Tropical Storm DALILA

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TROPICAL STORM DALILA DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP042013
800 PM PDT MON JUL 01 2013
 
THE CONVECTIVE BANDING PATTERN ASSOCIATED WITH DALILA HAS GRADUALLY
MORPHED INTO A SMALL CDO FEATURE OVER THE PAST 6 HOURS...WITH CLOUD
TOPS OF -80C AND COLDER ALMOST COMPLETELY ENCIRCLING THE CENTER. A
01/1801 UTC TRMM OVERPASS THAT CAME IN AFTER THE PREVIOUS ADVISORY
ALSO REVEALED A CLOSED 10-15 NMI DIAMETER MID-LEVEL EYE. SATELLITE
INTENSITY ESTIMATES FROM TAFB REMAIN AT T3.5/55 KT...BUT THE DATA-T
NUMBER FROM TAFB WAS 4.0/65 KT. A RECENT CIRA INTENSITY ESTIMATE OF
62 KT...ALONG WITH THE TRMM MICROWAVE EYE FEATURE...JUSTIFIES
INCREASING THE INITIAL INTENSITY TO 60 KT. ALTHOUGH DALILA HAS BEEN
INCREASING AT THE RATE OF ONE T-NUMBER PER DAY OR 20 KT EVERY 24
HOURS...THAT INTENSIFICATION TREND IS NOT EXPECTED TO LAST MUCH
LONGER. THE VERTICAL SHEAR ACROSS DALILA IS FORECAST TO REMAIN
MODEST AT 12-15 KT FOR ANOTHER 24 HOURS...WHICH IS EXPECTED TO
OFFSET THE FAVORABLE OCEANIC CONDITIONS OF 27-28C SSTS. NOW THAT
DALILA HAS SLOWED DOWN MARKEDLY...COLD UPWELLING BENEATH THE
CYCLONE IS ALSO EXPECTED TO BECOME A FACTOR SINCE UPPER-OCEAN HEAT
CONTENT VALUES ARE QUITE LOW AT ONLY 3-5 UNITS. EVEN THOUGH THE
SHEAR IS FORECAST TO DECREASE TO 5 KT OR SO AFTER 24 HOURS...COOLER
WATERS AND DRIER MID-LEVEL AIR ARE EXPECTED TO HINDER THE
DEVELOPMENT PROCESS. AS A RESULT...THE OFFICIAL FORECAST IS SIMILAR
TO THE PREVIOUS ADVISORY...AND IS A BLEND OF THE SHIPS...LGEM...AND
FSSE INTENSITY MODELS.
 
VISIBLE AND MICROWAVE SATELLITE FIXES SUGGEST THAT DALILA HAS SLOWED
DOWN CONSIDERABLY AS EXPECTED...AND THE INITIAL MOTION ESTIMATE IS
NOW 290/05 KT. THE EXTENSIVE MID-LEVEL RIDGE TO THE NORTH OF DALILA
IS EXPECTED TO REMAIN INTACT THROUGH THE 5-DAY FORECAST PERIOD AND
KEEP THE CYCLONE MOVING IN A GENERAL WESTWARD DIRECTION. BY 48
HOURS...HOWEVER...THE GFS AND THE ECMWF MODELS INDICATE THAT A
SOUTHWESTWARD MOTION COULD OCCUR DUE TO SOME BINARY INTERACTION
WITH THE DEVELOPING LARGE DISTURBANCE CURRENTLY LOCATED TO THE EAST
OVER THE GULF OF TEHUANTEPEC. GIVEN THE UNCERTAINTY IN THE
DEVELOPMENT OF AND INFLUENCE BY THE LATTER FEATURE...BOTH THE
REASONING AND THE FORECAST TRACK REMAIN BASICALLY UNCHANGED FROM
THE PREVIOUS ADVISORY.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  02/0300Z 18.2N 106.9W   60 KT  70 MPH
 12H  02/1200Z 18.3N 107.4W   65 KT  75 MPH
 24H  03/0000Z 18.4N 108.1W   65 KT  75 MPH
 36H  03/1200Z 18.4N 108.7W   60 KT  70 MPH
 48H  04/0000Z 18.3N 109.3W   55 KT  65 MPH
 72H  05/0000Z 18.3N 110.5W   50 KT  60 MPH
 96H  06/0000Z 18.4N 112.8W   45 KT  50 MPH
120H  07/0000Z 18.5N 115.8W   35 KT  40 MPH
 
$$
FORECASTER STEWART
 
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