5:00 PM AST Tue Oct 16
Location: 30.6°N 63.8°W Moving: NNE at 26 mph
Min pressure: 969 mb Max sustained: 85 mph

HURRICANE RAFAEL DISCUSSION NUMBER  17 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL172012 500 PM AST TUE OCT 16 2012

THE SATELLITE APPEARANCE OF RAFAEL HAS RECENTLY TRANSITIONED FROM A CENTRAL DENSE OVERCAST TO AN EYE PATTERN…WITH A RECENT MICROWAVE PASS SHOWING A SOLID INNER CORE.  THIS WOULD NORMALLY SUGGEST SOME STRENGTHENING…BUT THE AIR FORCE RESERVE HURRICANE HUNTERS REPORTED THAT FLIGHT-LEVEL AND SFMR WINDS HAD COME DOWN A BIT DURING THE PAST FEW HOURS.  THE PLANE DATA SUGGEST AN INITIAL INTENSITY OF ABOUT 75 KT…WITH A LITTLE HIGHER UNCERTAINTY THAN AVERAGE GIVEN THE RECENT SATELLITE TREND.  A NOAA AIRCRAFT WILL BE IN THE AREA THIS EVENING FOR ANOTHER LOOK AT THE INTENSITY.  HOWEVER…SLOW WEAKENING SEEMS LIKE THE BEST BET DUE TO GRADUALLY COOLING WATERS AND INCREASING SHEAR.  THE NHC INTENSITY FORECAST IS AN UPDATE OF THE PREVIOUS ONE…NEAR THE LGEM MODEL BUT A BIT BELOW THE INTENSITY CONSENSUS.  GLOBAL MODELS SUGGESTS EXTRATROPICAL TRANSITION BETWEEN 24-36H DUE TO INTERACTION OF RAFAEL WITH A COLD FRONT AND AN UPPER-LEVEL TROUGH.

AIRCRAFT FIXES SHOW THAT RAFAEL HAS RECENTLY BEEN MOVING A BIT LEFT OF THE PREVIOUS ESTIMATE…BUT A LONGER-TERM ESTIMATE IS 020/23.  THERE HAS BEEN NO CHANGE TO PREDICTED STEERING FLOW WITH THE HURRICANE MOVING BETWEEN A RIDGE OVER THE CENTRAL ATLANTIC AND A TROUGH OVER THE NORTHWESTERN ATLANTIC.  THIS SHOULD CAUSE RAFAEL TO TURN TOWARD THE NORTHEAST BY WEDNESDAY AND TO MOVE FASTER.  MODEL GUIDANCE IS WELL CLUSTERED ON THIS TRACK…AND EVEN THE SPEED DIFFERENCES ARE LESS NOTICEABLE THAN ON THE PREVIOUS FORECAST CYCLE.  THE NHC FORECAST IS ADJUSTED WESTWARD TOWARD THE CONSENSUS…BUT STILL LIES ON THE SPEEDIER SIDE OF THE GUIDANCE FOR THE FIRST 48 HOURS OR SO.  AFTERWARD…MOST OF THE GLOBAL MODELS SUGGEST THAT POST-TROPICAL RAFAEL WILL COMPLETE A LARGE CYCLONIC LOOP OVER THE NORTHEASTERN ATLANTIC.

FORECAST POSITIONS AND MAX WINDS

INIT  16/2100Z 30.6N  63.8W   75 KT  85 MPH

12H  17/0600Z 34.0N  61.6W   70 KT  80 MPH

24H  17/1800Z 38.8N  57.5W   65 KT  75 MPH

36H  18/0600Z 43.1N  50.3W   60 KT  70 MPH…POST-TROP/EXTRATROP

48H  18/1800Z 46.6N  40.8W   60 KT  70 MPH…POST-TROP/EXTRATROP

Hurricane Rafael poses no threat to the Cayman Islands