349  
WTPA41 PHFO 061506  
TCDCP1  
 
 
POST-TROPICAL CYCLONE WALAKA DISCUSSION NUMBER 28  
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP012018  
500 AM HST SAT OCT 06 2018  
 
WALAKA'S LOW-LEVEL CIRCULATION CENTER (LLCC) REMAINS COMPLETELY  
DEVOID OF DEEP CONVECTION EARLY THIS MORNING. THE LAST FEW  
THUNDERSTORMS ASSOCIATED WITH THE SYSTEM ARE SLIGHTLY MORE THAN  
90 N MI SOUTHEAST OF THE EXPOSED LLCC. ASCAT PASSES OVER WALAKA AT  
0735Z AND 0838Z SHOWED THE SYSTEM WAS STRONGER THAN EXPECTED, WITH  
SURFACE WIND SPEEDS UP TO 45 KT. IT WAS ALSO APPARENT THE CENTER OF  
THE SYSTEM WAS BECOMING ELONGATED INSTEAD OF CIRCULAR. IN ADDITION,  
THE WIND FIELD WAS HIGHLY ASYMMETRIC, WITH THE STRONGEST WINDS IN A  
BROAD AREA COVERING THE SOUTHEASTERN SEMICIRCLE, WHILE THE WINDS  
WERE MUCH WEAKER OVER MOST OF THE NORTHWESTERN SEMICIRCLE. BASED ON  
THIS EVIDENCE, WALAKA HAS ALREADY TRANSITIONED TO AN EXTRATROPICAL  
GALE LOW THIS MORNING. THE INITIAL INTENSITY FOR THIS ADVISORY IS  
45 KT DUE TO THE ASCAT DATA FROM LAST EVENING.  
 
THE INITIAL MOTION FOR THIS ADVISORY IS 035/23 KT. WALAKA IS BEING  
STEERED BY THE DEEP SOUTHWESTERLY FLOW ASSOCIATED WITH AN ADVANCING  
UPPER-LEVEL TROUGH. AS A RESULT, IT WILL LIKELY CONTINUE TO MOVE  
TOWARD THE NORTHEAST OR NORTH-NORTHEAST AT AN INCREASING FORWARD  
SPEED THIS WEEKEND. THE LATEST TRACK FORECAST HAS BEEN ADJUSTED  
SLIGHTLY TO THE LEFT COMPARED WITH THE PREVIOUS ADVISORY PACKAGE.  
THIS FOLLOWS A BLEND OF THE TRACK GUIDANCE BASED ON THE LATEST  
OPERATIONAL RUNS AND THE ENSEMBLE MEANS FROM THE GFS AND ECMWF  
MODELS.  
 
THE BAROCLINIC PROCESSES DRIVING WALAKA'S NEW LIFE AS AN  
EXTRATROPICAL SYSTEM WILL LIKELY MAINTAIN AN AREA OF GALE FORCE  
WINDS OVER THE SOUTHEASTERN SEMICIRCLE DURING THE NEXT 36 HOURS.  
THE LATEST INTENSITY FORECAST HAS BEEN ADJUSTED UP COMPARED WITH  
THE PREVIOUS ADVISORY PACKAGE TO ACCOUNT FOR THESE GALES. THIS  
INTENSITY FORECAST IS BASED ON A BLEND OF THE MOST RECENT GFS AND  
ECMWF MODELS, WHICH ARE IN GOOD AGREEMENT THROUGH 24 HOURS. THE  
ECMWF MAINTAINS 35 KT WINDS FOR THE 36 HOUR TIME PERIOD, WHILE THE  
GFS OUTPUT INDICATES THE WINDS MAY DROP BELOW GALE FORCE BY THAT  
TIME. BOTH MODELS CONTINUE TO INSIST THE SYSTEM WILL BE ABSORBED BY  
A LARGER EXTRATROPICAL LOW AFTER 36 HOURS. THEREFORE, DISSIPATION  
WILL OCCUR BY THE 48 HOUR TIME PERIOD.  
 
THIS IS THE LAST TROPICAL CYCLONE DISCUSSION ISSUED BY THE CENTRAL  
PACIFIC HURRICANE CENTER ON THIS SYSTEM.  
 
 
FORECAST POSITIONS AND MAX WINDS  
 
INIT 06/1500Z 36.2N 163.5W 45 KT 50 MPH...POST-TROPICAL  
12H 07/0000Z 41.0N 160.5W 40 KT 45 MPH...POST-TROP/EXTRATROP  
24H 07/1200Z 48.0N 154.0W 35 KT 40 MPH...POST-TROP/EXTRATROP  
36H 08/0000Z 55.0N 148.0W 35 KT 40 MPH...POST-TROP/EXTRATROP  
48H 08/1200Z...DISSIPATED  
 

 
FORECASTER HOUSTON  
 
 
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