000 WTPZ44 KNHC 100857 TCDEP4 TROPICAL DEPRESSION FOUR-E DISCUSSION NUMBER 1 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP042009 200 AM PDT FRI JUL 10 2009 THE CIRCULATION ASSOCIATED WITH THE AREA OF LOW PRESSURE LOCATED WELL TO THE SOUTHWEST OF MEXICO HAS CONTINUED TO BECOME BETTER ORGANIZED AND IS BECOMING DETACHED FROM THE INTERTROPICAL CONVERGENCE ZONE. SATELLITE INTENSITY ESTIMATES AT 0600 UTC FROM TAFB AND SAB WERE T1.5 AND T2.0...RESPECTIVELY...ALTHOUGH DATA-T NUMBERS AT THE TIME WERE 2.0 AND 2.5. RECENTLY...A CLUSTER OF DEEP CONVECTION HAS BECOME CONSOLIDATED NEAR THE LOW-LEVEL CENTER AND A PROMINENT CONVECTIVE BAND HAS FORMED WITHIN THE SOUTHEASTERN SEMICIRCLE. THE STRUCTURE OF THE CIRCULATION AND THE CONVECTION HAVE BECOME WELL-DEFINED ENOUGH TO JUSTIFY THE HIGHER END OF THE ESTIMATES...AND ADVISORIES ARE BEING INITIATED ON THIS SYSTEM AS A 25-KT DEPRESSION. THE DEPRESSION IS MOVING AT AN INITIAL MOTION OF 275/7. THE SUITE OF GLOBAL MODELS SHOWS FAIRLY TIGHT CLUSTERING THROUGH THE ENTIRE 5-DAY FORECAST PERIOD AND INDICATES THAT THE DEPRESSION WILL NOT MAKE MUCH OF A NORTHWARD DISPLACEMENT. THE CYCLONE IS CURRENTLY APPROACHING A WEAKNESS IN THE SUBTROPICAL RIDGE DUE TO THE REMNANTS OF BLANCA AND A CLOSED UPPER LOW OFF THE OREGON COAST...BUT THE MODELS QUICKLY RE-BUILD THE RIDGE WESTWARD OVER THE NEXT 48 HOURS. AS THE RIDGE BUILDS...THE DEPRESSION IS EXPECTED TO ACCELERATE AND MOVE AT A CONSISTENT 11 OR 12 KNOTS IN ABOUT 24-36 HOURS. THE OFFICIAL FORECAST LIES GENERALLY JUST SOUTH OF THE MODEL CONSENSUS AND SHADES CLOSER TO THE TRACKS OF THE GFDL AND HWRF. OCEAN TEMPERATURES ALONG THE FORECAST TRACK OF THE DEPRESSION ARE AROUND 28-29C AND VERTICAL SHEAR IS EXPECTED TO REMAIN LOW OVER THE NEXT 5 DAYS...SO IT DOES NOT LOOK LIKE THERE IS MUCH TO LIMIT INTENSIFICATION. HOWEVER...MOST OF THE MODELS SHOW ONLY SLOW STRENGTHENING THROUGH THE FIRST 24-36 HOURS WITH QUICKER INTENSIFICATION THEREAFTER. THE GFDL PRODUCES THE MOST STRENGTHENING AND BRINGS THE CYCLONE TO NEAR 90 KT WITHIN 5 DAYS WHILE THE SHIPS AND LGEM MODELS LEVEL OFF THE INTENSITY AROUND 70 KT FROM 84-120 HOURS. SINCE IT IS NOT APPARENT WHAT WOULD LIMIT INTENSIFICATION AT DAYS 4 AND 5...THE OFFICIAL FORECAST IS SLIGHTLY ABOVE THE SHIPS/LGEM GUIDANCE...AND CLOSER TO THE GFDL AND HWRF MODELS. FORECAST POSITIONS AND MAX WINDS INITIAL 10/0900Z 10.0N 111.5W 25 KT 12HR VT 10/1800Z 10.2N 112.6W 30 KT 24HR VT 11/0600Z 10.4N 114.8W 35 KT 36HR VT 11/1800Z 10.6N 117.2W 40 KT 48HR VT 12/0600Z 11.0N 119.6W 45 KT 72HR VT 13/0600Z 12.0N 124.5W 60 KT 96HR VT 14/0600Z 13.0N 129.5W 70 KT 120HR VT 15/0600Z 13.5N 134.5W 80 KT $$ FORECASTER BERG