WDXS32 PGTW 261500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 22S (HALIMA) WARNING 
NR 007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.2S 74.7E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 620 NM SOUTH-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
MEDIUM-SIZED SYSTEM THAT HAS ELONGATED SOUTHEASTWARD AND RAPIDLY
WEAKENED AS EVIDENCED BY WARMING CENTRAL CONVECTIVE TOPS AND
UNRAVELING FEEDER BANDS. THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON A LARGE MICROWAVE EYE FEATURE IN THE 261140Z
SSMIS IMAGE. THE INITIAL INTENSITY IS ALSO PLACED WITH MEDIUM
CONFIDENCE BASED ON AN OVERALL ASSESSMENT OF AGENCY AND AUTOMATED
DVORAK ESTIMATES (SEE BELOW) AND REFLECTS THE RAPID DETERIORATION.
ANALYSIS INDICATES THE ENVIRONMENT HAS BECOME UNFAVORABLE AS THE
WARM SST AND STRONG POLEWARD OUTFLOW ARE NOW OFFSET BY INCREASING
VERTICAL WIND SHEAR. THE CYCLONE IS TRACKING ALONG THE SOUTHWEST
PERIPHERY OF A DEEP-LAYERED NER TO THE NORTHEAST.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: NEAR EQUATORIAL RIDGE (NER) TO THE
NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   FMEE: T4.5 - 77 KTS
   CIMSS SATCON: 69 KTS AT 260845Z
   CIMSS ADT: 77 KTS AT 261215Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 HALIMA WILL CONTINUE TO TRACK SOUTHEASTWARD
UNDER THE NER. AFTER TAU 36, THE SYSTEM WILL TRACK MORE EASTWARD AS
THE NER EXTENDS WESTWARD. AROUND TAU 72, A BUILDING SUBTROPICAL
RIDGE TO THE SOUTHWEST WILL ASSUME STEERING AND DRIVE A WEAKER AND
SHALLOWER TC 22S NORTHWARD THEN WEST-NORTHWESTWARD. INCREASING VWS
WILL MOSTLY BE RESPONSIBLE FOR GRADUALLY WEAKENING OF THE SYSTEM. BY
TAU 36, COOLING SST THEN DRY AIR INTRUSION WILL ALSO CONTRIBUTE TO
FURTHER WEAKENING. BY TAU 120, TC 22S WILL BE REDUCED TO 45KTS.
HOWEVER, AS IT CONTINUES TO MOVE EQUATORWARD, SST WILL ONCE AGAIN
WARM AND MAY TRIGGER RE-INTENSIFICATION BEYOND THE FORECAST.   

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT UP
TO TAU 72. AFTERWARD, THE MODELS SIGNIFICANTLY DIVERGE WITH UKMET
AND NAVGEM THE NOTABLE OUTLIERS INDICATING CONTINUED EASTWARD AND
POLEWARD VORTEX TRAJECTORIES. IN VIEW OF THIS, THERE IS MEDIUM
CONFIDENCE IN THE JTWC TRACK FORECAST UP TO TAU 72 THEN LOW
CONFIDENCE AFTERWARD. 

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