901 
 WTNT43 KNHC 082041
 TCDAT3
  
 TROPICAL STORM CHANTAL DISCUSSION NUMBER   4
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL032013
 500 PM AST MON JUL 08 2013
  
 LITTLE CHANGE IN THE CONVECTIVE ORGANIZATION OF CHANTAL HAS OCCURRED
 TODAY...SO THE INTENSITY IS BEING MAINTAINED AT 40 KT. HOWEVER...AN
 AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT IS ENROUTE TO THE CYCLONE
 AND IT WILL PROVIDE A BETTER ESTIMATE OF THE INTENSITY SHORTLY.
 VISIBLE AND WATER VAPOR IMAGERY CONTINUE TO INDICATE AN INCREASE IN
 THE UPPER-LEVEL ANTICYCLONIC OUTFLOW PATTERN.
  
 THE INITIAL MOTION ESTIMATE IS NOW 290/23 KT. CHANTAL IS FORECAST TO
 REMAIN SOUTH OF A STRONG DEEP-LAYER SUBTROPICAL RIDGE FOR THE NEXT
 2 DAYS...SO A GENERAL WEST-NORTHWESTWARD MOTION IS EXPECTED DURING
 THAT TIME. BY DAYS 3-5...A LARGE MID-/UPPER-LEVEL LOW CURRENTLY
 MOVING WESTWARD THROUGH THE BAHAMAS IS FORECAST BY THE GLOBAL
 MODELS TO MOVE ACROSS FLORIDA AND PHASE UP WITH A MID-LATITUDE
 TROUGH...WHICH SHOULD CREATE A BREAK IN THE RIDGE AXIS AND PRODUCE
 A WEAKER STEERING PATTERN OVER THE SOUTHEASTERN U.S. AND THE
 BAHAMAS. AS A RESULT...CHANTAL IS EXPECTED TO SLOW DOWN AND TURN
 NORTHWESTWARD BY 72 HOURS AS IT APPROACHES THE WEAKNESS IN THE
 RIDGE...AND THEN MOVE SLOWLY NORTH-NORTHWESTWARD OR NORTHWARD ON
 DAYS 4 AND 5 AS THE STEERING FLOW COLLAPSES. THE OFFICIAL FORECAST
 TRACK HAS BEEN SHIFTED SLIGHTLY TO THE RIGHT OF THE PREVIOUS
 ADVISORY TRACK...BUT NOT NEARLY AS FAR RIGHT AS THE MODEL CONSENSUS. 
  
 ENVIRONMENTAL CONDITIONS AROUND AND AHEAD OF CHANTAL FAVOR AT LEAST
 MODEST STRENGTHENING DURING THE NEXT 48 HOURS OR SO WHILE THE
 CYCLONE REMAINS UNDER THE INFLUENCE OF UPPER-LEVEL RIDGING...AND
 CHANTAL IS EXPECTED TO BE NEAR HURRICANE STRENGTH BEFORE IT REACHES
 HISPANIOLA. AFTER CHANTAL MOVES PAST HISPANIOLA ON DAY 2/3...THE
 CYCLONE SHOULD BE AFFECTED BY MODERATE TO STRONG WESTERLY VERTICAL
 WIND SHEAR ASSOCIATED WITH AN UPPER-LEVEL TROUGH ACROSS FLORIDA...
 WHICH IS EXPECTED TO FURTHER ENHANCE THE WEAKENING PROCESS. THE
 OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND
 ESSENTIALLY FOLLOWS THE ICON CONSENSUS MODEL.
 
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  08/2100Z 11.8N  53.9W   40 KT  45 MPH
  12H  09/0600Z 13.0N  57.3W   45 KT  50 MPH
  24H  09/1800Z 14.6N  61.7W   50 KT  60 MPH
  36H  10/0600Z 16.2N  66.0W   55 KT  65 MPH
  48H  10/1800Z 17.8N  69.6W   60 KT  70 MPH
  72H  11/1800Z 21.0N  74.5W   45 KT  50 MPH
  96H  12/1800Z 24.3N  76.6W   30 KT  35 MPH
 120H  13/1800Z 26.7N  78.0W   30 KT  35 MPH
  
 $$
 FORECASTER STEWART