000 WTPZ42 KNHC 222035 TCDEP2 TROPICAL STORM ANDRES DISCUSSION NUMBER 5 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP022009 200 PM PDT MON JUN 22 2009 GEOSTATIONARY AND MICROWAVE SATELLITE IMAGERY INDICATE THAT ANDRES HAS CONTINUED TO BECOME BETTER ORGANIZED TODAY. THE INITIAL INTENSITY IS SET TO 50 KT...A BLEND OF THE 1800 UTC DVORAK ESTIMATES FROM SAB AND TAFB. ANDRES HAS BEEN MOVING UNSTEADILY OVER THE LAST 12 TO 18 HOURS... ALTERNATING BETWEEN A MORE NORTHERLY AND WESTERLY HEADING. THE 12-HOUR INITIAL MOTION ESTIMATE IS 315/04. THE UNSTEADY MOTION IS LIKELY DUE TO THE RELATIVELY WEAK DEEP-LAYER FLOW BETWEEN THE SUBTROPICAL RIDGE EAST OF ANDRES AND AN UPPER-TROUGH SOUTHWEST OF CALIFORNIA. THE GLOBAL MODELS SHOW THE SUBTROPICAL RIDGE BUILDING NORTH OF THE CYCLONE IN 2 TO 3 DAYS. THIS WILL FORCE ANDRES TOWARD THE WEST...BUT NOT BEFORE IT TRACKS CLOSE TO THE SOUTHWESTERN COAST OF MEXICO IN THE NEXT 24 TO 48 HOURS. THE MAIN CHANGE IN THE TRACK MODEL GUIDANCE FOR THIS CYCLE IS AN INCREASE IN FORWARD SPEED DURING THE FIRST 48 HOURS. THE CURRENT FORECAST IS FASTER THAN THE PREVIOUS PACKAGE...BUT NOT AS FAST AS THE MODEL CONSENSUS. BEYOND 72 HOURS...THIS PACKAGE IS ESSENTIALLY AN UPDATE OF THE PREVIOUS FORECAST. WHILE THE SHIPS MODEL ANALYZES NEARLY 20 KT OF SHEAR...IT DOES NOT APPEAR TO BE HAVING ANY ADVERSE IMPACT ON THE CYCLONE. ANDRES WILL REMAIN OVER WARM SSTS THROUGH 36 HOURS...AND THE CYCLONE IS FORECAST TO BECOME A HURRICANE A LITTLE FASTER NOW DUE TO THE STEADY INTENSIFICATION SEEN TODAY. BEYOND 36 HOURS...THE CYCLONE WILL BE MOVING OVER COOLER SSTS AND INGESTING MORE STABLE AIR...RESULTING IN SLOW WEAKENING AND DEGENERATION INTO A REMNANT LOW BY THE END OF THE PERIOD. IF ANDRES MOVES TO THE RIGHT OF THE FORECAST TRACK AND INTERACTS WITH LAND...IT COULD WEAKEN MORE QUICKLY THAN INDICATED HERE. THE INCREASE IN INTENSITY AND THE FASTER FORWARD SPEED IN THIS PACKAGE REQUIRES THE ISSUANCE OF A HURRICANE WARNING FOR A PORTION OF THE COAST OF MEXICO AT THIS TIME. FORECAST POSITIONS AND MAX WINDS INITIAL 22/2100Z 16.2N 102.4W 50 KT 12HR VT 23/0600Z 17.1N 103.2W 60 KT 24HR VT 23/1800Z 18.4N 104.5W 65 KT 36HR VT 24/0600Z 19.6N 105.8W 65 KT 48HR VT 24/1800Z 20.6N 107.5W 55 KT 72HR VT 25/1800Z 21.5N 110.0W 45 KT 96HR VT 26/1800Z 22.0N 113.0W 35 KT 120HR VT 27/1800Z 22.0N 116.5W 25 KT...REMNANT LOW $$ FORECASTER BRENNAN/BLAKE