Tropical Storm HUMBERTO

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TROPICAL STORM HUMBERTO DISCUSSION NUMBER  30
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092013
500 PM AST TUE SEP 17 2013
 
HUMBERTO HAS NOT CHANGED MUCH SINCE THIS MORNING...AND IT STILL HAS
SOME CHARACTERISTICS OF A SUBTROPICAL CYCLONE. THE ASSOCIATED DEEP
CONVECTION IS ORGANIZED INTO A BROKEN BAND THAT EXTENDS ABOUT
THREE-QUARTERS OF THE WAY AROUND THE CENTER. THE INITIAL WIND SPEED
IS HELD AT 40 KT...WHICH IS A LITTLE HIGHER THAN THE DVORAK
CLASSIFICATIONS.

THE STORM IS LOCATED DIRECTLY BENEATH AN UPPER-LEVEL LOW...WHICH HAS
ALLOWED THE SHEAR TO RELAX A LITTLE. THIS UPPER-LEVEL SYSTEM IS
EXPECTED TO WEAKEN AND SHIFT EASTWARD DURING THE NEXT DAY OR TWO...
AND HUMBERTO COULD LOSE SOME OF THE SUBTROPICAL CHARACTERISTICS
WHILE THAT OCCURS. REGARDLESS...THE ATMOSPHERIC AND OCEANIC
ENVIRONMENTS FAVOR SLIGHT STRENGTHENING DURING THE NEXT COUPLE OF
DAYS...AND THE NHC INTENSITY FORECAST IS NUDGED UPWARD FROM THE
PREVIOUS ONE...BUT IT LIES ON THE LOW SIDE OF THE GUIDANCE.
HUMBERTO IS FORECAST TO BECOME EXTRATROPICAL IN 3 TO 4 DAYS...
ALTHOUGH THERE IS SOME GUIDANCE THAT SHOWS THE CYCLONE DEGENERATING
INTO A TROUGH BEFORE THAT OCCURS.

HUMBERTO HAS BEEN MOVING NORTHWARD AT ABOUT 10 KT FOR THE PAST FEW
HOURS. A SLOWER NORTH-NORTHWESTWARD TO NORTHWARD MOTION IS FORECAST
DURING THE NEXT DAY OR SO. AFTER THAT TIME...THE SYSTEM IS EXPECTED
TO ACCELERATE NORTHEASTWARD WHEN IT BECOMES EMBEDDDED IN THE
STRONGER FLOW TO THE EAST OF AN APPROACHING DEEP-LAYER TROUGH. THE
NHC TRACK FORECAST IS NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  17/2100Z 30.3N  42.8W   40 KT  45 MPH
 12H  18/0600Z 30.9N  43.3W   45 KT  50 MPH
 24H  18/1800Z 32.0N  43.4W   45 KT  50 MPH
 36H  19/0600Z 33.3N  43.2W   50 KT  60 MPH
 48H  19/1800Z 35.0N  42.1W   50 KT  60 MPH
 72H  20/1800Z 40.7N  37.2W   55 KT  65 MPH
 96H  21/1800Z 51.5N  27.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
120H  22/1800Z...DISSIPATED
 
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FORECASTER CANGIALOSI
 
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