Tropical Depression INGRID

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TROPICAL DEPRESSION INGRID DISCUSSION NUMBER  19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082007
1100 PM EDT SUN SEP 16 2007
 
DEEP CONVECTION ESSENTIALLY DISAPPEARED AFTER ABOUT 21Z. ANALYSIS OF
THE AMBIGUITIES FROM A 2145Z QUIKSCAT OVERPASS REVEALED WINDS NO
STRONGER THAN 25 KT...AND EVEN THOSE WINDS WERE IN AN ISOLATED AREA
OF SHOWERS ABOUT 80-90 N MI EAST OF THE CENTER. SHOWER ACTIVITY HAS
CONTINUED TO DISSIPATE SINCE THEN...SO THE NEW ADVISORY INTENSITY
IS SET TO 25 KT...DESPITE SLIGHTLY HIGHER DVORAK ESTIMATES. ALONG
THE FORECAST TRACK...GLOBAL MODEL FIELDS SHOW CONTINUED STRONG
WESTERLY SHEAR FOR AT LEAST THE NEXT 48 HOURS.  A SMALL WINDOW OF
OPPORTUNITY EXISTS FOR INGRID TO STRENGTHEN ON DAYS 3 AND 4 WHEN
THE SHEAR DECREASES A LITTLE...BUT THAT IS ASSUMING THE SYSTEM
STILL EXISTS AT THAT TIME.  THE NEW OFFICIAL INTENSITY FORECAST
KEEPS THE CYCLONE AS A 25-KT DEPRESSION THROUGHOUT THE FIVE-DAY
PERIOD...AS SUGGESTED BY THE LGEM GUIDANCE...BUT IT MIGHT NOT BE A
TROPICAL CYCLONE FOR NEARLY THAT LONG.

THE QUIKSCAT DATA SHOWED THAT THE CENTER IS A LITTLE SOUTH OF THE
PREVIOUS TRACK...WITH AN INITIAL MOTION ESTIMATE OF 280/8.  INGRID
CONTINUES TO MOVE LEFT OF MOST OF THE MODEL GUIDANCE SINCE...IT IS
SUCH A SHALLOW SYSTEM AND IS MOVING WITH THE LOW-LEVEL EASTERLIES. 
FOR THE SAME REASON...THE NEW OFFICIAL FORECAST WILL BE LEFT OF
MOST OF THE TRACK MODELS AND THE PREVIOUS ADVISORY...ALONG A
TRACK THAT IS CLOSEST TO THE GFDL AND SHALLOW BAM.  A GRADUAL BEND
TO THE RIGHT IS STILL FORECAST SINCE THE LOW-LEVEL RIDGE NORTH OF
INGRID IS EXPECTED TO WEAKEN.  BY DAYS 4 AND 5...INGRID OR WHATEVER
IS LEFT OF IT WILL BE IN A VERY WEAK LOW-LEVEL STEERING REGIME...FAR
TO THE SOUTH OF HIGH PRESSURE NEAR THE NORTHEAST U.S. COAST.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/0300Z 17.4N  59.4W    25 KT
 12HR VT     17/1200Z 17.6N  60.5W    25 KT
 24HR VT     18/0000Z 18.0N  61.7W    25 KT
 36HR VT     18/1200Z 18.7N  62.8W    25 KT
 48HR VT     19/0000Z 19.3N  63.6W    25 KT
 72HR VT     20/0000Z 20.5N  65.0W    25 KT
 96HR VT     21/0000Z 21.5N  66.0W    25 KT
120HR VT     22/0000Z 22.5N  67.0W    25 KT
 
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FORECASTER KNABB
 
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