000 WTPZ45 KNHC 131433 TCDEP5 TROPICAL STORM OCTAVE DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL EP152013 800 AM PDT SUN OCT 13 2013 ALTHOUGH CLOUD TOPS HAVE WARMED SIGNIFICANTLY SINCE THE PREVIOUS ADVISORY...THE CONVECTION HAS BECOME MORE CONCENTRATED NEAR AND AROUND THE CIRCULATION CENTER OF OCTAVE. IN ADDITION...THE PRESSURE AT SOCORRO ISLAND...LOCATED ABOUT 80 NMI NORTHEAST OF THE TROPICAL STORM...FELL TO AS LOW AS 1001.4 MB AROUND 11Z...WHICH INDICATES THAT THE CENTRAL PRESSURE OF THE CYCLONE IS BELOW 1000 MB. BASED ON PRESSURE-WIND RELATIONSHIPS AND A SATELLITE INTENSITY ESTIMATE OF T3.0/45 KT FROM TAFB...THE INTENSITY HAS BEEN INCREASED TO 45 KT. THE INITIAL MOTION ESTIMATE IS 330/12 KT. THE DECREASE IN CONVECTIVE CLOUD COVER HAS ALLOWED FOR THE CENTER OF OCTAVE TO BE BETTER DETERMINED...WHICH HAS RESULTED IN A MORE WESTWARD LOCATION. OTHER THAN THAT...THERE REMAINS NO SIGNIFICANT CHANGE TO THE PREVIOUS ADVISORY TRACK OR REASONING. OCTAVE IS EXPECTED TO GRADUALLY MOVE AROUND THE SOUTHWESTERN AND WESTERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE THAT EXTENDS WESTWARD ALONG 22N FROM CENTRAL MEXICO INTO THE EXTREME EASTERN NORTH PACIFIC. THE CYCLONE IS FORECAST TO GRADUALLY SLOW DOWN AND TURN NORTHWARD ON MONDAY... FOLLOWED BY A TURN TOWARD THE NORTH-NORTHEAST OR NORTHEAST ON TUESDAY. AS OCTAVE WEAKENS...THE SYSTEM WILL BECOME VERTICALLY SHALLOW AND SLOW DOWN EVEN FURTHER WHEN IT APPROACHES THE SOUTHWESTERN COAST OF THE BAJA CALIFORNIA PENINSULA ON WEDNESDAY. THE OFFICIAL TRACK FORECAST IS SIMILAR TO BUT SLIGHTLY WEST OF THE PREVIOUS TRACK...AND LIES CLOSE TO THE CONSENSUS MODEL TCVE AND THE FLORIDA STATE SUPERENSEMBLE MODEL FSSE. ANOTHER BURST OF CONVECTION NEAR THE CENTER COULD RESULT IN SOME SLIGHT ADDITIONAL STRENGTHENING GIVEN THAT THE CYCLONE IS OVER RELATIVELY WARM WATER AND IN LOW VERTICAL SHEAR CONDITIONS. HOWEVER...THE RECENT INGESTION OF COOLER AND DRIER MID-LEVEL AIR IN THE EASTERN SEMICIRCLE SHOULD PREVENT ANY SIGNIFICANT STRENGTHENING FROM OCCURRING FOR THE NEXT 12 HOURS OR SO. AFTER THAT...OCTAVE WILL BE MOVING OVER PROGRESSIVELY COOLER WATERS...WHICH SHOULD INDUCE GRADUAL WEAKENING BY MONDAY. ON TUESDAY...STRONG SOUTHWESTERLY WIND SHEAR IN EXCESS OF 30 KT SHOULD STRIP AWAY ANY REMAINING CONVECTION...RESULTING IN OCTAVE BECOMING A REMNANT LOW PRESSURE SYSTEM BEFORE IT REACHES BAJA CALIFORNIA. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ONE...AND CLOSELY FOLLOWS THE CONSENSUS INTENSITY MODEL ICON. THE TRACK AND INTENSITY FORECASTS DO NOT REQUIRE THE ISSUANCE OF ANY TROPICAL STORM WATCHES OR WARNINGS FOR THE BAJA CALIFORNIA. FORECAST POSITIONS AND MAX WINDS INIT 13/1500Z 18.3N 112.1W 45 KT 50 MPH 12H 14/0000Z 19.9N 113.1W 45 KT 50 MPH 24H 14/1200Z 21.7N 113.7W 40 KT 45 MPH 36H 15/0000Z 23.3N 113.7W 35 KT 40 MPH 48H 15/1200Z 24.3N 113.4W 30 KT 35 MPH 72H 16/1200Z 25.1N 113.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 17/1200Z 26.0N 112.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 18/1200Z...DISSIPATED $$ FORECASTER STEWART