WDXS31 PGTW 212100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05S (FINA) WARNING NR 
015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 11.7S 131.8E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 71 NM NORTHEAST OF DARWIN, AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE FINA (05S) HAS CROSSED THE COBOURG PENINSULA AND
IS TRACKING THROUGH THE VAN DIEMEN GULF WHILE INTENSIFYING, ON A
TRACK THAT WILL TAKE THE SYSTEM PERILOUSLY CLOSE TO DARWIN. ANIMATED
WATER VAPOR IMAGERY SHOWS EQUATORWARD OUTFLOW IMPROVING AND
VERTICAL WIND SHEAR EASING, ESPECIALLY OVER THE NORTHEAST QUADRANT,
WHERE THE SYSTEM HAD BEEN FIGHTING THE SHEAR FOR THE PAST 48 HOURS.
THERE IS STILL MODERATE MID-LEVEL SHEAR FROM THE NORTH, BUT OVERALL
THE SYSTEM IS MOVING INTO A MORE FAVORABLE ENVIRONMENT AND THE
ORGANIZATION AND VIGOR HAVE VISIBLY IMPROVED OVER THE PAST 12
HOURS. THE CURRENT INTENSITY ASSESSMENT IS BASED ON THE JTWC DVORAK
OF T4.0 AND THEN RAISED A NOTCH DUE TO SURGING ADT RAW AND AIDT
VALUES AND ESPECIALLY A JUMP IN THE DMINT VALUES WITH THE 211611
AMSR-2 PASS. THE COLOR 37-89 IMAGES SHOW SOME OMINOUS SIGNS OF EVEN
MORE THAN THE 76KT ESTIMATE, BUT THE SYSTEM WAS TRACKING OVER THE
COBOURG PENINSULA AT THE TIME AND ALL OTHER DATA SHOWED A MUCH
LOWER INTENSITY, SO THE MICROWAVE SIGNATURE IS BEING DISCOUNTED
SOMEWHAT FOR THE MOMENT. THE MICROWAVE SIGNATURE IS SO STRONG, 
HOWEVER, THAT IT HAS ACTED AS A CONFIDENCE WRECKER AND THE SYSTEM IS 
BEING WATCHED WARILY FOR ANOTHER SIGN OF INTENSIFICATION. ANOTHER 
FACTOR IN SITTING TIGHT FOR ANOTHER CYCLE IS THAT TC 05S IS MOVING OUT 
OF THE DIURNAL MAXIMUM PHASE AND INTO THE WINDOW OF AVAILABLE VISUAL 
IMAGERY, SO AT WORST CASE THE ANALYSIS WILL LAG FOR ONE CYCLE.

INITIAL WIND RADII BASIS: 211247Z ASCAT.

CURRENT STEERING MECHANISM: THE SUBTROPICAL RIDGE, WHICH IS ANCHORED
OVER THE CONTINENT NEAR 20S 140E IS KEEPING THE SYSTEM OFF-SHORE. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   ADRM: T3.5 - 55 KTS
   CIMSS ADT: 72 KTS AT 211730Z
   CIMSS AIDT: 75 KTS AT 211730Z
   CIMSS D-MINT: 76 KTS AT 211611Z
   CIMSS D-PRINT: 66 KTS AT 211900Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: LAND INTERACTION ON EITHER SIDE AS THE SYSTEM
TRACKS BETWEEN MELVILLE ISLAND AND THE TOP END. 

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: A 120 HOUR POSITION HAS BEEN ADDED TO
THE FORECAST AS THE LATEST GUIDANCE INDICATES THE SYSTEM MAY TAKE
24 HOURS TO DISSIPATE OVER THE SANDY SOILS OF THE NORTHERN
TERRITORY, ESPECIALLY AS THE RAIN BANDS AHEAD OF THE SYSTEM ADD
MOISTURE TO THE HEAT BATTERY.  

FORECAST DISCUSSION: THE VORTEX OF TROPICAL CYCLONE 05S MAY REMAIN
NARROWLY OFF-SHORE OF DARWIN BUT THE WIND FIELDS AND RAINFALL WILL
BE VIGOROUS AS THE SYSTEM PASSES. A GRADUAL EASING OF VERTICAL WIND
SHEAR WILL ALLOW THE SYSTEM TO SUSTAIN DEVELOPMENT THROUGH THE NEXT
48 HOURS BEFORE INCREASING DRY AIR ENTRAINMENT BEGINS TO WEAKEN THE
SYSTEM PRIOR TO LANDFALL. TOTAL PRECIPITABLE WATER LOOPS ARE
ALREADY SHOWING THAT THE SOUTHEASTERLIES FLOWING INTO THE SYSTEM
FROM OVER THE CONTINENT ARE ALREADY HAVING AN EFFECT ON THE
MOISTURE CONTENT OVER THE SOUTHERN HEMISPHERE OF THE STORM, AND
700-300MB COLUMN MOISTURE PROGS INDICATE THE SYSTEM WILL BE
SURROUNDED BY DRY AIR AND LIMITED TO A SMALL CORE OF MOISTURE BY
THE TIME IT MAKES LANDFALL NORTH OF WYNDHAM. THE SYSTEM IS EXPECTED
TO COME ASHORE OVER THE WESTERN PART OF THE JOSEPH BONAPARTE GULF
AND THEN DISSIPATE AT A SLOW RATE DUE TO THE BROWN OCEAN EFFECT. 

MODEL DISCUSSION: TRACK GUIDANCE IS TIGHT THROUGH THE FIRST 24
HOURS BUT THEN SPREADS TO A HIGHER DEGREE THAN USUAL AS THE SYSTEM
MOVES INTO THE JOSEPH BONAPARTE GULF, THEN SPREADS EVEN FURTHER IN
THE EXTENDED RANGE. THE MORE HIGHLY SKILLED TRACKERS AND NEWER AI
TRACKERS, WHICH HAD A GOOD RUN IN THE WESTERN PACIFIC THIS PAST
SEASON, DIVERGE TO THE SOUTH AND TAKE THE SYSTEM INLAND IN A
DISSIPATION SCENARIO. ONLY ONE ENSEMBLE (GEFS) KEEPS THE SYSTEM OVER
WATER THROUGH THE ENTIRE FORECAST. CONFIDENCE IN THE TRACK FORECAST
AFTER TAU 72 PLUNGES TO A LEVEL FAR LOWER THAN AVERAGE.  THE
INTENSITY GUIDANCE FOLLOWS A SMOOTH AND COHERENT SLOPE WITH JTWC
STAYING ON THE HIGH END OF CONSENSUS, BUT ALTHOUGH THE POTENTIAL
FOR RAPID INTENSIFICATION (RI) STILL EXISTS, CONSISTENT FALSE 
POSITIVES OVER THE PAST TWO DAYS HAVE RESULTED IN A MORE SKEPTICAL 
OUTLOOK FOR RI.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 00-72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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