WTNT44 KNHC 040859 RRA

TCDAT4



POST-TROPICAL CYCLONE HERMINE DISCUSSION NUMBER  28

NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092016

500 AM EDT SUN SEP 04 2016



THE OVERALL STRUCTURE OF HERMINE HAS CHANGED LITTLE DURING THE PAST

6 HOURS. A RING OF SHALLOW CONVECTION HAS DEVELOPED WITHIN 60-100

N MI NORTHWEST THROUGH NORTHEAST OF THE CENTER, POSSIBLY DUE TO THAT

PORTION OF THE CIRCULATION PASSING OVER THE GULF STREAM, WHERE WATER

TEMPERATURES ARE 29-30C. AN EARLIER ASCAT-B PASS INDICATED THAT

WINDS HAD DECREASED TO 50-55 KT, AND RECENT DATA FROM AN AIR FORCE

RESERVE RECONNAISSANCE AIRCRAFT CONFIRMS THAT HERMINE HAS PEAK

WINDS OF 55 KT.



THE INITIAL MOTION ESTIMATE IS 065/10 KT. HERMINE IS EXPECTED TO

MOVE SLOWLY NORTHWARD AND PERHAPS ERRATICALLY DURING THE NEXT 36

HOURS AS THE POST-TROPICAL CYCLONE BEGINS TO INTERACT WITH AN

APPROACHING STRONG MID-/UPPER-LEVEL SHORTWAVE TROUGH THAT IS

GRADUALLY BECOMING MORE NEGATIVELY TILTED BASED ON WATER VAPOR

IMAGERY. BY 36-48 HOURS, HERMINE IS EXPECTED TO BECOME VERTICALLY

STACKED BENEATH A CUT-OFF LOW, WHICH COULD RESULT IN THE CYCLONE

BRIEFLY STALLING SOUTH OF SOUTHERN NEW ENGLAND BEFORE LIFTING OUT TO

THE NORTHEAST BY 72 HOURS. THE MODELS ARE IN FAIRLY GOOD AGREEMENT

ON THIS DEVELOPING TRACK SCENARIO THROUGH ABOUT 36 HOURS, BUT THEN

DIVERGE SIGNIFICANTLY AFTER THAT WITH THE UKMET MODEL TURNING

HERMINE FARTHER WEST CLOSER TO THE NEW JERSEY COAST WHILE THE ECMWF

LIFTS OUT HERMINE MORE QUICKLY. THE GFS SOLUTION LIES BETWEEN THESE

TWO EXTREMES, AND THE NEW FORECAST TRACK CLOSELY FOLLOWS THAT MODEL.

HOWEVER, THERE REMAINS LOW CONFIDENCE IN ANY PARTICULAR MODEL.



LITTLE CHANGE IN STRENGTH IS LIKELY TODAY. HOWEVER, BY LATE TONIGHT=