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Tropical Depression SIX-E


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TROPICAL DEPRESSION SIX-E DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP062010
200 PM PDT THU JUL 15 2010
 
INTERMITTENT BURSTS OF DEEP CONVECTION HAVE CONTINUED TO DEVELOP
MAINLY SOUTHWEST OF THE EXPOSED LOW-LEVEL CIRCULATION CENTER. THE
CENTER OF TD-06E HAD TO BE RELOCATED FARTHER NORTH BASED ON VISIBLE
SATELLITE IMAGERY AND A 1623Z ASCAT OVERPASS. THE ASCAT PASS ALSO
INDICATED SURFACE WINDS OF 25-30 KT THAT EXTEND 160-250 NMI NORTH
THROUGH NORTHEAST OF THE CENTER...WHICH MAY BE DUE TO OROGRAPHIC
EFFECTS. MANZANILLO MEXICO HAS REPORTED A SUSTAINED EAST WIND OF
ABOUT 20 KT FOR THE PAST SEVERAL HOURS...WHICH SUPPORTS THE ASCAT
WINDS SITUATED OFFSHORE. SATELLITE INTENSITY ESTIMATES FROM TAFB
AND SAB REMAIN AT T1.5/25 KT. UW-CIMSS ADT ESTIMATES HAVE AVERAGED
T2.5/35 KT OVER THE PAST 3 HOURS...WHILE UW-CIMSS AND CIRA-NESDIS
AMSU INTENSITY ESTIMATES HAVE BEEN BOUNCING BETWEEN 30 TO 40 KT
DURING THE PREVIOUS 6 HOURS. A BLEND OF THESE DATA WOULD GIVE AN
INTENSITY OF ABOUT 35 KT...BUT GIVEN THAT THE LOW-LEVEL CENTER IS
SHEARED ABOUT 85 NMI NORTHEAST OF THE MID-LEVEL CIRCULATION...THE
ADVISORY INTENSITY IS BEING HELD AT 30 KT.
 
THE INITIAL MOTION ESTIMATE IS AN UNCERTAIN 295/04. THE INITIAL
POSITION AND 12Z POSITION WERE RELOCATED FARTHER NORTH AND EAST
BASED ON VISIBLE IMAGERY AND THE ASCAT WIND DATA THAT SHOWED A MORE
NORTHWARD POSITION. HOWEVER...THIS NORTHWARD JOG IS BELIEVED TO BE
A TEMPORARY MOTION AND THAT TD-06E SHOULD SOON RESUME A SLOW
WEST-NORTHWESTWARD MOTION. OVERALL...THERE REMAINS NO SIGNIFICANT
CHANGE TO THE PREVIOUS TRACK FORECAST REASONING. THE NHC MODEL
GUIDANCE IS IN GOOD AGREEMENT ON A WEST-NORTHWESTWARD MOTION
THROUGH 48-60 HOURS WITH A GRADUAL TURN TOWARD THE WEST...OR EVEN
WEST-SOUTHWEST...AFTER THAT WHEN THE CYCLONE IS EXPECTED TO WEAKEN
OVER COOLER WATER AND BE STEERED MORE BY THE LOW-LEVEL EASTERLY
FLOW. THE OFFICIAL FORECAST TRACK IS A LITTLE NORTH OF THE PREVIOUS
ADVISORY AND REMAINS ALONG THE SOUTHERN EDGE OF THE GUIDANCE
ENVELOPE.
 
INTERMITTENT BURSTS OF DEEP CONVECTION NEAR THE CENTER SHOULD
CONTINUE FOR THE NEXT 24 HOURS OR SO...WHICH COULD RESULT IN THE
DEPRESSION BRIEFLY PRODUCING TROPICAL-STORM-FORCE WINDS. MODERATE
EAST-NORTHEASTERLY VERTICAL SHEAR IS FORECAST TO CONTINUE FOR THE
NEXT 18-24 HOURS...AND THEN GRADUALLY RELAX TO LESS THAN 15 KT BY
36 HOURS. AS THE SHEAR SLOWLY ABATES...CONVECTION SHOULD GRADUALLY
DEVELOP CLOSER TO AND PERSIST NEAR THE LOW-LEVEL CENTER...ALLOWING
FOR SOME SLIGHT STRENGTHENING TO OCCUR. HOWEVER...BY 48 HOURS THE
CYCLONE IS FORECAST TO MOVE OVER SSTS COLDER THAN 26C...WHICH
SHOULD INHIBIT ANY FURTHER INTENSIFICATION. THE SHIPS MODEL BRINGS
THE DEPRESSION UP TO TROPICAL STORM INTENSITY BY 24 HOURS...WHEREAS
THE LGEM MODEL KEEPS THE SYSTEM AS A 30-KT DEPRESSION. BOTH THE
GFDL AND HWRF MODELS MAKE THE DEPRESSION A TROPICAL STORM IN 24-36
HOURS. THE OFFICIAL INTENSITY FORECAST IS A BLEND OF THESE MODELS 
AND ONLY SHOWS SLIGHT STRENGTHENING TO A TROPICAL STORM...WHICH
COULD OCCUR AT ANY TIME.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      15/2100Z 15.9N 108.2W    30 KT
 12HR VT     16/0600Z 16.4N 109.6W    30 KT
 24HR VT     16/1800Z 17.0N 111.3W    35 KT
 36HR VT     17/0600Z 17.5N 113.3W    35 KT
 48HR VT     17/1800Z 17.8N 115.2W    35 KT
 72HR VT     18/1800Z 18.0N 119.0W    30 KT...DISSIPATING
 96HR VT     19/1800Z 18.0N 123.0W    25 KT...POST-TROP/REMNT LOW
120HR VT     20/1800Z...DISSIPATED
 
$$
FORECASTER STEWART
 
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