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Tropical Storm IGNACIO (Text)

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TROPICAL STORM IGNACIO DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP122009
200 PM PDT TUE AUG 25 2009
 
VISIBLE SATELLITE PICTURES SUGGEST THAT THE CLOUD PATTERN OF IGNACIO
HAS BECOME BETTER ORGANIZED...WITH SOME HINT OF THE BEGINNING STAGE
OF A CENTRAL DENSE OVERCAST FORMING. EVEN THOUGH THE NORTHWEST
SEMICIRCLE IS VOID OF DEEP CONVECTIVE CLOUDS...A WELL-DEFINED BAND
IS OBSERVED OVER THE SOUTHEAST SEMICIRCLE.  DVORAK T-NUMBERS REMAIN
AT T3.0 FROM BOTH TAFB AND SAB AND THE OFFICIAL INTENSITY IS
MAINTAINED AT 45 KT.  A 1417 UTC QUIKSCAT PASS REVEALED A FEW
UNCONTAMINATED 45-50 KT WIND VECTORS...WHICH AGREE WELL WITH THE
CURRENT INTENSITY ESTIMATE. EVEN THOUGH THE SHEAR SHOULD REMAIN
RELATIVELY LIGHT...THE WINDOW OF OPPORTUNITY FOR STRENGTHENING WILL
BE CLOSING SOON SINCE THE CYCLONE SHOULD REMAIN OVER 26.5C WATERS
FOR LESS THAN 12 HOURS.  THEREAFTER...PROGRESSIVELY COOLER WATERS
ALONG THE FORECAST TRACK SHOULD CAUSE RAPID WEAKENING...AND IGNACIO
IS EXPECTED TO BECOME A REMNANT LOW BY 72 HOURS.
 
THE EARLIER QUIKSCAT PASS AND RECENT VISIBLE SATELLITE FIXES HAVE
YIELDED FAIRLY HIGH CONFIDENCE ESTIMATES OF THE CENTER LOCATION.
BASED UPON THOSE ESTIMATES...THE INITIAL MOTION IS 300/11.  THERE
HAS BEEN LITTLE CHANGE TO THE OFFICIAL FORECAST TRACK.  IGNACIO
SHOULD MAINTAIN A NORTHWESTERLY COURSE AS IT MOVES AROUND THE
WESTERN PERIPHERY OF A DEEP-LAYER ANTICYCLONE EXTENDING FROM THE
SOUTHERN UNITED STATES INTO THE EAST PACIFIC TO NEAR 130W.  TOWARD
THE END OF THE PERIOD...THE CYCLONE SHOULD ASSUME A MORE WESTERLY
TRACK ONCE IGNACIO WEAKENS AND BECOMES MORE SHALLOW.  THE OFFICIAL
TRACK DIFFERS LITTLE FROM THE PREVIOUS ADVISORY AND LIES BETWEEN THE
PREVIOUS FORECAST AND THE MODEL CONSENSUS.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      25/2100Z 19.4N 120.3W    45 KT
 12HR VT     26/0600Z 20.4N 121.8W    50 KT
 24HR VT     26/1800Z 21.9N 123.8W    50 KT
 36HR VT     27/0600Z 23.6N 125.7W    45 KT
 48HR VT     27/1800Z 25.2N 127.6W    35 KT
 72HR VT     28/1800Z 27.0N 130.5W    25 KT...REMNANT LOW
 96HR VT     29/1800Z 27.0N 134.0W    20 KT...REMNANT LOW
120HR VT     30/1800Z...DISSIPATED
 
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FORECASTER KIMBERLAIN
 
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