000
WTNT44 KNHC 102033
TCDAT4
 
TROPICAL STORM MARIA DISCUSSION NUMBER  17
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142011
500 PM AST SAT SEP 10 2011
 
MARIA HAS CHANGED LITTLE IN ORGANIZATION DURING THE DAY.  THE
CENTER...SUCH AS IT IS...IS EXPOSED TO THE SOUTHWEST OF AN AREA
OF DEEP CONVECTION THAT IS PASSING JUST NORTH OF THE NORTHEASTERN
LEEWARD ISLANDS.  THE EARLIER RECONNAISSANCE AIRCRAFT FLEW THROUGH
THE NORTHEASTERN QUADRANT JUST AFTER THE RELEASE OF THE PREVIOUS
ADVISORY AND FOUND WINDS TO SUPPORT A SLIGHTLY HIGHER INTENSITY OF
40 KT. GLOBAL MODEL AND SHIPS MODEL GUIDANCE INDICATE THAT THE
MODERATE WESTERLY SHEAR SHOULD CONTINUE DURING THE NEXT DAY OR SO.
MOST OF THE GLOBAL MODELS THEN SHOW THE UPPER-LEVEL LOW/TROUGH TO
THE NORTHWEST OF MARIA WEAKENING IN A COUPLE OF DAYS...WHICH WOULD
RESULT IN A MORE FAVORABLE UPPER-LEVEL WIND PATTERN FOR
STRENGTHENING. HOWEVER...THE ECMWF MODEL DOES NOT WEAKEN THE
UPPER-LEVEL TROUGH AS MUCH AND KEEPS SOUTHWESTERLY SHEAR OVER THE
CYCLONE. THE NEW INTENSITY FORECAST...LIKE THE PREVIOUS ONE...SHOWS
NO CHANGE IN WIND SPEED DURING THE FIRST 36 HOURS. AFTER THAT TIME
THE NHC FORECAST INDICATES SOME STRENGTHENING...BUT IT REMAINS NEAR
THE LOW END OF THE INTENSITY GUIDANCE...IN AGREEMENT WITH THE LGEM
MODEL.
 
THE TRACK FORECAST REASONING HAS NOT CHANGED.  MARIA IS EXPECTED TO
MOVE WEST-NORTHWESTWARD AROUND THE WESTERN SIDE OF A MID- TO
UPPER-LEVEL RIDGE OVER THE CENTRAL ATLANTIC.  IN 2 TO 3 DAYS MARIA
IS FORECAST TO TURN NORTHWARD AND THEN NORTHEASTWARD AHEAD OF A
TROUGH APPROACHING THE SOUTHEAST UNITED STATES COAST. THE TRACK 
GUIDANCE REMAINS IN GOOD AGREEMENT...BUT THERE ARE SOME SPEED
DIFFERENCES...WITH THE AFOREMENTIONED ECMWF MOVING A WEAKER MARIA
MORE SLOWLY TO THE NORTH.  THE NHC FORECAST IS NEAR THE MIDDLE OF
THE GUIDANCE ENVELOPE AND VERY CLOSE TO THE PREVIOUS ADVISORY.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  10/2100Z 17.9N  62.4W   40 KT  45 MPH
 12H  11/0600Z 19.0N  63.8W   40 KT  45 MPH
 24H  11/1800Z 20.6N  65.4W   40 KT  45 MPH
 36H  12/0600Z 21.9N  67.0W   40 KT  45 MPH
 48H  12/1800Z 22.9N  68.2W   45 KT  50 MPH
 72H  13/1800Z 25.5N  70.1W   50 KT  60 MPH
 96H  14/1800Z 30.0N  70.0W   60 KT  70 MPH
120H  15/1800Z 37.5N  65.5W   60 KT  70 MPH
 
$$
FORECASTER BROWN