WTPZ41 KNHC 060845 RRA

TCDEP1



HURRICANE SERGIO DISCUSSION NUMBER  28

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP212018

200 AM PDT SAT OCT 06 2018



SERGIO HAS CHANGED LITTLE IN STRUCTURE SINCE THE LAST ADVISORY.  IT

STILL HAS A 25-30 N MI WIDE EYE SURROUNDED BY COLD CONVECTIVE TOPS,

AND WITH NOT MUCH CHANGE IN INTENSITY ESTIMATES, THE ESTIMATED

MAXIMUM WINDS REMAIN 110 KT.  SERGIO'S INTENSITY IS NOT LIKELY TO

CHANGE MUCH DURING THE NEXT DAY OR TWO, ALTHOUGH SOME SLIGHT

WEAKENING IS POSSIBLE AS THE HURRICANE'S SPEED SLOWS DOWN AND IT

UPWELLS SOME COLDER WATER FROM BELOW, OR DUE TO POSSIBLE INTERNAL

STRUCTURAL CHANGES.  MORE DEFINITIVE WEAKENING IS ANTICIPATED BY

DAYS 4 AND 5 DUE TO AN INCREASE IN WESTERLY AND SOUTHWESTERLY

SHEAR AND THE HURRICANE REACHING COLDER WATERS.  THE NHC INTENSITY

FORECAST REMAINS CLOSE TO A BLEND OF THE ICON CONSENSUS AND THE HCCA

MODEL.  HOWEVER, THE STATISTICAL-DYNAMICAL MODELS REMAIN A BIT

HIGHER, AND IT IS POSSIBLE THAT SERGIO WON'T LOSE QUITE AS MUCH

PUNCH DURING THE NEXT SEVERAL DAYS AS IS INDICATED BY THE OFFICIAL

FORECAST.



SERGIO CONTINUES TO DIVE SOUTHWESTWARD WITH AN INITIAL MOTION OF

235/7 KT.  A SHORTWAVE TROUGH SWINGING ACROSS THE BAJA CALIFORNIA

PENINSULA WILL BYPASS SERGIO DURING THE DAY, LEAVING A WEAKNESS IN

THE RIDGE THAT WILL ALLOW THE HURRICANE TO BEGIN MAKING A SHARP

NORTHWARD AND THEN NORTHEASTWARD TURN DURING THE NEXT 24-72 HOURS.

ANOTHER SHORTWAVE TROUGH FORECAST TO DIG SOUTHWARD OFF THE

CALIFORNIA COAST WILL THEN CAUSE SERGIO TO ACCELERATE NORTHEASTWARD

ON DAYS 4 AND 5.  NOTABLE CHANGES IN THIS FORECAST UPDATE INCLUDE A

SLIGHTLY WIDER TURN FROM 24-72 HOURS, AND MORE SPREAD IN THE MODEL