383  
WTNT42 KNHC 141438  
TCDAT2  
 
HURRICANE OPHELIA DISCUSSION NUMBER 22  
NWS NATIONAL HURRICANE CENTER MIAMI FL AL172017  
1100 AM AST SAT OCT 14 2017  
 
DURING THE PAST FEW HOURS, OPHELIA'S SATELLITE PRESENTATION HAS  
IMPROVED SIGNIFICANTLY. THE EYE HAS BECOME EVEN MORE DISTINCT  
WITH A TEMPERATURE OF 16 DEG C, AND HAS BEEN SURROUNDED BY VERY  
DEEP CONVECTION. T-NUMBERS FROM TAFB AND SAB HAVE REACHED 5.5 ON THE  
DVORAK SCALE, AND THE OBJECTIVE NUMBERS FROM CIMMS HAVE BEEN  
OSCILLATING AROUND T5.8 AND T5.9 RECENTLY. BASED ON THESE ESTIMATES,  
THE INITIAL INTENSITY HAS BEEN INCREASED CONSERVATIVELY TO 100 KT,  
MAKING OPHELIA A CATEGORY 3 HURRICANE ON THE SSHS. OPHELIA IS A  
QUITE INTENSE AND RARE HURRICANE FOR ITS LOCATION IN THE  
NORTHEASTERN ATLANTIC. INCREASING SHEAR AND COLD WATERS WILL  
SOON BEGIN TO IMPACT OPHELIA, AND THE HURRICANE SHOULD BEGIN TO  
ACQUIRE EXTRATROPICAL CHARACTERISTICS IN ABOUT 36 HOURS OR SOONER.  
ALTHOUGH SOME WEAKENING IS ANTICIPATED, OPHELIA IS EXPECTED TO REACH  
THE BRITISH ISLES AS A POWERFUL EXTRATROPICAL CYCLONE WITH HURRICANE  
FORCE WINDS. DISSIPATION IS FORECAST IN ABOUT 4 DAYS AFTER THE  
SYSTEM MOVED OVER THESE ISLES.  
 
SATELLITE FIXES INDICATE THAT OPHELIA IS MOVING TOWARD THE NORTHEAST  
OR 055 DEGREES AT 22 KT. THE HURRICANE IS WELL EMBEDDED WITHIN THE  
SOUTHWESTERLY FLOW ASSOCIATED WITH THE SOUTHERN EXTENSION OF A LARGE  
MID-LATITUDE TROUGH, AND THIS PATTERN SHOULD CONTINUE TO STEER THE  
CYCLONE NORTHEASTWARD AND NORTH-NORTHEASTWARD WITH INCREASING  
FORWARD SPEED FOR THE NEXT 2 TO 3 DAYS UNTIL DISSIPATION. TRACK  
MODELS ARE IN EXCELLENT AGREEMENT AND THE GUIDANCE ENVELOPE IS QUITE  
TIGHT. THE NHC FORECAST IS NOT DIFFERENT FROM PREVIOUS ONES, AND IT  
IS VERY CLOSE TO THE HFIP CORRECTED CONSENSUS HCCA AND THE  
MULTI-MODEL ENSEMBLE TVCX.  
 
GIVEN THAT OPHELIA IS FORECAST TO BECOME EXTRATROPICAL, THE WIND  
FIELD SHOULD EXPAND, RESULTING IN IMPACTS OVER PORTIONS OF THE  
BRITISH ISLES REGARDLESS OF ITS EXACT LOCATION OR STRENGTH.  
 
ALTHOUGH THE CENTER OF OPHELIA IS NOT FORECAST TO REACH IRELAND OR  
THE UK FOR ANOTHER COUPLE OF DAYS, WIND AND RAINS WILL ARRIVE  
WELL IN ADVANCE OF THE CYCLONE CENTER. INDIVIDUALS 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  
AFTER OPHELIA PASSES TO THE SOUTH AND EAST LATER TODAY AND TONIGHT  
AS A COLD FRONT MOVES THROUGH 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 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 14/1500Z 34.8N 26.6W 100 KT 115 MPH  
12H 15/0000Z 36.5N 23.0W 95 KT 110 MPH  
24H 15/1200Z 40.5N 18.0W 90 KT 105 MPH  
36H 16/0000Z 46.5N 14.0W 85 KT 100 MPH...POST-TROP/EXTRATROP  
48H 16/1200Z 51.5N 11.0W 75 KT 85 MPH...POST-TROP/EXTRATROP  
72H 17/1200Z 59.0N 6.0W 40 KT 45 MPH...POST-TROP/EXTRATROP  
96H 18/1200Z...DISSIPATED  
 

 
FORECASTER AVILA  
 
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