WTPZ45 KNHC 261438 RRA

TCDEP5



TROPICAL STORM MIRIAM DISCUSSION NUMBER   2

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP152018

800 AM PDT SUN AUG 26 2018



DEEP CONVECTION ASSOCIATED WITH THE TROPICAL CYCLONE HAS CONTINUED

TO BECOME BETTER ORGANIZED THIS MORNING, WITH A SIGNIFICANT INCREASE

IN BANDING NOTED IN CONVENTIONAL SATELLITE IMAGERY.  AN EARLIER

AMSR2 MICROWAVE OVERPASS ALSO REVEALED THE INCREASE IN BANDING, BUT

THE LOW-LEVEL CENTER WAS LOCATED NEAR THE NORTHEASTERN PORTION OF

THE MAIN CONVECTIVE MASS.  A DVORAK SATELLITE INTENSITY ESTIMATE OF

T2.5 (35 K) WAS THE BASIS FOR THE 1200 UTC SYNOPTIC INTENSITY, BUT

WITH THE CONTINUED INCREASE IN ORGANIZATION, THE INITIAL WIND SPEED

FOR THIS ADVISORY HAS BEEN SET TO 40 KT.



MIRIAM IS MOVING WESTWARD OR 275/11 KT. THE TROPICAL STORM SHOULD

REMAIN ON A GENERAL WESTWARD HEADING DURING THE NEXT FEW DAYS WHILE

IT REMAINS TO THE SOUTH OF A DEEP-LAYER RIDGE.  THE ORIENTATION OF

THE RIDGE MAY SHIFT MORE WEST-SOUTHWESTWARD WITHIN THE NEXT DAY OR

SO, WHICH COULD STEER THE TROPICAL STORM ON A TRACK SLIGHTLY SOUTH

OF DUE WEST.  THE BULK OF THE DYNAMICAL MODEL GUIDANCE HAS SHIFTED

SOUTHWARD, SO THE NHC FORECAST TRACK HAS BEEN ADJUSTED ACCORDINGLY

THROUGH THE FIRST 3 DAYS.  AFTER THAT TIME, A WEAKNESS IN THE

SUBTROPICAL RIDGE BETWEEN 140W-145W LONGITUDE IS EXPECTED TO CAUSE

MIRIAM TO TURN NORTHWESTWARD, THEN NORTH-NORTHWESTWARD BY THE END

OF THE FORECAST PERIOD.  THE LATTER PORTION OF THE OFFICIAL FORECAST

IS SIMILAR TO THE PREVIOUS ADVISORY AND IS IN BEST AGREEMENT WITH

THE HFIP CORRECTED CONSENSUS MODEL.



THE ENVIRONMENT AHEAD OF MIRIAM IS EXPECTED TO REMAIN FAVORABLE FOR