WDPN31 PGTW 010300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (RUMBIA) WARNING NR 
13//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 06W (RUMBIA), LOCATED APPROXIMATELY 235 NM 
SOUTH-SOUTHEASTWARD OF HONG KONG, HAS TRACKED WEST-NORTHWESTWARD AT 
16 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTI-SPECTRAL SATELLITE 
IMAGERY (MSI) DEPICTS AN INTENSIFYING CORE OF DEEP CONVECTION 
BUILDING AROUND THE LOW LEVEL CIRCULATION CENTER (LLCC), WITH SPIRAL 
BANDING WRAPPING INTO A NASCENT EYE-LIKE FEATURE. A WELL DEFINED 
MICROWAVE EYE IS CLEARLY DEPICTED IN A TIMELY 010048Z SSMIS 91-GHZ 
IMAGE. THERE IS HIGH CONFIDENCE IN THE INITIAL POSITION BASED ON THE 
AFOREMENTIONED MSI AND SSMIS IMAGERY. BASED ON THE IMPROVING MSI 
PRESENTATION AND THE APPEARANCE OF A MICROWAVE EYE, THE INITIAL 
INTENSITY IS ASSESSED AT 50 KNOTS, WHICH IS SLIGHTLY HIGHER THAN 
DVORAK CURRENT INTENSITY ESTIMATES FROM PGTW AND KNES. TS 06W 
CONTINUES TO QUICKLY TRACK ALONG THE SOUTHWESTERN PERIPHERY OF A 
DEEP-LAYER SUB-TROPICAL RIDGE (STR), HOWEVER THE FORWARD MOTION HAS 
SLOWED SLIGHTLY OVER THE PAST SIX HOURS. THE OVERALL ENVIRONMENT IS 
MARGINALLY FAVORABLE. UPPER LEVEL ANALYSIS INDICATES NORTHEASTERLY 
VERTICAL WIND SHEAR HAS BECOME HIGH (20-25 KNOTS) AND IS HAMPERING 
POLEWARD OUTFLOW. HOWEVER, EQUATORWARD OUTFLOW REMAINS ROBUST AND TS 
06W IS CLEARLY INTENSIFYING DESPITE THE INCREASED VWS ACTING UPON 
IT. SEA SURFACE TEMPERATURE AND OCEAN HEAT CONTENT REMAIN FAVORABLE. 
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 CONTINUE TRACKING GENERALLY 
NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE STR THROUGHOUT 
THE REMAINDER OF THE FORECAST PERIOD (TAU 36). THE AVAILABLE DYNAMIC 
MODEL GUIDANCE IS IN TIGHT AGREEMENT UP THROUGH LANDFALL, WITH A 45 
NM SPREAD IN THE LANDFALL POSITION SHORTLY BEFORE TAU 24. AFTERWARD, 
THE SOLUTIONS DIVERGE SOMEWHAT WITH GFDN AND COAMPS-TC INDICATING A 
PRONOUNCED NORTHWARD TURN WHILE THE MAJORITY OF GUIDANCE INDICATES A 
CONTINUED NORTHWESTWARD MOTION, RESULTING FROM A STRONGER STR OVER 
EASTERN CHINA IN THE MODEL FIELDS. AVAILABLE ENSEMBLE MODEL PRODUCTS 
SUPPORT THE JTWC FORECAST TRACK. TS 06W IS FORECAST TO INTENSIFY TO 
55 KNOTS AT TAU 12 BASED ON THE CURRENT LEVEL OF OBSERVED 
INTENSIFICATION AS WELL AS GUIDANCE FROM THE GFDN AND HWRF MESOSCALE 
MODELS. THE SYSTEM WILL DISSIPATE RAPIDLY AFTER MAKING LANDFALL. 
BASED ON GOOD AGREEMENT AMONG BOTH DETERMINISTIC AND ENSEMBLE MODEL 
AIDS, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
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