392  
WTNT42 KNHC 130250  
TCDAT2  
 
HURRICANE OPHELIA DISCUSSION NUMBER 16  
NWS NATIONAL HURRICANE CENTER MIAMI FL AL172017  
1100 PM AST THU OCT 12 2017  
 
REMARKABLY, THE HURRICANE HAS CONTINUED TO STRENGTHEN THIS EVENING.  
SATELLITE IMAGES INDICATE THAT CLOUD TOPS IN THE EYEWALL HAVE COOLED  
IN THE PAST SEVERAL HOURS, WITH A WARM EYE REMAINING. DVORAK  
ESTIMATES FROM TAFB, SAB AND CIMSS RANGE BETWEEN 90 TO 95 KT, SO THE  
INITIAL INTENSITY IS RAISED TO 90 KT.  
 
IT SEEMS THAT THE MARGINAL SSTS THAT OPHELIA HAS BEEN MOVING OVER  
HAVE BEEN OFFSET BY THE COLD UPPER-LEVEL TEMPERATURES AND LOW SHEAR  
ENVIRONMENT. SSTS ONLY SLIGHTLY COOL IN THE NEXT 24 HOURS WITH  
SIMILAR SHEAR CONDITIONS, SO A MINOR DECREASE IN STRENGTH IS IN THE  
FORECAST. AFTER THAT TIME, WHILE THE HURRICANE SHOULD MOVE OVER  
COLDER WATERS, IT WILL LIKELY BE ACCELERATING TO THE NORTHEAST AND  
EXPERIENCING FAVORABLE MID-LATITUDE JET DYNAMICS, WHICH WILL HELP TO  
MAINTAIN THE CYCLONE'S INTENSITY. ALL OF THE GUIDANCE SHOW  
EXTRATROPICAL TRANSITION BY 3 DAYS WITH THE CYCLONE KEEPING  
HURRICANE-FORCE WINDS, AS INDICATED IN THE NEW FORECAST. LITTLE  
CHANGE WAS MADE TO THE PREVIOUS PREDICTION, EXCEPT TO ACCOUNT FOR  
THE HIGHER INITIAL WIND SPEED.  
 
OPHELIA IS FINALLY MOVING, ESTIMATED AT 6 KT TO THE EAST-NORTHEAST.  
THIS GENERAL MOTION WITH AN INCREASE IN FORWARD SPEED IS EXPECTED  
FOR THE NEXT COUPLE OF DAYS AS THE HURRICANE GETS PICKED UP BY A  
LARGE MID-LATITUDE TROUGH. CONFIDENCE IN THE TRACK FORECAST REMAINS  
FAIRLY HIGH FOR THE FIRST 72 H, ALTHOUGH THE SPREAD INCREASES AFTER  
THAT TIME. THE GFS-BASED GUIDANCE GENERALLY THEN SHOW A MORE  
NORTHWARD TRACK TO THE WEST OF IRELAND THEN OVER THE FAR NORTH  
ATLANTIC, WHILE THE UKMET/ECMWF SHOW A TRACK OVER IRELAND AND GREAT  
BRITAIN THEN EASTWARD AND DISSIPATING OVER NORTHERN EUROPE.  
THE FORECAST IS CLOSE TO THE CONSENSUS AT LONG RANGE, BUT SOME LARGE  
CHANGES COULD BE REQUIRED FOR LATER FORECASTS.  
 
WHILE THE NHC TRACK KEEPS THE CENTER OF OPHELIA SOUTH AND EAST  
OF THE AZORES, TROPICAL-STORM-FORCE WINDS ARE POSSIBLE THROUGHOUT  
THE AZORES BY SATURDAY NIGHT DUE TO AN APPROACHING FRONT. IN  
ADDITION, THE WIND FIELD OF OPHELIA WILL LIKELY EXPAND AS THE  
CYCLONE BEGINS EXTRATROPICAL TRANSITION, AND ANY DEVIATION TO THE  
LEFT OF THE FORECAST TRACK COULD BRING STRONGER WINDS TO THE  
ISLANDS. INTERESTS IN THE AZORES SHOULD REFER TO PRODUCTS ISSUED BY  
THE AZORES WEATHER FORECAST AND WATCH CENTER.  
 
KEY MESSAGES:  
 
1. OPHELIA IS EXPECTED TO TRANSITION TO A HURRICANE-FORCE POST-  
TROPICAL CYCLONE BY MONDAY WHEN IT MOVES NEAR IRELAND AND THE  
UNITED KINGDOM. WHILE POST-TROPICAL OPHELIA WILL LIKELY BRING SOME  
DIRECT IMPACTS FROM WIND AND HEAVY RAIN TO PORTIONS OF THESE AREAS,  
AS WELL AS DANGEROUS MARINE CONDITIONS, GIVEN THE FORECAST  
UNCERTAINTY AT THESE TIME RANGES IT IS TOO SOON TO DETERMINE THE  
EXACT MAGNITUDE, TIMING AND LOCATION OF THE IMPACTS. RESIDENTS IN  
IRELAND AND THE UNITED KINGDOM SHOULD MONITOR THE PROGRESS OF  
OPHELIA FOR THE NEXT SEVERAL DAYS. FOR MORE INFORMATION ON LOCAL  
IMPACTS, RESIDENTS OF 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 13/0300Z 30.7N 34.7W 90 KT 105 MPH  
12H 13/1200Z 31.2N 33.5W 90 KT 105 MPH  
24H 14/0000Z 32.2N 31.1W 85 KT 100 MPH  
36H 14/1200Z 33.7N 27.5W 80 KT 90 MPH  
48H 15/0000Z 36.0N 23.0W 80 KT 90 MPH  
72H 16/0000Z 45.0N 14.5W 75 KT 85 MPH...POST-TROP/EXTRATROP  
96H 17/0000Z 56.0N 7.0W 55 KT 65 MPH...POST-TROP/EXTRATROP  
120H 18/0000Z 64.0N 0.5W 50 KT 60 MPH...POST-TROP/EXTRATROP  
 

 
FORECASTER BLAKE  
 
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