Tropical Depression INGRID

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TROPICAL DEPRESSION INGRID DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082007
500 PM EDT SAT SEP 15 2007
 
SATELLITE IMAGES SHOW A TIGHT CENTER EMBEDDED WITHIN A WELL-DEFINED
AND LARGER LOW-LEVEL CIRCULATION...BUT DEEP CONVECTION IS LIMITED
TO THE EASTERN SEMICIRCLE. SOME CONVECTIVE CELLS HAVE BEEN TRYING
TO DEVELOP ELSEWHERE...BUT BECOME IMMEDIATELY SHEARED AWAY BY THE
STRONG UPPER-LEVEL WINDS. SATELLITE IMAGES SHOW A BAND OF EVEN
STRONGER UPPER-LEVEL WINDS HEADING FOR INGRID.  THIS COULD FURTHER
LESSEN THE DEEP CONVECTION...RESULTING IN ADDITIONAL WEAKENING AS
INDICATED IN THE OFFICIAL FORECAST.  AS IN THE PREVIOUS FORECAST...
INGRID IS KEPT AS A 25-KT DEPRESSION THROUGH DAY 5...SINCE THE
DEPRESSION MIGHT SURVIVE THE HOSTILE ENVIRONMENT FOR THE NEXT 48
HOURS. THEREAFTER...THE SHEAR COULD WEAKEN...AND CONSEQUENTLY ALL
VERSIONS OF THE SHIPS MODELS SUGGEST A SLIGHT REJUVENATION OF
INGRID BEYOND 3 DAYS IN THE SUBTROPICAL ATLANTIC. THIS SOLUTION
APPEARS UNLIKELY SINCE BOTH THE SOPHISTICATED GFDL AND HWRF MODELS
DISSIPATE THE CYCLONE.

BECAUSE THE CYCLONE IS SHEARED AND MORE SHALLOW...DURING THE PAST
FEW HOURS IT HAS BEEN STEERED WESTWARD...OR 280 DEGREES AT 10
KNOTS...BY THE LOWER-LEVEL WINDS ALONG THE SOUTHERN PERIPHERY OF A
SUBTROPICAL RIDGE.  THE CYCLONE SHOULD BEGIN TO TURN MORE TO THE
NORTHWEST AROUND THE RIDGE DURING THE NEXT 24 HOURS...WITH A
DECREASE IN FORWARD SPEED AS THE STEERING CURRENTS WEAKEN. DUE TO
THE INITIAL WESTWARD MOTION...THE OFFICIAL FORECAST HAS BEEN
SHIFTED A LITTLE BIT FARTHER TO THE WEST FOR THE FIRST 2 TO 3
DAYS...BUT STILL KEEPS THE CYCLONE WELL NORTHEAST OF THE LEEWARD
ISLANDS.  THE SPREAD IN THE TRACK MODELS HAS INCREASED BEYOND 3
DAYS. SOME SHOW A CONTINUATION OF A WEST-NORTHWEST TRACK...WHILE
OTHERS SHOW A TURN TO THE NORTH AND NORTH-NORTHEAST. THE OFFICIAL
FORECAST FOLLOWS THE CONSENSUS WHICH IS IN THE MIDDLE OF THE
GUIDANCE ENVELOPE. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      15/2100Z 16.5N  55.0W    30 KT
 12HR VT     16/0600Z 16.7N  56.2W    25 KT
 24HR VT     16/1800Z 17.8N  58.0W    25 KT
 36HR VT     17/0600Z 19.0N  59.5W    25 KT
 48HR VT     17/1800Z 20.0N  60.5W    25 KT
 72HR VT     18/1800Z 22.0N  62.0W    25 KT
 96HR VT     19/1800Z 23.5N  63.0W    25 KT
120HR VT     20/1800Z 25.0N  64.0W    25 KT
 
$$
FORECASTER AVILA
 
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