Tropical Depression COSME

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TROPICAL DEPRESSION COSME DISCUSSION NUMBER  18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP062007
200 PM PDT WED JUL 18 2007
 
QUIKSCAT DATA AT 1521Z INDICATED 30-35 KT WINDS NEAR THE CENTER OF
COSME.  SINCE THEN...THE ASSOCIATED CONVECTION HAS DIMINISHED
SIGNIFICANTLY AND IT IS LIKELY THAT THE WINDS HAVE DECREASED
SLIGHTLY.  BASED ON THIS...COSME IS DOWNGRADED TO A 30 KT TROPICAL
DEPRESSION.  12 FT SEAS RADII WILL BE INCLUDED IN THIS ADVISORY
SINCE THE CYCLONE WAS STILL OF STORM STRENGTH A FEW HOURS AGO.

THE INITIAL MOTION REMAINS 275/11.  THE LOW/MID-LEVEL RIDGE NORTH
AND NORTHWEST OF COSME REMAINS THE PRIMARY STEERING MECHANISM...AND
THE LARGE-SCALE MODELS CONTINUE TO MAINTAIN THIS RIDGE THROUGH 5
DAYS.  COSME SHOULD THUS CONTINUE GENERALLY WESTWARD THROUGH THE
FORECAST PERIOD AS SHOWN BY ALL GUIDANCE.  THE GFDL AND HWRF HAVE
SHIFTED SOUTH OF THEIR PREVIOUS FORECASTS...WITH ONLY THE BAM
MODELS AND LBAR NOW CALLING FOR THE CENTER TO PASS OVER THE ISLAND
OF HAWAII.  THE NEW FORECAST TRACK IS AGAIN SHIFTED SLIGHTLY
SOUTHWARD AND IS DOWN THE MIDDLE OF THE DYNAMICAL MODEL GUIDANCE.
 
THE INTENSITY FORECAST IS STILL PROBLEMATIC.  IN THE SHORT TERM...
COSME SHOULD REACH GRADUALLY INCREASING SEA SURFACE TEMPERATURES IN
ABOUT 30 HR IN A LIGHT SHEAR ENVIRONMENT.  THIS SUGGEST THE
POSSIBILITY OF SOME STRENGTHENING...ASSUMING THAT THE SYSTEM DOES
NOT DISSIPATE FROM LACK OF CONVECTION BEFORE THEN.  AFTER 72 HR...
COSME SHOULD REACH SIGNIFICANTLY WARMER WATER AND QUITE POSSIBLY
SIGNIFICANT VERTICAL WIND SHEAR...AS FORECAST BY THE NOGAPS...
UKMET...AND ECMWF MODELS.  BASED ON THIS...THE INTENSITY FORECAST
WILL CALL FOR COSME TO PERSIST AS A DEPRESSION FOR 72 HR...THEN
WEAKEN TO A REMNANT LOW DUE TO SHEAR.  SINCE THE GFS STILL
FORECASTS LESS SHEAR THAN THE OTHER MODELS AND THERE IS STILL A
POSSIBILITY COSME COULD TRACK SOUTH OF THE AREA OF STRONG SHEAR...
THE INTENSITY FORECAST AFTER 72 HR REMAINS LOW CONFIDENCE.
 
THIS IS THE LAST ADVISORY ON COSME FROM THE NATIONAL HURRICANE
CENTER.  FUTURE ADVISORIES WILL BE ISSUED BY THE CENTRAL PACIFIC
HURRICANE CENTER IN HONOLULU HAWAII.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      18/2100Z 15.0N 140.1W    30 KT
 12HR VT     19/0600Z 15.2N 142.0W    30 KT
 24HR VT     19/1800Z 15.7N 144.9W    30 KT
 36HR VT     20/0600Z 16.2N 148.0W    30 KT
 48HR VT     20/1800Z 16.7N 151.4W    30 KT
 72HR VT     21/1800Z 17.5N 157.5W    30 KT
 96HR VT     22/1800Z 18.0N 163.0W    25 KT...DISSIPATING
120HR VT     23/1800Z 18.0N 168.0W    20 KT...REMNANT LOW
 
$$
FORECASTER BEVEN
 
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