MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (TEMBIN) WARNING NR 24//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 15W (TEMBIN), LOCATED APPROXIMATELY 210 NM SOUTHWEST
OF TAIPEI, TAIWAN, HAS TRACKED WEST-SOUTHWESTWARD AT 07 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
(EIR) SHOWS THE ORGANIZATION MAINTAINED, WITH CONVECTION BEGINNING TO
WRAP ANEW INTO THE LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL
INTENSITY IS BASED ON A MICROWAVE EYE FEATURE IN THE 241656Z TRMM
IMAGE. CURRENT INTENSITY OF 75 KNOTS IS BASED ON CONGRUENT DVORAK
ESTIMATES FROM PGTW, KNES AND RJTD. UPPER LEVEL ANALYSIS INDICATES A
WEAK POINT SOURCE ANTICYCLONE THAT CONTINUES TO PROVIDE A RADIAL
VENTING MECHANISM AND LOW VERTICAL WIND SHEAR ENVIRONMENT (05 TO 10
KNOTS) HAS SUSTAINED THE CYCLONE. TY 15W IS TRACKING ALONG THE
SOUTHERN EXTENSION OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE
NORTHWEST AND APPEARS TO BE TRACKING INTO A WEAK STEERING ENVIRONMENT.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TY 15W WILL CONTINUE TO STEER IN A GENERAL SOUTHWESTWARD
DIRECTION SOUTHWEST OF THE TAIWAN STRAIT FOR THE NEXT 24 TO 36 HOURS,
SLOWLY INTENSIFYING IN A FAVORABLE SURFACE ENVIRONMENT WITH THE POINT
SOURCE ANTICYCLONE PROVIDING GOOD EQUATORWARD VENTING THROUGH TAU 48.
AS THE STR CURRENTLY STEERING TY 15W BEGINS TO WEAKEN UNDER THE
INFLUENCE OF TY 16W (BOLAVEN), THE NEAR EQUATORIAL RIDGE (NER) TO THE
SOUTHEAST IS EXPECTED TO BUILD BRINGING TY 15W EASTWARD. THE NER WILL
MODIFY SLIGHTLY WITH THE PASSAGE OF TY 16W TO THE NORTHWEST, CAUSING
TY 15W TO TURN TO THE EAST-NORTHEAST BETWEEN TAU 48 AND 72.
C. AFTER TAU 72, TY 15W IS EXPECTED TO ACCELERATE NORTH-
NORTHEASTWARD AS THE NER AMPLIFIES AND EVENTUALLY TRANSITIONS TO THE
STR AS IT RE-BUILDS WHEN TY 16W MOVES INTO THE YELLOW SEA. THERE ARE
INDICATIONS THAT TY 16W WILL HAVE SOME BINARY INTERACTIONS WITH
TY 15W IN THE LATER TAUS AS TY 16W PASSES TO THE NORTH OF TY 15W. AS
TY 16W MOVES TO THE NORTHEAST OF TY 15W, THE OUTFLOW OF TY 16W IS
EXPECTED TO HAMPER THE OUTFLOW FROM TY 15W, CAUSING THE SYSTEM TO
SLOWLY WEAKEN AS IT TRACKS INTO THE YELLOW SEA BEYOND TAU 72.
DYNAMIC MODEL GUIDANCE REMAINS IN FAIR AGREEMENT (ALL INDICATING A
LOOPING TRACK WITH THE EXCEPTION OF GFDN) WITHIN 72 HOURS. HOWEVER,
THERE IS A LARGE VARIATION IN THE FORECAST GUIDANCE BEYOND TAU 72
DUE TO THE POSSIBILITY OF INTERACTION WITH TY 16W AND THE VARIATION
IN STR ORIENTATION. AS SUCH, THERE REMAINS LOW CONFIDENCE IN THE
EXTENDED FORECAST TRACK. //
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