884
WTPZ43 KNHC 260233
TCDEP3
TROPICAL STORM SONIA DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182025
800 PM PDT SAT OCT 25 2025
SONIA SEEMS TO BE HOLDING STEADY THIS EVENING. DATA FROM A
MICROWAVE SATELLITE OVERPASS SHOWED THE CIRCULATION WAS STILL OPEN
TO THE WEST, WITH A CURVED BAND WRAPPED AROUND THE EASTERN AND
SOUTHERN PORTIONS OF THE STORM. CONVECTION HAS WANED DURING THE
PAST FEW HOURS AND OBJECTIVE AND SUBJECTIVE SATELLITE INTENSITY
ESTIMATES HAVE REMAINED GENERALLY STABLE. THE INITIAL INTENSITY IS
HELD AT 45 KT FOR THIS ADVISORY.
THE STORM IS MOVING WESTWARD AT 4 KT. THERE IS STILL A LARGE SPREAD
IN THE MODEL GUIDANCE THROUGH THE FORECAST PERIOD. THE FORECAST
REASONING HAS NOT CHANGED. A STEADILY STRENGTHENING SYSTEM IS
EXPECTING TO TURN WEST-NORTHWESTWARD TO NORTHWESTWARD. THE MODEL
FORECASTS WITH SHALLOWER VORTEX STRUCTURES TEND TO REMAIN ON A MORE
WESTWARD TRAJECTORY WHILE THE DEEPER CYCLONES TEND TO TRACK MORE
POLEWARD. THE PRIMARY STEERING FEATURES INFLUENCING SONIA ARE A
SUBTROPICAL RIDGE EXTENDING TO THE NORTH OF THE TROPICAL STORM AND
AN AMPLIFYING MID-LATITUDE TROUGH THAT IS EXPECTED TO ERODE THE
RIDGE IN THE COMING DAYS. THE LATEST NHC TRACK FORECAST IS SIMILAR
TO THE PREVIOUS PREDICTION AND LIES SOUTH OF THE CORRECTED CONSENSUS
AID AND NORTH OF THE GOOGLE DEEPMIND ENSEMBLE MEAN.
SONIA HAS ABOUT A DAY OR SO TO GRADUALLY STRENGTHEN BEFORE
ATMOSPHERIC AND OCEANIC CONDITIONS BEGIN TO SIGNIFICANTLY INHIBIT
INTENSIFICATION. AFTER THAT TIME, VERTICAL WIND SHEAR IS EXPECTED
TO INCREASE, WITH SEA SURFACE TEMPERATURES DECREASING, PARTICULARLY
IF SONIA TAKES A MORE NORTHERN PATH. THE MODEL GUIDANCE ENVELOPE
SHIFTED NOTICEABLY LOWER THIS CYCLE, THOUGH ONLY MINIMAL CHANGES
WERE MADE TO THE OFFICIAL INTENSITY FORECAST. THE LATEST PREDICTION
LIES NEAR THE TOP OF THE GUIDANCE, CLOSE TO HAFS-A, PEAKING IN ABOUT
36 HOURS, AND THEN CALLS FOR SONIA TO BECOME A POST-TROPICAL CYCLONE
BY DAY 3.
FORECAST POSITIONS AND MAX WINDS
INIT 26/0300Z 13.5N 119.3W 45 KT 50 MPH
12H 26/1200Z 13.5N 119.8W 50 KT 60 MPH
24H 27/0000Z 13.8N 120.4W 55 KT 65 MPH
36H 27/1200Z 14.2N 121.3W 60 KT 70 MPH
48H 28/0000Z 14.7N 122.3W 55 KT 65 MPH
60H 28/1200Z 14.9N 123.8W 45 KT 50 MPH
72H 29/0000Z 15.0N 125.4W 35 KT 40 MPH...POST-TROPICAL
96H 30/0000Z 14.8N 128.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 31/0000Z...DISSIPATED
FORECASTER BUCCI
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