WTPZ41 KNHC 140249 RRA

TCDEP1



HURRICANE ORLENE DISCUSSION NUMBER  13

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP162016

800 PM PDT TUE SEP 13 2016



MICROWAVE SATELLITE IMAGERY INDICATES THAT THE INNER-CORE CONVECTION

OF ORLENE HAS STEADILY DEGRADED DURING THE PAST 6 HOURS, WITH THE

EYEWALL NO LONGER CLOSED. THE EYE BRIEFLY APPEARED IN VISIBLE AND

INFRARED IMAGERY AROUND 0000Z, BUT IS NOT EVIDENT IN CONVENTIONAL

SATELLITE IMAGERY. THE INITIAL REMAINS AT 75 KT BASED ON CONSENSUS

SUBJECTIVE SATELLITE ESTIMATES OF T4.5/77 KT FROM TAFB AND SAB.



THE MICROWAVE AND CONVENTIOANL SATELLITE DATA INDICATE THAT ORLENE

IS DRIFTING NORTHWARD OR 360/01 KT. THE CYCLONE IS EXPECTED TO

REMAIN NEARLY STATIONARY OVERNIGHT, EMBEDDED WITHIN A NARROW BREAK

IN THE SUBTROPICAL RIDGE. A SLOW WESTWARD MOTION IS EXPECTED TO

BEGIN BY EARLY WEDNESDAY AS A SHORTWAVE TROUGH LIFTS OUT, ALLOWING

THE RIDGE TO BUILD BACK IN TO THE NORTH OF ORLENE IN 12-24 HOURS.

AFTER THAT TIME, THE RIDGE IS FORECAST TO STEADILY STENGTHEN,

FORCING THE CYCLONE ON A GENERAL WESTWARD DIRECTION AT A MUCH FASTER

FORWARD SPEED. THE NEW FORECAST TRACK IS SIMILAR TO THE PREVIOUS

ADVISORY TRACK, AND LIES CLOSE TO THE CONSENSUS MODEL TVCN AND A

BELDN OF THE GFS AND ECMWF MODEL SOLUTIONS.



ALTHOUGH MODERATE SOUTHWESTERLY VERTICAL WIND SHEAR CURRENTLY

AFFECTING THE CYCLONE IS FORECAST TO DECREASE TO AROUND 5 KT

THROUGHOUT THE FORECAST PERIOD, THE CYCLONE WILL ALSO BE MOVING OVER

NEAR 26 DEG C SSTS AND INTO A VERY DRY AND STABLE AIRMASS. THE

RESULT SOULD BE A GRADUAL EROSION OF THE INNER-CORE CONVECTION,

CAUSING THE CYCLONE TO SLOWLY BUT STEADILY WEAKEN. THE NEW NHC=