085  
WTNT42 KNHC 152042  
TCDAT2  
 
HURRICANE OPHELIA DISCUSSION NUMBER 27  
NWS NATIONAL HURRICANE CENTER MIAMI FL AL172017  
500 PM AST SUN OCT 15 2017  
 
OPHELIA'S CLOUD STRUCTURE IS DECLINING RAPIDLY, AND MICROWAVE AND  
SHORTWAVE IR IMAGERY INDICATE THAT THE LOW-LEVEL AND MID-LEVEL  
CENTERS ARE BECOMING SEPARATED. HOWEVER, SOME DEEP CONVECTION IS  
STILL PRESENT NEAR OPHELIA'S CENTER, AND AN SSMIS PASS FROM 1827 UTC  
INDICATED THAT THE HURRICANE STILL HAS AN INNER CORE THAT IS  
SEPARATED FROM A FRONT TO THE NORTH AND WEST. THE ESTIMATED MAXIMUM  
WINDS HAVE BEEN DECREASED SLIGHTLY TO 75 KT GIVEN THE OVERALL DECAY  
OF THE CLOUD STRUCTURE. HOWEVER, THE CYCLONE'S FAVORABLE POSITION  
RELATIVE TO AN UPPER-LEVEL JET STREAK IS LIKELY CONTRIBUTING TO  
DEEPENING OF THE LOW AS THE WIND FIELD EXPANDS SUBSTANTIALLY. ONLY  
A SLIGHT DECREASE IN THE MAXIMUM WINDS IS THEREFORE EXPECTED BEFORE  
THE POST-TROPICAL CYCLONE REACHES IRELAND. AFTER THAT TIME,  
INTERACTION WITH LAND WHILE THE CYCLONE OCCLUDES SHOULD CAUSE IT TO  
WEAKEN MORE RAPIDLY. AROUND 48 H, THE CYCLONE'S CIRCULATION IS  
LIKELY TO BECOME ILL-DEFINED AND DISSIPATE NEAR THE WESTERN COAST OF  
SCANDINAVIA.  
 
OPHELIA HAS CONTINUED TO MOVE TOWARD THE NORTH-NORTHEAST, AND THE  
INITIAL MOTION ESTIMATE REMAINS 025/33 KT. THERE HAS BEEN NO CHANGE  
TO THE TRACK FORECAST REASONING SINCE OPHELIA IS ALREADY EMBEDDED  
WITHIN THE FLOW ASSOCIATED WITH A LARGE MID-LATITUDE TROUGH. THIS  
SHOULD KEEP OPHELIA ON A NORTH-NORTHEAST HEADING AS IT PASSES OVER  
IRELAND AND THE UK ON MONDAY. THE DYNAMICAL GUIDANCE REMAINS IN  
VERY GOOD AGREEMENT ON THE TRACK OF OPHELIA, AND VERY LITTLE CHANGE  
HAS BEEN MADE TO THE TRACK FORECAST.  
 
SINCE OPHELIA WILL BE POST-TROPICAL AS IT APPROACHES IRELAND AND THE  
UK, STRONG WINDS AND RAIN WILL ARRIVE OVER LAND AREAS SOONER THAN  
THE CENTER. FOR MORE INFORMATION ON LOCAL IMPACTS, CONSULT PRODUCTS  
FROM LOCAL METEOROLOGICAL SERVICES IN IRELAND AND THE UNITED KINGDOM  
FOR MORE INFORMATION.  
 
KEY MESSAGES:  
 
1. OPHELIA IS EXPECTED TO BE A POWERFUL EXTRATROPICAL CYCLONE WITH  
HURRICANE FORCE WINDS WHILE IT MOVES NEAR IRELAND AND THE UNITED  
KINGDOM. DIRECT IMPACTS FROM WIND AND HEAVY RAIN IN PORTIONS OF  
THESE AREAS ARE LIKELY, 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 15/2100Z 44.6N 13.3W 75 KT 85 MPH  
12H 16/0600Z 49.2N 11.3W 70 KT 80 MPH...POST-TROP/EXTRATROP  
24H 16/1800Z 54.3N 7.5W 55 KT 65 MPH...POST-TROP/EXTRATROP  
36H 17/0600Z 58.5N 2.0W 40 KT 45 MPH...POST-TROP/EXTRATROP  
48H 17/1800Z...DISSIPATED  
 

 
FORECASTER ZELINSKY  
 
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