WTPZ42 KNHC 071447 RRA

TCDEP2



HURRICANE JOHN DISCUSSION NUMBER   8

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP122018

900 AM MDT TUE AUG 07 2018



VISIBLE AND INFRARED SATELLITE IMAGES HAVE CONTINUED TO SHOW THE

RAGGED EYE OF JOHN THIS MORNING, BUT THE SURROUNDING CONVECTIVE

CLOUD TOPS HAVE BECOME MORE SYMMETRIC AND COOLED SINCE THE PREVIOUS

ADVISORY.  THE LATEST DVORAK SATELLITE INTENSITY ESTIMATES FROM

TAFB AND SAB WERE T5.0/90 KT, WHICH SUPPORT INCREASING THE INITIAL

WIND SPEED TO THAT VALUE.  JOHN HAS ABOUT ANOTHER 24 HOURS OVER

WARM WATER IN WHICH TO INTENSIFY, AND THE NHC INTENSITY FORECAST

CALLS FOR JOHN TO ATTAIN MAJOR HURRICANE STRENGTH LATER TODAY OR

TONIGHT.  AFTER THAT TIME, DECREASING SSTS AND A MORE STABLE

ENVIRONMENT SHOULD LEAD TO STEADY OR RAPID WEAKENING, AND JOHN IS

EXPECTED TO BECOME A POST-TROPICAL CYCLONE BY DAY 4.  THE NHC

INTENSITY FORECAST IS NEAR THE SHIPS AND HCCA MODELS FOR THE FIRST

12 TO 24 HOURS, AND THEN IS BETWEEN THE AFOREMENTIONED MODELS AND

THE INTENSITY CONSENSUS THEREAFTER.



JOHN IS MOVING NORTHWESTWARD OR 320/8 KT.  THE TRACK GUIDANCE IS IN

GOOD AGREEMENT ON TAKING THE HURRICANE NORTHWESTWARD AROUND THE

WESTERN PORTION OF A MID-LEVEL RIDGE CENTERED OVER NORTHERN MEXICO.

ONCE JOHN WEAKENS AND BECOMES A VERTICALLY SHALLOW SYSTEM IT SHOULD

TURN WESTWARD IN THE LOW-LEVEL FLOW.  THE NHC TRACK FORECAST IS

NEAR THE MIDDLE OF THE TIGHTLY CLUSTERED GUIDANCE ENVELOPE.



THE DANGEROUS CORE OF JOHN IS FORECAST TO REMAIN WELL OFFSHORE OF

THE BAJA CALIFORNIA PENINSULA.  HOWEVER, AN EASTWARD SHIFT OF THE

FORECAST TRACK OR AN UNEXPECTED INCREASE IN THE SIZE OF THE OUTER

WIND FIELD OF THE HURRICANE COULD BRING TROPICAL-STORM-FORCE WINDS