WTNT42 KNHC 170250 RRA

TCDAT2



TROPICAL STORM KARL DISCUSSION NUMBER  11

NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122016

1100 PM AST FRI SEP 16 2016



THE DEEP CONVECTION WITH KARL IS LIMITED TO THE NORTHEASTERN

QUADRANT BECAUSE OF THE 20 KT WESTERLY VERTICAL SHEAR CURRENTLY

AFFLICTING THE TROPICAL STORM.  DESPITE THIS, A 0007 UTC ASCAT

SCATTEROMETER PASS INDICATED MAXIMUM WINDS OF ABOUT 40 KT, WHICH IS

THE INITIAL INTENSITY.



KARL SHOULD CONTINUE TO STRUGGLE FOR THE NEXT DAY OR SO DUE TO THE

HOSTILE VERTICAL SHEAR.  THE SHEAR SHOULD RELAX AS KARL REACHES THE

WEST SIDE OF AN UPPER-LEVEL TROUGH IN ABOUT 36 TO 48 HOURS.  FROM

THAT POINT IN TIME ONWARD, KARL SHOULD BE EXPERIENCING MORE

CONDUCIVE CONDITIONS: GRADUALLY WARMING SSTS, A MOIST LOW TO MIDDLE

TROPOSPHERE, AND LOW VERTICAL SHEAR.  THE NHC INTENSITY FORECAST IS

FOR KARL TO WEAKEN SLIGHTLY WITHIN THE NEXT DAY AND THEN STEADILY

STRENGTHEN STARTING IN ABOUT TWO DAYS ONWARD.  THIS IS QUITE

SIMILAR TO THE PREVIOUS ADVISORY AND IS BASED UPON THE IVCN

MULTI-MODEL CONSENSUS.  HOWEVER, CONFIDENCE IN KARL ACTUALLY

BECOMING A HURRICANE IN FIVE DAYS IS LOW BECAUSE OF THE SPREAD IN

THE GUIDANCE.



KARL IS MOVING TOWARD THE WEST AT 13 KT.  THE BERMUDA-AZORES

HIGH WILL BE BUILDING IN NORTH OF THE TROPICAL STORM, HELPING TO

PROPEL KARL ON A GENERAL WESTWARD TRACK FOR THE NEXT COUPLE OF

DAYS.  BEGINNING IN ABOUT THREE DAYS, KARL WILL REACH THE WESTERN

PERIPHERY OF THE BERMUDA-AZORES HIGH AND BEND TOWARD THE

WEST-NORTHWEST.  THE RELIABLE TRACK MODELS HAVE SUBSTANTIAL SPREAD

- ESPECIALLY DURING DAYS ONE TO THREE - WITH SOME SOLUTIONS

SHOWING A WEST-SOUTHWESTERLY TRACK, WHICH IS RARELY SEEN IN=