Tropical Storm MEGI Advisory Sat Sep 24

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (MEGI) WARNING NR 07//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 20W (MEGI), LOCATED APPROXIMATELY 582 NM SOUTHEAST OF
KADENA AB, HAS TRACKED WEST-NORTHWESTWARD AT 14 KNOTS OVER THE PAST
SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS
A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH A CENTRAL
DENSE OVERCAST FEATURE OBSCURING THE CENTER, AND AN INTENSE
CONVECTIVE BAND OVER THE EASTERN SEMI-CIRCLE OF THE LLCC. A 240932Z
SSMIS 37GHZ COLOR COMPOSITE IMAGE INDICATES TIGHTLY-CURVED BANDING
WRAPPING INTO A MICROWAVE EYE FEATURE, WHICH SUPPORTS THE CURRENT
POSITION WITH GOOD CONFIDENCE. DVORAK INTENSITY ESTIMATES HAVE
CONTINUED TO INCREASE AND NOW RANGE FROM T4.0 TO T4.5 (65 TO 77
KNOTS) WITH A 241030Z SATCON ESTIMATE OF 73 KNOTS. THE CURRENT
INTENSITY IS ASSESSED AT 65 KNOTS, WHICH IS ON THE LOWER END OF THE
ESTIMATES. ANIMATED WATER VAPOR IMAGERY REVEALS RADIAL OUTFLOW,
ENHANCED BY A STRONG TUTT CELL TO THE EAST. OVERALL, ENVIRONMENTAL
CONDITIONS TO INCLUDE LOW VERTICAL WIND SHEAR AND WARM SST ARE
FAVORABLE FOR FURTHER DEVELOPMENT. TY MEGI IS TRACKING ALONG THE
SOUTHWESTERN PERIPHERY OF THE DEEP LAYERED SUBTROPICAL RIDGE (STR).
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 THROUGH TAU 72 WHILE INTENSIFYING RAPIDLY
UNDER VERY FAVORABLE CONDITIONS. THE STR IS EXPECTED TO REMAIN
STRONG AND EAST-WEST ORIENTED THROUGH THE FORECAST PERIOD. AS A
RESULT, THE DYNAMIC GUIDANCE IS IN EXCELLENT AGREEMENT WITH A 60-NM
SPREAD IN SOLUTIONS AT TAU 72, JUST AFTER LANDFALL OVER SOUTHERN
TAIWAN. THE SYSTEM IS FORECAST TO PEAK AT 105 KNOTS BY TAU 48.
    C. AFTER TAU 72, TY MEGI WILL CROSS OVER SOUTHERN TAIWAN AND
WEAKEN SIGNIFICANTLY DUE TO LAND INTERACTION. AFTER RE-EMERGING OVER
THE TAIWAN STRAIT, THE SYSTEM WILL MAKE LANDFALL AGAIN OVER
SOUTHEAST CHINA NEAR TAU 96, AND WILL BEGIN DISSIPATING AS IT TRACKS
FURTHER INLAND. DUE TO THE TIGHT MODEL AGREEMENT IN THE EXTENDED
TAUS, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK, WHICH IS
POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS.//
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