WDXS33 PGTW 140900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 14S (TALIAH) WARNING NR 
027//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.7S 84.4E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 991 NM SOUTHWEST OF THE COCOS ISLANDS
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC), WHICH IS DEVOID OF
SIGNIFICANT CONVECTION, PARTICULARLY ACROSS THE NORTHERN PORTIONS
OF THE CIRCULATION. A 140713Z GMI 36GHZ MICROWAVE IMAGE CONFIRMS
THE NORTHERN HALF OF THE SYSTEM IS QUITE SHALLOW, WITH SIGNIFICANT
DRY AIR ABOVE ABOUT 700MB, WHILE THE SOUTHERN HEMISPHERE OF THE
SYSTEM IS MUCH MOISTER WITH MODERATE CONVECTIVE ACTIVITY. THE
INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE
EXPOSED LLCC IN THE MSI AND THE LOW EMISSIVITY REGION (LER) IN THE
36GHZ MICROWAVE IMAGE NOTED ABOVE. THE INITIAL INTENSITY OF 45
KNOTS IS ASSESSED WITH MEDIUM CONFIDENCE, HELD HIGHER THAN THE
OBJECTIVE AND SUBJECTIVE INTENSITY ESTIMATES, CONSISTENT WITH SAR
DATA FROM 132350Z. THE ENVIRONMENT IS MARGINAL AT BEST, WITH
RELATIVELY COOL SSTS, LOW TO MODERATE NORTHERLY SHEAR, MODERATE
POLEWARD OUTFLOW AND DRY MID-LEVEL AIR.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   DEMS: T2.0 - 30 KTS
   CIMSS ADT: 26 KTS AT 140430Z
   CIMSS AIDT: 33 KTS AT 140430Z
   CIMSS D-PRINT: 31 KTS AT 140430Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 25-26 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: SIGNIFICANT MID-LEVEL DRY AIR INTRUSION FROM THE
NORTH. 

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 14S IS FORECAST TO TRACK
SOUTHWESTWARD THROUGH THE MAJORITY OF THE FORECAST PERIOD, THOUGH
MAJOR SHIFTS IN TRACK SPEED ARE EXPECTED. A DEEP MID-LATITUDE
TROUGH IS STARTING TO MOVE WEST TO EAST FAR TO THE SOUTH AND
BREAKING DOWN THE RIDGING PATTERN. WITHIN THE NEXT 12 TO 24 HOURS,
THE TROUGH WILL PASS BY TO THE SOUTHEAST, BUT THE STR CURRENTLY
STEERING THE SYSTEM WILL BE REPLACED BY A COL REGION, RESULTING IN
A FAIRLY DRASTIC SLOW-DOWN OF TC 14S. A TRANSIENT RIDGE MOVES IN
BEHIND THE TROUGH FAIRLY QUICKLY AND BY TAU 36, TC 14S WILL ONCE
AGAIN, ACCELERATE ALONG THE NORTHERN SIDE OF THIS TRANSIENT RIDGE.
THE PATTERN REPEATS ITSELF, AS ANOTHER MID-LATITUDE TROUGH PASSES
BY TO THE SOUTH BEGINNING AROUND TAU 60 AND THE SYSTEM WILL SLOW
DOWN ONCE MORE. THIS TIME AROUND HOWEVER, THE MODELS DISAGREE
SHARPLY ON WHAT OCCURS AFTER THE TROUGH PASSES. THE GFS SHOWS
ANOTHER TRANSIENT RIDGE MOVING IN, PUSHING TC 14S WESTWARD ONCE
AGAIN, AFTER TAU 96. THE ECMWF SHOWS NO TRANSIENT RIDGE AND PULLS TC
14S TO THE EAST AND INTO THE TROUGH. THE MORE LIKELY SCENARIO IS
THAT A TRANSIENT RIDGE WILL PUSH IN BEHIND THE TROUGH BUT WITH SUCH
A LARGE DISPARITY IN THE AVAILABLE GUIDANCE THE FORECAST CALLS FOR
THE SYSTEM TO BECOME QUASI-STATIONARY AT THE END OF THE FORECAST,
UNTIL A FIRMER MODEL SOLUTION PRESENTS ITSELF. TC IS EXPECTED TO
MAINTAIN ITS CURRENT INTENSITY FOR THE NEXT 12 HOURS OR SO, THEN
INTENSIFY SLIGHTLY AS IT TAPS INTO SOME ENHANCED OUTFLOW INTO THE
JET STREAM ASSOCIATED WITH THE DEEP TROUGH PASSING TO THE SOUTH. BY
TAU 72, THE SYSTEM BEGINS TO WEAKEN STEADILY AS IT MOVES INTO
COOLER WATERS AND IS OVERWHELMED BY HIGH VWS AND DRY AIR
ENTRAINMENT. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS SHOWING
INCREASING UNCERTAINTY WITH EACH SUCCESSIVE RUN AND THE CONSENSUS
MEMBERS SPREAD OUT STEADILY TO 210NM AT TAU 72, WITH NAVGEM ON THE
WEST AND ECMWF ON THE EAST SIDE OF THE ENVELOPE. CROSS-TRACK SPREAD
REMAINS STEADY THROUGH TAU 96, BUT BY TAU 120, THE GFS AND ECMWF
MOST NOTABLY, BEGIN TO TAKE DIAMETRICALLY OPPOSITE TRACKS, GFS TO
THE WEST AND ECMWF TO THE EAST. THE RESULT IS CROSS-TRACK SPREAD
APPROACHING 400NM BY TAU 120. THE JTWC FORECAST HUGS THE CONSENSUS
MEAN THOUGH THE FORECAST AND BECOMES QUASI-STATIONARY BY TAU 120.
INTENSITY GUIDANCE IS IN GOOD AGREEMENT OVERALL, THOUGH THE HAFS-A
PEAKS THE INTENSITY AT 60 KNOTS BY TAU 36. THE JTWC FORECAST
CLOSELY TRACKS THE CONSENSUS MEAN THROUGH THE ENTIRE FORECAST
PERIOD. 

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