104  
FXUS64 KLCH 171759  
AFDLCH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LAKE CHARLES LA  
1259 PM CDT TUE SEP 17 2019  
   
DISCUSSION
 
 
18Z TAFS  
 

 
   
AVIATION
 
 
TROPICAL BANDING ASSOCIATED WITH NEWLY DEVELOPED TROPICAL STORM  
IMELDA WILL CONTINUE TO PUSH INLAND ACROSS SOUTHEAST TEXAS  
THROUGH THE TAF PERIOD. BPT WILL SEE THE MOST SIGNIFICANT IMPACTS  
WITH GUSTY WINDS AND PERIODS OF VISIBILITY REDUCING HEAVY  
RAINFALL. LOUISIANA TERMINALS WILL SEE MORE SCATTERED RAINFALL.  
CEILINGS WILL FLUCTUATE BETWEEN VFR AND IFR DEPENDING ON THE  
PROXIMITY OF BANDING.  
 
JONES  
 

 
   
PREV DISCUSSION
 
/ISSUED 913 AM CDT TUE SEP 17 2019/  
 
UPDATE...AN AREA OF LOW PRESSURE WILL CONTINUE TO MOVE INLAND TO  
THE CENTRAL TEXAS COAST THROUGH THE NEXT 24 HOURS. THIS WILL KEEP  
POPS ELEVATED WHILE KEEPING TEMPERATURES LOWER. THE PREVIOUS  
FORECAST REMAINS ON TRACK AND NO CHANGES ARE NEEDED AT THE CURRENT  
TIME.  
 
PREV DISCUSSION... /ISSUED 632 AM CDT TUE SEP 17 2019/  
 
DISCUSSION...  
FOR THE 17/12Z TAF ISSUANCE.  
 
AVIATION...  
RAIN BANDS ROTATING AROUND A TROPICAL DISTURBANCE OFF THE MIDDLE  
TEXAS COAST WILL IMPACT THE AVIATION TERMINALS DURING THE PERIOD.  
THIS MORNING KBPT WILL HAVE THE MAIN IMPACTS WITH PREVAILING LIGHT  
SHOWERS THAT WILL BE OCCASIONALLY STRONG. MVFR TO IFR  
CEILINGS/VISIBILITIES WITH THE ACTIVITY AND SOME WIND GUSTS TO 25  
KNOTS CAN BE EXPECTED. THE ACTIVITY WILL GRADUALLY PUSH INLAND  
DURING THE AFTERNOON HOURS WITH IMPACTS AT KLCH/KLFT/KARA, WITH  
THE POSSIBILITY OF SOME MORE SCATTERED ACTIVITY REACHING KAEX BY  
LATE AFTERNOON. DURING THE EVENING HOURS, ACTIVITY INLAND WILL  
DISSIPATE WITH MAINLY VFR EXPECTED AT KAEX/KLCH/KLFT/KARA THROUGH  
THE OVERNIGHT. KBPT HOWEVER, AFTER A BREAK IN THE EVENING, WILL  
SEE A REDEVELOPMENT OF SHOWER ACTIVITY DURING THE OVERNIGHT.  
 
RUA  
 
PREV DISCUSSION... /ISSUED 415 AM CDT TUE SEP 17 2019/  
 
DISCUSSION...  
 
SHORT TERM [TODAY THROUGH THURSDAY]  
 
WATER VAPOR GOES-16 IMAGERY THIS MORNING INDICATES AN UPPER LEVEL  
LOW REMAINS LOCATED ABOVE A SURFACE TROUGH EXTENDING ALONG THE  
NORTHWESTERN GULF OF MEXICO. THE UPPER LEVEL LOW IS EXPECTED TO  
SUPPORT THE SURFACE TROUGH BECOMING MORE ORGANIZED AS IT GRADUALLY  
MOVES INLAND OVER THE NEXT 48 HOURS. THE 2 AM TROPICAL WEATHER  
OUTLOOK NOTED THAT WHILE SURFACE PRESSURE IS ALREADY FALLING  
ACROSS THIS PORTION OF THE GULF, NO EVIDENCE OF A SURFACE  
CIRCULATION CURRENTLY EXISTS. HOWEVER, GIVEN THE POTENTIAL FOR THE  
SYSTEM TO BECOME MORE VERTICALLY STACKED BASED ON THE COLLOCATION  
OF THE UPPER LEVEL AND SURFACE FEATURES, NHC IS INDICATING AT  
LEAST A LOW (30% CHANCE) THAT A WEAK SURFACE LOW COULD DEVELOP  
OVER THE NEXT 48 HOURS.  
 
REGARDLESS OF THE DEVELOPMENT OF ANY SURFACE SYSTEM, THERE WILL BE  
THE POTENTIAL FOR HEAVY RAINFALL AND FLASH FLOODING ALONG THE  
TEXAS COAST THROUGH THURSDAY. SATELLITE DERIVED SOUNDINGS INDICATE  
PWAT VALUES OF 2"-2.5" ARE ASSOCIATED WITH THIS SYSTEM AND WILL BE  
BROUGHT INLAND AS IT MOVES NORTHWARD. MEANWHILE, FAIRLY  
UNIDIRECTIONAL FLOW IN THE LOW- TO MID- LEVELS OF THE ATMOSPHERE  
WILL SUPPORT THE POTENTIAL FOR BANDS OF CONVECTION TO TRAIN OVER  
THE SAME AREA. THESE TRAINING BANDS MOVING THROUGH AN ENVIRONMENT  
THAT IS SUPPORTIVE OF EFFICIENT PRECIPITATION WILL SUPPORT THE  
THREAT OF VERY HEAVY RAINFALL AMOUNTS AND FLASH FLOODING. MUCH OF  
THE CAM GUIDANCE SUPPORTS THE POTENTIAL FOR LOCALIZED AMOUNTS OF  
6-9"+ OF RAINFALL SOMEWHERE ALONG THE TEXAS COAST. CURRENTLY, THE  
GREATEST POTENTIAL FOR THESE HEAVIER RAINFALLS LOOKS TO BE AROUND  
THE HOUSTON AREA. HOWEVER, THESE HEAVIER RAINFALL TOTALS CANNOT BE  
RULED OUT FOR PORTIONS OF SOUTHEAST TEXAS AND ADJACENT WESTERN  
LOUISIANA AS THE EXACT PLACEMENT OF BANDS WILL BE DEPENDENT ON  
WHERE A MORE ORGANIZED SURFACE CIRCULATION IS ABLE TO DEVELOP.  
 
IN COORDINATION WITH WPC AND NEIGHBORING OFFICES, THE FORECAST  
TODAY INCLUDES A MARGINAL RISK (5%-10%) OF FLASH FLOODING FOR THE  
ALL OF SOUTHERN LOUISIANA AND A SLIGHT RISK (10%-20%) OF FLASH  
FLOODING ACROSS SOUTHEAST TEXAS. ONE HOUR AND SIX HOUR FLASH  
FLOOD GUIDANCE ACROSS PORTIONS OF SOUTHEAST TEXAS RANGES FROM 3.5"  
TO OVER 6" RESPECTIVELY. MEANWHILE THE BEST FORCING FOR  
PRECIPITATION IS EXPECTED TO BE CONFINED TO THE SOUTH-CENTRAL  
TEXAS COAST TODAY. THEREFORE, ELECTED NOT TO ISSUE A FLASH FLOOD  
WATCH FOR SOUTHEAST TEXAS AT THIS TIME.  
 
THE GREATER POTENTIAL FOR FLASH FLOODING WILL COME ON WEDNESDAY  
AND THURSDAY AS THE SYSTEM LIFTS NORTHWARD INTO EASTERN TEXAS.  
THIS WILL ADVECT RICHER PWATS INTO THE REGION AND ALSO PROVIDE  
GREATER SUPPORT FOR CONVECTIVE BANDS TO DEVELOP ACROSS SOUTHEAST  
TEXAS AND WESTERN LOUISIANA. AS A RESULT, WPC EXPANDED THE SLIGHT  
RISK OF FLASH FLOODING EASTWARD INTO WESTERN LOUISIANA AND A  
MODERATE RISK (20%-50%) OF FLASH FLOODING CLIPS THE WESTERN EDGE  
OF THE CWA. THESE AREAS COULD SHIFT FURTHER EAST OR WEST DEPENDING  
ON THE EVENTUAL DEVELOPMENT AND TRACK OF ANY ORGANIZED SURFACE  
LOW. SHOULD CONFIDENCE INCREASE, A FLASH FLOOD WATCH WILL BE  
ISSUED FOR SOUTHEAST TEXAS AND POSSIBLY AREAS FURTHER EAST.  
REGARDLESS OF ANY WATCHES BEING ISSUED, THOSE IN SOUTHEAST TEXAS  
AND WESTERN LOUISIANA SHOULD CONTINUE TO BE PREPARED FOR THE  
POTENTIAL OF FLASH FLOODING ON WEDNESDAY AND THURSDAY.  
 
LONG TERM [FRIDAY THROUGH MONDAY]  
 
THE LONG TERM PERIOD WILL FEATURE A RETURN TO A MORE TYPICAL  
SEPTEMBER WEATHER PATTERN AS THE UPPER LEVEL AND SURFACE LOW LIFT  
NORTH OF THE GULF COAST. THIS WILL ALLOW FOR WEAK RIDGING TO BUILD  
INTO THE AREA. AS A RESULT, PWATS ARE FORECAST TO RETURN TO  
AROUND 1.7"-2" BY THE LATER HALF OF THE WEEKEND. THIS WILL SUPPORT  
THE TYPICAL 20%-30% CHANCE OF AFTERNOON SHOWERS AND THUNDERSTORMS  
EACH DAY WITH HIGHS IN THE LOW TO MID 90S.  
 
MARINE...  
 
AN UPPER LEVEL LOW OVER THE WESTERN GULF OF MEXICO WILL MOVE  
INLAND ACROSS EAST TEXAS OVER THE NEXT FEW DAYS. THIS WILL RESULT  
IN ELEVATED PRECIPITATION CHANCES OVER THE COASTAL WATERS THROUGH  
THURSDAY. THE SURFACE PRESSURE GRADIENT ASSOCIATED WITH THIS  
SYSTEM WILL ALLOW FOR ELEVATED SOUTHEAST WINDS WILL CONTINUE TODAY  
AND WEDNESDAY, PARTICULARLY OVER THE COASTAL WATERS WEST OF  
CAMERON WHERE WINDS WILL RANGE FROM 15 TO 20 KNOTS. THEREFORE,  
SMALL CRAFT EXERCISE CAUTION HEADLINES REMAIN IN THE FORECAST.  
 
WINDS AND SEAS WILL BEGIN TO DECREASE ON FRIDAY AS THE UPPER LEVEL  
AND SURFACE LOWS LIFT NORTH OF THE REGION. THIS WILL ALSO RESULT  
IN WINDS BECOMING MORE SOUTHERLY BY EARLY NEXT WEEK.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
AEX 71 91 70 90 / 0 50 20 40  
LCH 76 85 76 87 / 70 80 50 60  
LFT 75 88 74 90 / 20 60 20 30  
BPT 76 83 76 82 / 80 90 70 70  
 

 
   
LCH WATCHES/WARNINGS/ADVISORIES
 
 
LA...COASTAL FLOOD ADVISORY UNTIL 1 PM CDT WEDNESDAY FOR LAZ052>054-  
073-074.  
 
TX...COASTAL FLOOD ADVISORY UNTIL 1 PM CDT WEDNESDAY FOR TXZ215-216.  
 
GM...SMALL CRAFT EXERCISE CAUTION UNTIL 7 PM CDT THIS EVENING FOR  
GMZ450-470.  
 

 
 

 
 
AVIATION...04  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab LA Page
The Nexlab TX Page Main Text Page