WDPN32 PGTW 210900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (GAEMI) WARNING NR 
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.8N 125.7E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 594 NM SOUTH-SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WESTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM (TS) 05W (GAEMI) WITH VIGOROUS BURTS OF CONVECTION SLIGHTLY
OFFSET TO THE WEST OF A PARTIALLY EXPOSED LOW-LEVEL CIRCULATION
CENTER (LLCC). THE SYSTEM APPEARS TO BE QUICKLY CONSOLIDATING
THOUGH AND THE CONVECTIVE BURSTS ARE BEGINNING TO ALIGN OVER THE
CENTER. BANDING FEATURES CAN BE SEEN IN THE NORTHERN PERIPHERY
WRAPPING INTO THE LLCC. NORTHEASTERLY SHEAR IS EVIDENT WITH
CONVECTION BLOWING OFF TO THE WEST-SOUTHWEST. 05W HAS BEEN
QUASI-STATIONARY OVER THE PAST 6 HOURS WITH A VERY SLOW DRIFT TO
THE WEST. ENVIRONMENTAL ANALYSIS INDICATES THAT 05W IS IN A
MARGINALLY FAVORABLE ENVIRONMENT FOR FURTHER INTENSIFICATION
CHARACTERIZED BY MODERATE POLEWARD AND EQUATORWARD OUTFLOW ALOFT,
AROUND 20 KTS OF VERTICAL WIND SHEAR, AND WARM (30-31 C) SEA
SURFACE TEMPERATURES. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE PARTIALLY EXPOSED AND WELL-DEFINED LLCC
SEEN IN THE ANIMATED MSI. THE INITIAL INTENSITY OF 50 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE OBJECTIVE AND
SUBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: COMPETING STEERING ENVIRONMENT, WITH A
SUBTROPICAL RIDGE (STR) TO THE NORTH AND A NEAR EQUATORIAL RIDGE
(NER) TO THE SOUTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 47 KTS AT 210600Z
   CIMSS ADT: 45 KTS AT 210600Z
   CIMSS DPRINT: 47 KTS AT 210600Z
   CIMSS DMINT: 51 KTS AT 210506Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 05W IS FORECAST TO BEGIN A NORTHWARD TURN
OVER THE NEXT 12 HOURS AS THE RIDGE TO THE NORTH REORIENTS TO A
NORTH-SOUTH ORIENTATION, WHICH WILL DRIVE 05W NORTHWARD THROUGH TAU
72. AFTER TAU 72, RIDGING EXTENDING OVER EASTERN CHINA WILL DEVELOP
AND STEER THE SYSTEM NORTHWESTWARD THROUGH THE REMAINDER OF THE
FORECAST PERIOD. 05W IS CURRENTLY FORECAST TO MAKE LANDFALL ALONG
THE EASTERN COAST OF CHINA AROUND TAU 108. REGARDING THE INTENSITY
FORECAST, 05W HAS RECENTLY ACQUIRED RAPID INTENSIFICATION (RI)
INDICATORS, CALLING FOR RI OVER THE NEXT 48 HOURS. HOWEVER,
MODERATE VERTICAL WIND SHEAR VALUES OF AROUND 20 KTS ARE
ANTICIPATED TO PERSIST AND PREVENT RI. INTENSIFICATION OVER THE
NEXT 72 HOURS IS STILL EXPECTED THOUGH, DUE TO VERY WARM SEA
SURFACE TEMPERATURES (SST) AND HIGH OHC VALUES. A PEAK INTENSITY OF
100 KTS IS FORECAST TO OCCUR AROUND TAU 72, NEAR ISHIGAKIJIMA.
AFTER TAU 72, 05W IS EXPECTED TO BEGIN ITS WEAKENING TREND AS IT
ENTERS COOLER SSTS AND VERTICAL WIND SHEAR BEGINS TO QUICKLY RISE. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS GOOD AGREEMENT WITH A
225 NM CROSS-TRACK SPREAD AT TAU 72. GALWEM AND UKMET MAKE UP THE
WESTERNMOST MEMBERS, TRACKING THE SYSTEM OVER CENTRAL TAIWAN. THE
REMAINDER OF GUIDANCE SUGGESTS A TRACK THAT IS JUST EAST AND NORTH
OF TAIWAN. THE JTWC TRACK FORECAST IS THEREFORE PLACED WITH OVERALL
MEDIUM CONFIDENCE AND IS ALIGNED MORE WITH THE LATTER OF THE TWO
MENTIONED SCENARIOS. INTENSITY GUIDANCE IS IN RELATIVELY POOR
AGREEMENT, THE APPEARANCE OF RI INDICATORS HAS LOWERED THE
CONFIDENCE IN THE SHORT TERM. MODELS DO AGREE THAT THE SYSTEM WILL
STEADILY INTENSIFY TO A PEAK INTENSITY AROUND TAU 72, BUT DISAGREE
ON THE PEAK, RANGING FROM 65 KTS (COAMPS-TC NAVGEM BASED) TO 115
KTS (HAFS-A). THEREFORE, THE JTWC INTENSITY FORECAST IS PLACED WITH
MEDIUM CONFIDENCE THROUGH TAU 72 AND LOW THEREAFTER. 

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