Tropical Storm ETAU Advisory mar, 10-11

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (ETAU)
WARNING NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 24W (ETAU), LOCATED APPROXIMATELY 293 NM EAST-
SOUTHEAST OF DA NANG, VIETNAM, HAS TRACKED WESTWARD AT 13 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
DEPICTS RELATIVELY SYMMETRIC DEEP CONVECTION FLARING OVER THE
ASSESSED CENTER, WITH SHALLOWER CONVECTIVE BANDING WRAPPING INTO THE
NORTHWESTERN QUADRANT OF THE OBSCURED LOW-LEVEL CIRCULATION CENTER
(LLCC). A 090544Z ATMS 88GHZ MICROWAVE IMAGE REVEALS SHALLOW BANDING
IN THE SOUTHEASTERN QUADRANT, WITH AN ELONGATED BAND OF DEEPER
BANDING IN THE NORTHWESTERN QUADRANT AND LENDS HIGH CONFIDENCE TO
THE INITIAL POSITION BASED ON A NASCENT MICROWAVE EYE FEATURE. THE
INITIAL INTENSITY IS ASSESSED AT 35 KTS WITH MODERATE CONFIDENCE AND
IS HEDGED SLIGHTLY HIGHER THAN MULTI-AGENCY DVORAK CURRENT INTENSITY
ESTIMATES OF T2.5 (35 KNOTS) FROM PGTW/RJTD IN LIGHT OF A DVORAK
ESTIMATE OF T3.0 (40 KNOTS) FROM BOTH KNES AND VIA THE ADVANCED
DVORAK TECHNIQUE (ADT). UPPER-LEVEL ANALYSIS INDICATES A GENERALLY
FAVORABLE ENVIRONMENT WITH LOW TO MODERATE (15-20 KNOTS) EASTERLY
VERTICAL WIND SHEAR AND SINGLE CHANNEL OUTFLOW, WHICH IS OFFSETTING
WEAKLY SUPPORTIVE SST VALUES BETWEEN 27C TO 28C. TS 24W CONTINUES
TRACKING ALONG THE SOUTHERN PERIPHERY OF A LOW- TO MID-LEVEL
SUBTROPICAL RIDGE (STR) ENTRENCHED TO THE NORTH.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS 24W IS FORECAST TO CONTINUE TRACKING WESTWARD THROUGH THE
ENTIRE FORECAST PERIOD UNDER THE STEERING INFLUENCE OF THE
AFOREMENTIONED STR THROUGH, MAKING LANDFALL OVER EASTERN VIETNAM
NEAR TAU 18. TS 24W HAS LIKELY REACHED PEAK INTENSITY. AS THE SYSTEM
CONTINUES TRACKING WEST, SSTS STEADILY DECREASE AS IT APPROACHES THE
COAST OF VIETNAM WHILE VWS WILL STEADILY INCREASE THROUGH TAU 24.
AFTER LANDFALL, THE SYSTEM WILL TRACK INLAND AND DISSIPATE OVER
CENTRAL CAMBODIA BY TAU 48. NUMERICAL MODEL GUIDANCE IS IN TIGHT
AGREEMENT WITH A SPREAD OF 50NM AT LANDFALL WITH JGSM BEING A
EQUATORWARD OUTLIER, THE REMAINDER OF THE GUIDANCE BEING EXTREMELY
TIGHTLY PACKED (19NM SPREAD) AT LANDFALL, LENDING HIGH CONFIDENCE IN
THE JTWC FORECAST TRACK.//
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