000
WTNT41 KNHC 210845
TCDAT1
 
TROPICAL STORM OPHELIA DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL162011
500 AM EDT WED SEP 21 2011
 
CURVED CONVECTIVE BANDS OVER THE NORTHERN AND SOUTHERN PORTIONS OF
THE LARGE CIRCULATION HAVE BECOME A LITTLE BETTER DEFINED THIS
MORNING...HOWEVER THERE IS STILL A LACK OF DEEP CONVECTION NEAR 
THE CENTER OF THE TROPICAL STORM.  THE INITIAL INTENSITY OF THE
CYCLONE HAS BEEN INCREASED TO 40 KT...BASED ON DATA FROM A SHIP
LOCATED TO THE NORTH OF THE CENTER AND AN EARLIER ASCAT PASS.  
THE UPPER-LEVEL WIND PATTERN AHEAD OF OPHELIA DOES NOT FAVOR
SIGNIFICANT STRENGTHENING.  MODERATE SOUTHWESTERLY SHEAR CURRENTLY
OVER THE CYCLONE IS EXPECTED TO BECOME MORE WESTERLY AND INCREASE
IN A FEW DAYS AS AN UPPER-LEVEL LOW FORMS NORTH OF PUERTO RICO. 
MOST OF THE INTENSITY GUIDANCE AGREES WITH THIS SCENARIO AND CALLS
FOR ONLY A LITTLE ADDITIONAL STRENGTHENING.  THE NHC FORECAST IS IN
GOOD AGREEMENT WITH THE SHIPS/LGEM GUIDANCE AND IS VERY SIMILAR TO
THE PREVIOUS ADVISORY.

THE INITIAL MOTION ESTIMATE REMAINS RATHER UNCERTAIN...HOWEVER 
IT APPEARS THAT OPHELIA IS MOVING A LITTLE FASTER THAN BEFORE. THE
TRACK FORECAST REASONING IS UNCHANGED FROM THE PREVIOUS NHC
ADVISORY.  OPHELIA IS EXPECTED TO MOVE WESTWARD DURING THE NEXT
COUPLE OF DAYS TO THE SOUTH OF THE SUBTROPICAL RIDGE.  AFTER 72
HOURS...THE WESTERN PORTION OF THE RIDGE IS EXPECTED TO WEAKEN AS A
LARGE MID/UPPER-LEVEL LOW DEVELOPS OVER THE EASTERN UNITED STATES. 
THIS SHOULD RESULT IN THE CYCLONE TURNING TOWARD THE WEST-NORTHWEST
WITH SOME REDUCTION IN FORWARD SPEED.  THE UPDATED NHC FORECAST
LIES BETWEEN THE TYPICALLY RELIABLE GFS AND ECMWF MODELS...AND IS
VERY CLOSE TO THE PREVIOUS ADVISORY.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/0900Z 12.7N  41.8W   40 KT  45 MPH
 12H  21/1800Z 13.0N  43.8W   40 KT  45 MPH
 24H  22/0600Z 13.2N  46.5W   45 KT  50 MPH
 36H  22/1800Z 13.5N  49.2W   45 KT  50 MPH
 48H  23/0600Z 14.0N  52.0W   45 KT  50 MPH
 72H  24/0600Z 15.7N  57.0W   45 KT  50 MPH
 96H  25/0600Z 18.0N  61.5W   40 KT  45 MPH
120H  26/0600Z 20.0N  65.5W   35 KT  40 MPH
 
$$
FORECASTER BROWN