WTPZ42 KNHC 082032 RRA

TCDEP2



HURRICANE JOHN DISCUSSION NUMBER  13

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP122018

300 PM MDT WED AUG 08 2018



JOHN HAS SHOWN SOME IMPROVED ORGANIZATION SINCE THE LAST ADVISORY

AS THE SYSTEM HAS FORMED A 20 N MI WIDE CLOUD-FILLED EYE.  SATELLITE

INTENSITY ESTIMATES REMAIN IN THE 65-77 KT RANGE, SO THE INITIAL

INTENSITY WILL BE HELD AT 75 KT FOR THIS ADVISORY.  OTHER THAN

THIS TEMPORARY BREAK IN THE WEAKENING, THERE IS LITTLE CHANGE TO THE

INTENSITY FORECAST, AS THE FORECAST TRACK TAKES JOHN OVER

PROGRESSIVELY COLDER SEA SURFACE TEMPERATURES AND INTO A MORE STABLE

AIR MASS. THE NEW INTENSITY FORECAST IS IN THE CENTER OF THE

INTENSITY GUIDANCE, WITH JOHN EXPECTED TO WEAKEN TO A TROPICAL STORM

IN 24 H OR LESS AND TO A REMNANT LOW BETWEEN 48-72 H.



THE INITIAL MOTION IS 325/13, A BIT FASTER THAN EARLIER.  A

COMBINATION OF AN UPPER-LEVEL LOW NEAR 19N 124W AND A MID- TO

UPPER-LEVEL RIDGE OVER NORTHWESTERN MEXICO SHOULD STEER JOHN

NORTHWESTWARD FOR THE NEXT 36 H OR SO.  AFTER THAT, THE CYCLONE OR

ITS REMNANTS IS FORECAST TO TURN WEST-NORTHWESTWARD IN THE LOW-LEVEL

TRADE WIND FLOW.  NEAR THE END OF THE FORECAST PERIOD, A SLOW MOTION

IS EXPECTED AS THE REMNANTS OF JOHN MOVE INTO AN AREA OF LIGHT

STEERING CURRENTS.  THE GUIDANCE ENVELOPE HAS SHIFTED A LITTLE TO

THE NORTH FROM THE PREVIOUS ADVISORY, AND THE NEW FORECAST TRACK IS

NORTH OF AND FASTER THAN THE PREVIOUS FORECAST.



ALTHOUGH THE CENTER OF JOHN IS FORECAST TO REMAIN WELL OFFSHORE OF

THE BAJA CALIFORNIA PENINSULA, A SURGE OF MOISTURE AROUND JOHN'S

OUTER CIRCULATION IS EXPECTED TO BRING SOME LOCALLY HEAVY RAINFALL

TO PORTIONS OF BAJA CALIFORNIA SUR DURING THE NEXT COUPLE OF DAYS.