Tropical Storm DALILA

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TROPICAL STORM DALILA DISCUSSION NUMBER  17
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP042013
200 PM PDT WED JUL 03 2013
 
CLOUD TOPS HAVE BEEN WARMING RECENTLY...AND THE CDO HAS TAKEN ON A
PATTERN THAT IS MORE INDICATIVE OF EASTERLY VERTICAL WIND SHEAR.
OBJECTIVE DVORAK INTENSITY ESTIMATES HAVE BEEN DECREASING FOR THE
PAST SEVERAL HOURS...AND SUBJECTIVE DATA T-NUMBERS HAVE ALSO
DECREASED.  BASED ON THE DVORAK ESTIMATES...DALILA HAS BEEN
DOWNGRADED TO A 60-KT TROPICAL STORM.  THERE HAS BEEN VERY LITTLE
CHANGE IN THE INTENSITY GUIDANCE.  ALTHOUGH THE DYNAMICAL MODELS
INDICATE THAT THE INTENSITY COULD FLUCTUATE DURING THE NEXT 48
HOURS...ALL OF THE MODELS GENERALLY FORECAST A SLOW WEAKENING TREND.
THE INTENSITY FORECAST HAS BEEN ADJUSTED DOWNWARD A LITTLE TO
ACCOUNT FOR THE NEW INITIAL INTENSITY...AND STILL SHOWS DALILA
GRADUALLY WEAKENING TO A REMNANT LOW BY THE END OF THE FORECAST
PERIOD.
 
ALTHOUGH THE LOW-LEVEL CENTER IS STILL OBSCURED...A COUPLE OF
MICROWAVE PASSES SUGGEST THAT IT IS DISPLACED SLIGHTLY TO THE
NORTHEAST OF THE CENTER OF THE CDO.  THE TROPICAL STORM HAS BEEN
DRIFTING SOUTHWESTWARD DURING THE DAY...AND THE INITIAL MOTION
ESTIMATE IS 230/3.  DALILA IS BEING STEERED BY A LARGE DEEP-LAYER
RIDGE TO THE NORTH-NORTHWEST.  A TURN TOWARD THE WEST...AND
EVENTUALLY THE NORTH-NORTHWEST...IS EXPECTED AS THE RIDGE
PROPAGATES EASTWARD.  THE MODEL GUIDANCE STILL DOES NOT AGREE ON
HOW QUICKLY THIS TURN WILL OCCUR...AND THERE IS A LOT OF SPREAD AT
3-5 DAYS.  THE OFFICIAL TRACK FORECAST HAS BEEN SHIFTED A LITTLE TO
THE SOUTH...BUT REMAINS NEAR THE FSSE AND GFS MODEL PREDICTIONS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  03/2100Z 17.4N 108.1W   60 KT  70 MPH
 12H  04/0600Z 17.1N 108.9W   55 KT  65 MPH
 24H  04/1800Z 16.8N 109.9W   55 KT  65 MPH
 36H  05/0600Z 16.8N 111.0W   55 KT  65 MPH
 48H  05/1800Z 16.9N 112.1W   55 KT  65 MPH
 72H  06/1800Z 17.6N 114.7W   45 KT  50 MPH
 96H  07/1800Z 18.0N 117.0W   35 KT  40 MPH
120H  08/1800Z 18.5N 120.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
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FORECASTER PASCH/ZELINSKY
 
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