Tropical Storm KALMAEGI Advisory Tue Sep 16

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (KALMAEGI) WARNING NR 19//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 15W (KALMAEGI), LOCATED APPROXIMATELY 252 NM SOUTH-
SOUTHEAST OF HONG KONG, HAS TRACKED WEST-NORTHWESTWARD AT 18
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY SHOWS TIGHTLY CURVED CONVECTIVE BANDING WRAPPING INTO A
FORMATIVE, YET FRAGMENTED EYE WALL FEATURE AS THE SYSTEM CONTINUES
TO RECOVER FROM THE LAND INTERACTION WITH LUZON. A 150346Z GCOM 36
GHZ MICROWAVE IMAGE DEPICTS IMPROVED BANDING IN ALL QUADRANTS AS AN
IRREGULAR EYE FEATURE HAS DEVELOPED. THERE IS GOOD CONFIDENCE IN THE
INITIAL POSITION AND DIRECTION BASED ON THE AFOREMENTIONED SATELLITE
IMAGERY. THE INITIAL INTENSITY IS ASSESSED AT 65 KNOTS BASED ON THE
CONSISTENT STRUCTURE AND DVORAK INTENSITY ESTIMATES OF 65 KNOTS FROM
PGTW AND RJTD. UPPER LEVEL ANALYSIS REVEALS MODERATE (15 TO 25
KNOTS) NORTHEASTERLY VERTICAL WIND SHEAR (VWS) CONTINUES TO PRESS
UPON THE SYSTEM WHICH IS BEING OFFSET BY STRONG EQUATORWARD OUTFLOW
AND THE MOTION OF THE SYSTEM. TY 15W IS CURRENTLY TRACKING ALONG THE
SOUTHERN PERIPHERY OF A BROAD, EAST-WEST ORIENTED SUBTROPICAL RIDGE
(STR) ENTRENCHED TO THE NORTH.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TY 15W IS FORECAST TO ACCELERATE WEST-NORTHWESTWARD UNDER THE
STEERING INFLUENCE OF THE STRONG STR THROUGH TAU 72. A SHORT WINDOW
OF INTENSIFICATION IS EXPECTED IN THE NEXT 12 TO 18 HOURS DUE TO
FAVORABLE ENVIRONMENTAL CONDITIONS OF WARM SEA SURFACE TEMPERATURES
ACROSS THE SOUTH CHINA SEA AND FAVORABLE OUTFLOW. BY TAU 24, THE
SYSTEM IS EXPECTED TO CROSS NORTHERN HAINAN ISLAND WHICH WILL INDUCE
A WEAKENING TREND. AS TY KALMAEGI APPROACHES THE COAST OF VIETNAM,
THE SYSTEM IS FORECAST TO FURTHER WEAKEN AS IT TRACKS FURTHER INLAND
AND DISSIPATES BY TAU 72. DYNAMIC MODEL GUIDANCE (INCLUDING THE
MODEL ENSEMBLES) IS IN TIGHT AGREEMENT, THEREFORE, THERE IS HIGH
CONFIDENCE IN THE JTWC FORECAST TRACK, WHICH IS POSITIONED CLOSE TO
THE MULTI-MODEL CONSENSUS.//
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