WDPN32 PGTW 090900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W (MAN-YI) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.4N 158.8E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 767 NM EAST OF TINIAN
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM 25W (MAN-YI) AND ITS CONSOLIDATING CENTRAL CONVECTION,
OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC). SYSTEM IS STILL
UTILIZING THE MODERATE TO STRONG POLEWARD OUTFLOW, ENHANCED BY A
BAND OF SOUTHWESTERLY FLOW STRETCHING NORTHWEST OF TS 25W. THE
DIVERGENCE ALOFT IS STRONGER OVER THE NORTHEASTERN QUADRANT OF THE
SYSTEM, THEREFORE EQUATORWARD OUTFLOW IS PRESENT, BUT WEAK. A 090528Z
F18 SSMIS MICROWAVE PASS SHOWS THE MAJORITY OF THE CONVECTIVE 
ACTIVITY PRESENT TO THE EAST AND SOUTHEAST OF THE LLCC. THE INITIAL 
POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE AFOREMENTIONED 
SSMIS PASS, AS WELL AS ANIMATED EIR IMAGERY. THE INITIAL INTENSITY OF 
35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON OBJECTIVE 
ESTIMATES LISTED BELOW AND PERSISTENCE.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: TRANSITIONING STEERING INFLUENCE FROM A
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST TO ANOTHER STR TO THE
NORTHWEST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 32 KTS AT 090530Z
   CIMSS AIDT: 32 KTS AT 090530Z
   CIMSS D-MINT: 36 KTS AT 090529Z
   CIMSS D-PRINT: 33 KTS AT 090640Z

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

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 25W WILL TRACK NORTHWESTWARD THROUGH TAU 36 
STEERED PRIMARILY BY THE SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. AS 
THE SYSTEM CONTINUES TO INTENSIFY, REACHING PEAK INTENSITY OF 50 KTS 
NEAR TAU 36, ANOTHER STR WILL BECOME THE DOMINANT UPPER-LEVEL 
FEATURE, LEADING TS 25W ON A MORE WESTWARD TRACK. AS THE SYSTEM 
TRANSITS WEST, IT WILL BE EXPOSED TO INCREASINGLY STRONG VERTICAL 
WIND SHEAR, REACHING 25-30 KTS BY TAU 48. ADDITIONALLY, IT WILL 
INTERACT WITH A POCKET OF DRY AIR, FURTHER HINDERING ITS DEVELOPMENT 
AT THAT STAGE, LEADING TO STEADY WEAKENING THROUGHOUT THE REST OF 
FORECAST PERIOD. AT TAU 72 THE SYSTEM STEERING PATTERN WILL DIRECT IT 
ON A WEST-SOUTHWESTWARD TRACK, AS IT PASSES NORTH OF THE NORTHERN 
MARIANA ISLANDS.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT,
WITH A CROSS-TRACK SPREAD OF 80 NM BY TAU 36 AND 200 NM BY TAU 72,
WITH ALL THE CONSENSUS MEMBERS FORECASTING A GENERALLY NORTHWESTWARD 
TRACK THROUGH TAU 36, FOLLOWED BY A GRADUAL TURN WESTWARD AND THEN TO 
THE SOUTHWEST. THE CROSS-TRACK SPREAD INCREASES TO NEARLY 300 NM BY 
THE TIME TS 25W PASSES THE NORTHERN MARIANAS, WITH MODERATE 
UNCERTAINTY TO THE TRACK PROXIMITY TO ROTA AND GUAM. THE JTWC TRACK 
FORECAST IS LAID ON THE SOUTHERN SIDE, BUT IN CLOSE PROXIMITY TO THE 
MULTI-MODEL CONSENSUS. INTENSITY MODEL GUIDANCE IS ALSO IN FAIR 
AGREEMENT WITH ALL MODELS REFLECTING THE STEADY INTENSIFICATION 
THROUGH THE INITIAL 24 HOURS, FOLLOWED BY WEAKENING TOWARDS THE END 
OF THE FORECAST PERIOD. INTENSITY GUIDANCE UNCERTAINTY INCREASES 
SIGNIFICANTLY AFTER TAU 72, WITH POTENTIAL FOR RE-INTENSIFICATION 
AROUND TAU 120, AS INDICATED BY HAFS, AS WELL AS THE MULTI-MODEL 
CONSENSUS.

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