WDPN31 PGTW 201500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 26W (KROVANH) 
WARNING NR 003//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 26W (KROVANH), LOCATED APPROXIMATELY 439 NM 
EAST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED WESTWARD AT 08 KNOTS 
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE 
IMAGERY DEPICTS A STRUGGLING SYSTEM, EXPERIENCING SIGNIFICANT 
EASTERLY VERTICAL WIND SHEAR (VWS), WITH SPOTTY, DISORGANIZED 
CONVECTION FLARING TO THE NORTH AND WEST OF THE LOW-LEVEL 
CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS PLACED WITH FAIR 
CONFIDENCE IN THE CENTER OF ELONGATED AND DISORGANIZED CONVECTIVE 
BANDING FEATURES EVIDENT IN A 201038Z SSMIS 37GHZ MICROWAVE IMAGE. 
THE INITIAL INTENSITY IS ASSESSED AT 30 KNOTS WITH FAIR CONFIDENCE, 
CONTINUING TO TREND ABOVE THE SUBJECTIVE DVORAK INTENSITY ESTIMATES 
OF T1.0 (25 KNOTS) FROM PGTW AND T1.5 (25 KNOTS) FROM RJTD IN LIGHT 
OF AN ADVANCED DVORAK TECHNIQUE (ADT) ESTIMATE OF T2.2 (32KTS). 
INTERACTION BETWEEN THE LLCC AND NORTHEASTERLY WINDS ASSOCIATED WITH 
A SURGE EVENT IS CREATING CONVERGENT LOW LEVEL FLOW, PROVIDING A 
FOCUS FOR GENERATION OF SPOTTY CONVECTION TO THE NORTH AND WEST OF 
THE LLCC. THE ENVIRONMENT IS MARGINAL WITH MODERATE TO HIGH (25-
30KTS) VWS OFFSETTING THE ROBUST POLEWARD OUTFLOW AND WARM (27-28C) 
SSTS, INHIBITING THE CONSOLIDATION OF THE CONVECTIVE CORE. THE 
SYSTEM IS TRACKING GENERALLY WESTWARD FOLLOWING THE FLOW ASSOCIATED 
WITH A LOW TO MID-LAYER STEERING RIDGE TO THE NORTH. 
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TD 26W IS EXPECTED TO CONTINUE TRACKING GENERALLY WEST-
SOUTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF THE STEERING RIDGE 
ENTRENCHED TO THE NORTH THROUGH TAU 48. THE SYSTEM IS FORECAST TO 
INTENSIFY SLIGHTLY OVER THE NEXT 12-24 HOURS AS VWS IS EXPECTED TO 
SLACKEN TO MORE MODERATE LEVELS, AND IT REMAINS UNDER DIFFLUENT 
POLEWARD OUTFLOW AND TRANSITS ACROSS WARM (26-28C) WATERS. BY TAU 48 
AS THE SYSTEM TRACKS TO THE WEST, IT BECOMES SEPARATED FROM THE 
WEAKENING NORTHEAST SURGE FLOW, WHICH COMBINED WITH INCREASING VWS 
AND WEAK UPPER-LEVEL DIVERGENCE, WILL LEAD TO A RAPID WEAKENING 
TREND WITH THE SYSTEM EXPECTED TO DISSIPATE OVER WATER BY TAU 72 
JUST SOUTH OF THE SOUTHERN TIP OF VIETNAM. NUMERICAL MODEL GUIDANCE 
IS IN FAIR AGREEMENT WITH THE OVERALL TRACK FORECAST SCENARIO, BUT 
INDICATES SOME SIGNIFICANT SPREAD THROUGH THE DURATION OF THE 
FORECAST. THE NAVGEM, UKMET ENSEMBLE AND HWRF SOLUTIONS SHOW A TRACK 
GENERALLY DUE WEST FROM TAU 12, AND TAKE THE SYSTEM OVER SOUTHERN 
VIETNAM TO THE SOUTH OF HO CHI MINH CITY. THE REMAINDER OF THE 
CONSENSUS MEMBERS TAKE THE SYSTEM WEST-SOUTHWEST THROUGH TAU 48, 
THEN WEST INTO THE GULF OF THAILAND. THE JTWC FORECAST TRACK LIES 
NORTH OF THE MAJORITY OF THE GUIDANCE THROUGH TAU 24, THEN CLOSELY 
TRACKS THE GFS SOLUTION THROUGH TAU 72 WITH OVERALL LOW CONFIDENCE.//
NNNN