WTNT42 KNHC 161451 RRA

TCDAT2



TROPICAL STORM KARL DISCUSSION NUMBER   9

NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122016

1100 AM AST FRI SEP 16 2016



KARL REMAINS A SHEARED TROPICAL CYCLONE THIS MORNING WITH ALL

OF ITS DEEP CONVECTION IN THE NORTHEASTERN QUADRANT DUE TO SHEAR

RELATED TO ITS INTERACTION WITH A MID- TO UPPER-LEVEL TROUGH.  THE

INITIAL WIND SPEED IS KEPT AT 40 KT FOR THIS ADVISORY, A COMPROMISE

BETWEEN LOWER DVORAK ESTIMATES AND HIGHER, BUT NOISY, SCATTEROMETER

VALUES.   VERTICAL SHEAR IS EXPECTED TO DECREASE IN ABOUT 36 HOURS,

AND, DESPITE A SOMEWHAT DRY ENVIRONMENT, WARMING SEA SURFACE

TEMPERATURES SHOULD ALLOW FOR AT LEAST GRADUAL STRENGTHENING.  THE

INTENSITY MODELS CONTINUE TO TREND HIGHER AT THE END OF THE

FORECAST PERIOD, AND THE OFFICIAL FORECAST FOLLOWS THIS TREND.  THIS

FORECAST IS REMAINS CLOSE TO THE SHIPS AND LGEM MODELS.



THE CENTER OF KARL HAS BECOME A LITTLE DISTORTED DUE TO THE SHEAR

AND CONVECTION, BUT IT STILL SEEMS TO BE MOVING ABOUT 280/11.

KARL IS FORECAST TO TURN MORE TO THE WEST AND SOUTH-OF-WEST THIS

WEEKEND AS THE SUBTROPICAL RIDGE STRENGTHENS TO THE NORTH OF THE

CYCLONE. HOWEVER, THE CURRENT INTERACTION OF KARL WITH THE MID- TO

UPPER-LEVEL TROUGH HAS NOT BEEN WELL FORECAST, AND KARL PROBABLY

WILL NOT GET AS FAR TO THE SOUTH AS EXPECTED YESTERDAY. IN A FEW

DAYS, THE STORM SHOULD MOVE TO THE WEST-NORTHWEST AND EVENTUALLY

MORE TO NORTHWEST AROUND DAY 5 AS IT REACHES THE EDGE OF THE RIDGE.

THE NEW FORECAST IS CLOSE TO A BLEND OF THE ECMWF AND GFS, PLUS

THEIR RESPECTIVE ENSEMBLE MEANS, ENDING UP A LITTLE NORTH OF THE

PREVIOUS NHC PREDICTION AT LONG RANGE.





FORECAST POSITIONS AND MAX WINDS=