Tropical Storm VONGFONG Advisory Paz, 05.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (VONGFONG) WARNING NR 09//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 19W (VONGFONG), LOCATED APPROXIMATELY 407 NM EAST-
SOUTHEAST OF ANDERSEN AFB, GUAM, HAS TRACKED WEST-NORTHWESTWARD AT
16 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY(EIR) CONTINUES TO SHOW DEEPENED CENTRAL CONVECTION
WITH TIGHT-CURVED BANDING WRAPPING INTO THE LOW-LEVEL CIRCULATION,
ALSO EVIDENT IN A 041658Z SSMI MICROWAVE IMAGE. THE CURRENT POSITION
IS BASED ON THE EIR ANIMATION, TIGHT-GROUPING OF SATELLITE FIXES
FROM ALL AGENCIES AND SSMI IMAGE WITH HIGH CONFIDENCE. THE INITIAL
INTENSITY OF 65 KNOTS IS BASED ON MATCHING DVORAK INTENSITY
ESTIMATES FROM PGTW AND KNES. UPPER-LEVEL ANALYSIS INDICATES THE
SYSTEM REMAINS IN A FAVORABLE ENVIRONMENT WITH LOW VERTICAL WIND
SHEAR AND EXCELLENT RADIAL OUTFLOW. ADDITIONALLY, THERE IS A POINT-
SOURCE DIRECTLY OVER THE SYSTEM SUSTAINING THE INCREASED CONVECTION.
TY 19W IS CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-
LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. THE EXTENDED TRACK FORECAST HAS CHANGED DUE TO A DISAGREEMENT
AMONG MODEL GUIDANCE. SEE PARA 3.C. FOR DETAILS. OTHERWISE, THERE IS
NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TY 19W WILL CONTINUE TRACKING WEST-NORTHWESTWARD UNDER THE
STEERING INFLUENCE OF THE STR THROUGH TAU 72. FAVORABLE
ENVIRONMENTAL CONDITIONS CONTINUE TO PERSIST, ALLOWING TY 19W TO
STEADILY INTENSIFY, REACHING 120 KNOTS BY TAU 72. DYNAMIC MODEL
GUIDANCE REMAINS IN TIGHT AGREEMENT LENDING HIGH CONFIDENCE TO THE
FIRST 72 HOURS OF THE FORECAST.
   C. BEYOND TAU 72, TY VONGFONG IS EXPECTED TO TRACK ON A MORE
NORTHWESTWARD DIRECTION AS THE STR RECEDES SLIGHTLY IN RESPONSE TO A
MID-LATITUDE TROUGH APPROACHING FROM THE NORTHWEST. FAVORABLE
CONDITIONS ARE EXPECTED TO PERSIST ALLOWING TY 19W TO FURTHER
INTENSIFY PEAKING AT 125 KNOTS BY TAU 96. AVAILABLE MODEL GUIDANCE
SIGNIFICANTLY DIVERGES AFTER TAU 72. GFS SOLUTION INDICATES THE
SYSTEM SHIFTS POLEWARD SOONER THAN THE MAJORITY OF THE AVAILABLE
TRACKERS WHICH TAKES TY 19W FURTHER WESTWARD BEFORE TURNING
POLEWARD.  DUE TO A LARGE SPREAD AND THE UNCERTAINTY IN THE EXTEND
OF THE STEERING STR, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE
FORECAST PERIOD .//
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