WTNT44 KNHC 022045 RRA

TCDAT4



TROPICAL STORM HERMINE DISCUSSION NUMBER  22

NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092016

500 PM EDT FRI SEP 02 2016



WHILE THE CLOUD PATTERN OF HERMINE HAS BECOME ELONGATED NORTH AND

EAST OF THE CENTER, AND THE CENTRAL CONVECTIVE TOPS HAVE WARMED,

NUMEROUS SURFACE OBSERVATIONS OF 40-KT WINDS ALONG THE SOUTH

CAROLINA COAST SUPPORT MAINTAINING AN INITIAL INTENSITY OF 45 KT FOR

THIS ADVISORY.  WHILE THE CENTER OF HERMINE REMAINS OVER LAND FOR

THE NEXT 12 TO 18 HOURS, LITTLE CHANGE IN INTENSITY IS EXPECTED,

AS THE STRONGEST WINDS SHOULD REMAIN OVER THE COASTAL WATERS OF THE

CAROLINAS.  AFTER THE CENTER MOVES OFFSHORE, INTENSIFICATION IS

EXPECTED THROUGH A COMBINATION OF DIABATIC AND BAROCLINIC PROCESSES.

THE GLOBAL MODELS CONTINUE TO SHOW HERMINE INTERACTING WITH A POTENT

UPPER-LEVEL SHORTWAVE TROUGH IN 2-3 DAYS, AND THE SYSTEM IS EXPECTED

TO RESTRENGTHEN TO NEAR HURRICANE FORCE IN 48 TO 72 HOURS.  AS THE

UPPER-LEVEL FORCING MOVES AWAY, SLOW WEAKENING IS EXPECTED LATER IN

THE PERIOD.  THE NHC INTENSITY FORECAST IS ABOVE THE TROPICAL

CYCLONE GUIDANCE SUITE AND IS BASED LARGELY ON GLOBAL MODELS.



THE INITIAL MOTION ESTIMATE IS 055/17, AS HERMINE IS CURRENTLY

EMBEDDED IN DEEP-LAYER SOUTHWESTERLY FLOW AHEAD OF A POSITIVELY-

TILTED MID-LATITUDE TROUGH.  DURING THE NEXT 36 TO 48 HOURS THE

CYCLONE SHOULD GRADUALLY SLOW DOWN AND THEN TURN MORE POLEWARD AS

THE SHORTWAVE TROUGH AMPLIFIES OVER THE CENTRAL APPALACHIANS AND

MID-ATLANTIC STATES.  THIS TROUGH INTERACTS WITH AND SUPERIMPOSES

ITSELF ON TOP OF HERMINE BETWEEN 48 AND 72 HOURS.  NOT SURPRISINGLY,

THERE ARE DIFFERENCES IN THE DETAILS OF HOW THE MODEL GUIDANCE=