WTNT42 KNHC 201436 RRA

TCDAT2



TROPICAL STORM KARL DISCUSSION NUMBER  25

NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122016

ISSUED BY THE NWS WEATHER PREDICTION CENTER COLLEGE PARK MD

1100 AM AST TUE SEP 20 2016



KARL'S CENTER REMAINS EXPOSED TO THE SOUTHWEST OF THE DEEP

CONVECTION, AS IT APPEARS THAT THE CYCLONE HAS BEEN UNABLE TO

ESCAPE THE INFLUENCE OF A MID-/UPPER-LEVEL LOW TO ITS WEST.  DVORAK

CURRENT INTENSITY ESTIMATES REMAIN 3.0 FROM TAFB AND 2.5 FROM SAB,

AND THE LATEST UW-CIMSS ADT ESTIMATE IS T2.5.  THE INITIAL

INTENSITY IS THEREFORE HELD AT 35 KT.



SHIPS AND UW-CIMSS SHEAR ANALYSES INDICATE THAT THE VERTICAL SHEAR

THAT HAS BEEN AFFECTING KARL HAS NOT YET DECREASED, BUT IT IS NOW

SOUTHERLY AT AROUND 15 KT.  THE GLOBAL MODELS CONTINUE TO INDICATE

THAT THE SHEAR SHOULD DECREASE DURING THE NEXT FEW DAYS, BUT THIS

PROBABLY WON'T HAPPEN UNTIL KARL BECOMES MORE SEPARATED FROM THE

UPPER-LEVEL LOW.  THE THERMODYNAMIC ENVIRONMENT HAS IMPROVED

SLIGHTLY SINCE YESTERDAY, AS THE CYCLONE APPEARS TO BE ASSOCIATED

WITH A LARGE MOISTURE ENVELOPE WITH MID-LEVEL RELATIVE HUMIDITIES

INCREASING INTO THE 50 PERCENT RANGE.  LITTLE CHANGE IN STRENGTH IS

LIKELY DURING THE NEXT 24 HOURS, BUT AFTER THAT TIME INTENSIFICATION

IS EXPECTED DUE TO WARM SSTS, MORE MOISTURE, AND LOWER SHEAR.  THE

OFFICIAL INTENSITY FORECAST CONTINUES TO SHOW KARL AS A HURRICANE IN

THE 3-5 DAY RANGE, BUT THE UPDATED FORECAST HAS BEEN NUDGED DOWNWARD

SLIGHTLY BASED ON THE LATEST GUIDANCE.  THE NEW FORECAST IS VERY

CLOSE TO SHIPS GUIDANCE AND IS NEAR THE UPPER END OF THE GUIDANCE

ENVELOPE.



KARL'S CENTER HAS BEEN STRADDLING THE 20TH PARALLEL, BUT THE=