Tropical Storm MAN-YI Advisory 11月21日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 34W (MAN-YI) WARNING NR
05//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 34W (MAN-YI), LOCATED APPROXIMATELY 99 NM
SOUTH-SOUTHEAST OF CHUUK, FSM, HAS TRACKED NORTHWESTWARD AT 20
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY SHOWS AN EXPANDING SYSTEM THAT HAS RAPIDLY
CONSOLIDATED WITH DEEPENED RAIN BANDS WRAPPING IN FROM ALL QUADRANTS.
THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE TRACING THE
TIGHTLY CURVED BANDS. THE INITIAL INTENSITY OF 45 KNOTS IS BASED ON
THE DVORAK ESTIMATES OF T3.0 FROM PGTW AND KNES THAT REFLECTS THE
SIGNIFICANT INTENSIFICATION TO A TROPICAL STORM. THE ENVIRONMENT IS
VERY FAVORABLE WITH LOW (10-15 KNOT) VERTICAL WIND SHEAR (VWS), WARM
(29-30 CELSIUS) SEA SURFACE TEMPERATURES (SST), AND EXCELLENT
WESTWARD OUTFLOW. TS 34W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF
A HIGH ZONAL SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. THROUGH TAU 72, TS 34W WILL CONTINUE TO TRACK NORTHWESTWARD
UNDER THE STR. THE FAVORABLE ENVIRONMENT WILL PREVAIL AND ALLOW TS
34W TO STEADILY INTENSIFY TO A PEAK OF 105 KNOTS BY TAU 36.
AFTERWARD, THE SYSTEM WILL GRADUALLY WEAKEN MOSTLY DUE TO INCREASING
VWS AS THE UPPER LEVEL WINDS BEGIN SWITCHING TO A WESTWARD COMPONENT.
 AFTER TAU 48, TS 34W WILL ROUND THE WESTERN EDGE OF THE STR AND TURN
MORE POLEWARD. THERE IS MINIMAL SPREAD IN THE NUMERICAL MODEL
GUIDANCE, LENDING HIGH CONFIDENCE TO THIS PORTION OF THE JTWC
FORECAST TRACK.
   C. AFTER TAU 72, TS MAN-YI WILL BECOME QUASI-STATIONARY AS IT
ENTERS A COL AREA BETWEEN THE CURRENT STEERING RIDGE AND ANOTHER
BUILDING STR TO THE WEST. THE INTENSITY WILL CONTINUE TO DROP AS
OUTFLOW DIMINISHES, IN ADDITION TO CONTINUED UNFAVORABLE VWS.
HOWEVER, BY TAU 120, THE SYSTEM WILL STILL BE AT TYPHOON INTENSITY
OF 65 KNOTS. DYNAMIC MODEL GUIDANCE SIGNIFICANTLY DISAGREE TOWARD
THE EXTENDED PORTION OF THE FORECAST WITH A POSSIBLE BIFURCATED
SCENARIO: ONE LEADING TO A NORTHEASTWARD RECURVATURE AND ANOTHER
SUGGESTING A LOOPING MOTION WITH AN EVENTUAL WESTWARD TRACK. IN VIEW
OF THIS, ALONG WITH DIFFERENCES IN ALONG TRACK SPEEDS, LEND LOW
CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC FORECAST TRACK.//
NNNN
NNNN