440  
FXUS64 KLCH 222323  
AFDLCH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LAKE CHARLES LA  
623 PM CDT TUE AUG 22 2017  
   
AVIATION
 
SHOWERS AND STORMS CONTINUE TO DECREASE ACROSS THE  
AREA THIS EVENING, HOWEVER PATCHY -RA WILL REMAIN IN PLACE FOR THE  
NEXT HOUR OR TWO. ADDITIONAL STORMS ARE EXPECTED TOMORROW AS  
DIURNAL HEATING OCCURS. MOSTLY VFR CONDITIONS ARE STILL EXPECTED.  
 

 
   
PREV DISCUSSION
 
/ISSUED 446 PM CDT TUE AUG 22 2017/  
 
DISCUSSION...  
LATEST WATER VAPOR SATELLITE IMAGERY SHOWED THE UPPER LOW OVER THE  
NW GULF STARTING TO ELONGATE/WEAKEN, WHILE A ROBUST UPPER TROF  
SWINGS INTO THE NE CONUS, ERODING THE SE CONUS RIDGE. TO THE  
SOUTH, THE REMNANTS OF HARVEY ARE JUST BEGINNING TO EXIT THE NW  
YUCATAN PENINSULA AND ENTER THE SOUTHERN GULF.  
 
RADAR IMAGERY CONTINUES TO SHOW SCATTERED SHOWERS AND  
THUNDERSTORMS ONGOING OVER A GOOD PART OF LOUISIANA ALONG AND  
NORTH OF I-10. THOUGH AIDED BY THE UPPER LOW, THIS ACTIVITY IS  
LARGELY DRIVEN BY DIURNAL INSTABILITY, AND SHOULD COME TO AN END  
OVER THE NEXT FEW HOURS. AFTER A RELATIVELY QUIET OVERNIGHT  
PERIOD, ANOTHER DAY OF SCATTERED SHOWERS AND THUNDERSTORMS IS ON  
TAP FOR TOMORROW AS THE WEAK UPPER LOW/TROF REMAINS OVER THE NW  
GULF. IN ADDITION, BY LATE TOMORROW, THE TROF DIGGING INTO THE  
ERN CONUS WILL SEND A WEAK FRONTAL BOUNDARY TOWARD AND EVENTUALLY  
INTO THE FORECAST AREA, PROVIDING AN ADDITIONAL FOCUS FOR SHOWER  
AND THUNDERSTORM DEVELOPMENT THAT WILL LIKELY PERSIST WED NIGHT  
AND ON INTO THU.  
 
MEANWHILE, TO THE SOUTH, THE REMNANTS OF HARVEY ARE EXPECTED TO  
REGENERATE INTO A TROPICAL CYCLONE BY TOMORROW, WITH THE SYSTEM  
SUBSEQUENTLY STRENGTHENING AND TRACKING TWD THE NW. CURRENT MODEL  
CONSENSUS IS FOR THE SYSTEM TO COME ASHORE THE LOWER TO MIDDLE TX  
COAST REGION LATE FRI. AN INVERTED TROF AXIS EXTENDING N OF  
HARVEY, ALONG WITH AN INFLUX OF ASSOCIATED TROPICAL MOISTURE, WILL  
BEGIN TO RESULT IN WIDESPREAD RAINFALL SPREADING INTO THE AREA ON  
FRI, WHICH COULD BE THE ONSET OF A SIGNIFICANT RAINFALL EVENT FOR  
THE AREA PENDING THE EVENTUAL STRENGTH/TRACK OF THE SYSTEM. WHILE  
MODEL DIVERGENCE INCREASES POST-LANDFALL, THERE IS BROAD CONSENSUS  
FOR A NEAR STALL OR AT LEAST SLOW NWD MOVEMENT OVER S CENTRAL TX  
THROUGH THE WEEKEND, WITH A SUBSEQUENT EJECTION EWD EARLY NEXT  
WEEK. THE GRIDDED FORECAST WAS CONSTRUCTED BASED ON THIS CONSENSUS,  
AND THUS DOES NOT REPRESENT EITHER THE WORST OR BEST CASE SCENARIO  
FOR THE AREA.  
 
BASED ON THIS CONSENSUS, A PROLONGED AND POTENTIALLY HEAVY  
RAINFALL EVENT IS FORECAST OVER THE WEEKEND AND INTO EARLY NEXT  
WEEK. EVENT TOTAL 6 TO 8 INCHES OF RAINFALL ARE POSSIBLE OVER E  
TX AND PARTS OF SW LA, WITH 4 TO 6 INCHES OVER CENTRAL AND SOUTH  
CENTRAL LA. IN ADDITION, DUE TO THE PERSISTENT PERIOD OF MODERATE  
TO POTENTIALLY STRONG ONSHORE FLOW, A PROLONGED PERIOD OF COASTAL  
FLOODING IS POSSIBLE.  
 
IT CANNOT BE STRESSED STRONGLY ENOUGH THAT WHILE CONFIDENCE HAS  
INCREASED SINCE THIS TIME YESTERDAY, THERE REMAINS A HIGH DEGREE  
OF UNCERTAINTY REGARDING THE EVENTUAL PATH AND STRENGTH OF THIS  
SYSTEM, AND THUS ITS RESULTANT IMPACTS. PLEASE STAY TUNED TO  
SUBSEQUENT FORECASTS FROM THIS OFFICE AND THE NHC.  
 
13  
 
MARINE...  
LIGHT SOUTHEAST WINDS AND LOW SEAS WILL CONTINUE THROUGH  
WEDNESDAY AS SURFACE HIGH PRESSURE RIDGES WEST ACROSS THE GULF  
STATES. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED EACH  
AFTERNOON. THE HIGH IS FORECAST TO BREAKDOWN LATE WEDNESDAY AS  
THE REGION IS SQUEEZED BETWEEN AN APPROACHING COLD FRONT TO THE  
NORTH AND WHAT IS LIKELY TO BE A REGENERATED HARVEY OVER THE  
SOUTHERN GULF OF MEXICO. ELEVATED WINDS AND SEAS ARE EXPECTED TO  
BEGIN AFFECTING THE COASTAL WATERS ON FRIDAY, AND CONTINUE THROUGH  
THE WEEKEND. THE MAGNITUDE OF THESE ELEVATED WINDS AND SEAS, AND  
THEIR DURATION, WILL DEPEND ON THE EVENTUAL TRACK AND STRENGTH OF  
THE SYSTEM. AT THIS TIME, THERE IS A BROAD CONSENSUS FOR THE  
TROPICAL CYCLONE TO COME ASHORE THE LOWER TO MIDDLE TEXAS COAST  
LATE FRIDAY, THEN SUBSEQUENTLY SLOW DOWN OVER SOUTH CENTRAL TEXAS  
OVER THE WEEKEND BEFORE TURNING EASTWARD EARLY NEXT WEEK. SHOULD  
THIS COME TO FRUITION, A PROLONGED PERIOD OF RAINFALL, GUSTY  
ONSHORE FLOW, AND ROUGH SEAS WILL RESULT.  
 
13  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
AEX 73 91 73 88 / 10 50 30 40  
LCH 77 92 77 90 / 10 40 30 50  
LFT 77 92 76 90 / 10 40 30 50  
BPT 75 91 75 89 / 10 40 20 40  
 

 
   
LCH WATCHES/WARNINGS/ADVISORIES
 
 
LA...NONE.  
TX...NONE.  
GM...NONE.  

 
 

 
 
AVIATION...05  
 
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