Tropical Storm ETAU Advisory пн, 07.09.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 18W (EIGHTEEN)
WARNING NR 01//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 18W (EIGHTEEN), LOCATED APPROXIMATELY 215 NM
SOUTHWEST OF IWO TO, JAPAN, HAS TRACKED NORTHWARD AT 10 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY SHOWS THE SYSTEM HAS DEEPENED AS FORMATIVE BANDS WRAPPED
TIGHTER INTO A RAGGED AND ILL-DEFINED LOW LEVEL CIRCULATION CENTER
(LLCC). THE INITIAL POSITION IS BASED ON THE EIR ANIMATION AND ON
RECENT MICROWAVE SATELLITE IMAGERY WITH LOW CONFIDENCE. THE INITIAL
INTENSITY IS BASED ON CONGRUENT DVORAK ESTIMATES FROM PGTW, KNES, AND
RJTD. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS WEST OF A
SUBTROPICAL HIGH IN AN AREA OF LOW TO MODERATE (10-15 KNOT) VERTICAL
WIND SHEAR (VWS). MODERATE RADIAL OUTFLOW IS PARTIALLY OFFSETTING THE
VWS AND PROVIDING VENTILATION TO THE CONVECTION THAT IS SLIGHTLY
DISPLACED NORTHWARD OF THE LLCC. THE CYCLONE IS CURRENTLY TRACKING
ALONG THE WESTERN EXTENSION OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR)
TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THIS IS THE INITIAL PROGNOSTIC REASONING MESSAGE AND SETS THE
FORECAST PHILOSOPHY.
   B. TD 18W WILL CONTINUE ALONG ITS CURRENT TRACK OVER THE NEXT 48
HOURS. AFTERWARDS, THE STR IS FORECAST TO REORIENT AND CAUSE THE
SYSTEM TO TRACK MORE NORTHWESTWARD. TD 18W IS EXPECTED TO SLOWLY
INTENSIFY AS POLEWARD OUTFLOW INCREASES, PEAKING AT 60 KNOTS BY TAU
48. AFTER TAU 48, INCREASING VWS AND INTERACTION WITH A FRONTAL
BOUNDARY WILL RAPIDLY ERODE THE SYSTEM BEFORE IT MAKES LANDFALL OVER
EASTERN SHIKOKU, JAPAN, BY TAU 72.
   C. AFTER TAU 72, TD 18W WILL DISSIPATE OVER THE JAPANESE ISLANDS
AS IT GETS EMBEDDED IN THE BAROCLINIC ZONE BEHIND THE AFOREMENTIONED
FRONTAL BOUNDARY. THE INITIAL SET OF NUMERIC GUIDANCE IS IN FAIRLY
GOOD AGREEMENT UP TO TAU 36. AFTERWARDS, THE CONSENSUS MEMBERS WIDELY
SPREAD. GIVEN THE UNCERTAINTY IN THE INITIAL POSITION AND THE
FORECAST STEERING MECHANISMS, THERE IS LOW CONFIDENCE IN THE FIRST
JTWC TRACK FORECAST ON THIS SYSTEM.//
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