Tropical Storm ATSANI Advisory dom, 01-11

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 23W (ATSANI)
WARNING NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 23W (ATSANI), LOCATED APPROXIMATELY 1029 NM
EAST OF MANILA, PHILIPPINES, HAS TRACKED NORTHWESTWARD AT 13 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) SHOWS A WEAK SYSTEM WITH DISORGANIZED FLARING CENTRAL
CONVECTION. THE INITIAL POSITION AND INTENSITY ARE PLACED WITH FAIR
CONFIDENCE BASED ON LOW CLOUD TRACING IN THE MSI LOOP AND NEXT TO
CLOSELY CLUSTERED AGENCY DVORAK FIXES, INCLUDING PGTW AND RJTD,
BOTH AT T2.0/30KTS. THE ENVIRONMENT IS MARGINALLY UNFAVORABLE WITH
MODERATE TO HIGH (20-25KT) VERTICAL WIND SHEAR AND WEAK OUTFLOW
ALOFT OFFSET SLIGHTLY BY FAVORABLE (30-31 CELSIUS) SEA SURFACE
TEMPERATURES (SST). THE CYCLONE IS TRACKING ALONG THE SOUTHWESTERN
PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TD 23W WILL CONTINUE ON ITS CURRENT TRACK IN THE PHILIPPINE
SEA UNDER THE SAME STR. AFTER TAU 48, A SHORTWAVE TROUGH APPROACHING
FROM THE NORTHWEST WILL SLIGHTLY WEAKEN THE STR AND PULL THE CYCLONE
MORE POLEWARD. THE ENVIRONMENT IS FORECAST TO IMPROVE SLIGHTLY AS
POLEWARD OUTFLOW IMPROVES LEADING TO A SLOW INTENSIFICATION TO 60KTS
BY TAU 72. NUMERICAL MODELS ARE IN FAIR AGREEMENT WITH NAVGEM THE
SOLE RIGHT-OF-TRACK OUTLIER, LENDING FAIR CONFIDENCE IN THIS PORTION
OF THE JTWC TRACK FORECAST WHICH IS PLACED SLIGHTLY LEFT OF THE
MULTI-MODEL CONSENSUS.
   C. IN THE EXTENDED FORECAST, A SECONDARY STR BEHIND THE SHORTWAVE
TROUGH WILL ASSUME STEERING AND SLOWLY DRIVE TD 23W WESTWARD.
ENVIRONMENTAL CONDITIONS ARE FORECAST TO IMPROVE DURING THIS TIME
WITH DECREASED VWS (10-15KTS) AND IMPROVED UPPER LEVEL OUTFLOW.
THESE CONDITIONS, COUPLED WITH CONTINUED WARM SST, WILL ALLOW FOR
FASTER INTENSIFICATION TO 105 KTS BY TAU 120. NUMERICAL MODELS
SIGNIFICANTLY DIVERGE, LENDING OVERALL POOR CONFIDENCE IN THE
EXTENDED PORTION OF THE JTWC FORECAST TRACK.//
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