000 WTPZ42 KNHC 250837 TCDEP2 TROPICAL STORM IGNACIO DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP122009 200 AM PDT TUE AUG 25 2009 A SERIES OF MICROWAVE IMAGES RECEIVED DURING THE PAST FEW HOURS INDICATE THAT THE LOW-LEVEL CENTER OF IGNACIO WAS A LITTLE BIT TO THE NORTH THAN PREVIOUSLY INDICATED AND REMOVED FROM THE MAIN CONVECTION. HOWEVER...A NEW AREA OF DEEP CONVECTION IS CURRENTLY DEVELOPING NEAR THE CENTER. THE OUTFLOW IS ESTABLISHED IN THE SOUTHERN SEMICIRCLE ONLY...SUGGESTING THAT THERE IS SOME NORTHERLY SHEAR AFFECTING THE CYCLONE. DVORAK T-NUMBER HAVE NOT CHANGED AND THE INITIAL INTENSITY IS KEPT AT 35 KNOTS. IN FACT...AN ASCAT PASS JUST CAME IN AND SHOWS 35-KT WINDS...THE DATA HELPED TO ADJUST THE INITIAL WIND RADII. IGNACIO HAS THE POTENTIAL TO GATHER SOME STRENGTH BEFORE IT MOVES OVER COOLER WATER IN A COUPLE OF DAYS. THEREAFTER... A WEAKENING IS INDICATED AND BY DAYS 4 AND 5 IGNACIO SHOULD HAVE BECOME A REMNANT LOW. WITH THE SMALL RELOCATION OF THE CENTER...THE INITIAL MOTION IS NOW 295 DEGREES OR WEST-NORTHWEST AT 10 KNOTS...WHICH IS NOT TOO DIFFERENT FROM THE PREVIOUS ADVISORY MOTION. IGNACIO IS ALREADY ON THE WESTERN EDGE OF THE SUBTROPICAL RIDGE WHILE A LARGE MID-LEVEL TROUGH IS APPROACHING THE CYCLONE FROM THE NORTHWEST. THIS PATTERN CALLS FOR IGNACIO TO GRADUALLY TURN MORE TO THE NORTHWEST DURING THE NEXT 2 TO 3 DAYS. THEREAFTER...IGNACIO SHOULD TURN TO THE WEST STEERED BY THE LOW-LEVEL FLOW AS IT BECOMES A SHALLOW REMNANT LOW. THIS IS THE SOLUTION PROVIDED BY MOST OF THE GUIDANCE AND THE OFFICIAL FORECAST IS IN THE MIDDLE OF THE TRACK GUIDANCE ENVELOPE. THE NEW FORECAST TRACK WAS ADJUSTED NORTHWARD A LITTLE BIT DUE TO THE SMALL RELOCATION OF THE CENTER AND NOT BECAUSE OF A CHANGE IN THE STEERING PATTERN. FORECAST POSITIONS AND MAX WINDS INITIAL 25/0900Z 18.1N 118.5W 35 KT 12HR VT 25/1800Z 18.7N 119.9W 40 KT 24HR VT 26/0600Z 19.7N 122.0W 45 KT 36HR VT 26/1800Z 21.0N 123.5W 50 KT 48HR VT 27/0600Z 23.0N 125.0W 40 KT 72HR VT 28/0600Z 26.5N 128.5W 30 KT 96HR VT 29/0600Z 27.5N 131.5W 25 KT...REMNANT LOW 120HR VT 30/0600Z 28.0N 135.5W 20 KT...REMNANT LOW $$ FORECASTER AVILA