WTPZ45 KNHC 010234 RRA

TCDEP5



TROPICAL STORM ROSA DISCUSSION NUMBER  24

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP202018

800 PM PDT SUN SEP 30 2018



ALL OF ROSA'S ASSOCIATED DEEP CONVECTION IS LOCATED WITHIN THE

NORTHEASTERN QUADRANT OF THE CIRCULATION, MOVING OUT AHEAD OF THE

CENTER DUE TO 25-30 KT OF SOUTHWESTERLY SHEAR.  SUBJECTIVE AND

OBJECTIVE INTENSITY ESTIMATES HAVE DECREASED SINCE THE PREVIOUS

ADVISORY BUT ENCOMPASS A WIDE RANGE FROM ABOUT 45 KT TO 65 KT. THE

INITIAL INTENSITY IS LOWERED TO 55 KT, THE AVERAGE OF THESE

ESTIMATES AND SIMILAR TO THE LATEST UW-CIMSS SATCON ESTIMATE. ROSA'S

CENTER IS NOW OVER SUB-24C WATERS, HEADING FOR WATERS AROUND 21C

ALONG THE BAJA CALIFORNIA COAST, AND THE SHEAR IS FORECAST TO

INCREASE FURTHER IN THE COMING DAYS.  AS A RESULT, ROSA IS EXPECTED

TO WEAKEN BELOW TROPICAL STORM INTENSITY BETWEEN 24-36 HOURS, AFTER

IT HAS REACHED THE BAJA CALIFORNIA COAST.  ALL OF THE CYCLONE'S DEEP

CONVECTION IS LIKELY TO BE SHEARED AWAY SOON THEREAFTER, MAKING ROSA

A REMNANT LOW BETWEEN 36-48 HOURS, IF NOT SOONER.  THE REMNANT LOW

SHOULD DISSIPATE OVER ARIZONA BY 48 HOURS.



ROSA CONTINUES TO MOVE NORTH-NORTHEASTWARD, OR 025/10 KT.  THE FLOW

ON THE EASTERN SIDE OF A LARGE MID-LEVEL TROUGH LOCATED OFF THE

U.S. WEST COAST SHOULD CONTINUE TO STEER ROSA NORTH-NORTHEASTWARD,

WITH SOME ACCELERATION BEGINNING BY MONDAY NIGHT.  ALTHOUGH THERE

ARE STILL SOME SPEED DIFFERENCES AMONG THE MODELS, PARTICULARLY

BETWEEN THE FASTER GFS AND SLOWER ECMWF, THE GUIDANCE REMAINS

TIGHTLY CLUSTERED OVERALL, AND THE NEW NHC TRACK FORECAST IS VERY

CLOSE TO THE MULTI-MODEL CONSENSUS AIDS.





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