WDXS31 PGTW 061500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 11S (FREDDY) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.6S 118.5E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 383 NM NORTHWEST OF BROOME, AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE 11S, NOW NAMED FREDDY, HAS CONTINUED TO
CONSOLIDATE AND RAPIDLY INTENSIFY UNDER FAVORABLE CONDITIONS.
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A VERY
COMPACT CENTRAL DENSE OVERCAST (CDO) FEATURE STARTING TO SEPARATE
FROM AND BECOME MORE DISTINCT FROM THE STATIONARY BANDING COMPLEX
(SBC) THAT IS TAILING OFF TO THE SOUTH OF THE CENTER. WHILE
CONVECTION IS STILL SOMEWHAT DISORGANIZED AND THE HOT TOWERS HAVE
YET TO ROTATE UPSHEAR, THE SYSTEM IS STILL COMING TOGETHER NICELY.
A 061210Z AMSU-B 89GHZ MICROWAVE IMAGE REVEALED THE ASYMMETRIC
NATURE OF THE CIRCULATION WITH A BAND OF DEEP CONVECTION WRAPPING
UP THE WESTERN SIDE AND INTO THE DEVELOPING CORE, WITH A LARGE
MOAT, DEVOID OF CONVECTION ENTRENCHED TO THE SOUTHEAST. THE INITIAL
POSITION IS ASSESSED WITH MEDIUM CONFIDENCE AND IS PLACED JUST
SOUTH OF THE CDO CENTROID AND AMONGST THE AGENCY FIX POSITIONS. THE
INITIAL INTENSITY IS ASSESSED WITH HIGH CONFIDENCE BASED ON A
CONGRUENCE OF THE BULK OF AGENCY FIXES, THE ADT, AND A 060946Z SMOS
AND 060949Z SMAP WHICH SHOWED A MAX OF 39 KNOTS (CONVERTED TO
1-MIN). THE AIDT AND OTHER OBJECTIVE METHODS ARE QUITE A BIT LOWER,
STRUGGLING WITH THE SMALL SIZE OF THE SYSTEM. THE ENVIRONMENT
REMAINS HIGHLY FAVORABLE FOR CONTINUED RAPID INTENSIFICATION (RI)
WITH JUICY SSTS (29-30C), LOW (0-10) VERTICAL WIND SHEAR (VWS) AND
THE PRESENCE OF A SMALL POINT SOURCE ALOFT WHICH IS PROVIDING
MODERATE RADIAL OUTFLOW TO THE SYSTEM.

INITIAL WIND RADII BASIS: SMAP AND SMOS DATA

CURRENT STEERING MECHANISM: NORTHWEST PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE SOUTH.

AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   APRF: T3.0 - 45 KTS
   CIMSS ADT: 43 KTS AT 061130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC FREDDY CONTINUES ITS RATHER IMPRESSIVE
INTENSIFICATION TREND, HAVING BEEN A WEE LAD OF JUST 25 KNOTS ONLY
24 HOURS AGO. THE SYSTEM CONTINUES TO MOVE SLOWLY TOWARDS THE
SOUTHWEST ALONG A WEAK STEERING GRADIENT ON THE NORTHWEST SIDE OF A
BUILDING STR CENTERED ALONG THE WESTERN COAST OF AUSTRALIA. THE
SYSTEM WILL TRACK IN A GRACEFUL ARC, BECOMING INCREASINGLY
WEST-SOUTHWESTWARD THROUGH THE FIRST 48 HOURS. AFTER TAU 72, THE
STR FLATTENS OUT AND MERGES INTO A LARGER RIDGE COMPLEX THAT
EXTENDS ALONG ROUGHLY 25S FROM 90E TO CENTRAL AUSTRALIA, WHICH WILL
RESULT IN A TRACK JUST SOUTH OF DUE WEST THROUGH THE REMAINDER OF
THE FORECAST PERIOD. CONDITIONS REMAIN NEARLY OPTIMAL FOR CONTINUED
RAPID INTENSIFICATION (RI). LATE RECEIPT OF A 061357Z GMI 37GHZ
MICROWAVE IMAGE SUGGESTS THE SYSTEM IS STILL NOT VERTICALLY
ALIGNED, WITH THE LOW LEVEL CIRCULATION CENTER (LLCC) DISPLACED TO
THE SOUTHEAST OF THE CDO AND THE DEEP CONVECTIVE BANDS ARE NOT YET
COMPLETELY ENCLOSING THE LLCC. WHILE THERE REMAINS WORK TO BE DONE
TO FURTHER DEVELOP THE CORE, THIS DOES NOT CHANGE THE INTENSITY
FORECAST. THE SYSTEM HAS ABOUT 48 HOURS WHERE ENVIRONMENTAL
CONDITIONS WILL BE PRIME FOR RI. THE MESOSCALE POINT SOURCE ALOFT
AND LOW SHEAR (LESS THAN 15 KTS) ARE EXPECTED TO PERSIST THROUGH
TAU 48, WHILE THE SYSTEM MOVES OVER A HIGH OHC POOL BETWEEN TAU 24
TO 36. THESE CONDITIONS WILL FUEL RI TO A PEAK OF AT LEAST 100
KNOTS, THOUGH SOME MODELS SUGGEST AND EVEN HIGHER PEAK INTENSITY.
SHEAR STARTS TO PICK UP AT TAU 48, AND AROUND TAU 60, HIGH
RESOLUTION MODELS SUGGEST A PUNCH OF MID-LEVEL DRY AIR AND ELEVATED
SHEAR WILL DISRUPT THE INNER CORE OF THE SYSTEM, WHICH WILL LEAD TO
A SIGNIFICANT WEAKENING THROUGH TAU 72. CONDITIONS ARE EXPECTED TO
IMPROVE AGAIN AFTER TAU 72, ENABLING REINTENSIFICATION THROUGH THE
REMAINDER OF THE FORECAST PERIOD. SOME GUIDANCE SUGGESTS A MORE
POLEWARD TRACK WHICH TAKES THE SYSTEM OVER COOL (24-26C) WATERS,
WHICH IF BORNE OUT WILL LEAD TO STEADY WEAKENING AFTER TAU 96.

MODEL DISCUSSION: THROUGH THE FIRST 72 HOURS OF THE FORECAST,
DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN GOOD AGREEMENT,
WITH ALL CONSENSUS MEMBERS ENCASED WITHIN A 70NM WIDE ENVELOPE,
LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK IN THIS
TIMEFRAME. AFTER TAU 72, THE MODELS ARE INDICATING THE BEGINNINGS
OF A BIFURCATION, WITH THE NAVGEM, GFS, GEFS AND HWRF DEVIATING TO
THE SOUTH, THE HWRF POSITIONING THE SYSTEM NEAR 20S AT TAU 120,
WHILE THE ECMWF, ECENS, UKMET AND UKMET ENSEMBLE, TAKE THE SYSTEM
ON A FLATTER TRAJECTORY ALONG 15S AND THE CONSENSUS SPLITS THE
DIFFERENCE. THE JTWC FORECAST HEDGES TOWARDS THE US MODELS ON A
MORE SOUTHERLY TRACK, WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS
IN FAIRLY GOOD AGREEMENT AS WELL. RI AIDS INCLUDING CTR1, FRIA,
RIPA, RICN AND THE BULK OF THE RI25-RI45 AIDS CONTINUE TO BE
TRIGGERED. NOT SURPRISINGLY THE GLOBAL MODELS ARE LESS EXCITED
ABOUT TC 11S, WITH PEAKS BELOW 75 KNOTS, WHILE THE MESOSCALE MODELS
ARE MORE AGGRESSIVE AND SUPPORTIVE OF THE JTWC FORECAST. ALL MODELS
SUGGEST A PEAK AROUND TAU 48, FOLLOWED BY WEAKENING AND EITHER A
FLAT LINE OR SLIGHT INTENSIFICATION THEREAFTER. THE JTWC FORECAST IS
CONSISTENT WITH THE RI AIDS THROUGH TAU 48 THOUGH PEAKS SLIGHTLY
HIGHER THAN MOST, THEN TRACKS THE CONSENSUS MEAN THEREAFTER.  

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