Tropical Storm KALMAEGI Advisory Mon Sep 15

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (KALMAEGI) WARNING NR 20//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 15W (KALMAEGI), LOCATED APPROXIMATELY 204 NM SOUTH OF
HONG KONG, HAS TRACKED WEST-NORTHWESTWARD AT 17 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS
CURVED CONVECTIVE BANDING WRAPPING INTO A DEFINED LOW LEVEL
CIRCULATION CENTER WHILE A LARGE BANDING FEATURE CAN BE OBSERVED
BUILDING ACROSS THE WESTERN PERIPHERY. A 151009Z CORIOLIS 37 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 HAS BEEN INCREASED TO 70 KNOTS BASED
ON THE IMPROVED STRUCTURE AND DVORAK INTENSITY ESTIMATES THAT RANGE
FROM 65 TO 77 KNOTS. 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 HOURS DUE TO FAVORABLE
ENVIRONMENTAL CONDITIONS OF WARM SEA SURFACE TEMPERATURES ACROSS THE
SOUTH CHINA SEA AND FAVORABLE OUTFLOW. AFTER TAU 12, 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.//
NNNN
NNNN