Tropical Depression INGRID

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TROPICAL DEPRESSION INGRID DISCUSSION NUMBER  16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082007
500 AM EDT SUN SEP 16 2007
 
THE CENTER OF INGRID CANNOT BE SEEN IN CONVENTIONAL IMAGERY...AND
THERE HAVEN'T BEEN ANY RECENT MICROWAVE PASSES. MY BEST...BUT
UNCERTAIN...GUESS AT THE INITIAL MOTION IS 280/10. INGRID IS
EXPECTED TO REMAIN IN A RELATIVELY HIGH-SHEAR ENVIRONMENT FOR THE
NEXT TWO TO THREE DAYS...AND SO THE FUTURE TRACK DEPENDS IN PART ON
HOW MUCH DEEP CONVECTION THE SYSTEM CAN MAINTAIN. EVEN THE
LOW-LEVEL EASTERLIES ARE FORECAST TO WEAKEN BY THE GLOBAL
MODELS...HOWEVER...AND SO SOME KIND OF BEND TO THE RIGHT IS
EXPECTED EVEN IF THE CYCLONE REMAINS WEAK. A SLOWING OF THE FORWARD
MOTION IS ALSO EXPECTED...AS MID-LEVEL STEERING CURRENTS ARE
EXPECTED TO SLOWLY BREAK DOWN OVER THE NEXT FEW DAYS. MODEL
GUIDANCE IS FAIRLY DIVERGENT...WITH THE HWRF WIDE RIGHT WITH A NET
NORTH-NORTHWEST TRACK...AND THE ECMWF ON THE LEFT TO THE
WEST-NORTHWEST. THE OFFICIAL FORECAST IS CLOSE TO THE MODEL
CONSENSUS AND THE PREVIOUS ADVISORY TRACK...AND IS IN BEST
AGREEMENT WITH A BLEND OF THE GFS AND GFDL. 

CONVECTION ASSOCIATED WITH INGRID PERSISTS BUT LACKS ORGANIZATION.
THE INITIAL INTENSITY OF 30 KT IS CONSISTENT WITH LATEST DVORAK
ESTIMATES AND THE 22Z QUIKSCAT PASS. THE CURRENT SOUTHWESTERLY
SHEAR IS FORECAST BY GLOBAL MODELS TO PERSIST...AT LEAST FOR THE
NEXT TWO DAYS...AND INGRID COULD DEGENERATE TO A NON-CONVECTIVE
REMNANT LOW OR DISSIPATE DURING THAT TIME...AS FORECAST BY THE
GFDL.  THIS IS THE SCENARIO FAVORED BY THE OFFICIAL FORECAST. 
HOWEVER...IF INGRID SURVIVES THE NEXT COUPLE OF DAYS...AND IT DOES
HAVE A LARGE CYCLONIC ENVELOPE...A WEAKER SHEAR ENVIRONMENT AT THAT
TIME WOULD FAVOR RESTRENGTHENING. THIS ALTERNATIVE SCENARIO IS
INDICATED BY THE SHIPS GUIDANCE.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/0900Z 17.0N  56.8W    30 KT
 12HR VT     16/1800Z 17.5N  58.1W    30 KT
 24HR VT     17/0600Z 18.2N  59.3W    25 KT
 36HR VT     17/1800Z 19.1N  60.4W    25 KT
 48HR VT     18/0600Z 20.0N  61.3W    25 KT...REMNANT LOW
 72HR VT     19/0600Z 21.5N  62.5W    25 KT...REMNANT LOW
 96HR VT     20/0600Z 23.5N  64.0W    25 KT...REMNANT LOW
120HR VT     21/0600Z...DISSIPATED
 
$$
FORECASTER FRANKLIN
 
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