WDPS31 PGTW 012100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 07P (KIRRILY)   
WARNING NR 012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.3S 139.5E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 41 NM SOUTH-SOUTHEAST OF MORNINGTON
                         ISLAND, AUSTRALIA
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 01 KTS
   SIGNIFICANT WAVE HEIGHT: 11 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
DESPITE THE SYSTEM'S LOCATION ALONG THE SOUTHERN COAST OF THE GULF
OF CARPENTARIA AND THE ASSOCIATED FRICTIONAL EFFECTS, ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A CONSOLIDATING
SYSTEM WITH A CENTRAL DENSE OVERCAST FEATURE PERSISTING AND
BUILDING OVER THE LOW-LEVEL CIRCULATION; SPIRAL BANDING HAS ALSO
IMPROVED ESPECIALLY OVER THE NORTHERN SEMICIRCLE. UPPER-LEVEL
CONDITIONS HAVE IMPROVED WITH DECREASING (10 KNOTS) EASTERLY
VERTICAL WIND SHEAR. ANIMATED RADAR IMAGERY DOES NOT REVEAL AN
EXACT CENTER LOCATION; HOWEVER, THE OVERALL BANDING STRUCTURE IS
WELL-ORGANIZED WITH MULTIPLE BANDS WRAPPING INTO THE CENTER. THE
INITIAL POSITION IS BASED LARGELY ON ANIMATED RADAR IMAGERY AS WELL
AS SURFACE OBSERVATIONS FROM MORNINGTON ISLAND AND BURKETOWN
AIRPORT. SURFACE OBSERVATIONS FROM MORNINGTON ISLAND RANGE FROM
32-34 KNOTS SUSTAINED (10-MINUTE AVERAGE) WITH GUSTS 43-47 KNOTS.
WHEN ADJUSTED TO A 1-MINUTE AVERAGE, THESE SUSTAINED WINDS RANGE
FROM ABOUT 34-36 KNOTS. PEAK SUSTAINED WINDS OCCURRED AT 011200Z
WITH WEST-NORTHWESTERLY SUSTAINED WINDS AT 40 KNOTS (10-MINUTE
AVERAGE). MINIMUM SLP VALUES WERE AROUND 992 MB, WHICH CORRESPONDS
TO A 40-KNOT INTENSITY USING THE STANDARD WIND PRESSURE
RELATIONSHIP. BASED ON THE SURFACE OBSERVATIONS, SLP VALUES AND THE 
OVERALL CONVECTIVE STRUCTURE, THE INITIAL INTENSITY IS ASSESSED AT 40 
KNOTS WITH MEDIUM CONFIDENCE.

INITIAL WIND RADII BASIS: SURFACE OBSERVATIONS

CURRENT STEERING MECHANISM: WEAK STEERING ENVIRONMENT HAS RESULTED
IN A QUASI-STATIONARY TRACK MOTION OVER THE PAST 12 HOURS.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS

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

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 07P IS EXPECTED TO TRACK
SLOWLY SOUTHWARD THROUGH THE FORECAST PERIOD UNDER THE STEERING
INFLUENCE OF A WEAK STEERING RIDGE TO THE EAST AND SOUTHEAST. THE
SYSTEM IS EXPECTED TO WEAKEN SLOWLY AS IT APPROACHES THE COAST AND
SHOULD TRACK INLAND AND DISSIPATE BY TAU 24. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT 
LENDING MEDIUM CONFIDENCE IN THE JTWC TRACK FORECAST. RELIABLE 
INTENSITY GUIDANCE SUPPORTS THE GRADUAL WEAKENING TREND EXCEPT FOR 
HAFS-A, WHICH SHOWS A SLIGHT INTENSIFICATION TO 48 KNOTS BY TAU 12.    

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