WDXS32 PGTW 220900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 06S (SIX) 
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.8S 129.1E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 107 NM WEST OF DARWIN, AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICT A QUICKLY
ORGANIZING CYCLONE OVER THE PAST SIX HOURS. DEEP CONVECTION HAS
BECOME PERSISTENT AND MORE CONCENTRATED NEAR THE LOW-LEVEL
CIRCULATION CENTER (LLCC), WITH A CIRCULAR CONVECTIVE BURST
RECENTLY FORMING OVER AND TO THE NORTHWEST OF THE CENTER. ANIMATED
RADAR IMAGERY FROM AUSTRALIA SHOWS THAT A NEW, COMPACT INNER
CORE IS FORMING, WITH A TIGHTLY WRAPPED BAND OF CONVECTION AROUND
THE LLCC FORMING A NEARLY CLOSED RING WITH A RADIUS OF ABOUT 15 NM.
THIS STRUCTURE IS INDICATIVE OF POTENTIALLY QUICK INTENSIFICATION
BEING UNDERWAY. A 212111Z SMAP PASS SHOWED 25-30 KT WINDS AROUND
THE LLCC, AND SUSTAINED SURFACE WINDS OBSERVED AT POINT FAUCETT AND
DARWIN WELL EAST OF THE CENTER HAVE BEEN AS HIGH AS 26 KT DURING
THE PAST FEW HOURS. DUE TO THE RAPIDLY IMPROVING CONVECTIVE
ORGANIZATION, THE INITIAL INTENSITY IS SET AT 35 KT, SUPPORTED BY
AN ADRM DVORAK ESTIMATE OF T2.5 (35 KT). OTHER DVORAK ESTIMATES
REMAIN LOWER, LAGGING BEHIND THE RAPID ORGANIZATION OF THE CYCLONE.

INITIAL WIND RADII BASIS: OTHER 

CURRENT STEERING MECHANISM: MID-LEVEL RIDGE OVER QUEENSLAND,
AUSTRALIA

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.0 - 25 KTS
   ADRM: T2.5 - 35 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TROPICAL CYCLONE 06S (SIX) HAS FORMED OVER THE
VERY WARM WATERS OF THE TIMOR SEA, 30 TO 31 DEGREES CELSIUS.
VERTICAL WIND SHEAR IS UNDER 15 KT, AND THE ENVIRONMENT IS
GENERALLY MOIST. WITHIN THIS FAVORABLE ENVIRONMENT, THE SHORT-TERM
INTENSITY EVOLUTION IS THUS EXPECTED TO DEPEND ON THE INTERNAL
STRUCTURE OF THE VORTEX, WHICH IS IN THE PROCESS OF DEVELOPING A
NASCENT, COMPACT INNER CORE. SUCH A STRUCTURE COULD LEAD TO RAPID
INTENSIFICATION IF CURRENT TRENDS CONTINUE. HOWEVER, THE CYCLONE
HAS LIMITED TIME OVER THE WATER OF THE JOSEPH BONAPARTE GULF BEFORE
MOVING ASHORE IN THE NORTHERN TERRITORY OF AUSTRALIA IN UNDER 24
HOURS. LANDFALL COULD OCCUR EVEN SOONER IF THE CYCLONE DEVIATES
MORE SOUTHEASTWARD THAN FORECAST. A MID-LEVEL RIDGE OVER QUEENSLAND
IN COMBINATION WITH AN UPPER-LEVEL TROUGH OVER WESTERN AUSTRALIA IS
CURRENTLY DIRECTING 06S SOUTHWARD, AND THIS GENERAL MOTION IS
EXPECTED TO CONTINUE DURING THE NEXT 5 DAYS AS THE CYCLONE MOVES
SLOWLY INLAND. THE JTWC INTENSITY FORECAST PEAKS AT 50 KT NEAR THE
TIME OF LANDFALL AT OR BEFORE 24 HOURS, ANTICIPATING THE CURRENT
RAPID ORGANIZATION OF THE CYCLONE TO CONTINUE UNTIL THAT TIME. THIS
FORECAST IS ABOVE THE MULTI-MODEL CONSENSUS, WHICH CONSISTS OF
SEVERAL MODELS THAT UNDERREPRESENT THE CURRENT INTENSITY OF 06S.
FOLLOWING LANDFALL, GRADUAL DECAY IS FORECAST, THOUGH THE VORTEX
MAY SURVIVE FOR MULTIPLE DAYS AS IT TRACKS DEEPER INTO AUSTRALIA.
DISSIPATION IS EXPECTED BY 120 HOURS BY MOST GLOBAL MODELS, AND
THUS BY THE JTWC FORECAST AS WELL.

MODEL DISCUSSION: THE JTWC TRACK FORECAST IS CLOSE TO THE
MULTI-MODEL CONSENSUS. THE JTWC INTENSITY FORECAST IS ABOVE THE
MULTI-MODEL CONSENSUS THROUGH 24 HOURS, THEN CLOSE TO THE CONSENSUS
THEREAFTER.

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