WDPN31 PGTW 301500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (RUMBIA) WARNING 
NR 11//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 06W (RUMBIA), LOCATED APPROXIMATELY 374 NM 
SOUTH-SOUTHEASTWARD OF HONG KONG, HAS TRACKED NORTHWESTWARD AT 16 
KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY 
DEPICTS A COMPACT LOW-LEVEL CIRCULATION CENTER (LLCC) WITH TIGHTLY-
CURVED BANDING (TCB) OVER THE SOUTH QUADRANT WRAPPING INTO THE 
NORTH QUADRANT OF THE LLCC. A 301213Z SSMIS 91 GHZ IMAGE SHOWS THE 
IMPROVED TCB ALTHOUGH THERE IS A LACK OF DEEP CONVECTION OVER THE 
NORTHWEST QUADRANT. THE CORRESPONDING 37 GHZ IMAGE AS WELL AS A 
301008Z 37 GHZ WINDSAT IMAGE DEPICT A MICROWAVE EYE FEATURE, WHICH 
LENDS GOOD CONFIDENCE TO THE INITIAL POSITION AND RECENT MOTION. THE 
RECENT CONSOLIDATION IS LIKELY ATTRIBUTABLE TO A SLIGHT DECREASE IN 
NORTHEASTERLY VERTICAL WIND SHEAR (VWS) TO ABOUT 10 TO 15 KNOTS. 
OVERALL, THE SYSTEM IS LOCATED WITHIN A FAVORABLE ENVIRONMENT WITH 
THE WEAK VWS, GOOD EQUATORWARD OUTFLOW, IMPROVING POLEWARD OUTFLOW 
AND WARM SST. THE INITIAL INTENSITY IS ASSESSED AT 45 KNOTS BASED ON 
DVORAK INTENSITY ESTIMATES OF 45 KNOTS FROM PGTW AND KNES. TS 06W IS 
TRACKING QUICKLY ALONG THE SOUTHERN PERIPHERY OF A DEEP SUBTROPICAL 
RIDGE (STR). 
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY 
FROM THE PREVIOUS PROGNOSTIC REASONING BULLETIN.
   B. TS 06W IS FORECAST TO TRACK GENERALLY NORTHWESTWARD ALONG THE 
SOUTHERN AND SOUTHWESTERN PERIPHERY OF THE STR THROUGH TAU 48. THE  
AVAILABLE DYNAMIC MODEL GUIDANCE IS IN TIGHT AGREEMENT WITH A 50 NM 
SPREAD IN SOLUTIONS AT TAU 24, JUST PRIOR TO LANDFALL. ADDITIONALLY, 
THE DYNAMIC MODELS (WITH THE EXCEPTION OF JENS) NOW SUPPORT A 
POLEWARD TURN ALONG THE WESTERN PERIPHERY OF THE LOW- TO MID-LEVEL 
STR AFTER TAU 36. THE BULK OF THE INTENSITY GUIDANCE HAS ALSO 
STABILIZED AND SHOWS AGREEMENT ON A PEAK INTENSITY OF 50 TO 55 KNOTS 
AROUND TAU 24. THE MESOSCALE MODELS, GFDN AND HWRF, ARE THE PRIMARY 
OUTLIERS AND PEAK THE SYSTEM SLIGHTLY HIGHER AT 60 TO 65 KNOTS. THE 
JTWC FORECAST REMAINS CONSISTENT IN BOTH TRACK AND PEAK INTENSITY 
(55 KNOTS), FAVORING THE STIPS GUIDANCE, WHICH INDICATES THAT THE 
SYSTEM WILL ENCOUNTER INCREASING (STRONG) VWS AS IT TRACKS 
NORTHWESTWARD. THIS NORTHERLY VWS IS ASSOCIATED WITH THE UPPER-LEVEL 
RIDGE BUILDING OVER SOUTHEAST CHINA AND THE NORTHERN SOUTH CHINA 
SEA. AFTER MAKING LANDFALL NEAR TAU 30, TS 06W SHOULD WEAKEN RAPIDLY 
DUE TO VWS AND LAND INTERACTION AND WILL DISSIPATE BY TAU 48. 
OVERALL, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
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