/SW KS LATER THIS AFTERNOON.  
 
THERE REMAINS SOME UNCERTAINTY AS TO THE AREAL EXTENT OF THE  
CONVECTION LATER THIS AFTERNOON, GIVEN THE UNKNOWN PLACEMENT OF THE  
MESOSCALE BNDRYS ASSOCIATED WITH THE ONGOING CONVECTION OF E TX, AND  
THE OVERTURNING OF THE AIR MASS THIS MORNING AS THE LINE CONTINUES TO  
PUSH E. THE HRRR HAS INITIALIZED POORLY WITH THE EXISTING CONVECTION,  
HAVING TO PLAY CATCHUP ALL NIGHT AND THUS HAVE LOW CONFIDENCE IN  
TIMING OF CONVECTION LATER TODAY. THE GFS REMAINS RATHER BULLISH  
(MORESO THAN THE NAM/ECMWF) WITH EXTENSIVE CONVECTION RAPIDLY  
REDEVELOPING THIS AFTERNOON OVER EXTREME ERN TX INTO WRN LA/SW AR, BUT  
NOT QUITE BUYING THIS JUST YET GIVEN THE CONSENSUS AMONGST THE  
NAM/ECMWF AND EVEN THE SLOWER HRRR. WHILE THE ONGOING CONVECTION  
SHOULD LEAVE BNDRYS BEHIND SOMEWHERE OVER SW AR/EXTREME ERN TX/WRN LA  
LATER THIS MORNING, WILL HAVE TO WAIT TO SEE HOW FAR E THE DRYLINE IS  
ABLE TO MIX LATER THIS AFTERNOON OVER E TX, BEFORE IT IS EVENTUALLY  
OVERTAKEN BY THE ATTENDANT COLD FRONT BY MID-EVENING. HAVE  
CONCENTRATED CATEGORICAL POPS OVER THE WRN SECTIONS OF E TX/SE OK THIS  
MORNING WHILE TAPERING POPS OFF TO LIKELY/CHANCE FARTHER E INTO SW  
AR/WRN LA, BUT BELIEVE THE MORE PLAUSIBLE SCENARIO WOULD BE FOR  
CONVECTION TO FIRE LATE THIS AFTERNOON AND ESPECIALLY THIS EVENING  
NEAR THE TX/LA/AR LINE WHERE MLCAPES CLIMB TO 1500-2000+ J/KG (IN A  
MOSTLY UNWORKED ENVIRONMENT) AND LARGE SCALE FORCING INCREASES IN  
RESPONSE TO THE SPLIT UPPER JET BENEATH THE CLOSED LOW OVER SE TX/NW  
GULF LIFTS NE. A SRLY LLJ OF 40-50KTS SHOULD INCREASE BY EARLY EVENING  
OVER THESE AREAS, ALTHOUGH SE LOW LEVEL WINDS LOOK TO VEER MORE SRLY  
AROUND INITIATION TIME WITH 0-1KM SRH A BIT LOWER THAN 24 HRS AGO  
RANGING FROM 200-300 M2/S2 BEFORE INCREASING A BIT THIS EVENING WITH  
THE ONSET OF THE LLJ. WILL ALSO CONTEND WITH DRY AIR ALOFT ENTRAINING  
NE AHEAD OF THE TROUGH THIS EVENING WHICH MAY FOCUS CONVECTION FURTHER  
AWAY FROM THE APPROACHING FRONTAL SYSTEM AND MORESO IN THE EXPANDING  
WARM/MOIST SECTOR FARTHER E. HOWEVER, STORM ORGANIZATION SHOULD OCCUR  
THIS EVENING ONCE THE PEAK INSTABILITY IS REALIZED WITH THE ONSET OF  
THE LLJ OVER SW AR/N LA. IT'S POSSIBLE THAT THE INITIAL DEVELOPMENT  
MAY BE DISCRETE BEFORE CONSOLIDATING INTO CONVECTIVE CLUSTERS. SHOULD  
THAT OCCUR, DAMAGING WINDS AND LARGE HAIL WILL BE THE PRIMARY THREATS,  
ALTHOUGH ISOLATED TORNADOES CAN'T BE RULED OUT GIVEN THE INCREASING  
SHEAR LATE IN THE DAY.  
 
HAVE TONED DOWN POPS FOR THIS EVENING AS WELL, BUT STILL CONCENTRATED  
LIKELY/CATEGORICAL POPS FOR N LA/SW AR, WITH THE CONVECTION EXITING  
OUR ERN ZONES AROUND/SHORTLY AFTER 06Z THURSDAY. IN ADDITION, THE  
PRESSURE GRADIENT SHOULD TIGHTEN LATER THIS MORNING THROUGH THE  
AFTERNOON AHEAD OF THE CNTRL OK SFC LOW, ESPECIALLY OVER MUCH OF E  
TX/N LA. AS A RESULT, HAVE EXPANDED THE CURRENT LAKE WIND ADVISORY  
FARTHER E ACROSS THE REMAINDER OF DEEP E TX INTO NCNTRL LA THROUGH 00Z  
THURSDAY, ALTHOUGH E TX WILL TAKE A LITTLE LONGER TO GUST TO CRITERIA  
(IF AT ALL) GIVEN THE CONVECTIVE OVERTURNING THAT WILL OCCUR THIS  
MORNING.  
 
THE SHORT TERM PROGS ARE IN AGREEMENT THOUGH WITH THE FRONT RAPIDLY  
MIXING E ACROSS THE REGION OVERNIGHT, EXITING OUR ERN ZONES BY MID TO  
LATE MORNING. GIVEN THE FASTER FRONTAL MOVEMENT AND THE DRY  
ENTRAINMENT OVER THE REGION BENEATH THE CLOSED LOW, CONVECTIVE  
AND SVR POTENTIAL OVER THE ERN ZONES HAS DIMINISHED, AND HAVE TONED  
DOWN POPS AS WELL TO CHANCE POPS THURSDAY MORNING, WITH ENOUGH DRY AIR  
ELIMINATING POPS ALL-TOGETHER FOR THE AFTERNOON. THE EXCEPTION MAY BE  
ACROSS SE OK/NRN SECTIONS OF SW AR WHERE WRAP-AROUND CU WILL ROUND  
THE BASE THE OF H850 LOW. THIS WILL ALSO RESULT IN COOLER TEMPS THAN  
PREVIOUSLY FORECAST AS WELL, BEFORE THEY CLEAR THE AREA THURSDAY  
EVENING WITH THE DEPARTURE OF THE LOW.  
 
FLAT RIDGING ALOFT WILL BUILD E OVER THE SRN PLAINS AND LOWER MS  
VALLEY FRIDAY, WITH SRLY WINDS EXPECTED TO RETURN WITH AMPLE  
INSOLATION. HAVE RAISED MAX TEMPS AREAWIDE, WITH MID 80S A GOOD BET  
OVER MUCH OF E TX/N LA. LOW LEVEL MOISTURE RETURN WILL COMMENCE LATE  
FRIDAY NIGHT INTO SATURDAY AS THE SRLY LLJ INCREASES IN RESPONSE TO  
THE NEXT BOWLING BALL CLOSED LOW THAT WILL DRIFT E ACROSS THE SRN  
ROCKIES. THE GFS REMAINS MOST AGGRESSIVE WITH WITH CONVECTIVE  
DEVELOPMENT BY SATURDAY EVENING, QUITE A BIT FASTER THAN ITS EARLIER  
RUN 24 HRS AGO. GIVEN THE CLOSED NATURE OF THE LOW, PREFER THE SLOWER  
ECMWF, WITH ISOLATED TO SCT CONVECTION DEVELOPING SATURDAY NIGHT,  
BEFORE BECOMING MORE WIDESPREAD SUNDAY. STILL CAN'T RULE OUT THE  
POTENTIAL FOR ANOTHER ROUND OF SVR CONVECTION SUNDAY, AS A SFC LOW  
DEVELOPS OVER E TX AND PROGRESSING NE ACROSS N LA/SRN AR ENHANCING THE  
SPREAD OF THE WARMER/MORE UNSTABLE AIR N ACROSS THESE AREAS.  
INCREASING SHEAR MAY HELP TO OFFSET THE INSTABILITY WHICH MAY BE  
HAMPERED BY THE CLOUDS/RAIN, BUT SHOULD RESULT IN WIDESPREAD WETTING  
RAINS NEEDED TO EASE THE ONGOING DROUGHT CONDITIONS. HAVE INCREASED  
POPS TO LIKELY AREAWIDE SUNDAY/SUNDAY NIGHT, BEFORE THE CONVECTION  
GRADUALLY DIMINISHES LATER MONDAY WITH THE DEPARTURE OF THIS SYSTEM.  
VERY WARM AND DRY CONDITIONS RETURN FOR THE MIDWEEK TIMEFRAME, BEFORE  
THE PROSPECTS FOR ISOLATED/SCT CONVECTION POSSIBLE INCREASE AGAIN WITH  
THE APPROACH OF THE NEXT UPPER TROUGH FROM THE NW.  
 
PRELIMS TO FOLLOW BELOW...  
 
15  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
SHV 82 58 74 50 / 60 60 20 0  
MLU 85 65 78 50 / 20 80 40 10  
DEQ 76 50 64 43 / 60 40 20 10  
TXK 78 53 67 49 / 70 50 20 10  
ELD 82 59 72 49 / 60 80 30 10  
TYR 80 52 72 53 / 70 30 10 0  
GGG 80 54 72 51 / 70 30 10 0  
LFK 80 57 78 54 / 70 40 10 0  
 

 
   
SHV WATCHES/WARNINGS/ADVISORIES
 
 
AR...LAKE WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ARZ070-071.  
 
LA...LAKE WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR LAZ001>003-  
010>013-017>022.  
 
OK...NONE.  
TX...LAKE WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR TXZ096-097-  
108>112-124>126-136>138-149>153-165>167.  
 

 
 

 
 
29/09/15  
 
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