WDXS33 PGTW 040900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 14S (TALIAH) WARNING NR 
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.5S 110.9E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 447 NM NORTH-NORTHWEST OF LEARMONTH,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: WESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 38 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RATHER
SMALL-SIZED SYSTEM WITH A WARM SPOT OR DIMPLE FEATURE, WHICH IS
COLLOCATED WITH A NASCENT EYE FEATURE IN THE ANIMATED ENHANCED
INFRARED (EIR) IMAGERY. A 0400624Z NOAA-21 ATMS SERIES INDICATES
THE EYE IS MOSTLY LOCATED IN THE UPPER-LEVELS AS IT SHOWS UP BEST
IN THE 165GHZ AND 183GHZ BANDS AND TO A LESSER DEGREE IN THE 89GHZ
BAND. THE LOWER FREQUENCY BAND ALSO SHOWS THE SYSTEM TO BE
ASYMMETRIC WITH THE CONVECTION BEING MOSTLY LIMITED TO THE NORTHERN
AND WESTERN PORTIONS OF THE CIRCULATION, AND SHALLOW BANDING
FEATURES CAPPED BY DRY AIR IN THE SOUTHEASTERN PORTIONS. THE
INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE
MICROWAVE IMAGERY NOTED ABOVE AND THE CLOUD-FILLED EYE IN THE MSI
AND EIR. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE,
HEDGED HIGHER THAN THE BULK OF THE SUBJECTIVE AND OBJECTIVE
INTENSITY ESTIMATES ABOVE BASED ON AN ANALYSIS OF AN EARLIER
032156Z RCM-3 SAR PASS AND REANALYSIS OF EARLIER INTENSITY
ESTIMATES. THE ENVIRONMENT IS MARGINALLY FAVORABLE, WITH THE
MARGINALITY DERIVED FROM THE CIMSS ESTIMATED SHEAR VALUES OF 33
KNOTS AND THE PRESENCE OF DRY MID-LEVEL AIR TO THE SOUTHEAST.
HOWEVER, THE SHEAR VALUE IS IN QUESTION DUE TO THE SYSTEM
DEVELOPING AN EYE FEATURE WITHOUT SIGNIFICANT UPSHEAR CONVECTION, SO
DEEP-LAYER SHEAR MAY IN FACT BE LESS THAN WHAT IS CURRENTLY
ESTIMATED. OTHERWISE, THE ENVIRONMENT IS FAVORABLE WITH GOOD
WESTWARD OUTFLOW AND WARM SSTS.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: NORTHERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) EXTENDING FROM WESTERN AUSTRALIA TO 100E. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   KNES: T4.0 - 65 KTS
   DEMS: T4.5 - 77 KTS
   APRF: T3.5 - 55 KTS
   CIMSS SATCON: 89 KTS AT 040700Z
   CIMSS ADT: 87 KTS AT 040600Z
   CIMSS AIDT: 74 KTS AT 040600Z
   CIMSS D-MINT: 63 KTS AT 040626Z
   CIMSS D-PRINT: 65 KTS AT 040600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 25-30 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG WESTWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   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 14S (VINCE) WILL CONTINUE TRUCKING ALONG
TOWARDS THE WEST-SOUTHWEST FOR THE NEXT 12 HOURS OR SO. THE
TRAJECTORY IS FORECAST TO FLATTEN OUT TO DUE WEST AFTER TAU 12, AND
CONTINUING THROUGH TAU 48 AS THE RIDGE ORIENTATION ALSO FLATTENS TO
MORE OF AN EAST-WEST AXIS. A DEEP MID-LATITUDE TROUGH WILL PASS BY
TO THE SOUTH AROUND TAU 72, THOUGH IT WILL REMAIN FAR ENOUGH SOUTH
TO NOT INFLUENCE THE TRACK OF TC 14S ALL THAT MUCH, EXCEPT FOR A
BRIEF SLOWDOWN IN TRACK SPEED IN RESPONSE TO A WEAKENED STEERING
GRADIENT. A NEW RIDGE CENTER WILL MOVE IN BEHIND THE TROUGH, THE
ORIENTATION OF WHICH WILL PUSH TC 14S ONTO A MORE
WEST-SOUTHWESTWARD TRACK THROUGH TAU 96. BY THE END OF THE FORECAST
PERIOD, THE SYSTEM WILL BEGIN TO TURN SLIGHTLY MORE SOUTHWARD AS
THE RIDGE STEERING RIDGE STARTS TO WEAKEN AND SHIFT SOUTHWESTWARD,
OPENING UP A LANE FOR TC 14S TO BEGIN A POLEWARD SHIFT. IN TERMS OF
INTENSITY, THE SYSTEM CLEARLY IS OUTPERFORMING EXPECTATIONS TO
DATE, ASSUMING THE SHEAR ESTIMATES ARE EVEN CLOSE TO BEING
ACCURATE, THE SYSTEM IS DOING VERY WELL CONSIDERING THE OBSTACLE IT
FACES IN THE FACE OF THE PERSISTENT EASTERLY SHEAR. THE LATEST EIR
IMAGERY SHOWS DEEP CONVECTION FORMING ON THE NORTHERN SIDE OF THE
CENTER, AND STARTING TO POTENTIALLY WRAP UPSHEAR, SO ANOTHER ROUND
OF INTENSIFICATION MAY BE IN THE OFFING. THE FORECAST CALLS FOR A
SOMEWHAT STEADY STATE FOR THE NEXT DAY OR TWO, AS BURSTS OF
CONVECTION WILL ALLOW THE SYSTEM TO MAINTAIN ITS CURRENT STATE. A
VERY SLOW WEAKENING IS ANTICIPATED BETWEEN TAU 36 AND TAU 72 DUE TO
A REDUCTION IN THE UPPER-LEVEL OUTFLOW. AFTER TAU 72, SHEAR IS
EXPECTED TO LOWER, AND OUTFLOW IS FORECAST TO IMPROVE, BUT THE
SYSTEM WILL BE MOVING OVER THE COOL WAKE FROM TC 13S AND EXPERIENCE
SOME DRY AIR INTRUSION. THUS, THE FORECAST CALLS FOR THE SYSTEM TO
MAINTAIN INTENSITY THROUGH THE END OF THE FORECAST AS COMPETING
ENVIRONMENTAL FACTORS WILL OFFSET ONE ANOTHER. 

MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN
GOOD AGREEMENT WITH A 105NM CROSS-TRACK SPREAD AT TAU 72,
INCREASING SLIGHTLY TO 190NM BY TAU 120. THE ECMWF AND UKMET MARK
THE NORTHERN EDGE OF THE GUIDANCE WHILE THE GFS AND GEFS MARK THE
SOUTHERN EDGE. THE JTWC FORECAST IS PLACED CLOSE TO THE MULTIMODEL
CONSENSUS MEAN WITH HIGH CONFIDENCE. INTENSITY GUIDANCE IS FOR THE
MOST PART IN AGREEMENT THAT THE SYSTEM WILL WEAKEN THROUGH THE
FORECAST PERIOD, WITH A SPREAD OF ABOUT 50 KNOTS BETWEEN THE
OUTLIERS. THE COAMPS-TC WEAKENS THE SYSTEM DOWN TO 35 KNOTS BY TAU
84, AND THE HAFS-A TO 50 KNOTS BY THE SAME TIME. THE SHIPS GUIDANCE
AND THE CONSENSUS DEPICT A WEAKENING TO ABOUT 70 KNOTS THEN A
STEADY STATE AFTER TAU 72, WHILE THE HWRF IS THE ONLY MODEL
DEPICTING INTENSIFICATION UP TO ABOUT 100 KNOTS THROUGH TAU 60
BEFORE SLOWLY WEAKENING. THE JTWC FORECAST GENERALLY FOLLOWS THE
CONSENSUS MEAN TREND LINE, THOUGH ABOUT 10 KNOTS HIGHER, THROUGH
THE FORECAST PERIOD. 

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