WTNT43 KNHC 201455 RRA

TCDAT3



TROPICAL STORM LISA DISCUSSION NUMBER   4

NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132016

1100 AM AST TUE SEP 20 2016



THE CLOUD PATTERN OF THE CYCLONE HAS STEADILY IMPROVED, WITH LONG

CURVED BANDS HAVING DEVELOPED IN THE NORTHERN SEMICIRCLE SINCE THE

PREVIOUS ADVISORY. ALTHOUGH DVORAK SATELLITE CLASSIFICATIONS FROM

TAFB AND SAB WERE 30 KT AT 1200Z, RECENT UW-CIMSS ADT VALUES HAVE

INCREASED TO 35 KT AND AMSU INTENSITY ESTIMATES RANGE FROM 35-45 KT.

THEREFORE THE INITIAL INTENSITY HAS BEEN INCREASED TO 35 KT, WHICH

IS A COMPROMISE OF THESE ESTIMATES, MAKING THE CYCLONE THE ELEVENTH

NAMED STORM OF THE 2016 HURRICANE SEASON.



VISIBLE SATELLITE IMAGERY INDICATES THAT TROPICAL STORM LISA IS NOW

MOVING NORTHWESTWARD OR 305/10 KT. WATER VAPOR IMAGERY AND

SATELLITE-DERIVED WINDS INDICATE THAT A LARGE MID-LATITUDE TROUGH

EXTENDS FROM NEAR THE CANARY ISLANDS SOUTHWESTWARD INTO THE TROPICS,

WHICH HAS CREATED A BREAK IN THE SUBTROPICAL RIDGE ALONG 30W-40W

LONGITUDE. LISA IS FORECAST TO MOVE GENERALLY NORTHWESTWARD TOWARD

THE BREAK IN THE RIDGE FOR THE NEXT 4 DAYS, FOLLOWED BY A NORTHWARD

TURN AS THE CYCLONE MOVES AROUND THE WESTERN PERIPHERY OF THE RIDGE

AXIS. THE LATEST MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON THIS

TRACK SCENARIO, AND THE NEW NHC FORECAST TRACK IS JUST A LITTLE TO

THE RIGHT OF THE PREVIOUS ADVISORY TRACK, MAINLY TO ACCOUNT FOR THE

MORE NORTHWARD INITIAL POSITION, AND LIES CLOSE TO THE CONSENSUS

MODEL TVCN.



LISA HAS ABOUT 48 HOURS REMAINING TO STRENGTHEN WHILE THE VERTICAL

WIND SHEAR AND UPPER-LEVEL OUTFLOW PATTERN REMAIN FAVORABLE, AND

SEA-SURFACE TEMPERATURES ARE ABOVE 27 DEG C. HOWEVER, A MARGINALLY=