Tropical Storm MEGI Advisory Tue Sep 27

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (MEGI) WARNING NR 14//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 20W (MEGI), LOCATED APPROXIMATELY 341 NM SOUTHEAST OF
TAIPEI, TAIWAN, HAS TRACKED WEST-NORTHWESTWARD AT 11 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS
AN 18-NM RAGGED EYE WITH TIGHTLY-CURVED BANDING WRAPPING INTO THE
LOW-LEVEL CIRCULATION CENTER (LLCC). A 260554Z SSMI 85GHZ IMAGE
SHOWS CONCENTRIC EYEWALLS WITH MULTIPLE CONVECTIVE BANDS WRAPPING
INTO A SYMMETRIC LLCC. BASED ON THE PRESENCE OF AN EYE, THERE IS
GOOD CONFIDENCE IN THE CURRENT POSITION AND RECENT TRACK MOTION. THE
INITIAL INTENSITY IS ASSESSED AT 95 KTS, AND IS BASED ON DVORAK
CURRENT INTENSITY ESTIMATES OF T5.0 (90 KNOTS) FROM ALL AGENCIES AND
A RECENT SATCON ESTIMATE OF 95 KNOTS. UPPER-LEVEL ANALYSIS REVEALS
EXCELLENT RADIAL OUTFLOW WITH ENHANCED POLEWARD OUTFLOW INTO A
MIDLATITUDE SHORTWAVE TROUGH TO THE NORTH. TY MEGI IS TRACKING WEST-
NORTHWESTWARD ALONG THE PERIPHERY OF A DEEP-LAYERED SUBTROPICAL
RIDGE (STR) POSITIONED TO THE NORTHEAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
   B. TY 20W WILL CONTINUE TO TRACK WEST-NORTHWESTWARD IN A
STRAIGHT-RUNNER PATTERN WHILE INTENSIFYING TO A PEAK OF 100 KNOTS
BEFORE MAKING LANDFALL NEAR TAU 24 ALONG THE EASTERN COAST OF
TAIWAN. NEAR TAU 36, TY MEGI WILL RE-EMERGE OVER THE TAIWAN STRAIT
AFTER WEAKENING SIGNIFICANTLY DUE TO LAND INTERACTION, AND WILL
CROSS THE SOUTHEAST COAST OF CHINA BY TAU 48. THE STR IS EXPECTED TO
REMAIN STRONG AND EAST-WEST ORIENTED THROUGH THE FORECAST PERIOD. AS
A RESULT, THE DYNAMIC GUIDANCE REMAINS IN TIGHT AGREEMENT.
   C. IN THE EXTENDED FORECAST PERIOD, THE SYSTEM WILL DISSIPATE
WHILE TURNING WEST-SOUTHWESTWARD OVER CHINA. OVERALL, THERE IS HIGH
CONFIDENCE IN THE JTWC FORECAST TRACK, WHICH IS POSITIONED CLOSE TO
THE MULTI-MODEL CONSENSUS AND IS HIGHLY CONSISTENT WITH PREVIOUS
JTWC FORECASTS.//
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