478
WTPZ45 KNHC 030841
TCDEP5
TROPICAL STORM OCTAVE DISCUSSION NUMBER 13
NWS NATIONAL HURRICANE CENTER MIAMI FL EP152025
200 AM PDT FRI OCT 03 2025
OCTAVE REMAINS A SHEARED TROPICAL CYCLONE, WITH THE LOW-LEVEL CENTER
MOSTLY EXPOSED AND DISPLACED EAST OF A RECENT BURST OF DEEP
CONVECTION. THE LATEST SUBJECTIVE DVORAK CURRENT INTENSITY ESTIMATES
FROM TAFB AND SAB ARE 3.5/55 KT AND 3.0/45 KT, RESPECTIVELY, WHILE
THE UW-CIMSS OBJECTIVE ESTIMATES HAVE RANGED BETWEEN 35 AND 44 KT
DURING THE PAST SEVERAL HOURS. A RECENT 03/0435Z METOP-B ASCAT PASS
WAS HELPFUL IN DETERMINING THE TROPICAL-STORM-FORCE WIND RADII AND
THE CENTER LOCATION, AND IT ALSO INDICATED PEAK WINDS OF 38 KT.
BASED ON A BLEND OF THESE DATA, AND ACCOUNTING FOR SOME
UNDERSAMPLING IN THE SCATTEROMETER DATA, THE INITIAL INTENSITY IS
SET AT 45 KT FOR THIS ADVISORY.
OCTAVE IS ESTIMATED TO BE MOVING WEST-NORTHWESTWARD, OR 290 DEGREES
AT 7 KT. THIS GENERAL MOTION IS EXPECTED TO CONTINUE THROUGH
TONIGHT AS THE CYCLONE IS STEERED ALONG THE SOUTHERN PERIPHERY OF A
WEAK SUBTROPICAL RIDGE LOCATED TO ITS NORTH. OCTAVE IS FORECAST TO
SLOW CONSIDERABLY AND TURN NORTHWARD BY LATE SATURDAY, FOLLOWED BY A
SHARP EASTWARD TURN BY LATE SUNDAY AS A MID-LEVEL TROUGH APPROACHES
FROM THE NORTHWEST AND THE SUBTROPICAL RIDGE TO ITS EAST WEAKENS DUE
TO THE INFLUENCE OF A LARGER TROPICAL CYCLONE DEVELOPING OFFSHORE OF
THE SOUTHWESTERN OR WEST-CENTRAL COAST OF MEXICO. THE NEW NHC TRACK
FORECAST IS SIMILAR TO THE PREVIOUS PREDICTION AND LIES NEAR A BLEND
OF THE MULTI-MODEL CONSENSUS AIDS.
OCTAVE WILL REMAIN OVER WARM WATERS AND WITHIN A MOIST ENVIRONMENT
FOR THE NEXT FEW DAYS. EAST-SOUTHEASTERLY VERTICAL WIND SHEAR IS
EXPECTED TO CONTINUE IMPACTING THE CYCLONE FOR THE NEXT 12 TO 24
HOURS, WHICH SHOULD INHIBIT STRENGTHENING. BEYOND 24 HOURS, THE
SHEAR IS FORECAST TO DECREASE TO LIGHT LEVELS, WHILE THE CYCLONE
REMAINS OVER WATERS NEAR 27C AND WITHIN A SUFFICIENTLY MOIST
ENVIRONMENT. THESE CONDITIONS SHOULD ALLOW FOR SOME MODEST
STRENGTHENING OVER THE WEEKEND. BY DAYS 4 AND 5, OCTAVE IS FORECAST
TO ENCOUNTER INCREASING SOUTHEASTERLY SHEAR AND A DRIER MID-LEVEL
ENVIRONMENT, WHICH SHOULD RESULT IN STEADY WEAKENING. THE OFFICIAL
INTENSITY FORECAST HAS BEEN LOWERED SLIGHTLY TO ACCOUNT FOR A
NOTABLE DECREASE AMONG THE VARIOUS INTENSITY AIDS. THE FORECAST NOW
LIES ABOVE MOST OF THE INTENSITY GUIDANCE THROUGHOUT THE PERIOD, AND
FUTURE FORECASTS MAY NEED TO ADJUST THE INTENSITY DOWNWARD FURTHER
IF THE WEAKENING TRENDS IN THE GUIDANCE PERSIST.
FORECAST POSITIONS AND MAX WINDS
INIT 03/0900Z 13.1N 120.4W 45 KT 50 MPH
12H 03/1800Z 13.6N 121.3W 45 KT 50 MPH
24H 04/0600Z 14.1N 122.6W 45 KT 50 MPH
36H 04/1800Z 14.6N 123.6W 50 KT 60 MPH
48H 05/0600Z 15.1N 124.0W 55 KT 65 MPH
60H 05/1800Z 15.5N 123.9W 55 KT 65 MPH
72H 06/0600Z 15.5N 123.3W 50 KT 60 MPH
96H 07/0600Z 15.4N 121.8W 40 KT 45 MPH
120H 08/0600Z 15.1N 119.4W 35 KT 40 MPH
FORECASTER JELSEMA (CPHC)
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