WTNT42 KNHC 240252 RRA

TCDAT2



TROPICAL STORM KARL DISCUSSION NUMBER  39

NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122016

1100 PM AST FRI SEP 23 2016



A FEW HOURS AGO, A NOAA HURRICANE HUNTER AIRCRAFT REPORTED

FLIGHT-LEVEL WINDS OF 71 KT AT 7800 FT ABOUT 30 N MI TO THE

SOUTHWEST OF THE CENTER, ALONG WITH SFMR SURFACE WIND ESTIMATES OF

NEAR 55 KT.  THE MINIMUM CENTRAL PRESSURE AT THE TIME WAS NEAR 990

MB.  SINCE THEN, THE CYCLONE HAS GOTTEN BETTER ORGANIZED, WITH

RADAR DATA FROM BERMUDA SHOWING A STRONG CONVECTIVE BAND WEST AND

NORTHWEST OF THE CENTER.  ONE CAVEAT TO THE INCREASED ORGANIZATION

IS THAT THE CENTER APPARENT IN BOTH RADAR AND MICROWAVE IMAGERY MAY

BE A LITTLE TO THE NORTHWEST OF THE SURFACE CENTER.  BASED ON THE

EARLIER AIRCRAFT DATA, THE INITIAL INTENSITY IS SET TO 55 KT, AND

THIS COULD BE A LITTLE CONSERVATIVE.



KARL IS EXPECTED TO REMAIN OVER SEA SURFACE TEMPERATURES OF BETWEEN

29-30C FOR THE NEXT 12-24 HOURS OR SO IN AN ENVIRONMENT OF MODERATE

VERTICAL WIND SHEAR.  THIS SHOULD ALLOW THE CYCLONE TO STRENGTHEN

TO A HURRICANE IN ABOUT 24 HOURS. AFTER THAT, THE CYCLONE SHOULD

UNDERGO EXTRATROPICAL TRANSITION AS IT MERGES WITH THE COLD FRONT,

AND THIS SHOULD BE COMPLETE BY 48 HOURS.  THE CYCLONE IS LIKELY TO

BE ABSORBED BY A LARGER EXTRATROPICAL LOW BETWEEN 48-72 HOURS.  THE

NEW INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS FORECAST, BUT IT

LIES A LITTLE BELOW THE FORECASTS OF THE SHIPS AND LGEM MODELS.



THE INITIAL MOTION IS 020/11.  KARL IS ABOUT TO ENTER STRONG

SOUTHWESTERLY FLOW IN ADVANCE OF A DEEP-LAYER TROUGH AND ASSOCIATED

SURFACE COLD FRONT MOVING EASTWARD FROM THE NORTHEASTERN UNITED=