Tropical Storm ERIN

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TROPICAL STORM ERIN DISCUSSION NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL052013
500 PM AST SAT AUG 17 2013
 
THE LOW-LEVEL CENTER OF ERIN CONTINUES TO BE EXPOSED...AND IS
LOCATED SOUTH OF A SMALL AREA OF DEEP CONVECTION. THE INITIAL
INTENSITY REMAINS 35 KT...BUT ERIN SHOULD WEAKEN TO A DEPRESSION
SOON IN AN ENVIRONMENT OF SUB-26C WATER AND IN SOUTHWESTERLY SHEAR
OF AROUND 15 KT. WHILE THE CYCLONE WILL BE MOVING OVER SLIGHTLY
WARMER WATERS IN THE NEXT 2-3 DAYS...A DRY STABLE AIRMASS AND
MODERATE SHEAR SHOULD RESULT IN EVENTUAL WEAKENING TO A REMNANT
LOW. THE NHC FORECAST SHOWS REMNANT LOW STATUS IN 3 DAYS AND
DISSIPATION AT DAY 4...BUT THIS COULD OCCUR SOONER AS SHOWN BY
SEVERAL MODELS.
 
ERIN HAS CONTINUED TO MOVE TOWARD THE NORTHWEST OVER THE PAST FEW
HOURS...LIKELY DUE TO THE INFLUENCE OF A DEEP-LAYER LOW SOUTH OF
THE AZORES. RECENT SATELLITE IMAGES SHOW THAT ERIN HAS TURNED BACK
TOWARD THE LEFT...AND THE INITIAL MOTION ESTIMATE IS 315/11. THE
TRACK MODEL GUIDANCE IS INSISTENT ON ERIN TURNING BACK TOWARD THE
WEST-NORTHWEST IN THE NEXT DAY OR SO AS IT COMES UNDER THE INFLUENCE
OF A SUBTROPICAL RIDGE BUILDING TO THE NORTH AND ANOTHER CUTOFF LOW
CURRENTLY LOCATED NEAR 24N/49W. IF ERIN SURVIVES LONG ENOUGH...IT
WILL LIKELY TURN BACK TOWARD THE NORTHWEST INTO ANOTHER WEAKNESS IN
THE RIDGE THAT DEVELOPS BY 72 HOURS. THE NHC FORECAST HAS AGAIN
BEEN ADJUSTED NORTHWARD AND IS FASTER THAN THE PREVIOUS ONE TO
ACCOUNT FOR THE INITIAL POSITION AND MOTION. THE NHC TRACK LIES
NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE AND CLOSE TO THE FSU 
SUPERENSEMBLE.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  17/2100Z 21.0N  37.0W   35 KT  40 MPH
 12H  18/0600Z 21.5N  38.3W   30 KT  35 MPH
 24H  18/1800Z 22.2N  40.4W   30 KT  35 MPH
 36H  19/0600Z 23.0N  42.7W   30 KT  35 MPH
 48H  19/1800Z 24.0N  45.0W   30 KT  35 MPH
 72H  20/1800Z 26.5N  49.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  21/1800Z...DISSIPATED
 
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FORECASTER BRENNAN
 
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