Tropical Storm OCTAVE

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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
 
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