WDPN32 PGTW 040900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (FIVE) WARNING 
NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.6N 118.2E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 377 NM SOUTH-SOUTHWEST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A CONSOLIDATING 
LOW-LEVEL CIRCULATION (LLC), WITH IMPROVED CONVECTIVE BANDING DRIVEN 
BY THE IMPROVING DUAL CHANNEL OUTFLOW. A 040503Z AMSR2 37GHZ COLOR 
COMPOSITE MICROWAVE IMAGE REVEALS IMPROVED CONVECTIVE BANDING OVER THE 
SOUTHERN SEMICIRCLE, WRAPPING INTO THE NORTHERN QUADRANT. THE INITIAL 
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE AMSR2 IMAGE AND 
ANIMATED MSI. THE INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH HIGH 
CONFIDENCE BASED ON THE PGTW DVORAK ESTIMATE OF T2.0 (30 KNOTS), WHICH 
IS ALIGNED BEST WITH THE INITIAL POSITION. THE HIGHER AGENCY ESTIMATES 
OF T2.5 (35 KNOTS) MAY BE POSITIONED TOO FAR SOUTHWEST INTO THE DEEP 
CONVECTION THUS YIELDING HIGHER ESTIMATES. A SHIP OBSERVATION AT 
040400Z, APPROXIMATELY 109NM EAST (19.8N 120.3E), INDICATES SOUTHERLY 
WINDS AT 27 KNOTS (10-MINUTE AVERAGE), WHICH ALSO SUPPORTS THE INITIAL
INTENSITY ASSESSMENT.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: LOW-LEVEL SUBTROPICAL RIDGE (STR)
POSITIONED TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T2.5 - 35 KTS
   DEMS: T2.5 - 35 KTS
   CIMSS SATCON: 38 KTS AT 040700Z
   CIMSS ADT: 30 KTS AT 040530Z
   CIMSS AIDT: 31 KTS AT 040530Z
   CIMSS D-MINT: 37 KTS AT 040506Z
   CIMSS D-PRINT: 34 KTS AT 040630Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE DUAL-CHANNEL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL DEPRESSION (TD) 05W IS FORECAST TO
MEANDER SLOWLY WESTWARD TO WEST-NORTHWESTWARD UNDER THE STEERING
INFLUENCE OF THE LOW-LEVEL STR TO THE NORTH THROUGH TAU 24. AFTER
TAU 24, THE SYSTEM WILL INTENSIFY QUICKLY AND TRACK NORTH-
NORTHEASTWARD ALONG THE BUILDING STR ENTRENCHED TO THE EAST. TD 05W 
SHOULD REACH A PEAK INTENSITY OF 75 KNOTS BY TAU 48 DUE TO ROBUST DUAL 
CHANNEL OUTFLOW AND WARM SST VALUES. AS THE SYSTEM TRACKS THROUGH THE 
TAIWAN STRAIT, IT SHOULD WEAKEN AS WARM, DRY AIR ADVECTS OFF THE 
MOUNTAINS OF TAIWAN AND ENTRAINS INTO THE SYSTEM'S CORE. AFTER TAU 72, 
TD 05W WILL TURN SHARPLY NORTHWESTWARD OVER EASTERN CHINA UNDER THE 
STEERING INFLUENCE OF A STR POSITIONED TO THE NORTH. RAPID WEAKENING 
AND DISSIPATION WILL OCCUR AS THE SYSTEM TRACKS INLAND.    

MODEL DISCUSSION: OVERALL, TRACK AND INTENSITY CONFIDENCE IS ASSESSED 
AT LOW DUE TO HIGH UNCERTAINTY IN THE SHORT-TERM TRACK AND EXTENDED 
PERIOD TRACK NEAR TAIWAN. DUE TO THE TRACK UNCERTAINTY, THERE IS HIGH 
UNCERTAINTY IN THE JTWC INTENSITY FORECAST, WHICH WILL BE IMPACTED BY 
THE PROXIMITY TO LAND MASSES AS THE SYSTEM THREADS THE NEEDLE THROUGH 
THE TAIWAN STRAIT. THE GFS DETERMINISTIC TRACKER, HOWEVER, HAS SHIFTED 
FURTHER WEST AND IS IN BETTER ALIGNMENT WITH THE AIDS ENVELOPE. 
RELIABLE INTENSITY GUIDANCE SUPPORTS THE JTWC INTENSITY FORECAST 
THROUGH TAU 48, WITH RAPID INTENSIFICATION GUIDANCE TRIGGERING.  

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: LOW
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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