Tropical Storm VONGFONG Advisory Mon Oct 06

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (VONGFONG) WARNING NR 11//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 19W (VONGFONG), LOCATED APPROXIMATELY 176 NM EAST OF
ANDERSEN AFB, HAS TRACKED WEST-NORTHWESTWARD AT 21 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY
SHOWS TIGHTLY CURVED FEEDER BANDS WITH SIGNIFICANTLY DEEPENED
CONVECTIVE TOPS FEEDING INTO A PINHOLE EYE. THE INITIAL POSITION IS
BASED ON THE PINHOLE EYE ON THE EIR LOOP WITH HIGH CONFIDENCE. THE
INITIAL INTENSITY OF 90 KNOTS IS BASED ON AN OVERALL ASSESSMENT OF
DVORAK INTENSITY ESTIMATES FROM ALL REPORTING AGENCIES. UPPER-LEVEL
ANALYSIS INDICATES THE SYSTEM REMAINS IN A FAVORABLE ENVIRONMENT WITH
LOW VERTICAL WIND SHEAR (VWS) AND EXCELLENT RADIAL OUTFLOW WITH AN
IMPROVED NORTHEASTWARD CHANNEL INTO A TUTT CELL. TY 19W IS CURRENTLY
TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL
RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. 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 ARE EXPECTED TO PERSIST, ALLOWING TY 19W TO
STEADILY INTENSIFY, REACHING 130 KNOTS BY TAU 72. DYNAMIC MODEL
GUIDANCE REMAINS IN TIGHT AGREEMENT LENDING HIGH CONFIDENCE TO THE
FIRST 72 HOURS OF THE FORECAST.
   C. TY VONGFONG IS EXPECTED TO TRACK ON A MORE NORTHWEST TO
NORTHWARD DIRECTION AS THE STR RECEDES IN RESPONSE TO A MID-LATITUDE
TROUGH APPROACHING FROM THE NORTHWEST. THE SYSTEM WILL BEGIN TO
WEAKEN AFTER TAU 96, AS VWS INCREASES. AVAILABLE MODEL GUIDANCE
REMAINS SIGNIFICANTLY SPREAD DURING THIS PORTION OF THE FORECAST,
LENDING LOW CONFIDENCE IN THE JTWC TRACK FORECAST BEYOND TAU 72.//
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