WTPZ45 KNHC 010839 RRA

TCDEP5



TROPICAL STORM ROSA DISCUSSION NUMBER  25

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP202018

200 AM PDT MON OCT 01 2018



CONVECTION HAS BEEN STEADILY DECREASING DUE TO THE COMBINATION

OF SOUTHWESTERLY SHEAR OF ABOUT 30 KT AND COOL SSTS OF LESS THAN

24 DEG C. AS A RESULT, ONLY A SMALL PATCH OF THUNDERSTORMS

REMAINS IN THE NORTHEASTERN QUADRANT OF ROSA'S CIRCULATION. ASCAT

PASSES AROUND 0414Z AND 0516Z ONLY INDICATED WIND SPEEDS OF 41-42 KT

IN THE EASTERN SEMICIRCLE. ASSUMING THAT SOME UNDERSAMPLING IS

OCCURRING, THE INTENSITY HAS ONLY BEEN DECREASED TO 45 KT FOR THIS

ADVISORY. ADDITIONAL WEAKENING IS EXPECTED DUE TO A FURTHER INCREASE

IN THE VERTICAL WIND SHEAR AND DECREASING OCEAN TEMPERATURES BENEATH

THE CYCLONE. THE OFFICIAL INTENSITY FORECAST CALLS FOR ROSA TO BE

NEAR 35 KT AT THE TIME OF LANDFALL LATER TODAY, BUT IT IS POSSIBLE

THAT MORE WEAKENING COULD OCCUR THAN CURRENTLY INDICATED.

REGARDLESS, STRONG TROPICAL-STORM-FORCE WIND GUSTS WILL BE

WIDESPREAD ACROSS THE HIGHER ELEVATIONS OF THE NORTHERN BAJA

CALIFORNIA PENINSULA. ROSA IS EXPECTED TO BECOME REMNANT LOW BEFORE

THE CYCLONE REACHES ARIZONA DUE TO THE RUGGED TERRAIN OF BAJA AND

NORTHWESTERN MEXICO, AND THE CONTINUED STRONG WIND SHEAR.



ROSA IS MOVING NORTHEASTWARD NOW, OR 035/10 KT. A NORTHEASTWARD TO

NORTH-NORTHEASTWARD MOTION IS EXPECTED UNTIL AND AFTER LANDFALL,

WITH SOME ACCELERATION BEGINNING LATER TONIGHT. THE LATEST NHC

MODEL GUIDANCE REMAINS TIGHTLY CLUSTERED, AND THE OFFICIAL FORECAST

TRACK LIES CLOSE TO THE PREVIOUS TRACK AND AN AVERAGE OF THE TVCE,

HCCA, AND FSSE MULTI-MODEL CONSENSUS AIDS.



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