WTPZ44 KNHC 271437 RRA

TCDEP4



TROPICAL STORM MADELINE DISCUSSION NUMBER   4

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP142016

800 AM PDT SAT AUG 27 2016



A GPM OVERPASS FROM 1146 UTC INDICATED THAT THE LOW-LEVEL CENTER OF

MADELINE WAS LOCATED NORTHEAST OF PREVIOUS ESTIMATES, NEAR THE

NORTHEASTERN EDGE OF THE CONVECTION.  THIS IS CONSISTENT WITH THE

MODERATE NORTHEASTERLY SHEAR ANALYZED OVER THE CYCLONE BY THE SHIPS

MODEL OUTPUT BASED ON THE GFS AND ECMWF FIELDS.  THE INITIAL

INTENSITY IS HELD AT 45 KT FOR THIS ADVISORY IN AGREEMENT WITH THE

LATEST DVORAK ESTIMATES FROM TAFB AND SAB, AND THIS VALUE IS ALSO

CLOSE TO THE LATEST UW-CIMSS SATCON ANALYSIS.



GIVEN THE RELOCATION OF THE CENTER, THE BEST ESTIMATE OF THE INITIAL

MOTION IS AN UNCERTAIN 310/08.  MADELINE IS EXPECTED TO CONTINUE

MOVING GENERALLY NORTHWESTWARD FOR THE NEXT 72 HOURS AROUND THE

SOUTHWESTERLY PERIPHERY OF A MID-LEVEL RIDGE CENTERED NEAR 125W.

AFTER THAT TIME, A RIDGE CENTERED NORTH OF THE HAWAIIAN ISLANDS

BECOMES THE DOMINANT STEERING MECHANISM, AND SHOULD IMPART A

WESTWARD MOTION THROUGH THE REMAINDER OF THE FORECAST PERIOD.  WHILE

THE OVERALL TRACK FORECAST PHILOSOPHY HAS NOT CHANGED, THE MORE

NORTHERLY INITIAL POSITION HAS RESULTED IN A NORTHWARD SHIFT OF THE

GUIDANCE ENVELOPE AND THE NHC FORECAST BY 30 TO 50 N MI THROUGH THE

FORECAST PERIOD.  THE NEW NHC TRACK IS NEAR THE MIDDLE OF THE

GUIDANCE ENVELOPE AND CLOSE TO THE LATEST MULTI-MODEL CONSENSUS.



THE SHIPS MODEL SHOWS THE SHEAR DECREASING OVER MADELINE DURING THE

NEXT 12 HOURS OR SO, WHICH SHOULD ALLOW FOR SOME INTENSIFICATION

THROUGH 72 HOURS WHILE THE CYCLONE IS MOVING OVER SSTS ABOVE 27C.=