236 
 WTNT41 KNHC 032038
 TCDAT1
 TROPICAL DEPRESSION ERIKA DISCUSSION NUMBER   9
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062009
 500 PM AST THU SEP 03 2009
  
 THE CENTER OF ERIKA IS EXPOSED AS A LOW-LEVEL SWIRL MOVING OUT AHEAD
 OF THE WANING DEEP CONVECTION OVER THE LEEWARD ISLANDS. THE AIR
 FORCE RESERVE RECONNAISSANCE HURRICANE HUNTER AIRCRAFT FOUND A
 MINIMUM PRESSURE OF 1007 MB...BUT WERE UNABLE TO FIND ANY WINDS TO
 SUPPORT TROPICAL STORM STATUS. AS A RESULT...ERIKA IS DOWNGRADED TO
 A TROPICAL DEPRESSION ON THIS ADVISORY.
  
 THE INITIAL MOTION ESTIMATE IS 280/10...WELL TO THE SOUTH OF THE
 PREVIOUS OFFICIAL FORECAST TRACK AND THE MAJORITY OF ALL THE MODEL
 GUIDANCE. SINCE ERIKA SHOULD MOVE WITH THE LOW-LEVEL FLOW...THE
 SHALLOW BAM MODEL WAS FOLLOWED CLOSELY FOR THE NEW FORECAST TRACK.
 THIS FORECAST TURNS ERIKA TOWARD THE WEST-NORTHWEST...TAKING THE
 CYCLONE OR ITS REMNANT LOW SOUTH OF PUERTO RICO AND OVER HISPANIOLA
 ...WHERE THE LOW-LEVEL CENTER WILL LIKELY DISSIPATE OVER THE RUGGED
 TERRAIN IN 48 HOURS.
  
 THE OFFICIAL FORECAST ASSUMES THAT ERIKA WILL HAVE A DIFFICULT TIME
 SUSTAINING ANY DEEP CONVECTION AS IT MOVES INTO AN ENVIRONMENT OF
 INCREASING SHEAR AND DRY AIR IN THE LOWER TO MID-TROPOSPHERE. ERIKA
 IS MAINTAINED AS A TROPICAL DEPRESSION THROUGH 12 HOURS...AND IS
 FORECAST TO BE A REMNANT LOW BY 24 HOURS....ALTHOUGH THIS COULD
 OCCUR SOONER IF THE CONVECTION EAST OF THE LOW-LEVEL CENTER OVER
 THE LEEWARD ISLANDS CONTINUES TO WEAKEN. IT IS ALSO POSSIBLE THAT
 THE CENTER OF ERIKA COULD BECOME POORLY DEFINED AND THE CYCLONE
 COULD DEVOLVE INTO A TROPICAL WAVE AT ANY TIME. EVEN IF ERIKA LOSES
 TROPICAL CYCLONE STATUS...ITS REMNANTS COULD PRODUCE HEAVY RAINFALL
 OVER THE GREATER ANTILLES.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      03/2100Z 16.7N  65.3W    30 KT
  12HR VT     04/0600Z 17.2N  66.8W    30 KT
  24HR VT     04/1800Z 18.1N  68.6W    25 KT...REMNANT LOW
  36HR VT     05/0600Z 18.9N  70.3W    20 KT...REMNANT LOW
  48HR VT     05/1800Z 19.5N  72.2W    20 KT...DISSIPATING INLAND
  72HR VT     06/1800Z...DISSIPATED
  
 $$
 FORECASTER BRENNAN