Tropical Depression NINE

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TTAA00 KNHC DDHHMM
TROPICAL DEPRESSION NINE DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL092006
1100 PM EDT WED SEP 27 2006
 
ALTHOUGH THE DEPRESSION IS NOT VERY IMPRESSIVE IN CONVENTIONAL
SATELLITE IMAGERY... MICROWAVE OVERPASSES BY QUIKSCAT AT 2132 UTC
AND SSMIS AT 2309 UTC SUGGEST THAT IT IS NEARING TROPICAL STORM
STRENGTH.  LATEST DVORAK INTENSITY ESTIMATES...HOWEVER...REMAIN 30
KT FROM ALL AGENCIES AND THIS WILL BE THE ADVISORY INTENSITY.  THE
CENTER OF THE DEPRESSION IS LOCATED JUST SOUTH OF THE PRIMARY AREA
OF DEEP CONVECTION DUE TO SOUTHERLY WIND SHEAR IMPOSED BY AN
UPPER-LEVEL LOW TO THE WEST OF THE DEPRESSION.  MOST OF THE GLOBAL
MODELS GRADUALLY WEAKEN THIS FEATURE AND THEREFORE THE SHEAR OVER
THE NEXT DAY OR TWO.  THE OFFICIAL FORECAST CALLS FOR GRADUAL
STRENGTHENING DURING THE NEXT 48 HOURS.  THEREAFTER...SOUTHWESTERLY
SHEAR IS EXPECTED TO INCREASE AGAIN WHILE SSTS COOL...WHICH SHOULD
INHIBIT FURTHER STRENGTHENING.  THE NEW OFFICIAL INTENSITY FORECAST
IS CLOSE TO THE SHIPS AND GFDL INTENSITY GUIDANCE...AND SIMILAR TO
THE PREVIOUS ADVISORY.

THE INITIAL MOTION ESTIMATE IS 315/11.  GLOBAL MODEL GUIDANCE
INDICATES THAT THE DEPRESSION WILL BE STEERED AROUND THE WESTERN
PERIPHERY OF A MID-TROPOSPHERIC RIDGE LOCATED TO THE NORTHEAST OF
THE CYCLONE.  IN ABOUT 48 HOURS...A LARGE DEEP LAYERED TROUGH IS
PREDICTED TO BE DEPARTING THE EAST COAST OF THE UNITED STATES. 
THIS SHOULD ALLOW THE TROPICAL CYCLONE TO TURN NORTHWARD...THEN
NORTHEASTWARD AHEAD OF THIS TROUGH.  THE GFS IS ON THE WESTERN EDGE
OF THE MODEL GUIDANCE AS IT DEPICTS A MUCH WEAKER AND MORE SHALLOW
SYSTEM THAN ANTICIPATED BY THE SHIPS AND GFDL.  SINCE THE SHIPS AND
GFDL ARE IN SUCH GOOD AGREEMENT ON THE FUTURE INTENSITY OF THE
SYSTEM...THE GFDL TRACK MIGHT BE A MORE LIKELY SOLUTION.  THE
OFFICIAL FORECAST IS ADJUSTED WESTWARD AND SLOWER COMPARED TO THE
PREVIOUS ADVISORY TO BE IN BETTER AGREEMENT WITH THE GFDL TRACK.
 
INITIAL      28/0300Z 27.2N  53.8W    30 KT
 12HR VT     28/1200Z 28.2N  55.0W    35 KT
 24HR VT     29/0000Z 29.9N  56.5W    40 KT
 36HR VT     29/1200Z 31.6N  57.6W    45 KT
 48HR VT     30/0000Z 33.6N  58.1W    50 KT
 72HR VT     01/0000Z 38.0N  57.0W    50 KT
 96HR VT     02/0000Z 42.0N  52.5W    50 KT...EXTRATROPICAL
120HR VT     03/0000Z 46.0N  45.0W    50 KT...EXTRATROPICAL
 
$$
FORECASTER BROWN/KNABB
 
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