WDPS32 PGTW 070300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 11P (ELEVEN)     
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.2S 168.7W
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 53 NM EAST OF MANUA ISLANDS
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 20 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SMALL,
CONSOLIDATING SYSTEM WITH IMPROVED CONVECTIVE BANDING WRAPPING INTO
A DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC). A 070016Z ATMS 165
GHZ MICROWAVE IMAGE REVEALS DEEP CONVECTIVE BANDING OVER THE WESTERN
SEMICIRCLE WRAPPING INTO THE SOUTHERN QUADRANT OF THE LLCC, WHICH
SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE. A PARTIAL
062050Z ASCAT-B IMAGE SUPPORTS THE INITIAL POSITION AND SUGGESTS A
POSITION JUST NORTHWEST OF THE MANUA ISLANDS NEAR 062100Z. THE
ASCAT-B IMAGE SHOWS 30-35 KNOT WINDS OVER THE NORTHERN SEMICIRCLE.
AN EARLIER 061707Z SMAP IMAGE GENERALLY INDICATED 35-40 KNOT WINDS
OVER THE NORTHERN SEMICIRCLE WITH 20-25 KNOT WINDS OVER THE SOUTHERN 
SEMICIRCLE. THEREFORE, SMAP, ASCAT AND SURFACE OBSERVATIONS REFLECT A 
HIGHLY ASYMMETRICAL WIND FIELD WITH WESTERLY GALE-FORCE WINDS 
PERSISTING OVER THE NORTHERN SEMICIRCLE. UPPER-LEVEL CONDITIONS REMAIN 
FAVORABLE WITH NEAR-RADIAL OUTFLOW AND ENHANCED POLEWARD OUTFLOW 
VENTING INTO THE SUBTROPICAL JET TO THE SOUTH. THE INITIAL INTENSITY 
IS ASSESSED AT 35 KNOTS BASED ON RECENT ASCAT DATA AND SMAP DATA, AND 
IS HEDGED ABOVE THE SUBJECTIVE DVORAK ESTIMATES.

INITIAL WIND RADII BASIS: SMAP DATA 

CURRENT STEERING MECHANISM: NEAR-EQUATORIAL RIDGE (NER) ENTRENCHED
TO THE NORTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   PHFO: T1.5 - 25 KTS
   CIMSS ADT: 31 KTS AT 062340Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: TROPICAL CYCLONE (TC) 11P IS FORECASTED TO
TRACK SOUTHEASTWARD THROUGH TAU 24 ALONG THE SOUTHERN PERIPHERY OF
THE NER BUT IS EXPECTED TO TURN SOUTHWARD AND SLOW AS IT ENCOUNTERS
A BROAD LOW-LEVEL HIGH POSITIONED TO THE SOUTH. THIS HIGH WILL
EFFECTIVELY BLOCK POLEWARD PROGRESSION AND STEER THE SYSTEM SLOWLY
WESTWARD BY TAU 72. TC 11P WILL CONTINUE TO INTENSIFY THROUGH TAU
24 DUE TO ROBUST POLEWARD OUTFLOW INTO THE SUBTROPICAL JET AND WARM
SST (30-31 C) VALUES. THE PEAK INTENSITY WILL OCCUR NEAR TAU 24 AT
40 KNOTS. AFTER TAU 24, THE SYSTEM WILL APPROACH THE NORTHEAST
PERIPHERY OF A STRONG UPPER-LEVEL LOW, WHICH WILL LEAD TO A STEADY
WEAKENING TREND, WITH INCREASING VERTICAL WIND SHEAR. AS THE SYSTEM
STALLS AFTER TAU 48, THE STRONG UPPER-LEVEL LOW AND ITS ASSOCIATED
TROUGH WILL SHIFT SOUTH OF THE SYSTEM, WHICH WILL ACCELERATE THE
WEAKENING TREND AND LEAD TO DISSIPATION BY TAU 72.  

MODEL DISCUSSION: WITH THE EXCEPTION OF THE NAVGEM AND THE ECMWF
ENSEMBLE MEAN FORECASTS, NUMERICAL MODEL GUIDANCE IS IN GOOD
AGREEMENT THROUGH TAU 24 DIVERGING SIGNIFICANTLY THROUGH THE
REMAINDER OF THE FORECAST PERIOD. THE 061200Z GFS ENSEMBLE (GEFS)
AND 061800Z ECMWF ENSEMBLE (EPS) REVEAL A SIMILAR SPREAD OF
SOLUTIONS WITH A SQUASHED SPIDER PATTERN AFTER TAU 24, WITH
SOLUTIONS FANNING OUT. THE BULK OF THE SOLUTIONS TURN THE SYSTEM
WESTWARD AFTER TAU 48, WHICH FITS WITH THE JTWC TRACK FORECAST
PHILOSOPHY.     

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