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| #102478 (Received by flhurricane at: 11:00 PM 04.Aug.2006) TCDAT3 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 |
