Tropical Storm MEGI Advisory za, 24-09

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 20W (MEGI) WARNING
NR 05//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 20W (MEGI), LOCATED APPROXIMATELY 527 NM SOUTH-
SOUTHWEST OF IWO TO, HAS TRACKED WEST-NORTHWESTWARD AT 07 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
AND A 232156Z GPM 91 GHZ IMAGE DEPICTS A RAPIDLY CONSOLIDATING
SYSTEM WITH IMPROVED BANDING FEATURES WRAPPING INTO A TIGHTENING
CENTER. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON
MICROWAVE IMAGERY AND SATELLITE FIXES FROM PGTW AND RJTD WITH SOME
UNCERTAINTY DUE TO THE CONSOLIDATING CENTER. THE INITIAL INTENSITY
IS ASSESSED AT 45 KNOTS AND IS BASED ON DVORAK ESTIMATES FROM PGTW
AND KNES REPORTING T3.0 (45 KNOTS). A PARTIAL 240002Z METOP-B ASCAT
IMAGE SHOWS A REGION OF AT LEAST 40 KNOTS PRESENT ON THE NORTHEAST
QUADRANT. UPPER-LEVEL ANALYSIS SHOWS A FAVORABLE
ENVIRONMENT WITH AN IMPROVING RADIAL OUTFLOW CHANNEL AND LOW (5 TO
10 KNOTS) VERTICAL WIND SHEAR. SSTS ARE ALSO VERY FAVORABLE, NEAR 30
CELSIUS. CURRENTLY TS MEGI IS TRACKING NORTHWESTWARD ALONG THE
PERIPHERY OF A MID TO LOW LEVEL SUBTROPICAL RIDGE POSITIONED TO THE
NORTHEAST.
3. FORECAST REASONING.
    A. THERE IS NO CHANGE TO FORECAST PHILOSOPHY FROM THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
    B. TS MEGI WILL CONTINUE TO TRACK NORTHWESTWARD THROUGHOUT THE
FORECAST PERIOD AS THE STEERING RIDGE BUILDS AND EXTENDS WESTWARD.
STEADY INTENSIFICATION IS EXPECTED THROUGH TAU 72 AS TS MEGI
CONTINUES TO CONSOLIDATE WITHIN A VERY FAVORABLE ENVIRONMENT
REACHING A PEAK INTENSITY OF 85 KNOTS.
    C. IN THE EXTENDED PERIOD, BEYOND TAU 72 TS MEGI IS EXPECTED TO
CONTINUE ITS NORTHWESTERN TRACK MAKING LANDFALL OVER THE SOUTHERN
PORTION OF TAIWAN, WEAKENING RAPIDLY INTO A TROPICAL STORM. THIS
TRACK WILL CONTINUE INTO CHINA BEFORE DISSIPATING NEAR TAU 120.
DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGHOUT THE FORECAST
PERIOD WITH THE EXCEPTION OF GFDN DEPARTING FROM THE GROUP CLUSTER
SHOWING A TRACK SIGNIFICANTLY SOUTH. THE FORECAST TRACK IS PLACED
WITH GOOD CONFIDENCE LOCATED CLOSE TO THE MULTI-MODEL CONSENSUS.//
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