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| #101624 (Received by flhurricane at: 11:31 PM 01.Aug.2006) TCDAT3 TROPICAL STORM CHRIS DISCUSSION NUMBER 6 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032006 1100 PM EDT TUE AUG 01 2006 CHRIS APPEARS TO HAVE GRADUALLY GAINED ORGANIZATION TONIGHT. THE SERIES OF AIRCRAFT FIXES LEADING UP TO 00Z BOUNCED AROUND QUITE A BIT...ALTHOUGH I AM NOT SURE IF THAT WAS DUE TO REFORMATION OF THE CENTER...SMALLER VORTICES ROTATING ABOUT A MEAN CENTER...OR SOME COMBINATION OF THESE FACTORS. IN ANY EVENT...DURING THE PAST COUPLE OF HOURS THE DEEP CONVECTION HAS CONSOLIDATED OVER THE MEAN CIRCULATION CENTER...WHICH IS A CHANGE FROM EARLIER TONIGHT WHEN THE CONVECTION WAS CONFINED MOSTLY SOUTH OF THE CENTER. THE STRONGEST FLIGHT-LEVEL WIND OBSERVATION...SINCE THE PEAK VALUE OF 64 KT AT 2042Z...HAS BEEN 59 KT SOUTHEAST OF THE CENTER AT ABOUT 2235Z. THE CENTRAL PRESSURE FROM THE LAST AIRCRAFT FIX AT 00Z WAS STILL 1003 MB...SO THE INITIAL INTENSITY REMAINS 50 KT. THIS ESTIMATE IS ALSO SUPPORTED BY DVORAK ESTIMATES OF 45 KT FROM BOTH TAFB AND SAB. ANOTHER AIRCRAFT WILL INVESTIGATE CHRIS WITHIN THE NEXT FEW HOURS. SMOOTHING THROUGH THE SCATTERED AIRCRAFT FIXES STILL YIELDS AN ESTIMATED FORWARD MOTION OF 295/9. IN THE BIG PICTURE...THERE SHOULD BE NO SURPRISE IF CHRIS CONTINUES ON A GENERAL WEST-NORTHWESTWARD HEADING FOR THE NEXT SEVERAL DAYS...GIVEN THE STRONG DEEP-LAYER RIDGING FORECAST BY ALL OF THE DYNAMICAL MODELS TO PERSIST TO THE NORTH OF THE TROPICAL CYCLONE. HOWEVER... THE DETAILS OF THE TRACK FORECAST WILL LIKELY HAVE SIGNIFICANT IMPLICATIONS ON THE FUTURE INTENSITY OF CHRIS. FOR ONE... IF CHRIS TAKES A MORE SOUTHERLY TRACK AS SUGGESTED BY THE GFDL AND THE FSU SUPERENSEMBLE... THE STORM COULD WEAKEN OVER HISPANIOLA AND/OR CUBA. IF ON THE OTHER HAND CHRIS REMAINS OVER THE WARM WATERS JUST NORTH OF THE GREATER ANTILLES... ATMOSPHERIC CONDITIONS COULD REMAIN CONDUCIVE FOR CHRIS TO REACH AND PERHAPS MAINTAIN HURRICANE INTENSITY. THIS IS THE SOLUTION DEPICTED BY THE OFFICIAL FORECAST TRACK...INCLUDING THE PREVIOUS ONE...WHICH WOULD TAKE CHRIS BENEATH A NARROW EAST-WEST ORIENTED UPPER-LEVEL RIDGE AND LESSEN THE EFFECTS OF VERTICAL SHEAR THAT WOULD BE FELT FARTHER NORTH. IF CHRIS WERE TO TAKE A MORE NORTHERN TRACK THAN SHOWN BELOW...THE SHEAR WOULD BE STRONGER AND LESS SUPPORTIVE OF HURRICANE STRENGTH. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY BUT FORECASTS A HURRICANE A LITTLE SOONER. IT IS ALSO VERY CLOSE TO THE SHIPS GUIDANCE...BUT ABOVE THE GFDL SINCE THAT MODEL WEAKENS CHRIS OVER LAND. FORECAST POSITIONS AND MAX WINDS INITIAL 02/0300Z 18.3N 61.8W 50 KT 12HR VT 02/1200Z 18.9N 63.3W 55 KT 24HR VT 03/0000Z 19.5N 65.3W 60 KT 36HR VT 03/1200Z 20.1N 67.3W 65 KT 48HR VT 04/0000Z 20.6N 69.3W 65 KT 72HR VT 05/0000Z 21.5N 73.5W 65 KT 96HR VT 06/0000Z 22.5N 77.5W 65 KT 120HR VT 07/0000Z 23.5N 81.5W 65 KT |
