Tropical Storm HALONG Advisory sab, 02.08.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (HALONG) WARNING NR 19//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 11W (HALONG), LOCATED APPROXIMATELY 339 NM NORTH-
NORTHWEST OF YAP, HAS TRACKED WESTWARD AT 05 KNOTS OVER THE PAST SIX
HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A 30
NM DIAMETER EYE WITH TIGHTLY-CURVED CONVECTIVE BANDING WRAPPING INTO
A RAPIDLY-CONSOLIDATING LOW-LEVEL CIRCULATION CENTER. A 020024Z
METOP-B MICROWAVE IMAGE REVEALS SIGNIFICANT ENHANCED DEEP CONVECTION
AROUND A WELL-DEFINED MICROWAVE EYE. THE CURRENT POSITION IS BASED
ON THE EYE FEATURE IN THE MSI WITH HIGH CONFIDENCE. THE INITIAL
INTENSITY HAS INCREASED TO 100 KNOTS BASED ON CONSISTENT DVORAK
INTENSITY ESTIMATES FROM PGTW AND KNES. UPPER-LEVEL ANALYSIS
INDICATES THE SYSTEM IS NOW LOCATED IN VERY FAVORABLE ENVIRONMENT
WITH LOW TO MODERATE (10 TO 20) NORTHERLY VERTICAL WIND SHEAR (VWS)
OFFSET BY VIGOROUS EASTWARD AND EQUATORWARD OUTFLOW. TY 11W IS
CURRENTLY TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF THE
SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. THE INITIAL INTENSITY FORECAST HAS INCREASED TO 100 KNOTS DUE
TO THE ONSET OF A RAPID INTENSIFICATION PHASE; THEREFORE, THE PEAK
INTENSITY HAS BEEN INCREASED TO 125 KNOTS AT TAU 48 BASED ON AN
OVERALL INCREASE IN DYNAMICAL-STATISTICAL INTENSITY GUIDANCE.
   B. TY 11W IS EXPECTED TO MAINTAIN ITS WEST TO WEST-NORTHWEST
TRACK UNDER THE STEERING INFLUENCE OF THE STR TO THE NORTH OVER THE
NEXT 24 TO 36 HOURS. BETWEEN TAU 36 AND 48, A MIGRATORY UPPER-LEVEL
TROUGH LOCATED TO THE NORTHEAST OF NORTHERN JAPAN IS FORECAST TO
EXTEND SOUTHWESTWARD, MODIFYING THE STR AND CAUSING TY HALONG TO
TURN NORTHWESTWARD. IN ADDITION TO WARM SEA SURFACE TEMPERATURES,
UPPER-LEVEL CONDITIONS ARE EXPECTED TO IMPROVE WITH FAVORABLE
OUTFLOW AND DECREASED VWS, ALLOWING FURTHER INTENSIFICATION THROUGH
TAU 48. BY TAU 72, UPPER-LEVEL OUTFLOW IS EXPECTED TO DEGRADE AS AN
UPPER-LEVEL LOW DEVELOPS DIRECTLY NORTHEAST OF THE SYSTEM, CAUSING
TY 11W TO BEGIN ITS WEAKENING TREND DUE TO CONVERGENCE.
   C. IN THE EXTENDED TAUS, THE STR IS EXPECTED TO REORIENT TO THE
EAST OF TY 11 AND WILL ASSUME THE STEERING PATTERN, PERMITTING TY
HALONG TO TRACK NORTH-NORTHWESTWARD ALONG THE WESTERN PERIPHERY OF
THE STR THROUGH THE REMAINDER OF THE FORECAST PERIOD. AVAILABLE
MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 72 WITH SOME
DISAGREEMENT BY TAU 120 DUE TO UNCERTAINTY IN THE STEERING
ENVIRONMENT. DUE TO THE UNCERTAINTY IN THE NEAR TERM TRACK AND
INTENSITY FORECAST ALONG WITH DIVERGENCE IN THE MODEL GUIDANCE AT
EXTENDED TAUS, THERE IS OVERALL LOW CONFIDENCE IN THE JTWC FORECAST,
WHICH IS POSITIONED CLOSE TO MULTI-MODEL CONSENSUS.//
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