WTNT44 KNHC 010258 RRA

TCDAT4



TROPICAL STORM HERMINE DISCUSSION NUMBER  14

NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092016

1000 PM CDT WED AUG 31 2016



DATA FROM NOAA AND AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT THIS

AFTERNOON AND EVENING INDICATE THAT HERMINE HAS CONTINUED TO

STRENGTHEN, BASED ON MAXIMUM 850-MB FLIGHT-LEVEL WINDS OF 57 KT AND

PEAK SFMR SURFACE WINDS OF 52 KT. A RECENT DROPSONDE IN THE CENTER

OF HERMINE MEASURED A PRESSURE OF ABOUT 998 MB, WHICH IS A DECREASE

OF 6 MB FROM THE PREVIOUS ADVISORY.



RECON FIXES OVER THE PAST 4 HOURS INDICATE THAT THE ESTIMATED MOTION

IS NORTH-NORTHEASTWARD OR 025/09 KT. AN APPROACHING MID-TROPOSPHERIC

TROUGH LOCATED OVER THE SOUTHEASTERN UNITED STATES AND EXTENDING

SOUTHWARD INTO THE NORTH-CENTRAL GULF OF MEXICO IS EXPECTED TO

GRADUALLY LIFT OUT HERMINE TO THE NORTH-NORTHEAST TONIGHT AND

THURSDAY, AND THEN NORTHEASTWARD AFTER 24 HOURS. THE NHC MODEL IS

IN VERY GOOD AGREEMENT ON THIS DEVELOPING STEERING FLOW PATTERN.

LATER IN THE FORECAST PERIOD, SIGNIFICANT UNCERTAINTY IN THE TRACK

FORECAST REMAINS, DEPENDING ON HOW MUCH THE POST-TROPICAL CYCLONE

INTERACTS WITH A MID-LATITUDE CUTOFF LOW THAT DEVELOPS OVER THE

NORTHEASTERN UNITED STATES. THE NEW NHC FORECAST TRACK HAS BEEN

SHIFTED SLIGHTLY TO THE EAST OF THE PREVIOUS ADVISORY TRACK,

PRIMARILY DUE TO THE MORE EASTWARD INITIAL POSITION DETERMINED FROM

RECENT RECON FIXES, AND LIES JUST TO THE LEFT OF THE CONSENSUS MODEL

TVCN.



THE VERTICAL WIND SHEAR IS FORECAST BY THE GFS AND THE ECMWF MODELS

TO SHIFT FROM THE CURRENT WEST-NORTHWESTERLY DIRECTION TO

SOUTHWESTERLY BY 18-24 HOURS AT ABOUT 5 TO 10 KT. SSTS ARE EXPECTED=