WTNT42 KNHC 151437 RRA

TCDAT2



TROPICAL DEPRESSION TWELVE DISCUSSION NUMBER   5

NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122016

1100 AM AST THU SEP 15 2016



VISIBLE SATELLITE IMAGES INDICATE THAT THE DEPRESSION HAS A RATHER

IMPRESSIVE LOW-LEVEL CIRCULATION, ALTHOUGH ALL THE DEEP CONVECTION

IS FAR REMOVED FROM THE CENTER DUE TO SOUTHWESTERLY SHEAR.  GIVEN

SUCH A WELL-DEFINED CIRCULATION, THE DEPRESSION COULD HAVE BECOME A

TROPICAL STORM OVERNIGHT.  THE INITIAL WIND SPEED, HOWEVER, REMAINS

30 KT USING A BLEND OF THE TAFB/SAB ESTIMATES WITH ANY OF THE MORE

RELIABLE ASCAT PASSES UNFORTUNATELY MISSING THE CENTER DURING THE

PAST 18 HOURS.



AN UPPER-LEVEL TROUGH TO THE NORTHWEST OF THE CYCLONE IS EXPECTED TO

CAUSE AN INCREASE IN SHEAR DURING THE NEXT DAY OR SO, WHICH WILL

LIKELY CAUSE THE CYCLONE TO WEAKEN.  BEYOND 48 HOURS, MOST OF THE

MODELS SHOW THE SHEAR RELAXING, WITH AN UPPER-LEVEL HIGH TAKING THE

PLACE OF THE TROUGH, AND THE CYCLONE IS FORECAST TO MOVE OVER WARMER

WATERS.  THIS WILL PROBABLY PROMOTE A RESTRENGTHENING TREND,

ALTHOUGH GUIDANCE IS IN POOR AGREEMENT ON HOW MUCH THE WINDS COULD

INCREASE.  THUS, THE OFFICIAL FORECAST IS REDUCED A LITTLE BIT FOR

FRIDAY/SATURDAY DUE TO THE SHEAR, THEN IS THE SAME AS THE PREVIOUS

ONE, SHOWING A SLOW RESTRENGTHENING EARLY NEXT WEEK. IT IS ALSO

POSSIBLE THE CYCLONE WILL DEGENERATE INTO A REMNANT LOW FOR A WHILE

DUE TO THE SHEAR, ALTHOUGH THIS ISN'T THE LIKELIEST SCENARIO.



THE DEPRESSION IS MOVING WESTWARD AT ABOUT 11 KT, AND THIS GENERAL

MOTION SHOULD CONTINUE FOR A DAY OR SO WHILE IT MOVES AROUND THE

ATLANTIC SUBTROPICAL RIDGE.  THIS RIDGE IS FORECAST BY MUCH OF THE=