WTPZ41 KNHC 102040 RRA

TCDEP1



TROPICAL STORM SERGIO DISCUSSION NUMBER  46

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP212018

200 PM PDT WED OCT 10 2018



THE ORGANIZATION OF THE CLOUD PATTERN HAS REMAINED UNCHANGED DURING

THE DAY, EXCEPT THAT THE DEEP CONVECTION HAS CONTINUED TO WEAKEN.

NEVERTHELESS, DVORAK NUMBERS FROM TAFB AND SAB STILL SUPPORT AN

INITIAL INTENSITY OF 55 KT. SOME FLUCTUATIONS IN INTENSITY ARE

LIKELY DURING THE NEXT 12 HOURS WHILE THE CYCLONE IS OVER RELATIVELY

WARM WATERS AND IS EMBEDDED IN A LOW SHEAR ENVIRONMENT. SINCE BOTH

OF THESE FACTORS WILL BECOME UNFAVORABLE IN ABOUT 12 TO 24 HOURS,

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 050 DEGREES AT 12 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 A DAY AND HALF, BUT WINDS WILL REACH THE COAST A LITTLE BIT

EARLIER. TRACK MODELS CONTINUE TO BE IN VERY GOOD AGREEMENT, AND

CONSEQUENTLY THE GUIDANCE ENVELOPE IS QUITE TIGHT. THE NHC FORECAST

REMAINS UNCHANGED AND IS IN THE MIDDLE OF THE GUIDANCE ENVELOPE.



THE PRIMARY THREAT ASSOCIATED WITH SERGIO AND ITS REMNANTS CONTINUES

TO BE LIFE-THREATENING FLASH FLOODING AND MUDSLIDES WITHIN