WTPZ45 KNHC 272049 RRA

TCDEP5



HURRICANE ROSA DISCUSSION NUMBER  11

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP202018

200 PM PDT THU SEP 27 2018



ROSA IS UNDERGOING RAPID INTENSIFICATION, ACCOMPANIED BY THE

FORMATION OF A WELL-DEFINED 15 N MI WIDE EYE INSIDE THE CENTRAL

DENSE OVERCAST.  RECENT SUBJECTIVE AND OBJECTIVE SATELLITE INTENSITY

ESTIMATES ARE GENERALLY IN THE 100-115 KT RANGE, AND THE INITIAL

INTENSITY IS INCREASED TO 110 KT IN BEST AGREEMENT WITH THE CIMSS

ADT AND THE SUBJECTIVE DVORAK ESTIMATE FROM TAFB.  ROSA CONTINUES TO

HAVE GOOD CIRRUS OUTFLOW IN ALL DIRECTIONS.



THE INTENSITY FORECAST HAS SOME COMPLEXITIES.  THE FIRST IS HOW MUCH

MORE ROSA WILL STRENGTHEN BEFORE THE RAPID INTENSIFICATION STOPS.

THE NEW INTENSITY FORECAST FOLLOWS THE UPPER EDGE OF THE GUIDANCE IN

SHOWING ABOUT 12 H MORE STRENGTHENING WITH A PEAK INTENSITY OF

120 KT.  THAT BEING SAID, IT WOULD NOT BE SURPRISING IF ROSA GOT

STRONGER THAN THAT.  THE SIMPLEST PART OF THE FORECAST IS FROM 24-72

H, WHEN THE SEA SURFACE TEMPERATURES COOL ALONG THE FORECAST TRACK

WITH ROSA GRADUALLY WEAKENING AS A RESULT.  AFTER 72 H, THE CYCLONE

SHOULD MOVE ACROSS THE QUITE COLD WATERS OF THE NORTHEASTERN

PACIFIC, AND THEN MOVE ACROSS BAJA CALIFORNIA OVER THE WARM WATER OF

THE GULF OF CALIFORNIA.  WHILE THAT IS HAPPENING, A MID-LATITUDE

TROUGH TO THE NORTHWEST IS EXPECTED TO CAUSE BOTH STRONG SHEAR AND

STRONG UPPER-LEVEL DIVERGENCE OVER ROSA.  THE INTENSITY GUIDANCE

RESPONDS TO THIS COMBINATION OF INGREDIENTS WITH INTENSITY FORECASTS

OF ANYWHERE BETWEEN 30-65 KT AS ROSA MAKES LANDFALL ON THE BAJA

CALIFORNIA PENINSULA.  THE NEW INTENSITY FORECAST CONTINUES TO CALL