WDXS31 PGTW 072100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 11S (FREDDY) WARNING NR 
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.9S 115.3E
   INITIAL INTENSITY: 95 KTS
   GEOGRAPHIC REFERENCE: 449 NM NORTH OF LEARMONTH, AUSTRALIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A COMPACT
SYSTEM THAT HAS SLIGHTLY DEEPENED AS FEEDER BANDS TRAILING FROM
THE SOUTH WRAPPED TIGHTER INTO THE CENTRAL DENSE OVERCAST. THE 
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON AN
IRREGULAR EYE IN THE EIR LOOP, ADJUSTED FOR TILT AND LINED UP VERY
WELL WITH A CIRCULATION FEATURE IN THE 071431Z ASCAT BULLSEYE PASS.
THE INITIAL INTENSITY IS ALSO ASSESSED WITH HIGH CONFIDENCE AND
HELD SLIGHTLY HIGHER THAN AGENCY AND AUTOMATED DVORAK ESTIMATES,
MORE IN LINE WITH THE OPEN-AIIR INTENSITY ESTIMATOR, AND REFLECTS
THE SLIGHT 6-HR IMPROVEMENT. THE ENVIRONMENT REMAINS FAVORABLE WITH
WARM SSTS, LOW VWS AND MODERATE RADIAL OUTFLOW ALOFT.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   KNES: T5.0 - 90 KTS
   CIMSS ADT: 87 KTS AT 071730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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 WILL CONTINUE ON ITS CURRENT
WEST-SOUTHWESTWARD TRACK OVER THE NEXT 24 HOURS; AFTERWARD, IT WILL
LEVEL OFF ON A MORE WESTWARD TRAJECTORY AS THE STEERING STR BUILDS
AND EXTENDS WESTWARD. THE FAVORABLE ENVIRONMENT WILL FUEL A SLIGHT
INTENSIFICATION TO A PEAK OF 100KTS BY TAU 12. AFTERWARD, A
QUASI-EQUILIBRIUM IN THE ENVIRONMENTAL DYNAMICS WILL MOSTLY
MAINTAIN THE INTENSITY AROUND 90KTS UP TO TAU 120. 

MODEL DISCUSSION: NUMERICAL TRACK MODELS ARE IN TIGHT AGREEMENT
WITH A GRADUAL SPREADING TO 150NM BY TAU 120 WITH NAVGEM THE SOLE
LEFT-OF-TRACK OUTLIER. UP TO TAU 72, THERE IS HIGH CONFIDENCE IN
THE JTWC TRACK FORECAST THAT IS LAID JUST TO THE RIGHT OF CONSENSUS
TO OFFSET NAVGEM. AFTER TAU 72, THE TRACK CONFIDENCE IS MEDIUM AS
THE SPREAD WIDENS. THE INTENSITY FORECAST IS MEDIUM UP TO TAU 72
THEN LOW AFTERWARD DUE TO THE UNCERTAINTY IN THE FORECAST INTENSITY
DYNAMICS IN THE EXTENDED PERIOD.

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