Tropical Depression CHRIS

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TROPICAL DEPRESSION CHRIS DISCUSSION NUMBER  18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032006
1100 PM EDT FRI AUG 04 2006
 
PUFFS OF DEEP CONVECTION HAVE OCCASIONALLY BEEN FORMING IN THE
CIRCULATION OF CHRIS TONIGHT. HOWEVER THESE BURSTS HAVE BEEN
SHORT-LIVED AND THERE IS NO EVIDENCE THAT THEY ARE CONTRIBUTING TO
A REJUVENATION OF THE SYSTEM.  IN FACT THE LATEST SATELLITE
PICTURES SHOW THAT THE DEEP CONVECTION IS ALMOST GONE.  THE INITIAL
INTENSITY IS REDUCED TO 25 KT...IN ACCORDANCE WITH DECREASING
DVORAK SATELLITE ESTIMATES...A 2312 UTC QUIKSCAT PASS...AND A
RECENT SHIP OBSERVATION OF 24 KT IN A THUNDERSTORM NORTH OF THE
CENTER. EVEN THOUGH THE VERTICAL WIND SHEAR HAS DECREASED... MOST
GLOBAL MODELS SUGGEST THE CYCLONE WILL JUST GRADUALLY SPIN DOWN.
ONE FACTOR ON WHY THE MODELS DISSIPATE CHRIS MIGHT BE THE LACK OF
UPPER-LEVEL DIVERGENCE OVER THE SYSTEM...WHICH WOULD TEND TO LIMIT
CHRIS' CONVECTION. SHIPS ALSO DIAGNOSES UPPER-LEVEL CONVERGENCE AS
A SIGNIFICANT INHIBITING FACTOR FOR THE FUTURE INTENSITY OF CHRIS.
IN ADDITION...INTERACTION WITH CUBA COULD HASTEN THE DEMISE OF THE
SYSTEM. IF THE DEPRESSION SURVIVES AND REACHES THE GULF OF MEXICO..
IT WOULD BE PASSING OVER WARMER WATER AND EXPERIENCING LIGHT SHEAR.
THE INTENSITY FORECAST GENEROUSLY ASSUMES THAT CHRIS WILL HANG ON
AS A TROPICAL CYCLONE THROUGHOUT THE PERIOD. HOWEVER... GIVEN THE
WEAKENED STATE OF CHRIS...IT COULD CERTAINLY DISSIPATE AT ANY TIME.  
 
MOST OF THE CIRCULATION OF CHRIS IS OBSCURED WITH A THIN VEIL OF
CIRRUS CLOUDS...MAKING THE CENTER RATHER DIFFICULT TO FIND.  BEST
ESTIMATE IS THAT THE CYCLONE CONTINUES MOVING JUST NORTH OF DUE
WEST.. 280/11.  TRACK GUIDANCE IS TIGHTLY CLUSTERED...
PROBABLY DUE TO A STRONG LOW TO MIDDLE-LEVEL RIDGE NORTH OF THE
CYCLONE THAT IS PROVIDING WELL-DEFINED STEERING CURRENTS.  A MORE
WESTWARD TRACK IS FORESEEN IN ABOUT 3 DAYS DUE TO A STRONG
MIDDLE-LEVEL HIGH FORECAST BY ALL GUIDANCE OVER THE SOUTH-CENTRAL
UNITED STATES.  A SMALL SOUTHWARD ADJUSTMENT IS MADE TO THE TRACK
FORECAST... CLOSEST TO THE BAM SHALLOW MODEL WHICH SEEMS APPROPRIATE
FOR THIS TYPE OF SYSTEM.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      05/0300Z 21.6N  74.0W    25 KT
 12HR VT     05/1200Z 21.8N  75.8W    25 KT
 24HR VT     06/0000Z 22.2N  78.3W    25 KT...NEAR CUBA
 36HR VT     06/1200Z 22.8N  81.0W    25 KT...INLAND
 48HR VT     07/0000Z 23.3N  83.8W    25 KT
 72HR VT     08/0000Z 24.0N  89.0W    30 KT
 96HR VT     09/0000Z 24.5N  94.5W    35 KT
120HR VT     10/0000Z 25.0N  99.5W    20 KT...INLAND AND DISSIPATING
 
$$
FORECASTER BLAKE/KNABB
 
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