Tropical Storm MARIA

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TROPICAL STORM MARIA DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142011
1100 PM AST WED SEP 07 2011
 
MARIA HAS CHANGED LITTLE IN ORGANIZATION OVER THE PAST SEVERAL
HOURS...WITH THE LOW-LEVEL CENTER DISPLACED TO THE SOUTHWESTERN
EDGE OF THE DEEP CONVECTION BY SOUTHWESTERLY VERTICAL WIND SHEAR.
SATELLITE INTENSITY ESTIMATES ARE 45 KT FROM TAFB AND 35 KT FROM
SAB...WHILE NOAA BUOY 41041 JUST REPORTED 1-MINUTE MEAN WINDS OF
43 KT.  BASED ON THIS THE INITIAL INTENSITY REMAINS 45 KT.
 
THE INITIAL MOTION IS A FAST 275/20.  MARIA IS CURRENTLY ON THE
SOUTH SIDE OF A STRONG LOW/MID-LEVEL SUBTROPICAL RIDGE...AND THIS
SHOULD KEEP THE STORM MOVING QUICKLY WESTWARD FOR THE NEXT
24 HOURS OR SO.  FROM 24-72 HOURS...MARIA SHOULD APPROACH A WEAKNESS
IN THE RIDGE CAUSED BY AN UPPER-LEVEL LOW...WHICH SHOULD ALLOW THE
CYCLONE TO TURN WEST-NORTHWESTWARD WITH SOME DECREASE IN FORWARD
SPEED.  THE FORECAST TRACK IS MORE UNCERTAIN AFTER 72 HOURS AS
MARIA APPROACHES THE WESTERN END OF THE SUBTROPICAL RIDGE AND A
DEEP-LAYER TROUGH MOVES EASTWARD THROUGH THE EASTERN UNITED STATES.
WHILE THE GUIDANCE GENERALLY SHOWS A TURN TOWARD THE NORTHWEST...
THERE IS A SIGNIFICANT SPREAD BETWEEN THE MORE WESTERLY GFDL/ECMWF
AND THE MORE EASTERLY GFS/NOGAPS.  THE NEW FORECAST TRACK IS
SHIFTED A LITTLE TO THE SOUTH OF THE PREVIOUS TRACK DURING THE
FIRST 48 HOURS...THEN IS CLOSE TO THE THE PREVIOUS TRACK AFTER THAT
TIME.  THE NEW TRACK LIES CLOSE TO THE CENTER OF THE GUIDANCE
ENVELOPE AND THE VARIOUS CONSENSUS MODELS.
 
SIGNIFICANT SOUTHWESTERLY TO WESTERLY SHEAR IS EXPECTED TO CONTINUE
FOR THE NEXT 48-72 HOURS...AND THE NEW INTENSITY FORECAST CONTINUES
TO CALL FOR LITTLE CHANGE IN STRENGTH DURING THAT TIME.  AFTER THAT
THERE IS A POSSIBILITY THAT MARIA MAY FIND A DECREASED SHEAR
ENVIRONMENT...ALTHOUGH THE FORECAST PRESENCE OF THE UPPER-LEVEL LOW
NEAR THE STORM MAKES THIS UNCERTAIN.  ALL THE INTENSITY GUIDANCE
SHOWS STRENGTHENING AFTER 72 HOURS...SO THE INTENSITY FORECAST NOW
CALLS FOR SOME MODEST STRENGTHENING DURING THAT TIME.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  08/0300Z 13.4N  46.2W   45 KT  50 MPH
 12H  08/1200Z 13.7N  49.2W   45 KT  50 MPH
 24H  09/0000Z 14.3N  53.3W   45 KT  50 MPH
 36H  09/1200Z 15.1N  56.7W   45 KT  50 MPH
 48H  10/0000Z 16.1N  59.7W   45 KT  50 MPH
 72H  11/0000Z 19.0N  64.5W   45 KT  50 MPH
 96H  12/0000Z 22.5N  68.5W   50 KT  60 MPH
120H  13/0000Z 25.5N  71.0W   60 KT  70 MPH
 
$$
FORECASTER BEVEN
 
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