929  
WTNT42 KNHC 111439  
TCDAT2  
 
TROPICAL STORM OPHELIA DISCUSSION NUMBER 10  
NWS NATIONAL HURRICANE CENTER MIAMI FL AL172017  
1100 AM AST WED OCT 11 2017  
 
IF I ONLY HAD CONVENTIONAL SATELLITE IMAGERY, I WOULD DEFINITELY  
ESTIMATE THAT OPHELIA WAS A HURRICANE. THE CYCLONE HAS A RAGGED EYE  
SURROUNDED BY DEEP CONVECTION AND CYCLONICALLY CURVED BANDS.  
FURTHERMORE, DVORAK INTENSITY ESTIMATES, BOTH SUBJECTIVE AND  
OBJECTIVE, FROM ALL AGENCIES ARE T4.0 PLUS. HOWEVER, SEVERAL ASCAT  
PASSES DURING THE PAST DAY OR SO INDICATE THAT THE WINDS HAVE BEEN  
LOWER THAN THE WINDS ONE COULD ASSIGN THE CYCLONE BY USING DVORAK.  
ONCE AGAIN THIS MORNING, A PAIR OF ASCAT PASSES SHOWED WINDS OF  
LESS THAN 45 KT, BUT I AM ASSUMING THAT THE ASCAT CAN NOT RESOLVE  
THE SHARP WIND GRADIENT TYPICALLY ASSOCIATED WITH AN EYEWALL, AND  
EARLIER SSMIS DATA INDICATED THAT ONE IS PRESENT. SINCE WE DO NOT  
HAVE A HURRICANE HUNTER PLANE TO GIVE US EXACT MEASUREMENTS, WE  
NEED TO COMPROMISE BETWEEN THE VERY VALUABLE SATELLITE-BASED  
ESTIMATES, AND THE INITIAL INTENSITY IS SET AT 60 KT IN THIS  
ADVISORY.  
 
ALTHOUGH THE OCEAN IS NOT TOO WARM, THE SHEAR IS LOW AND THE  
UPPER-TROPOSPHERE IS COOL. THESE FACTORS SHOULD PROVIDE SOME  
LOW-OCTANE FUEL FAVORING SLIGHT STRENGTHENING, AND OPHELIA IS  
STILL EXPECTED TO BECOME A HURRICANE AT ANY TIME WITHIN THE NEXT 12  
HOURS. EXTRATROPICAL TRANSITION IS LIKELY TO START BETWEEN DAY 3 AND  
DAY 4, AND OPHELIA IS ANTICIPATED TO REMAIN A STRONG CYCLONE OVER  
THE NORTHEASTERN ATLANTIC.  
 
OPHELIA IS MOVING SLOWLY TOWARD THE EAST AT 3 KT, EMBEDDED WITHIN  
LIGHT STEERING CURRENTS, AND LITTLE MOTION IS EXPECTED TODAY. A  
MID-LEVEL TROUGH IS FORECAST TO AMPLIFY WEST OF OPHELIA, AND THIS  
PATTERN WILL PROVIDE A STRONGER SOUTHWESTERLY STEERING FLOW  
WHICH EVENTUALLY FORCE THE CYCLONE TO MOVE TOWARD THE NORTHEAST WITH  
INCREASING FORWARD SPEED. MOST OF THE TRACK MODELS AGREE WITH THIS  
SOLUTION INCREASING THE CONFIDENCE IN THE TRACK FORECAST. THE NHC  
FORECAST FOLLOWS VERY CLOSELY THE HFIP CORRECTED CONSENSUS HCCA  
WHICH HAS BEEN VERY SKILLFUL THIS SEASON.  
 
FORECAST POSITIONS AND MAX WINDS  
 
INIT 11/1500Z 30.0N 36.5W 60 KT 70 MPH  
12H 12/0000Z 29.9N 36.0W 65 KT 75 MPH  
24H 12/1200Z 30.1N 35.7W 70 KT 80 MPH  
36H 13/0000Z 30.8N 34.7W 70 KT 80 MPH  
48H 13/1200Z 31.5N 33.3W 70 KT 80 MPH  
72H 14/1200Z 34.0N 26.8W 70 KT 80 MPH  
96H 15/1200Z 40.0N 17.5W 70 KT 80 MPH...POST-TROP/EXTRATROP  
120H 16/1200Z 51.5N 12.5W 60 KT 70 MPH...POST-TROP/EXTRATROP  
 

 
FORECASTER AVILA  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab TPC Page Main Text Page