468  
WTNT42 KNHC 150240  
TCDAT2  
 
HURRICANE OPHELIA DISCUSSION NUMBER 24  
NWS NATIONAL HURRICANE CENTER MIAMI FL AL172017  
1100 PM AST SAT OCT 14 2017  
 
OPHELIA REMAINS AN IMPRESSIVE HURRICANE IN INFRARED SATELLITE  
IMAGERY. THE HURRICANE CONTINUES TO EXHIBIT A LARGE WELL-DEFINED  
EYE WITHIN A RING OF COLD CLOUD TOPS. HOWEVER, THE OVERALL CLOUD  
PATTERN HAS STARTED TO ELONGATE AND THERE HAS BEEN A SLIGHT EROSION  
OF THE AREA OF CLOUD TOPS OVER THE WEST AND SOUTHWEST PORTIONS OF  
THE CIRCULATION AS DRY AIR AND A FRONTAL BOUNDARY ENCROACHES ON THE  
HURRICANE. SATELLITE INTENSITY ESTIMATES FROM ALL AGENCIES  
CONTINUE TO SUPPORT AN INTENSITY OF 100 KT. THE AFOREMENTIONED  
CHANGES IN THE CLOUD PATTERN AND AN EXPANSION OF THE WIND FIELD AS  
NOTED BY AN EARLIER ASCAT OVERPASS SUGGEST THAT EXTRATROPICAL  
TRANSITION HAS BEGUN. THE WIND FIELD IS EXPECT TO SIGNIFICANTLY  
EXPAND OVER THE NEXT 12 TO 24 HOURS, WHICH IS LIKELY TO LEAD TO A  
GRADUAL DECREASE IN THE MAXIMUM WINDS. OPHELIA IS FORECAST TO  
COMPLETE EXTRATROPICAL TRANSITION WITHIN 24 HOURS, BUT IT IS  
EXPECTED TO REMAIN A POWERFUL POST-TROPICAL CYCLONE WITH  
HURRICANE-FORCE WINDS AS IT APPROACHES IRELAND ON MONDAY. THE  
SYSTEM IS FORECAST TO OCCLUDE AND INTERACT WITH LAND, WHICH  
SHOULD CAUSE A FASTER RATE OF WEAKENING IN 48 TO 72 HOURS, WITH  
DISSIPATION EXPECTED SHORTLY THEREAFTER.  
 
OPHELIA IS MOVING NORTHEASTWARD, OR 055/24 KT AHEAD OF A  
MID-LATITUDE TROUGH MOVING OVER THE NORTHEASTERN ATLANTIC. THE  
HURRICANE SHOULD CONTINUE TO ACCELERATE NORTHEASTWARD TONIGHT, THEN  
TURN NORTH-NORTHEASTWARD WITH AN ADDITIONAL INCREASE IN FORWARD  
SPEED BY LATE SUNDAY AND SUNDAY NIGHT. AFTER THE SYSTEM OCCLUDES IN  
A COUPLE OF DAYS, IT SHOULD BEGIN TO SLOW DOWN. THE TRACK GUIDANCE  
IS IN GOOD AGREEMENT, AND THE UPDATED NHC TRACK FORECAST IS VERY  
CLOSE TO THE PREVIOUS ADVISORY.  
 
ALTHOUGH THE CENTER OF OPHELIA IS NOT FORECAST TO REACH IRELAND OR  
THE UK UNTIL MONDAY, WIND AND RAINS WILL ARRIVE WELL IN ADVANCE OF  
THE CYCLONE CENTER. RESIDENTS IN THOSE LOCATIONS SHOULD CONSULT  
PRODUCTS FROM THEIR LOCAL METEOROLOGICAL SERVICE FOR MORE  
INFORMATION ON LOCAL IMPACTS.  
 
TROPICAL-STORM-FORCE WINDS ARE POSSIBLE THROUGHOUT THE AZORES  
TONIGHT BEHIND A COLD FRONT THAT HAS MOVED THROUGH THE ISLANDS IN  
THE WAKE OF OPHELIA. INTERESTS IN THE AZORES SHOULD REFER TO  
PRODUCTS ISSUED BY THE AZORES WEATHER FORECAST AND WATCH CENTER.  
 
KEY MESSAGES:  
 
1. OPHELIA IS EXPECTED TO BE A POWERFUL EXTRATROPICAL CYCLONE WITH  
HURRICANE FORCE WINDS MONDAY 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.  
 
FORECAST POSITIONS AND MAX WINDS  
 
INIT 15/0300Z 37.3N 21.5W 100 KT 115 MPH  
12H 15/1200Z 40.1N 17.7W 90 KT 105 MPH  
24H 16/0000Z 45.7N 13.8W 80 KT 90 MPH...POST-TROP/EXTRATROP  
36H 16/1200Z 51.4N 10.6W 70 KT 80 MPH...POST-TROP/EXTRATROP  
48H 17/0000Z 56.0N 7.0W 55 KT 65 MPH...POST-TROP/EXTRATROP  
72H 18/0000Z 60.0N 2.0W 35 KT 40 MPH...POST-TROP/EXTRATROP  
96H 19/0000Z...DISSIPATED  
 

 
FORECASTER BROWN  
 
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