000 WTNT42 KNHC 180831 TCDAT2 TROPICAL STORM JULIA DISCUSSION NUMBER 25 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL122010 500 AM AST SAT SEP 18 2010 STRONG NORTHERLY SHEAR CONTINUES TO WEAKEN JULIA. SATELLITE IMAGES SHOW THAT THE CENTER OF THE STORM IS PARTIALLY EXPOSED ON THE NORTHWESTERN EDGE OF A BURST OF CONVECTION. DVORAK CLASSIFICATIONS ARE DROPPING QUICKLY...AND A BLEND OF THE T/CI NUMBERS FROM TAFB/SAB AND ADT VALUES FROM UW-CIMSS GIVES AN INITIAL WIND SPEED OF 50 KT. A STEADY DECREASE IN STRENGTH IS LIKELY WITH THE STRONG SHEAR EXPECTED TO PERSIST. JULIA SHOULD BECOME A REMNANT LOW BY 72 HOURS...IF NOT SOONER BECAUSE OF EXPECTED COOL SSTS. THE NHC FORECAST IS CLOSE TO THE SHIPS MODEL...AND IS BELOW MOST OF THE GUIDANCE. THE REMNANT LOW IS EXPECTED TO BE ABSORBED BY IGOR IN ABOUT 96 HRS. THE INITIAL MOTION CONTINUES TO BEND A LITTLE TO THE RIGHT AND IS NOW 320/16. THE MODEL GUIDANCE IS TIGHTLY CLUSTERED ON A NORTHWESTWARD TRACK TODAY...WITH A NORTHWARD TURN TOMORROW AS JULIA MOVES AROUND A SUBTROPICAL RIDGE. MOST OF THE GUIDANCE SUGGESTS THAT JULIA WILL STAY FAR ENOUGH AWAY FROM IGOR THAT THE LARGER HURRICANE WILL NOT HAVE AN IMMEDIATE IMPACT ON THE TRACK OF JULIA. THE NHC FORECAST IS CLOSE TO THE PREVIOUS ONE...ON THE RIGHT EDGE OF THE GUIDANCE ENVELOPE...AND NOT TOO FAR FROM THE GFS. THE WIND RADII HAVE BEEN ADJUSTED BASED ON AN EARLIER ASCAT PASS. FORECAST POSITIONS AND MAX WINDS INITIAL 18/0900Z 27.4N 50.1W 50 KT 12HR VT 18/1800Z 29.5N 51.5W 45 KT 24HR VT 19/0600Z 32.3N 52.1W 40 KT 36HR VT 19/1800Z 34.5N 51.3W 35 KT 48HR VT 20/0600Z 36.0N 49.0W 30 KT 72HR VT 21/0600Z 39.5N 44.0W 25 KT...POST-TROP/REMNT LOW 96HR VT 22/0600Z...ABSORBED BY IGOR $$ FORECASTER BLAKE