732  
WTNT42 KNHC 160252  
TCDAT2  
 
POST-TROPICAL CYCLONE OPHELIA DISCUSSION NUMBER 28  
NWS NATIONAL HURRICANE CENTER MIAMI FL AL172017  
1100 PM AST SUN OCT 15 2017  
 
WITHIN JUST THE PAST SIX HOURS, THE LAST BIT OF DEEP CONVECTION  
NEAR OPHELIA'S CENTER HAS BEEN SHEARED OFF WELL TO THE NORTH, AND  
THE CYCLONE HAS ACQUIRED A DEFINITIVE EXTRATROPICAL STRUCTURE.  
OPHELIA HAS COMPLETED ITS TRANSITION TO AN OCCLUDED LOW, WITH AN  
ATTACHED WARM FRONT EXTENDING NORTHEASTWARD ACROSS IRELAND AND A  
COLD FRONT DRAPED SOUTHEASTWARD TOWARD SPAIN AND PORTUGAL. THE  
POWERFUL CYCLONE CONTINUES TO PRODUCE HURRICANE-FORCE WINDS, WITH  
RECENT ASCAT DATA SHOWING WIND VECTORS AS HIGH AS 70 KT TO THE EAST  
OF THE CENTER. BASED ON THESE DATA, THE INITIAL INTENSITY REMAINS  
75 KT TO ACCOUNT FOR UNDERSAMPLING. THE OCCLUDED LOW IS FORECAST TO  
GRADUALLY FILL AND WEAKEN DURING THE NEXT COUPLE OF DAYS, AND IT IS  
LIKELY TO DISSIPATE NEAR THE WESTERN COAST OF NORWAY BY 48 HOURS.  
DESPITE THE EXPECTED WEAKENING, THE POST-TROPICAL CYCLONE IS STILL  
LIKELY TO BRING HURRICANE-FORCE WINDS, ESPECIALLY IN GUSTS, TO  
PORTIONS OF WESTERN IRELAND ON MONDAY.  
 
OPHELIA HAS ACCELERATED AND RETROGRADED SLIGHTLY DURING THE PAST  
6-12 HOURS DURING THE OCCLUSION PROCESS, AND THE LONG-TERM MOTION  
ESTIMATE IS NORTHWARD, OR 010/38 KT. NOW THAT OCCLUSION IS  
COMPLETE, THE POST-TROPICAL CYCLONE SHOULD RESUME A NORTH-  
NORTHEASTWARD MOTION, WITH SOME DECREASE IN FORWARD SPEED, WITHIN  
THE NEXT 12 HOURS. THAT HEADING SHOULD CONTINUE FOR THE ENSUING DAY  
OR TWO, BRINGING THE CENTER OF THE CYCLONE NEAR THE WESTERN COAST OF  
IRELAND ON MONDAY AND THEN NEAR NORTHERN SCOTLAND MONDAY NIGHT.  
THE DYNAMICAL TRACK MODELS REMAIN IN GOOD AGREEMENT ON THIS  
SCENARIO, AND THE UPDATED NHC FORECAST IS NOT TOO DIFFERENT FROM  
THE PREVIOUS ONE.  
 
THIS IS THE LAST ADVISORY ISSUED BY THE NATIONAL HURRICANE CENTER  
NOW THAT OPHELIA HAS BECOME POST-TROPICAL. LOCAL FORECASTS,  
WARNINGS, AND OTHER COMMUNICATIONS REGARDING THE POST-TROPICAL  
CYCLONE THAT ARE PERTINENT TO IRELAND AND THE UNITED KINGDOM WILL  
CONTINUE TO BE AVAILABLE FROM MET EIREANN AND THE UK MET OFFICE.  
 
KEY MESSAGES:  
 
1. OPHELIA WILL REMAIN A POWERFUL EXTRATROPICAL CYCLONE WITH  
HURRICANE-FORCE WINDS WHILE IT MOVES NEAR IRELAND AND THE UNITED  
KINGDOM MONDAY AND MONDAY NIGHT. STRONG WINDS AND HEAVY RAIN ARE  
LIKELY IN PORTIONS OF THESE AREAS, ALONG WITH DANGEROUS MARINE  
CONDITIONS. FOR MORE DETAILS ON THE MAGNITUDE, TIMING, AND LOCATION  
OF IMPACTS FROM POST-TROPICAL OPHELIA, RESIDENTS IN IRELAND SHOULD  
REFER TO PRODUCTS ISSUED BY MET EIREANN, AND RESIDENTS IN THE  
UNITED KINGDOM SHOULD REFER TO PRODUCTS ISSUED BY THE MET OFFICE.  
 
2. INDIVIDUALS ARE URGED TO NOT FOCUS ON THE EXACT TRACK OF OPHELIA  
SINCE STRONG WINDS AND HEAVY RAINFALL WILL EXTEND WELL OUTSIDE OF  
THE NHC FORECAST CONE.  
 
FORECAST POSITIONS AND MAX WINDS  
 
INIT 16/0300Z 49.2N 13.3W 75 KT 85 MPH...POST-TROP/EXTRATROP  
12H 16/1200Z 53.2N 10.1W 65 KT 75 MPH...POST-TROP/EXTRATROP  
24H 17/0000Z 57.4N 5.9W 50 KT 60 MPH...POST-TROP/EXTRATROP  
36H 17/1200Z 61.9N 0.1W 40 KT 45 MPH...POST-TROP/EXTRATROP  
48H 18/0000Z...DISSIPATED  
 

 
FORECASTER BERG  
 
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