WTPZ41 KNHC 101445 RRA

TCDEP1



TROPICAL STORM SERGIO DISCUSSION NUMBER  45

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP212018

800 AM PDT WED OCT 10 2018



THE CLOUD PATTERN ASSOCIATED WITH SERGIO HAS NOT CHANGED VERY MUCH,

AND IT CONSISTS OF A CYCLONICALLY CURVED CONVECTIVE BAND SURROUNDING

A LARGE AND RAGGED EYE FEATURE. SINCE THE CONVECTION IS WEAKER, THE

DVORAK ESTIMATES SUGGEST THAT WINDS ARE GRADUALLY DECREASING, AND

THE INITIAL INTENSITY HAS BEEN LOWERED TO 55 KT.  SOME FLUCTUATIONS

IN INTENSITY ARE LIKELY DURING THE NEXT 12 TO 24 HOURS WHILE THE

CYCLONE IS STILL MOVING OVER RELATIVELY WARM WATERS AND IS EMBEDDED

IN A LOW SHEAR ENVIRONMENT. BOTH OF THESE FACTORS WILL BECOME

UNFAVORABLE SOON, AND CONSEQUENTLY, THE NHC FORECAST CALLS FOR

WEAKENING.  SERGIO, HOWEVER, IS EXPECTED TO STILL BE A TROPICAL

STORM BY THE TIME IT APPROACHES THE BAJA CALIFORNIA PENINSULA. AFTER

THAT TIME, SERGIO WILL MOVE OVER MAINLAND MEXICO AND WEAKEN MUCH

FASTER.



SERGIO IS MOVING TOWARD THE NORTHEAST OR 055 DEGREES AT 11 KT. THE

CYCLONE IS EMBEDDED WITHIN THE SOUTHWESTERLY WINDS ASSOCIATED

WITH A LARGE MID-LATITUDE TROUGH, AND THIS FLOW PATTERN WILL

CONTINUE TO STEER SERGIO TOWARD THE NORTHEAST WITH AN INCREASE IN

FORWARD SPEED. THE FORECAST TRACK BRINGS THE CENTER OF A WEAKENED

SERGIO OVER THE CENTRAL PORTION OF THE BAJA CALIFORNIA PENINSULA IN

ABOUT 2 DAYS, BUT WINDS ALONG THE COAST ARE ANTICIPATED TO INCREASE

EARLIER. TRACK MODELS ARE IN VERY GOOD AGREEMENT, AND CONSEQUENTLY

THE GUIDANCE ENVELOPE IS QUITE TIGHT. THE NHC FORECAST IS NOT

DIFFERENT FROM THE PREVIOUS ONE AND IS IN THE MIDDLE OF THE GUIDANCE

ENVELOPE.



THE PRIMARY THREAT ASSOCIATED WITH SERGIO AND ITS REMNANTS CONTINUES