WTNT42 KNHC 200858 RRA

TCDAT2



TROPICAL STORM KARL DISCUSSION NUMBER  24

NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122016

500 AM AST TUE SEP 20 2016



KARL'S SATELLITE APPEARANCE LATE YESTERDAY GAVE THE IMPRESSION THAT

IT HAD INCREASED SOME IN ORGANIZATION, WITH THE LOW-LEVEL CENTER

PARTIALLY UNDERNEATH A LARGE MASS OF DEEP CONVECTION.  SINCE THAT

TIME, THE LOW-LEVEL CENTER APPEARS TO HAVE OUTRUN THE CONVECTION,

BECOMING EXPOSED WELL TO THE WEST OF THE REMNANT CONVECTIVE MASS

WHOSE CLOUD TOP TEMPERATURES HAVE WARMED SIGNIFICANTLY.  THE CLOUD

PATTERN IS TYPICAL OF A TROPICAL CYCLONE UNDERGOING SIGNIFICANT

WESTERLY SHEAR.  DVORAK CLASSIFICATIONS HAVE DECREASED TO T2.5 FROM

TAFB AND SAB, AND ON THIS BASIS, THE INITIAL INTENSITY ESTIMATE IS

LOWERED TO 35 KT.



THE INITIAL MOTION IS A FASTER AND A MORE WESTERLY 290/15.  KARL

SHOULD CONTINUE TO BE STEERED GENERALLY WEST-NORTHWESTWARD AROUND

THE SOUTHWESTERN PERIPHERY OF WELL-DEFINED LOW- TO MID-LEVEL

SUBTROPICAL RIDGE OVER THE CENTRAL ATLANTIC DURING THE NEXT COUPLE

OF DAYS.  THE CYCLONE SHOULD MOVE INTO WEAKNESS IN THE RIDGE ALONG

65W IN 48 TO 72 HOURS, WHICH SHOULD RESULT IN A GRADUAL TURN TOWARD

THE NORTH WITH A CONSIDERABLE DECREASE IN FORWARD SPEED BY DAY 4.

AROUND 96 HOURS, KARL SHOULD BECOME SUSCEPTIBLE TO THE MID-LATITUDE

WESTERLY FLOW AFTER IT CROSSES 30N AS IT BEGINS TO UNDERGO A SHARP

RECURVATURE.  THE MODELS VARY TREMENDOUSLY ON HOW QUICKLY KARL WILL

RECURVE BY DAY 5, WITH THE GFS-BASED GUIDANCE WHISKING THE CYCLONE

RAPIDLY NORTHEASTWARD IN RESPONSE TO A DEEP-LAYER TROUGH MOVING

THROUGH THE NORTHEASTERN UNITED STATES AND ATLANTIC CANADA. THE

ECMWF AND THE MAJORITY OF ITS ENSEMBLE MEMBERS SHOW KARL LAGGING WAY=