WTPZ41 KNHC 092055 RRA

TCDEP1



TROPICAL STORM SERGIO DISCUSSION NUMBER  42

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP212018

200 PM PDT TUE OCT 09 2018



DAYS OF SLOW MOVEMENT AND COLD WATER UPWELLING APPEAR TO HAVE

FINALLY TAKEN A TOLL ON SERGIO.  CLOUD TOP TEMPERATURES ON THE WEST

SIDE OF THE CYCLONE HAVE WARMED CONSIDERABLY SINCE THIS MORNING,

AND MICROWAVE IMAGERY INDICATES THAT SERGIO'S EYEWALL IS NO

LONGER FULLY CLOSED.  DVORAK-BASED INTENSITY ESTIMATES HAVE

DECREASED ACCORDINGLY AND NOW SUPPORT AN INITIAL INTENSITY OF ONLY

60 KT.  A RECENT PARTIAL ASCAT OVERPASS ALSO SHOWED MAXIMUM WINDS

OF ONLY 50-55 KT IN THE EASTERN SEMICIRCLE OF THE CYCLONE, AND

THESE DATA ALSO SUPPORT MAKING SERGIO A TROPICAL STORM.



THE TROPICAL STORM IS MOVING EAST-NORTHEASTWARD, OR 060/8 KT.

NO IMPORTANT CHANGES WERE MADE TO THE TRACK FORECAST, WHICH IS

MERELY AN UPDATE OF THE PREVIOUS ADVISORY.  THE TROPICAL STORM WILL

LIKELY CONTINUE TO ACCELERATE TOWARD THE EAST-NORTHEAST OR NORTHEAST

OVER THE NEXT FEW DAYS, BEFORE APPROACHING THE BAJA CALIFORNIA

PENINSULA ON FRIDAY. THE NHC FORECAST REMAINS NEAR THE TRACK

CONSENSUS AT ALL TIMES AND CONFIDENCE IN THE TRACK FORECAST IS HIGH.



NOW THAT SERGIO IS MOVING A LITTLE FASTER, IT HAS A CHANCE TO MOVE

OVER SLIGHTLY WARMER WATERS DURING THE NEXT FEW HOURS.  THE

INTENSITY GUIDANCE IS IN FAIRLY GOOD AGREEMENT THAT LITTLE

ADDITIONAL WEAKENING IS LIKELY FOR THE NEXT DAY OR SO.  BEYOND 36

H, FASTER WEAKENING IS STILL POSSIBLE AS THE STORM REACHES MUCH

COLDER WATERS AND THE SHEAR OVER THE TROPICAL STORM INCREASES.

RAPID WEAKENING AND DISSIPATION IS EXPECTED AFTER SERGIO MAKES ITS

FINAL LANDFALL ALONG THE COAST OF MAINLAND MEXICO, THOUGH A 96 H