Tropical Storm VONGFONG Advisory Sun Oct 05

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (VONGFONG) WARNING NR 10//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 19W (VONGFONG), LOCATED APPROXIMATELY 299 NM EAST-
SOUTHEAST OF ANDERSEN AFB, GUAM, HAS TRACKED WEST-NORTHWESTWARD AT
18 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
DEPICTS A PINHOLE EYE WITH SPIRAL BANDING WRAPPING INTO THE LOW-
LEVEL CIRCULATION, ALSO EVIDENT IN A 2359Z METOP-B MICROWAVE IMAGE.
THE CURRENT POSITION IS BASED ON THE MSI AND MICROWAVE IMAGE WITH
HIGH CONFIDENCE. THE INITIAL INTENSITY OF 70 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 AND EXCELLENT
RADIAL OUTFLOW. 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 CONTINUE TO PERSIST, ALLOWING TY 19W TO
STEADILY INTENSIFY, REACHING 125 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 NORTHWESTWARD
DIRECTION AS THE STR RECEDES SLIGHTLY IN RESPONSE TO A MID-LATITUDE
TROUGH APPROACHING FROM THE NORTHWEST. AVAILABLE MODEL GUIDANCE HAS
SLIGHTLY IMPROVED OVER THE PAST SIX HOURS, BUT INDICATES A 450 NM
SPREAD AT TAU 120. DUE TO THE UNCERTAINTY IN THE EXTEND OF THE
STEERING STR AND AFOREMENTIONED MID-LATITUDE TROUGH, THERE IS LOW
CONFIDENCE IN THE FORECAST PERIOD BEYOND TAU 72.//
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