084
WTPZ43 KNHC 250834
TCDEP3
TROPICAL STORM SONIA DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182025
200 AM PDT SAT OCT 25 2025
SATELLITE IMAGERY SHOWS DEEP CONVECTION EXPANDING OVER THE LOW-LEVEL
CIRCULATION CENTER, WITH CLOUD-TOP TEMPERATURES NEAR −80 C.
SUBJECTIVE DVORAK CURRENT INTENSITY ESTIMATES FROM TAFB AND SAB ARE
IN AGREEMENT AT 2.5/35 KT, WHICH IS SUPPORTED BY THE LATEST UW–CIMSS
OBJECTIVE ESTIMATES. BASED ON THE IMPROVING SATELLITE PRESENTATION
AND THESE DATA, THE DEPRESSION HAS BEEN UPGRADED TO TROPICAL STORM
SONIA, WITH THE INITIAL INTENSITY SET AT 35 KT.
SONIA HAS A BRIEF WINDOW OF OPPORTUNITY TO GRADUALLY STRENGTHEN OVER
THE WEEKEND WHILE IT REMAINS OVER WARM WATERS AND WITHIN A MOIST,
LOW-SHEAR ENVIRONMENT. STRENGTHENING SHOULD LEVEL OFF BY MONDAY AS
SOUTHWESTERLY VERTICAL WIND SHEAR BEGINS TO INCREASE. BY TUESDAY, A
COMBINATION OF STRONGER SHEAR, DRIER MID- TO UPPER-LEVEL AIR, AND
COOLER SEA-SURFACE TEMPERATURES SHOULD INDUCE A GRADUAL WEAKENING
TREND. SIMULATED SATELLITE IMAGERY FROM THE GLOBAL MODELS SUPPORTS
THIS SCENARIO, DEPICTING CONVECTION DIMINISHING BY MIDWEEK. AS A
RESULT, SONIA IS FORECAST TO DEGENERATE INTO A POST-TROPICAL REMNANT
LOW BY DAY 4. THE NHC INTENSITY FORECAST REMAINS VERY SIMILAR TO THE
PREVIOUS ONE AND CONTINUES TO CLOSELY FOLLOW THE CONSENSUS AIDS.
THE INITIAL MOTION IS TOWARD THE WEST, OR 275/8 KT, ALONG THE
SOUTHERN SIDE OF A SUBTROPICAL RIDGE THAT IS EXPECTED TO PERSIST
THROUGH THE FIRST HALF OF THE WEEKEND. A TURN TOWARD THE NORTHWEST
IS ANTICIPATED FOR A BRIEF PERIOD LATE SUNDAY INTO EARLY NEXT WEEK
AS A WEAKNESS DEVELOPS IN THE RIDGE IN RESPONSE TO A MID-LATITUDE
TROUGH PASSING OVER THE NORTHERN PACIFIC. A TURN BACK TOWARD THE
WEST IS THEN EXPECTED BY TUESDAY AND INTO MIDWEEK AS THE RIDGE
RESTRENGTHENS TO THE NORTH. BY DAY 5, SONIA IS FORECAST TO BECOME
INCREASINGLY INFLUENCED BY THE LOW-LEVEL TRADE WIND FLOW, WHICH
SHOULD STEER IT SOUTHWESTWARD. THE LATEST NHC TRACK FORECAST REMAINS
CLOSE TO THE PREVIOUS ADVISORY AND LIES BETWEEN THE HCCA AND
GOOGLE DEEPMIND SOLUTIONS.
FORECAST POSITIONS AND MAX WINDS
INIT 25/0900Z 13.3N 117.6W 35 KT 40 MPH
12H 25/1800Z 13.4N 118.6W 40 KT 45 MPH
24H 26/0600Z 13.4N 119.5W 45 KT 50 MPH
36H 26/1800Z 13.6N 120.4W 50 KT 60 MPH
48H 27/0600Z 14.1N 121.0W 50 KT 60 MPH
60H 27/1800Z 14.6N 121.6W 50 KT 60 MPH
72H 28/0600Z 15.2N 122.4W 45 KT 50 MPH
96H 29/0600Z 15.5N 125.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
120H 30/0600Z 14.8N 128.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
FORECASTER GIBBS (CPHC)
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