WDXS31 PGTW 120300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 29S (TWENTYNINE) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 11.2S 127.5E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 214 NM WEST-NORTHWEST OF DARWIN, AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
A 120019Z ASCAT HOT OFF THE PRESS CONFIRMS 35-40KT PEAK WINDS OVER
THE SOUTHWEST QUADRANT. THE SYSTEM HAS NOT DEEPENED APPRECIABLY
DURING THE PAST SIX HOURS BUT HAS ALSO NOT WEAKENED DURING A PERIOD
TRENDING TOWARDS THE DIURNAL MINIMUM. BOTH ANIMATED WATER VAPOR AND
MULTISPECTRAL IMAGERY SHOW THE SYSTEM STRUGGLING BUT HOLDING ITS
OWN AGAINST 20KTS OF EAST-NORTHEASTERLY SHEAR, ALTHOUGH THE
FREQUENCY OF LIGHTING STRIKES IN THE SOUTHWEST QUADRANT HAS WANED
SUBSTANTIALLY OVER THE PAST THREE HOURS. 40KTS IS ON THE GENEROUS
SIDE OF AN OVERALL 35-40KT ASSESSMENT BUT THE APRF FIX IS UP TO
T3.0 AND THE FIRST ADT HITS HAVE ALSO BEEN ABOVE 40KTS. THE
INTENSITY IS BASED HEAVILY ON THE SCATTEROMETRY AND THE JTWC DVORAK
OF T2.5 AND THEN HEDGED UP A NOTCH DUE TO THE HIGHER DVORAKS FROM
APRF AND KNES AS WELL AS SOME OF THE CIMSS OBJECTIVE ASSESSMENTS. 
PLACEMENT OF THE LLCC CONTINUES TO BE AT THE UPSHEAR EDGE OF THE
COLD DARK GREY RING IN IRBDE IMAGERY. THE SCATTEROMETRY REVEALS A
LOP-SIDED SYSTEM LACKING VIGOROUS WESTERLIES OVER THE EQUATORWARD
SEMICIRCLE.  SUFFICIENT SPIN IS ONLY DUE TO A BOOST PROVIDED FROM A
LAZY MJO TRACKING THROUGH THE MARITIME CONTINENT, ALTHOUGH A SOLID
STREAM OF EAST SOUTHEASTERLIES EXTENDS OVER THE TOP END AND NORTHERN 
TERRITORY TO PROVIDE VORTICITY FROM THE POLEWARD SIDE. THE 
ENVIRONMENT IS SATURATED AND TPW LOOPS INDICATE THE SYSTEM IS 
CARRYING SOME OF ITS MOISTURE WITH IT, WHICH WILL BE NEEDED BECAUSE 
THE WATERS OFF-SHORE OF THE PILBARA COAST ARE SURPRISINGLY DRY. THE 
CURRENT SOUTHWESTERLY BEARING IS TAKING THE SYSTEM AWAY FROM THE 
WORST OF THE SHEAR AND ALONG A TRACK OF GRADUALLY DECREASING SHEER 
AND TOWARDS THE AXIS OF THE SUBTROPICAL RIDGE, WHICH EXTENDS ALONG 
THE 15TH LATITUDE AND IS ANCHORED IN AN ANTICYCLONE OVER THE EASTERN 
SIDE OF THE GULF OF CARPENTARIA. OUTFLOW REMAINS DECENT OVERALL BUT 
HAS ALSO BECOME LESS VIGOROUS DURING THE PAST FEW HOURS. 30-31 DEGREE 
SEA SURFACE TEMPERATURES WITH EXTREMELY HIGH OCEAN HEAT CONTENT ARE 
THE BEST THINGS GOING FOR THIS SYSTEM WHILE VERTICAL WINDSHEAR 
REMAINS ITS BIGGEST IMPEDIMENT.

INITIAL WIND RADII BASIS: A 120019Z ASCAT 25KM. 

CURRENT STEERING MECHANISM: STEERING IS CONFINED TO A RELATIVELY
NARROW CHANNEL BETWEEN AN UPPER LEVEL RIDGE EXTENDING FROM THE TOP
OF THE YORK PENINSULA TOWARDS THE MOLUCCAS AND A WARM RIDGE
EXTENDING FROM THE GIBSON DESERT OVER EXMOUTH AND FURTHER SEAWARD
FROM THERE.  


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T3.0 - 45 KTS
   APRF: T3.0 - 45 KTS
   CIMSS SATCON: 40 KTS AT 112244Z
   CIMSS ADT: 43 KTS AT 112340Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 18-22 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: WEAK RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 29S IS STILL EXPECTED TO INTENSIFY STEADILY
ALONG ITS SOUTHWESTWARD TRACK BEFORE SWITCHING STEERING FORCES AND
CURLING MORE WESTWARD NEAR TAU 48. THE POTENTIAL FOR RAPID
INTENSIFICATION IS STILL ON THE TABLE AND SOME RI MODELS TRIGGERED
DURING THE LAST CYCLE, BUT DUE TO THE WANING MJO INFLUENCE COUPLED
WITH THE LACK OF MOISTURE UPSTREAM AND VERTICAL WINDSHEAR THAT
NEVER QUITE EASES, THE FORECAST IS HELD TO LOW TYPHOON STRENGTH.
TPW LOOPS SHOW A GENERAL DEARTH OF DEEP MOISTURE IN THE NORTHEAST
INDIAN OCEAN SOUTH OF 10S AND 12-18KTS OF DEEP LAYER SHEAR. 200MB
CHI ANOMALIES ALSO INDICATE AN EASTWARD SHIFT IN DIVERGENCE ALOFT
AWAY FROM THE STORM, SO THE CURRENT ENVIRONMENT MAY BE AS GOOD AS IT 
GETS FOR TC 29S. 


MODEL DISCUSSION: THE GFS TRACKER AND INTENSITY AID DID NOT COME IN
THIS CYCLE. THE SUDDEN REEMERGENCE OF THREE RAPID INTENSIFICATION
TRIGGERS IS DISTURBING BUT CONTRARY TO EVERYTHING THE STORM IS
EXHIBITING. BOTH RI TRIGGERS AND HAFS-A HAVE BEEN FLIP-FLOPPING
ERRATICALLY FOR TWO DAYS NOW SO IT IS A FAIRLY EASY MATTER TO
DISCOUNT THEM FOR THE TIME BEING. THE EXTENDED INTENSITY GUIDANCE
IS NOW HINTING AT A DISSIPATION OVER WATER TREND TOWARDS TAU 120.
TRACK GUIDANCE IS FINE AND THE JTWC TRACK REMAINS TIGHT WITH THE
MULTI-MODEL CONSENSUS AND SLIGHTLY HEDGED TOWARDS THE ECMWF
ENSEMBLE MEAN. WITH EACH SUCCESSIVE RUN THE CONVICTION THAT THE
STORM WILL REMAIN WELL OFF-SHORE THROUGH ITS LIFECYCLE INCREASES. 

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