Tropical Storm CHANTAL

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TROPICAL STORM CHANTAL DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL032013
1100 PM EDT SUN JUL 07 2013
 
CONVENTIONAL AND MICROWAVE SATELLITE IMAGES SHOW THAT DEEP
CONVECTION ASSOCIATED WITH THE STRONG TROPICAL WAVE OVER THE
CENTRAL TROPICAL ATLANTIC HAS INCREASED IN ORGANIZATION SINCE THIS
AFTERNOON.  A RECENT ASCAT PASS INDICATED THAT THE CIRCULATION HAD
BECOME BETTER DEFINED SINCE THIS MORNING....WITH SEVERAL
UNCONTAMINATED 35-KT WIND VECTORS OVER THE EASTERN PORTION OF THE
CIRCULATION.  BASED ON THE ASCAT AND AFOREMENTIONED SATELLITE
DATA...THE SYSTEM IS UPGRADED TO A 35-KT TROPICAL STORM.

THE INITIAL MOTION ESTIMATE IS 275/23.  A STRONG SUBTROPICAL HIGH
OVER THE CENTRAL ATLANTIC IS EXPECTED TO STEER CHANTAL ON A
WESTWARD AND THEN WEST-NORTHWESTWARD TRACK FOR THE NEXT FEW DAYS
WITH LITTLE DECREASE IN FORWARD SPEED.  A SECOND SUBTROPICAL RIDGE
OVER THE WESTERN ATLANTIC SHOULD KEEP CHANTAL ON THE SAME HEADING
UNTIL A WEAKNESS BEGINS TO DEVELOP OVER EASTERN NORTH AMERICA LATE
IN THE PERIOD.  AS A RESULT...THE TRACK OF CHANTAL SHOULD BEND MORE
NORTHWESTWARD AND THEN POSSIBLY NORTHWARD AND DECELERATE BY DAYS 4
AND 5.  THE TRACK GUIDANCE IS IN GOOD AGREEMENT ON THIS SCENARIO
THROUGH 48 TO 72 HOURS BUT THEN BEGINS TO DIVERGE AFTER THAT TIME. 
THE OFFICIAL NHC TRACK FORECAST IS CLOSE TO THE MULTI-MODEL
CONSENSUS THROUGHOUT THE FORECAST PERIOD.

FAVORABLE ENVIRONMENTAL CONDITIONS AND WARM SEA SURFACE TEMPERATURES
SHOULD ALLOW CHANTAL TO INTENSIFY SOME DURING THE NEXT FEW DAYS. 
THE POSSIBILITY OF LAND INTERACTION WITH HISPANIOLA AND CUBA IN
ABOUT 72-96 HOURS COMPLICATES THE INTENSITY FORECAST BUT IS LIKELY
TO RESULT IN WEAKENING...ESPECIALLY SINCE UPPER-LEVEL WESTERLY FLOW
IS FORECAST TO BEGIN TO AFFECT CHANTAL BY THAT TIME.  THIS
INCREASING WESTERLY FLOW AND LAND INTERACTION COULD EVEN CAUSE
CHANTAL TO BECOME A REMNANT LOW OR DISSIPATE LATE IN THE FORECAST
PERIOD.  THE NHC INTENSITY FORECAST IS A BLEND OF THE SHIPS/LGEM
GUIDANCE AS WELL AS THE INTENSITY CONSENSUS AIDS.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  08/0300Z  9.8N  47.2W   35 KT  40 MPH
 12H  08/1200Z 10.8N  50.8W   40 KT  45 MPH
 24H  09/0000Z 12.1N  55.7W   45 KT  50 MPH
 36H  09/1200Z 13.9N  60.5W   50 KT  60 MPH
 48H  10/0000Z 15.6N  65.1W   55 KT  65 MPH
 72H  11/0000Z 18.4N  73.6W   45 KT  50 MPH
 96H  12/0000Z 22.0N  77.0W   35 KT  40 MPH
120H  13/0000Z 25.0N  78.0W   30 KT  35 MPH
 
$$
FORECASTER KIMBERLAIN/BROWN
 
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