WDPN31 PGTW 080900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 10W (LEKIMA) WARNING
NR 18//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUPER TYPHOON (STY) 10W (LEKIMA), LOCATED APPROXIMATELY 214 NM
SOUTHWEST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED
NORTH-NORTHWESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY SHOWS THE SYSTEM CONTINUED TO RAPIDLY
INTENSIFY AS EVIDENCED BY A TIGHTLY COMPACT CENTRAL CONVECTION WITH
ANNULAR CHARACTERISTICS AND A SHARPLY OUTLINED 8-NM EYE. THE TRAILING
RAIN BANDS TO THE SOUTHWEST HAVE DETACHED. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON THE EYE FEATURE THAT LINED UP
PERFECTLY WITH A WELL-DEFINED MICROWAVE PINHOLE EYE IN THE 080421Z
GPM 36GHZ COLORIZED IMAGE. THE INITIAL INTENSITY OF 130KTS IS BASED
ON THE DVORAK ESTIMATES OF T6.5/127KTS FROM PGTW AND RJTD AND
REFLECTS RAPID INTENSIFICATION (RI) OVER THE PAST SIX HOURS.
ENVIRONMENTAL ANALYSIS INDICATES EXCELLENT RADIAL OUTFLOW, LOW
VERTICAL WIND SHEAR (VWS) AND WARM SST (30C). STY 10W IS TRACKING
ALONG THE SOUTHWEST PERIPHERY OF A SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TY 10W WILL CONTINUE ON ITS CURRENT NORTHWESTWARD TRACK UNDER
THE INFLUENCE OF THE STR, MOVING MORE NORTHWARD AFTER TAU 36 AS THE
STR REORIENTS IN A NORTH-SOUTH CONFIGURATION TO THE EAST. BY TAU 48,
THE SYSTEM WILL REACH THE EAST COAST OF CHINA NEAR TAIZHOU. THE
FAVORABLE CONDITIONS WILL SUSTAIN THE CURRENT STY UP TO TAU 12.
AFTERWARD, INCREASING VWS AND LAND INTERACTION WILL WEAKEN IT TO
60 KNOTS BY TAU 72, SHORTLY AFTER TRACKING OVER SHANGHAI. NUMERICAL
MODEL GUIDANCE IS IN GOOD AGREEMENT WITH A 100NM SPREAD IN SOLUTIONS
AT TAU 72, LENDING FAIR CONFIDENCE IN THIS PORTION OF THE JTWC
FORECAST TRACK.
C. AFTER TAU 72, STY LEKIMA WILL TURN MORE NORTH-NORTHWESTWARD AND
FURTHER INLAND ALONG THE WESTERN PERIPHERY OF THE BUILDING STR. RAPID
WEAKENING IS EXPECTED PRIMARILY DUE TO LAND INTERACTION, LEADING TO
DISSIPATION BY TAU 120. NUMERICAL MODELS SIGNIFICANTLY DIVERGE IN ALL
DIRECTIONS AS THEY LOSE THE WEAK VORTEX; THEREFORE, THERE IS LOW
CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC FORECAST TRACK.//
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