WDPN32 PGTW 041500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (FIVE)         
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.3N 118.0E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 347 NM SOUTHWEST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A CONSOLIDATING 
LOW-LEVEL CIRCULATION (LLC), WITH IMPROVED CONVECTIVE BANDING AND A 
DEVELOPING CENTRAL DENSE OVERCAST DRIVEN BY THE IMPROVING DUAL CHANNEL 
OUTFLOW. A 041051Z GMI 37GHZ COLOR COMPOSITE MICROWAVE IMAGE REVEALS 
IMPROVED CONVECTIVE BANDING OVER THE SOUTHERN SEMICIRCLE, WRAPPING 
INTO THE EASTERN QUADRANT, WITH A DEFINED LOW-LEVEL CIRCULATION 
CENTER. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON 
THE GMI IMAGE AND A 041244Z ASCAT-B BULLSEYE IMAGE. THE INITIAL 
INTENSITY OF 35 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE 
ASCAT-B IMAGE, WHICH SHOWS 30-35 KNOT WINDS, AND THE PGTW, KNES AND 
DEMS SUBJECTIVE DVORAK ESTIMATES.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: COMPETING STEERING ENVIRONMENT WITH A
LOW-LEVEL SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH AND A
NEAR-EQUATORIAL RIDGE BUILDING TO THE SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T2.5 - 35 KTS
   DEMS: T2.5 - 35 KTS
   CIMSS ADT: 35 KTS AT 041130Z
   CIMSS AIDT: 36 KTS AT 041130Z
   CIMSS D-MINT: 32 KTS AT 041048Z
   CIMSS D-PRINT: 34 KTS AT 041150Z

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: LOW

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL STORM (TS) 05W IS FORECAST TO MEANDER 
SLOWLY NORTHWESTWARD WITHIN THE COMPETING STEERING ENVIRONMENT THROUGH 
TAU 12. AFTER TAU 12, THE SYSTEM WILL INTENSIFY QUICKLY AND TRACK 
NORTHWARD TO NORTH-NORTHEASTWARD ALONG THE BUILDING STR ENTRENCHED TO 
THE EAST. TS 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, TS 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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