000 WTNT43 KNHC 212046 TCDAT3 TROPICAL STORM CRISTOBAL DISCUSSION NUMBER 12 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032008 500 PM EDT MON JUL 21 2008 A LARGE BALL OF CONVECTION REMAINS ON THE SOUTH SIDE OF THE TROPICAL CYCLONE. MICROWAVE AND CONVENTIONAL SATELLITE IMAGERY SUGGESTS THE CENTER IS IN THE NORTHERN PORTION OF THE DEEP CONVECTION. THERE HAS BEEN LITTLE CHANGE TO INTENSITY ESTIMATES...SO THE INITIAL INTENSITY WILL REMAIN 55 KT. IT IS POSSIBLE THAT CRISTOBAL COULD BE CLOSE TO HURRICANE STRENGTH BEFORE MOVING OVER THE COOLER WATERS NORTH OF THE GULF STREAM TOMORROW. THE INTENSITY FORECAST IS VERY SIMILAR TO THE PREVIOUS AND IS CLOSE TO A CONSENSUS OF THE STATISTICAL MODELS. PHASE SPACE DIAGRAMS FROM FLORIDA STATE SUGGEST THAT A RAPID EXTRATROPICAL TRANSITION SHOULD START TOMORROW AND BE COMPLETED BY WEDNESDAY. THE INITIAL MOTION ESTIMATE IS 055/12...A LITTLE FASTER THAN EARLIER. GLOBAL MODELS ARE IN EXCELLENT AGREEMENT ON AN ACCELERATING NORTHEASTWARD TRACK DURING THE NEXT DAY OR SO. THEREAFTER...THE STORM IS NOW FORECAST TO AVOID ANY TROUGHING OVER NORTH AMERICA AND INSTEAD RIDE ALONG THE WESTERLIES TO THE NORTH OF A SUBTROPICAL RIDGE OVER THE CENTRAL ATLANTIC OCEAN. IN A COUPLE DAYS...A NEW TROUGH IS FORECAST TO AMPLIFY TO THE EAST OF THE STORM...WHICH SHOULD STEER THE CYCLONE MORE TO THE SOUTHEAST. THE OFFICIAL FORECAST IS SHIFTED TO THE SOUTH AND IS NOT TOO FAR FROM THE GFS BY 96 HOURS. MOST OF THE MODELS SUGGEST NO BAROCLINIC REINTENSIFICATION WILL OCCUR AND INSTEAD CRISTOBAL MAY DISSIPATE OVER THE COLD NORTH ATLANTIC WATERS IN ABOUT 120 HOURS. FORECAST POSITIONS AND MAX WINDS INITIAL 21/2100Z 37.1N 71.4W 55 KT 12HR VT 22/0600Z 38.9N 68.7W 60 KT 24HR VT 22/1800Z 41.7N 64.7W 60 KT 36HR VT 23/0600Z 44.0N 60.0W 50 KT...EXTRATROPICAL 48HR VT 23/1800Z 45.0N 55.0W 40 KT...EXTRATROPICAL 72HR VT 24/1800Z 42.5N 45.0W 35 KT...EXTRATROPICAL 96HR VT 25/1800Z 38.5N 40.5W 25 KT...EXTRATROPICAL 120HR VT 26/1800Z...DISSIPATED $$ FORECASTER BLAKE