Tropical Storm MARIA

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TROPICAL STORM MARIA DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142011
500 PM AST FRI SEP 09 2011

THERE HAS BEEN LITTLE CHANGE TO THE ORGANIZATION OF MARIA SINCE THIS
MORNING. VISIBLE IMAGERY DURING THE EARLY AFTERNOON REVEALED
SEVERAL BANDS OF DEEP CONVECTION OVER THE NORTH AND EAST PORTIONS
OF THE CIRCULATION...BUT RECENT INFRARED IMAGERY AND RADAR DATA FROM
GUADELOUPE SHOW WARMING CLOUD TOPS AND SOME WEAKENING OF THE
CONVECTION.  BEFORE DEPARTING MARIA...THE AIR FORCE RECONNAISSANCE
AIRCRAFT FOUND PEAK 850-MB FLIGHT-LEVEL WINDS OF 47 KT...WHICH
SUPPORT AN INITIAL INTENSITY OF 40 KT. THE GLOBAL MODELS NOW
INDICATE THAT THE UPPER-LEVEL LOW TO THE NORTH OF THE LEEWARD
ISLANDS WILL WEAKEN AND MOVE NORTHWESTWARD DURING THE NEXT 36
HOURS...ALLOWING FOR A MORE FAVORABLE UPPER-LEVEL WIND PATTERN. 
HOWEVER...THE CURRENT LACK OF INNER-CORE STRUCTURE SUGGESTS 
THAT STRENGTHENING IS LIKELY TO BE MORE GRADUAL THAN INDICATED BY
SOME OF THE INTENSITY GUIDANCE. THE NEW OFFICIAL FORECAST IS 
ABOVE THE PREVIOUS ADVISORY...BUT LOWER THAN THE INTENSITY
CONSENSUS DURING THE FIRST COUPLE OF DAYS. AFTER 48 HOURS...THE
ENVIRONMENT IS EXPECTED TO BE EVEN MORE CONDUCIVE FOR
INTENSIFICATION. 

IT APPEARS THAT MARIA HAS SLOWED DOWN TODAY. SURFACE OBSERVATIONS
SUGGEST THAT THE LOW-LEVEL CENTER...SUCH AS IT IS...IS LOCATED TO
THE SOUTHWEST OF THE MID-LEVEL CENTER SEEN IN VISIBLE SATELLITE
IMAGERY. IT WOULD NOT BE SURPRISING IF THE SURFACE CENTER REFORMS
CLOSER TO THE MID-LEVEL CENTER OVERNIGHT OR ON SATURDAY. IN FACT...
THIS MAY BE WHY THE GLOBAL MODELS SHOW A TRACK FARTHER NORTH ACROSS
THE LEEWARD ISLANDS. PARTLY FOR THIS REASON...THE NEW TRACK HAS
BEEN ADJUSTED A LITTLE NORTH OF THE PREVIOUS ADVISORY DURING THE
FIRST 24 TO 36 HOURS. AFTER THAT...THE TRACK GUIDANCE HAS COME INTO
BETTER AGREEMENT SHOWING MARIA TURNING NORTHWESTWARD AND THEN
NORTHWARD AS A TROUGH OVER THE SOUTHEASTERN UNITED STATES WEAKENS
THE WESTERN PORTION OF THE SUBTROPICAL RIDGE. THE OFFICIAL FORECAST
AS BEEN SHIFTED EASTWARD AT DAYS 4 AND 5...CLOSER TO THE
MULTI-MODEL CONSENSUS.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  09/2100Z 14.8N  58.6W   40 KT  45 MPH
 12H  10/0600Z 15.8N  60.6W   45 KT  50 MPH
 24H  10/1800Z 17.2N  62.8W   50 KT  60 MPH
 36H  11/0600Z 18.7N  64.9W   55 KT  65 MPH
 48H  11/1800Z 20.0N  66.6W   60 KT  70 MPH
 72H  12/1800Z 22.7N  69.5W   70 KT  80 MPH
 96H  13/1800Z 25.5N  71.5W   80 KT  90 MPH
120H  14/1800Z 31.0N  71.0W   90 KT 105 MPH
 
$$
FORECASTER BROWN
 
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