087  
FXUS64 KSHV 261811  
AFDSHV  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SHREVEPORT LA  
111 PM CDT WED APR 26 2017  
   
AVIATION
 
 
FOR THE ARKLATEX, SQUALL LINE COMING TOGETHER NEAR KTYR/KTXK/KLIT  
MOVING E AT 30KTS. AT THIS PACE 19Z-01Z IS CURRENTLY IN TAFS WITH  
ALL TERMINALS SPORTING TEMPO GROUPS FOR WIND TO 40KT AND 1SM, OF  
COURSE SOME VARIATION WILL OCCUR AND FURTHER AMENDMENTS TO FOLLOW  
OBSERVED PACE ON OUR RADAR. SFC WINDS ARE S/SE OVER LA, BUT SW/S  
OVER TX WITH THE FORMER POTENTIALLY TORNADIC THIS AFTN WITH DECENT  
HEATING. W/NW WILL FOLLOW CONVECTION CLOSELY AND STRONG SUSTAINED  
VALUES WILL QUICKLY DROP OFF W TO E WITH ONLY WEAK HIGH PRESSURE.  
/24/  
 

 
   
PREV DISCUSSION
 
/ISSUED 105 PM CDT WED APR 26 2017/  
 
UPDATE...  
LEADING EDGE OF COLD FRONT EARLY THIS WEDNESDAY AFTERNOON HAS  
MOVED THROUGH KDEQ, SE OK, AND MINEOLA, TX. HAVE ALREADY UPDATED  
GRIDDED AND TEXT FORECASTS TO REMOVE SEVERE TSTM WATCH FROM NE TX  
AND SE OK. /VIII/.  
 
PREV DISCUSSION... /ISSUED 1145 AM CDT WED APR 26 2017/  
 
UPDATE...  
JUST UPDATED GRIDDED FORECASTS FOR HIGH TEMPERATURE TRENDS RISING  
INTO THE LOWER TO MID 80S ACROSS N LA AND E TX THIS AFTERNOON.  
WILL UPDATE THE TEXT FORECASTS AS WELL BY NOON.  
 
ALSO WILL UPDATE FORECASTS TO REMOVE MENTION OF SEVERE TSTM WATCH  
EXPIRATION AT 1 PM FROM RED RIVER AND MORRIS COUNTIES IN NE TX  
AND MCCURTAIN COUNTY IN SE OK. /VIII/.  
 
PREV DISCUSSION... /ISSUED 1026 AM CDT WED APR 26 2017/  
 
UPDATE...  
WILL UPDATE ZONES FOR THE ISSUANCE OF TORNADO WATCH 162 ISSUANCE  
EFFECTIVE UNTIL 5 PM. THE CAP DISCUSSED IN THE PREVIOUS DISCUSSION  
SHOULD INHIBIT CONVECTION ACROSS THE SOUTHERN HALF OF THE ARKLATEX  
REGION UNTIL AFTER LUNCHTIME. A SPECIAL 18Z RAOB WILL DIAGNOSE THE  
CAP STRENGTH AGAIN EARLY THIS AFTERNOON. /VIII/.  
 
PREV DISCUSSION... /ISSUED 946 AM CDT WED APR 26 2017/  
 
DISCUSSION...  
A COLD FRONT EXTENDED ACROSS EXTREME W AR THROUGH EXTREME SE OK AND  
THROUGH THE DFW METROPLEX THIS MID WEDNESDAY. ALONG AND AHEAD OF THE  
FRONT, EXPECT AN UNSTABLE AIRMASS TO CONTINUE THROUGH THIS EVENING  
WITH CAPE APPROACHING 3000 J/KG. THAT SAID, SEVERE TSTMS WILL NOT  
DEVELOP UNTIL LUNCHTIME AT BEST WITH A 8 DEG C CAP IN PLACE FROM 850  
TO 830 HPA.  
 
A LAKE WIND ADVISORY WILL REMAIN IN EFFECT THROUGH 9 PM THIS  
WEDNESDAY EVENING AND WILL LIKELY BE EXTENDED THROUGH 1 AM THURSDAY.  
 

 
 
PREV DISCUSSION... /ISSUED 612 AM CDT WED APR 26 2017/  
 
UPDATE...  
A LINE OF SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ACROSS SOUTHERN  
AND SOUTHEASTERN OK AND NORTH CENTRAL TX EARLY THIS MORNING ALONG  
THE COLD FRONT, AS ANTICIPATED. THIS ACTIVITY WILL CONTINUE TO  
SLOWLY SHIFT EAST TOWARDS THE FOUR-STATE REGION. NEIGHBORING NWS  
OFFICES ARE ISSUING WARNINGS FOR PORTIONS OF THE LINE AND THUS A  
SEVERE THUNDERSTORM WATCH IS NOW IN EFFECT UNTIL 1 PM CDT THIS  
AFTERNOON FOR PORTIONS OF NORTHEAST TX, SOUTHEAST OK AND  
SOUTHWEST AR. HAVE UPDATED THE WEATHER PACKAGE TO REFLECT THIS  
WATCH AND ADD SEVERE WORDING TO THE MORNING WEATHER.  
 
PREV DISCUSSION... /ISSUED 356 AM CDT WED APR 26 2017/  
 
DISCUSSION...  
AN UA TROUGH WAS DIGGING EAST-SOUTHEAST ACROSS THE SOUTHERN PLAINS  
EARLY THIS MORNING, RESULTING IN THE SHARPENING OF SOUTHWEST FLOW  
ALOFT ACROSS THE FOUR-STATE REGION. THIS DISTURBANCE HAS ALREADY  
AIDED IN THE DEVELOPMENT OF A LINE OF SHOWERS AND THUNDERSTORMS  
ACROSS PORTIONS OF EAST OK, NORTHWEST AR INTO SOUTHWEST MO. ADEQUATE  
INSTABILITY HAS LED TO THE ISSUANCE OF SEVERAL WARNINGS ALONG THE  
LEADING EDGE OF THE LINE, WHICH IS A TELL-TELL SIGN OF WHAT IS TO  
COME FOR THE ARKLATEX LATER TODAY.  
 
PERSISTENT SFC SRLY FLOW AND A LLJ OF 30-40 KTS HAS LED TO A  
SURGE IN LOW LEVEL MOISTURE, WITH DEWPOINTS HAVING CLIMBED INTO  
THE 60S /AND A FEW 70S/ ACROSS THE ENTIRE CWA EARLY THIS MORNING.  
THE AFOREMENTIONED UA TROUGH IS EXPECTED TO MOVE ACROSS THE REGION  
LATE THIS AFTN/EARLY THIS EVENING AND AS SUCH, A 75+ KT 500 MB  
JET WILL INFRINGE UPON THE AREA CAUSING SIGNIFICANT MID-UPPER  
LEVEL HEIGHT FALLS. UL SUPPORT WILL BE ON THE RISE WITH MUCAPE  
VALUES INCREASING TO BETWEEN 2500-3500 J/KG AND 0-6 KM BULK  
SHEAR OF 40-70 KTS. IT IS INTERESTING TO NOTE THAT MODEL SOLUTIONS  
DEPICT THE HIGHEST AFOREMENTIONED SEVERE INDICES TO BE ACROSS  
PORTIONS OF SOUTHWEST AR, EXTREME NORTHEAST TX AND NORTHERN LA,  
WHICH IS WHY THE STORM PREDICTION CENTER HIGHLIGHTS THESE AREAS  
WITH A MODERATE RISK. IN ADDITION, WITHIN THE SAME AREAS, 0-1 KM  
HELICITY VALUES ARE PROGGED TO INCREASE INTO THE 200-300 M2/S2  
RANGE. WHAT THIS ALL IMPLIES IS THE POTENTIAL FOR STORMS TO BECOME  
SEVERE WITH LARGE HAIL, DAMAGING WIND GUSTS AND ISOLATED  
TORNADOES THE PRIMARY THREATS. MODEL SOLUTIONS EXHIBIT THE PRECIP  
ACTIVITY TO EVOLVE AS FOLLOWS: ISOLATED SHOWERS AND THUNDERSTORMS  
MAY DEVELOP JUST ABOUT ANYWHERE AHEAD OF THE MAIN CONVECTION MID-  
LATE THIS MORNING DUE TO INCREASED DAYTIME DESTABILIZATION.  
ATTENTION WILL QUICKLY TURN TO A LINE OF STORMS THAT WILL DEVELOP  
ALONG A RATHER BREEZY COLD FRONT ACROSS NORTH CENTRAL TX AND  
SOUTHEAST OK LATE THIS MORNING/EARLY THIS AFTN, WHICH IS EXPECTED  
TO IMPINGE ON THE AREA FROM WEST TO EAST THROUGH THE AFTN AND INTO  
THE EVENING HOURS. PRECIP WILL COME TO AN END ACROSS THE EASTERN  
ZONES AOA MIDNIGHT. ALTHOUGH ISOLATED TORNADOES CAN NOT BE RULED  
OUT, CURRENT THINKING IS THAT AS THE PRECIP ACTIVITY EVOLVES INTO  
A MORE LINEAR NATURE, IT WILL BECOME LESSER OF A THREAT AS OPPOSED  
TO LARGE HAIL AND DAMAGING WIND GUSTS. FURTHERMORE, CAN NOT RULE  
OUT MODERATE RAINFALL, WITH THE WEATHER PREDICTION CENTER SHOWING  
RAINFALL AMOUNTS OF 1-2 INCHES ESPECIALLY NORTH OF THE INTERSTATE  
20 CORRIDOR.  
 
AS PREVIOUSLY MENTIONED, A RATHER BREEZY COLD FRONT WILL MOVE IN  
ACROSS THE REGION TODAY, WITH PRESSURE RISES ON THE ORDER OF 3-5  
MB/3 HRS WHICH WILL LEAD TO WEST-NORTHWEST WIND SPEEDS OF 20-25  
MPH WITH GUSTS NEAR 40 MPH /AND POSSIBLY HIGHER IF CONVECTIVELY  
DRIVEN/. AS A RESULT, A LAKE WIND ADVISORY IS IN EFFECT FROM 9 AM  
THIS MORNING /WIND SPEEDS INCREASING INITIALLY ACROSS SOUTHEAST OK  
AND NORTHEAST TX DURING THE EARLY MORNING HOURS/ TO 9 PM CDT THIS  
EVENING, AS THE CONVECTION AND PRESSURE GRADIENT WILL COMMENCE TO  
DEMISE/RELAX.  
 
WE WILL GET A REPRIEVE FROM THE WET AND WINDY CONDITIONS TOMORROW  
AS SFC RIDGING SETTLES ACROSS THE AREA. TEMPS WILL BE IN THE 70S  
/WITH A FEW 80S/ SIMILAR TO WHAT IS EXPECTED TODAY SO THE CAA  
WHICH WILL BE USHERED IN BY TODAY/S COLD FRONT WILL NOT BE OVERLY  
COLD. HOWEVER, TEMPS WILL SOAR INTO THE 80S /AND PERHAPS A FEW 90S  
ACROSS THE SOUTHERN ZONES/ BY FRIDAY COURTESY OF A RETREATING  
WARM FRONT. THIS FRONT WILL SETTLE ACROSS THE FAR NORTHERN ZONES  
WHICH MAY BE A FOCUS FOR THUNDERSTORM DEVELOPMENT ALONG AND NORTH  
OF THE FRONT DURING THE AFTN WHEN DAYTIME DESTABILIZATION IS  
MAXIMIZED. WHAT IS INTERESTING TO NOTE IS THAT 0-6 KM BULK SHEAR  
OF 40-50 KTS AND MUCAPE AOA 2000 J/KG COULD AID IN THE DEVELOPMENT  
OF STRONG TO SEVERE STORMS WITH HAIL AND GUSTY WINDS THE MAIN  
THREATS /BUT CAN NOT RULE OUT ISOLATED TORNADOES/.  
 
THE UNSETTLED WEATHER PATTERN WILL CONTINUE AS WE HEAD INTO THE  
WEEKEND WHICH COULD BE OUR NEXT WIDESPREAD SEVERE WX MAKER. THIS UA  
TROUGH IS PROGGED TO CLOSE OFF WHILST DIGGING EAST-SOUTHEAST ACROSS  
THE FOUR-CORNERS REGION ON SATURDAY MORNING TO ACROSS THE SOUTHERN  
PLAINS SATURDAY NIGHT/EARLY SUNDAY MORNING, AND FINALLY THE CENTER  
OF THE LOW EJECTS NORTHEAST TO NEAR THE GREAT LAKES REGION MONDAY  
MORNING. THE GFS IS SLIGHTLY QUICKER IN ENDING THE PRECIP THAN  
THE ECMWF SO SOME FINE DETAILS STILL NEED TO BE IRONED OUT.  
KEEPING THAT IN MIND, SCATTERED SHOWERS AND THUNDERSTORMS WILL BE  
ONGOING FRIDAY NIGHT/EARLY SATURDAY MORNING NEAR THE LINGERING  
WARM FRONT, BUT THE BEST WIDESPREAD CONVECTION IS EXPECTED TO  
DEVELOP ALONG A COLD FRONT, AND IMPACT THE REGION FROM WEST TO  
EAST SATURDAY EVENING THROUGH SUNDAY. ONCE AGAIN, SIGNIFICANT  
INSTABILITY AND DEEP-LAYER WIND SHEAR WILL EXIST WITH THIS  
DISTURBANCE, RAISING CONCERN FOR LARGE HAIL, DAMAGING WIND GUSTS  
AND ISOLATED TORNADOES. FURTHERMORE, MODEL SOLUTIONS CONTINUE TO  
INSIST THAT THIS COULD ALSO SHAPE OUT TO BECOME A FLOOD EVENT WITH  
PWATS SOARING INTO THE 1.30-1.90 INCH RANGE. THE WEATHER  
PREDICTION CENTER DEPICTS RAINFALL AMOUNTS OF 1-6 INCHES WITH  
HIGHEST AMOUNTS NOTED ACROSS PORTIONS OF SOUTHEAST OK, EXTREME  
NORTHEAST TX, SOUTHWEST AR AND NORTHERN LA /VALID FROM 12Z  
SATURDAY THROUGH 12Z MONDAY/. THEREAFTER, QUIET WX WILL ENSUE AND  
TEMPS WILL GRADUALLY REBOUND FROM THE 60S AND 70S OF THIS WEEKEND  
INTO THE 70S AND 80S BY TUESDAY.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
SHV 85 48 78 62 / 60 30 10 10  
MLU 85 52 77 60 / 50 50 10 10  
DEQ 72 42 75 56 / 90 30 0 10  
TXK 82 46 76 59 / 80 40 0 10  
ELD 82 48 76 58 / 80 60 10 10  
TYR 82 47 80 64 / 60 20 0 10  
GGG 84 46 79 63 / 60 20 0 10  
LFK 85 51 85 65 / 50 20 0 10  
 

 
   
SHV WATCHES/WARNINGS/ADVISORIES
 
 
AR...LAKE WIND ADVISORY UNTIL 9 PM CDT THIS EVENING FOR ARZ050-051-  
059>061-070>073.  
 
LA...LAKE WIND ADVISORY UNTIL 9 PM CDT THIS EVENING FOR LAZ001>006-  
010>014-017>022.  
 
OK...LAKE WIND ADVISORY UNTIL 9 PM CDT THIS EVENING FOR OKZ077.  
 
TX...LAKE WIND ADVISORY UNTIL 9 PM CDT THIS EVENING FOR TXZ096-097-  
108>112-124>126-136>138-149>153-165>167.  
 

 
 

 
 
24/08/29  
 
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