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| #151179 (Received by flhurricane at: 11:03 PM 16.Sep.2007) TCDAT3 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 $$ FORECASTER KNABB |
