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| #519851 (Received by flhurricane at: 4:38 AM 21.Jun.2012) TCDAT3 TROPICAL STORM CHRIS DISCUSSION NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL AL032012 500 AM AST THU JUN 21 2012 CHRIS HAS MAINTAINED AN EYE-LIKE FEATURE SURROUNDED BY A RING OF CONVECTION WITH CLOUD TOP TEMPERATURES OF -50C TO -60C DURING THE PAST FEW HOURS. SUBJECTIVE AND OBJECTIVE DVORAK T-NUMBERS ARE ESSENTIALLY UNCHANGED SINCE THE LAST ADVISORY AND DO NOT SUPPORT A HIGHER INTENSITY...SO THE INITIAL INTENSITY IS KEPT AT 50 KT. EVEN IF CHRIS IS STRONGER THAN ESTIMATED...THE PASSAGE OF THE CYCLONE OVER SUB-22C SEA SURFACE TEMPERATURES COULD BE INHIBITING AN EFFICIENT CONVECTIVE TRANSPORT OF THE STRONGEST WINDS TO THE OCEAN SURFACE. THE INITIAL MOTION IS 065/17...WHICH IS A BIT SLOWER AND TO THE LEFT OF THE PREVIOUS ESTIMATE. CHRIS IS EXPECTED TO TURN NORTH- NORTHEASTWARD AND THEN NORTHWARD AS IT DECELERATES AND DUMBBELLS CYCLONICALLY AROUND A LARGE MID- TO UPPER-LEVEL LOW FORECAST TO CUT OFF SOUTHEAST OF THE CANADIAN MARITIME PROVINCES DURING THE NEXT 24-36 HOURS. MODEL GUIDANCE GENERALLY SHOWS CHRIS BEING ABSORBED BY THIS WEATHER FEATURE IN 36-48 HOURS...WITH THE NEW ENTITY COMPLETING A CYCLONIC LOOP AND THEN MOVING EASTWARD TO EAST- NORTHEASTWARD OVER THE FAR NORTH ATLANTIC. GLOBAL MODELS ARE IN GOOD AGREEMENT WITH REGARD TO THIS SCENARIO...AND THE TRACK FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS ONE. DESPITE THE FACT THAT CHRIS IS MOVING OVER RATHER COOL WATERS... A 0505 UTC AMSU PASSES STILL SHOWED THE PRESENCE OF A WELL-DEFINED MODERATE TO DEEP WARM CORE IN ASSOCIATION WITH THE CYCLONE. ALTHOUGH CHRIS IS EXPECTED TO MAINTAIN WARM-CORE CHARACTERISTICS DURING THE NEXT 24 HOURS OR SO...IT COULD LOSE ITS DEEP CONVECTION WHILE MOVING OVER EVEN COOLER WATERS AND BE DECLARED POST-TROPICAL. SHOULD IT MAINTAIN DEEP CONVECTION LONGER...EITHER ITS INTERACTION WITH A LOW-LEVEL BAROCLINIC ZONE TO THE NORTH AND/OR ITS INTERACTION WITH THE CUT-OFF LOW TO ITS WEST SHOULD RESULT IN EXTRATROPICAL TRANSITION IN ABOUT 36 HOURS. FORECAST POSITIONS AND MAX WINDS INIT 21/0900Z 39.9N 44.8W 50 KT 60 MPH 12H 21/1800Z 41.6N 43.1W 50 KT 60 MPH 24H 22/0600Z 43.6N 43.0W 50 KT 60 MPH...POST-TROPICAL 36H 22/1800Z 44.3N 44.8W 45 KT 50 MPH...POST-TROP/EXTRATROP 48H 23/0600Z 43.0N 46.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 24/0600Z...ABSORBED BY ANOTHER EXTRATROPICAL LOW $$ FORECASTER KIMBERLAIN |
