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Tropical Depression EIGHTEEN (Text)

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TROPICAL DEPRESSION EIGHTEEN DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL182012
1100 AM EDT MON OCT 22 2012
 
SATELLITE IMAGES AND SURFACE OBSERVATIONS INDICATE THAT THE LOW
PRESSURE SYSTEM OVER THE SOUTHWESTERN CARIBBEAN SEA HAS ACQUIRED
SUFFICIENT ORGANIZATION TO BE CLASSIFIED AS A TROPICAL DEPRESSION. 
THE EXACT CENTER IS STILL A LITTLE DIFFICULT TO PINPOINT...BUT THE
SYSTEM HAS CLOSED SURFACE CIRCULATION...AND CONVECTIVE BANDING HAS
INCREASED MARKEDLY SINCE OVERNIGHT.  REFINEMENTS TO THE POSITION
COULD BE REQUIRED LATER TODAY ONCE THE AIR FORCE HURRICANE HUNTER
PLANE INVESTIGATES THE SYSTEM.

THE DEPRESSION HAS BEEN MOVING SLOWLY SOUTHWESTWARD...AND THE
INITIAL MOTION IS ESTIMATED TO BE 230/4 KT.  THE CYCLONE IS
CURRENTLY LOCATED TO THE SOUTH OF A MID-LEVEL RIDGE THAT EXTENDS
ACROSS THE GULF OF MEXICO AND FLORIDA...AND THIS FEATURE SHOULD
CAUSE THE DEPRESSION TO MOVE LITTLE DURING THE NEXT DAY OR SO. 
AFTER 24 HOURS...A DEVELOPING MID- TO UPPER-LEVEL TROUGH OVER CUBA
SHOULD PULL THE DEPRESSION NORTH-NORTHEASTWARD TOWARD JAMAICA AND
EASTERN CUBA.  WHILE THE GLOBAL MODELS SHOW VARYING SCENARIOS BY
THE END OF THE WEEK...THEY ALL AGREE ON A PERSISTENT NORTH-
NORTHEASTWARD MOTION THROUGH DAY 5.  THE NHC TRACK FORECAST IS VERY
NEAR THE CENTER OF THE TIGHTLY PACKED GUIDANCE ENVELOPE.

THE DEPRESSION IS LOCATED IN AN ENVIRONMENT THAT IS HIGHLY CONDUCIVE
FOR STRENGTHENING...AT LEAST DURING THE NEXT 36 TO 48 HOURS.  IN
FACT...THERE IS A 50/50 CHANCE THAT THE DEPRESSION WILL STRENGTHEN
BY AT LEAST 25 KT DURING THE NEXT 24 HOURS BASED ON THE RAPID
INTENSIFICATION INDEX.  THEREFORE...THE OFFICIAL FORECAST SHOWS
FAIRLY QUICK STRENGTHENING DURING THE NEXT 48 HOURS...AND THE
DEPRESSION COULD BE ON THE CUSP OF BECOMING A HURRICANE AS IT IS
APPROACHING JAMAICA.  AFTER 48 HOURS...VERTICAL SHEAR IS EXPECTED
TO INCREASE SUBSTANTIALLY...AND NEARLY ALL THE GLOBAL MODELS
SUGGEST THAT THE CYCLONE WILL TAKE ON MORE HYBRID
CHARACTERISTICS...SUCH AS AN EXPANDING WIND FIELD TO THE NORTH AND
ITS INTERACTION WITH A MID- TO UPPER-LEVEL LOW.  THE OFFICIAL
FORECAST THEREFORE SHOWS THE CYCLONE BECOMING A SUBTROPICAL STORM
BY DAY 5. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  22/1500Z 13.5N  78.0W   25 KT  30 MPH
 12H  23/0000Z 13.7N  78.3W   35 KT  40 MPH
 24H  23/1200Z 14.3N  78.1W   45 KT  50 MPH
 36H  24/0000Z 15.7N  77.6W   55 KT  65 MPH
 48H  24/1200Z 17.4N  77.0W   60 KT  70 MPH
 72H  25/1200Z 20.5N  76.0W   55 KT  65 MPH...INLAND OVER CUBA
 96H  26/1200Z 24.5N  74.5W   55 KT  65 MPH...OVER WATER
120H  27/1200Z 27.0N  73.0W   50 KT  60 MPH...SUBTROPICAL
 
$$
FORECASTER BERG/AVILA
 
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