WTPZ45 KNHC 252054 RRA

TCDEP5



TROPICAL STORM ROSA DISCUSSION NUMBER   3

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP202018

300 PM MDT TUE SEP 25 2018



ROSA HAS BECOME BETTER ORGANIZED THIS AFTERNOON.  AN EARLIER 1601

UTC GMI MICROWAVE IMAGE SHOWED IMPRESSIVE BANDING FEATURES IN THE

SOUTH SEMICIRCLE WITH A BANDING EYE TYPE FEATURE WRAPPING THREE

QUARTERS AROUND THE CENTER OF CIRCULATION.  A BLEND OF THE DVORAK

INTENSITY ESTIMATES FROM TAFB AND SAB YIELD AN INITIAL INTENSITY OF

45 KT FOR THIS ADVISORY.



ALTHOUGH THERE IS SOME MODEST NORTHEASTERLY SHEAR IMPINGING IN THE

NORTHEAST SIDE OF THE CYCLONE, THE SHIPS INTENSITY GUIDANCE

INDICATE THAT THIS SHEAR WILL DIMINISH IN 12 HOURS.  SUBSEQUENTLY,

THE SHIPS RI INDEX AND THE DTOPS MODEL INDICATE A RELATIVELY HIGH

PROBABILITY OF RAPID INTENSIFICATION IN 24 HOURS.  ACCORDINGLY, THE

NHC FORECAST CALLS FOR ROSA TO BECOME A HURRICANE IN 12 HOURS BASED

ON THESE DATA.  FURTHER STRENGTHENING THROUGH THE 72 HOUR PERIOD IS

EXPECTED AND IS BASED ON THE IVCN MULTI-MODEL INTENSITY CONSENSUS.

BEYOND DAY 3, GRADUAL WEAKENING IS EXPECTED DUE TO INCREASING SHEAR

AND SLIGHTLY COOLER WATERS.



THE INITIAL MOTION IS ESTIMATED TO BE WEST-NORTHWESTWARD, OR 290 AT

8 KT, AND THIS GENERAL MOTION IS FORECAST TO CONTINUE THROUGH THE

NEXT 3 DAYS SOUTH OF A MID-LEVEL RIDGE EXTENDING FROM NORTHERN

MEXICO WESTWARD OVER THE EASTERN PACIFIC. IN RESPONSE TO A

MID-LATITUDE TROUGH APPROACHING FROM THE NORTHWEST, ROSA SHOULD TURN

TOWARDS THE NORTHWEST TO NORTH OVER THE WEEKEND.  IT IS WORTH NOTING

THAT THERE IS CONSIDERABLE ALONG AND CROSS-TRACK SPREAD IN THE TRACK

GUIDANCE BEYOND DAY 3.  THEREFORE, THE OFFICIAL TRACK FORECAST