WDPS31 PGTW 100900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 13P (KOJI) WARNING NR 
001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.0S 148.1E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 132 NM EAST OF CAIRNS, AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE (TC) 13P (KOJI) WITH A BROAD WIND FIELD AND IMPROVING
CONVECTIVE BANDING ALONG THE NORTHERN SEMICIRCLE. 13P CONTINUES TO
HAVE A CORE OF WEAKER WINDS WITH STRONGER WINDS ALONG THE
PERIPHERY. OVER THE PAST 6 HOURS DEEP CONVECTION HAS STARTED
FORMING CLOSER TO THE CENTER OF THE SYSTEM AND THE RADIUS OF MAX
WINDS HAS CONTRACTED, INDICATING A MORE TC-LIKE STRUCTURE. A
100329Z AMSR2 89 GHZ MICROWAVE IMAGE REVEALED FRAGMENTED BANDS OF
DEEP CONVECTION DISPLACED FROM THE CENTER, DISPLAYING THE BROAD
NATURE OF THE SYSTEM. THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON THE ANIMATED MSI AND EXTRAPOLATION FROM THE
AFOREMENTIONED AMSR2 MICROWAVE IMAGE. THE INITIAL INTENSITY OF 40
KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED PRIMARILY ON NEARBY
SURFACE OBSERVATIONS FROM WILLIS ISLAND AND FLINDERS REEF. AGENCY
DVORAK ESTIMATES ARE SLIGHTLY UNDERESTIMATING THE CURRENT INTENSITY
DUE TO THE GENERALLY WEAK CONVECTIVE SIGNATURE COMPARED TO THE
SURFACE CIRCULATION STRENGTH.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: RIDGING TO THE EAST AND SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   KNES: T2.5 - 35 KTS
   APRF: T2.0 - 30 KTS
   CIMSS D-MINT: 29 KTS AT 100329ZZ
   CIMSS D-PRINT: 24 KTS AT 100600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: BROAD WIND FIELD

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: TC 13P IS FORECAST TO TRACK
SOUTH-SOUTHWESTWARD THROUGH TAU 24 WITH LANDFALL CURRENTLY EXPECTED
TO OCCUR JUST BEFORE TAU 24, NEAR TOWNSVILLE CITY. THE 34-KNOT WIND
RADII IS EXPECTED TO SLIGHTLY CONTRACT, BUT WILL REMAIN LARGE
THROUGHOUT THE TIME OF LANDFALL, CAUSING GALE-FORCE WINDS TO IMPACT
A RELATIVELY LARGE PORTION OF THE QUEENSLAND COAST. AFTER MAKING
LANDFALL, 13P IS FORECAST TO TURN WESTWARD AS A SUBTROPICAL RIDGE
CENTERED OVER WESTERN AUSTRALIA BEGINS TO INTERACT WITH THE SYSTEM.
REGARDING INTENSITY, 13P IS FORECAST TO MAINTAIN INTENSITY THROUGH
THE TIME OF LANDFALL BEFORE TERRAIN INTERACTION BECOMES A FACTOR.
13P IS FORECAST TO WEAKEN BELOW 35 KTS AROUND TAU 36 AS THE SYSTEM
TRACKS FURTHER INLAND INTO THE QUEENSLAND REGION. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT WITH NO SIGNIFICANT OUTLIERS THROUGHOUT THE FORECAST
PERIOD. CROSS-TRACK SPREAD NEAR THE TIME OF LANDFALL IS AROUND 75
NM, WITH ECMWF BEING THE NORTHERNMOST MODEL AND GALWEM BEING THE
SOUTHERNMOST. THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE
MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE. INTENSITY GUIDANCE
GENERALLY AGREES ON A STAGNANT INTENSITY THROUGH TAU 12 BEFORE
STEADY WEAKENING. THE JTWC INTENSITY FORECAST IS ALSO PLACED NEAR
THE CONSENSUS WITH HIGH CONFIDENCE. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: HIGH//
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