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TROPICAL STORM KENNA DISCUSSION NUMBER   2
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT TUE OCT 22 2002
 
TROPICAL DEPRESSION FOURTEEN-E HAS BECOME BETTER ORGANIZED DURING 
THE PAST 6 HOURS WITH BOTH BANDING FEATURES AND UPPER-LEVEL OUTFLOW 
IMPROVING. THE INNER-CORE DEEP CONVECTION APPEARS TO BE LOCATED JUST 
WEST OF THE LOW-LEVEL CENTER...BUT BOTH TAFB AND SAB OBTAINED A 
DVORAK SATELLITE INTENSITY OF T2.5...OR 35 KT..BASED ON THE IMPROVED 
BANDING FEATURES. THEREFORE...THE DEPRESSION HAS BEEN UPGRADED TO 
TROPICAL STORM KENNA.
 
THE INITIAL MOTION ESTIMATE IS 285/10.  THE ACTUAL MOTION OVER THE 
PAST 6 HOURS HAS BEEN 275/10. HOWEVER...I BELIEVE THAT THIS IS A 
TEMPORARY MOTION THAT IS MOST LIKELY DUE TO RE-ORGANIZATION OF THE 
INNER-CORE CIRCULATION CLOSER TO THE DEEP CONVECTION. A QUIKSCAT 
OVERPASS AT 22/0020Z INDICATED THE LOW-LEVEL CIRCULATION WAS 
ELONGATED SLIGHTLY EAST-WEST AND THIS COULD ALSO EXPLAIN SOME OF THE 
RECENT WESTWARD JOG THAT KENNA HAS MADE. HOWEVER...THE CYCLONE IS 
EXPECTED TO RETURN TO A BASE COURSE OF 290 DEGREES WITHIN THE NEXT 
12 HOURS AS IT TRACKS AROUND THE SOUTHWEST PERIPHERY OF THE MEXICAN 
SUBTROPICAL HIGH. BY 48 HOURS...THE GLOBAL MODELS INDICATE THAT A 
DEEPENING SHORTWAVE TROUGH CURRENTLY LOCATED ABOUT 800 NMI WEST OF 
CALIFORNIA IS EXPECTED TO DIG SOUTHEASTWARD AND ERODE THE WESTERN 
PORTION OF THE SUBTROPICAL RIDGE AND ALLOW KENNA TO BEGIN TO TURN 
MORE NORTHWARD. THIS SEEMS LIKE A REASONABLE SCENARIO GIVEN THE HIGH 
AMPLITUDE RIDGING THAT IS PRESENTLY OCCURRING BETWEEN THE SHORTWAVE 
TROUGH AND THE DEEP POLAR LOW OVER THE ALEUTIAN ISLANDS. IN FACT... 
THE GLOBAL MODELS MAY BE UNDERFORECASTING THE AMPLITUDE OF THE 
TROUGH WHEN IT REACHES BAJA CALIFORNIA IN 72 HOURS...WHICH WOULD 
ALLOW KENNA TO BEGIN RECURVING TO THE NORTHEAST. THE OFFICIAL 
FORECAST IS A LITTLE LEFT OF THE PREVIOUS TRACK THROUGH 36 HOURS AND 
THEN BACK ON TRACK AFTER THAT. THIS IS ALSO CLOSE TO THE GUNA 
ENSEMBLE MODEL TRACK.

THERE IS A SIGNIFICANT CHANGE TO THE PREVIOUS INTENSITY FORECAST. 
THE INNER-CORE CONVECTION AND ORGANIZATION OF KENNA HAS IMPROVED 
SIGNIFICANTLY BASED ON NIGHTTIME VISIBLE AND INFRARED SATELLITE 
IMAGERY. THE IMPROVING BANDING FEATURES...ESPECIALLY IN THE NORTHERN 
SEMICIRCLE...ALSO SUGGESTS THAT THE LOW-LEVEL WIND FIELD IS BECOMING 
MORE SYMMETRICAL. THE UPPER-LEVEL OUTFLOW PATTERN HAS ALSO IMPROVED 
SIGNIFICANTLY IN THE NORTHERN SEMICRICLE. SINCE THE VERTICAL SHEAR 
IS FORECAST TO BE LESS THAN 10 KT THROUGHOUT THE PERIOD...THEN THE 
INTENSIFICATION RATE WAS INCREASED...ESPECIALLY SINCE KENNA IS 
EXPECTED TO REMAIN OVER 29C OR GREATER SSTS THROUGH 72 HOURS AND 
BEYOND. HOWEVER...THE OFFICIAL FORECAST IS STILL BELOW THE SHIPS 
MODEL WHICH BRINGS KENNA TO 75 KT IN 48 HOURS AND 83 KT IN 72 HOURS. 
BUT IF THE INNER-CORE CIRCULATION AND CONVECTION TIGHTENS UP MORE 
DURING THE NEXT 12 HOURS...THEN THE INTENSITY FORECAST MAY HAVE TO 
BE INCREASED CLOSER TO THE GFDL MODEL WHICH MAKES KENNA A 111 KT 
MAJOR HURRICANE BY 72 HOURS.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     22/0900Z 11.6N 100.8W    35 KTS
12HR VT     22/1800Z 12.3N 102.5W    40 KTS
24HR VT     23/0600Z 13.0N 104.2W    45 KTS
36HR VT     23/1800Z 13.8N 105.9W    55 KTS
48HR VT     24/0600Z 14.8N 107.1W    65 KTS
72HR VT     25/0600Z 17.0N 107.7W    75 KTS
 
 
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