WDXS31 PGTW 192100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05S (DARIAN) WARNING 
NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.1S 93.4E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 1304 NM WEST-NORTHWEST OF LEARMONTH,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 27 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE 05S (DARIAN) FLARED UP TO HURRICANE STRENGTH 12
HOURS AGO, BUT HAS SINCE STABILIZED. THE MOST RECENT JTWC DVORAK
ASSESSMENT SWITCHED BACK FROM THE EYE TECHNIQUE TO THE EMBEDDED 
CENTER TECHNIQUE DUE TO SOME EYE FILLING. ANIMATED INFRARED IMAGERY 
SHOWS TOPS WARMING SLIGHTLY AND SOME EROSION OF THE MOISTURE FIELDS 
OVER THE SOUTHEAST QUADRANT. BUT OVERALL, THE SYSTEM REMAINS WELL 
ORGANIZED AND VIGOROUS. A FRESH 191832Z GMI MICROWAVE SERIES VERIFIES 
A ROBUST STORM WITH A SYMMETRICAL MICROWAVE EYE WITH DEEP CONVECTION 
EXTENDING FROM THE SOUTHERN PORTION OF THE EYEWALL UP INTO THE 
NORTHWESTERN QUADRANT. THE DUE SOUTHWARD MOVEMENT ALSO CONFIRMS THAT 
THE SYSTEM IS LEAVING THE INFLUENCE OF THE NEAR EQUATORIAL RIDGE AND 
BEGINNING THE ARC INTO A LAZY TURN TO THE WEST AS IT COMES UNDER THE 
INFLUENCE OF THE SUBTROPICAL RIDGE. INTENSITY IS SET AT 75 KTS BASED 
ON UNANIMOUS DVORAKS OF T4.5 FROM KNES JTWC AND APRF, AS WELL AS A 
MATCHING RATING FROM ADT. DARIAN IS TRACKING THROUGH A FAVORABLE 
ENVIRONMENT CHARACTERIZED BY WELL DEVELOPED POLEWARD OUTFLOW AND LOW 
VERTICAL WIND SHEAR. SEA SURFACE TEMPERATURE AND OCEAN HEAT CONTENT 
ARE DECENT BUT NOTHING SPECIAL, HENCE THE EXPECTATION THAT TC DARIAN 
WILL NOT INTENSIFY MUCH FURTHER. THE ENVIRONMENT ALONG THE EXPECTED 
TRACK OF TC DARIAN IS EXPECTED TO REMAIN STEADY THROUGH THE NEXT FOUR 
DAYS.

INITIAL WIND RADII BASIS: 191556Z ASCT.

CURRENT STEERING MECHANISM: TC 19S SOUTH IS LEAVING THE INFLUENCE
OF THE NEAR EQUATORIAL RIDGE (NER) AND MOVING INTO A COL BETWEEN
THE NER AND THE SUBTROPICAL RIDGE THAT EXTENDS OVER THE VAST
MAJORITY OF THE SOUTHERN INDIAN OCEAN. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   APRF: T4.5 - 77 KTS
   CIMSS ADT: 74 KTS AT 191740Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: MODERATE OCEAN HEAT CONTENT AND SEA SURFACE
TEMPERATURES ALONG TRACK WITH A SLIGHT IMPROVEMENT EXPECTED ON 23
DECEMBER. 

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: TROPICAL CYCLONE 05S WILL CRUISE ALONG AT A
STEADY STATE IN A REMARKABLY CONSISTENT ENVIRONMENT FOR THE NEXT 96
HOURS.  VERTICAL WIND SHEAR REMAINS BELOW 15 KTS AND WILL NOT BE A
FACTOR. THE STORM IS LEAVING THE INFLUENCE OF THE NEAR EQUATORIAL
RIDGE AND WILL DRIFT POLEWARD UNTIL IT BEGINS TO FEEL A PUSH FROM
THE SUBTROPICAL RIDGE. IT WILL GRADUALLY BEND TO A WESTWARD TRACK
ALONG THE 14TH LATITUDE BY 20DEC1800Z. THERE IS A BRIEF WINDOW FOR
MILD INTENSIFICATION DUE TO ONE DEGREE WARMER SEA SURFACE
TEMPERATURES BEGINNING NEAR TAU 72. DRY AIR ENTRAINMENT WILL PROVIDE
AN ADDITIONAL NUANCE TO THE INTENSITY TREND. MID-LEVEL MOISTURE
PROGS SHOW DRY AIR WRAPPING OVER THE TOP SIDE OF THE SYSTEM AND
COMPLETELY CUTTING OFF THE CORE FROM THE SURROUNDING ENVIRONMENT
DURING THE NEXT 48 HOURS, BUT THEY ALSO INDICATE THAT THE CORE WILL
BE ABLE TO MAINTAIN ITS INTEGRITY AND NEVER QUITE BE ERODED BY THE
DRY AIR.  LONG RANGE MODELS ARE CONSISTENT IN SHOWING A POLEWARD
BEND AFTER TAU 96 BUT THE AMBIGUITY IN THE TRACK FORECAST INCREASES
SHARPLY AS THE SYSTEM NEARS THE 15TH LATITUDE (TAU 96-120).  FOR
THE NEXT FOUR DAYS THOUGH--STEADY ALMOST TO THE POINT OF DULL.     

MODEL DISCUSSION: THERE IS GREATER THAN AVERAGE CROSS-TRACK SPREAD
OF THE VORTEX TRACKERS BUT THEY ALL TELL THE SAME QUALITATIVE
STORY.  THE TRACK FORECAST STAYS IN THE MIDDLE FAVORING THE
MULTI-MODEL CONSENSUS WITH A HEDGE TOWARD THE ECMWF AND GFS
ENSEMBLES. INTENSITY GUIDANCE SHOWS THE SAME WIDER THAN AVERAGE
SPREAD BUT ALSO SHOWS GREAT CONSISTENTLY IS SHOWING A SLIGHT WEAKENING 
TREND THROUGH TAU 48 THEN A SLIGHT INTENSIFICATION THROUGH TAU 96, 
WHERE WE END UP BACK TO WHERE WE STARTED AT TAU 00.  STATISTICAL-
DYNAMICAL GUIDANCE IS ON THE LOWER SIDE OF THE CONSENSUS.  THE 
INTENSITY FORECAST STAYS VERY CLOSE TO CONSENSUS. 

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