WDXS32 PGTW 251500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 22S (HALIMA) WARNING 
NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.2S 73.4E
   INITIAL INTENSITY: 120 KTS
   GEOGRAPHIC REFERENCE: 429 NM SOUTH OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TC 22S HAS RAPIDLY INTENSIFIED (35 KNOTS) OVER THE PAST 24 HOURS
FROM 85 KNOTS AT 241200Z TO THE CURRENT INTENSITY OF 120 KNOTS.
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
COMPACT SYSTEM WITH A 10NM ROUND EYE, WHICH SUPPORTS THE INITIAL
POSITION WITH HIGH CONFIDENCE, AND SPIRAL BANDING OVER THE SOUTHERN
AND WESTERN SEMICIRCLES. DURING THE PAST SIX HOURS, DVORAK
ESTIMATES HAVE RANGED FROM T6.0 TO T6.5 (115 TO 127 KNOTS) WITH THE
EYE TEMPERATURE WARMING UP TO +4C FOR A BRIEF PERIOD OF TIME BEFORE
COOLING TO -13C. CLOUD TOP TEMPERATURES HAVE ALSO FLUCTUATED
SIGNIFICANTLY AND NOW APPEAR TO BE COOLING AGAIN. THUS, THE INITIAL
INTENSITY OF 120 KTS IS ASSESSED WITH MEDIUM CONFIDENCE AND IS
HEDGED ABOVE THE PGTW AND FMEE DVORAK ESTIMATES CLOSER TO A 251315Z 
AI-ENHANCED ADT ESTIMATE OF 118 KNOTS.

INITIAL WIND RADII BASIS: OTHER (250843Z AMSR2 WINDSPEED IMAGE)  

CURRENT STEERING MECHANISM: DEEP-LAYERED, NORTH-SOUTH ORIENTED
SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST AND SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   FMEE: T6.0 - 115 KTS
   CIMSS SATCON: 108 KTS AT 250904Z
   CIMSS ADT: 112 KTS AT 251215Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL
   OTHER FACTORS: UPWELLING COOLER WATER

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: DUE TO THE RAPID INTENSIFICATION
PHASE, THE PEAK INTENSITY HAS BEEN INCREASED TO 130 KNOTS. THIS
REPRESENTS A SLIGHT INCREASE FROM THE 125 KNOT PEAK DISCUSSED IN
THE 250000Z PROGNOSTIC REASONING.

FORECAST DISCUSSION: TC 22S IS FORECAST TO TRACK GENERALLY
SOUTHWARD ALONG THE WESTERN PERIPHERY OF THE NORTH-SOUTH ORIENTED
STEERING RIDGE THROUGH TAU 36. DUE TO HIGHLY FAVORABLE CONDITIONS,
THE SYSTEM IS EXPECTED TO INTENSIFY THROUGH TAU 12 WITH A PEAK
INTENSITY OF 130 KNOTS AT TAU 12. THERE IS POTENTIAL FOR THE SYSTEM
TO PEAK HIGHER WITHIN THE NEXT 24 HOURS AS ENVIRONMENTAL CONDITIONS
REMAIN HIGHLY FAVORABLE. AFTER TAU 36, THE SYSTEM WILL WEAKEN
SIGNIFICANTLY AS VERTICAL WIND SHEAR (VWS) INCREASES TO 20-25 KNOTS
WITH THE APPROACH OF A BROAD UPPER-LEVEL TROUGH OVER THE SYSTEM.
DURING THIS TIMEFRAME, TC 22S WILL TURN SOUTHEASTWARD THEN EASTWARD
THROUGH TAU 96 AS IT TRACKS WITHIN THE EVOLVING FLOW BETWEEN THE
EASTWARD-PROPAGATING, UPPER-LEVEL TROUGH AND THE SHIFTING STEERING
RIDGE TO THE NORTHEAST. AFTER TAU 72, A STRONG LOW- TO MID-LEVEL
HIGH WILL BUILD TO THE SOUTHEAST AND EAST EFFECTIVELY BLOCKING THE
EASTWARD PROGRESSION AND PRODUCING A SLOWER, MORE ERRATIC TRACK. TC
HALIMA WILL STEADILY WEAKEN THROUGH THE REMAINDER OF THE FORECAST
AS IT TRACKS UNDER UPPER-LEVEL SUBTROPICAL WESTERLIES WITH WEAK
DIFFLUENCE ALOFT AND SLIGHTLY COOLER SST VALUES. IN THE EXTENDED
PERIOD, AS THE SYSTEM STALLS OVER 26-27C WATER, THE VWS IS EXPECTED
TO DECREASE AS THE WESTERLIES WEAKEN WHICH MAY ALLOW THE SYSTEM TO
RE-STRENGTHEN OR AT LEAST MAINTAIN STORM-FORCE WINDS.
   
MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, NUMERICAL MODEL
GUIDANCE IS IN FAIR AGREEMENT THROUGH TAU 72 LENDING MEDIUM
CONFIDENCE TO THE JTWC FORECAST TRACK. HOWEVER, BOTH DETERMINISTIC
AND PROBABILISTIC GUIDANCE ARE IN POOR AGREEMENT AFTER TAU 72
REFLECTING A LIKELY STALL AND ERRATIC MOTION AS THE HIGH BUILDS TO
THE SOUTH AND EAST THUS THERE IS LOW CONFIDENCE IN THE JTWC
FORECAST TRACK. INTENSITY GUIDANCE NO LONGER INDICATES RAPID
INTENSIFICATION, HOWEVER, THE COAMPS-TC ENSEMBLE STILL INDICATES
MODERATE INTENSIFICATION IS LIKELY OVER THE NEXT 24 HOURS. HWRF
CONTINUES TO WEAKEN THE SYSTEM OVER THE NEXT 12 HOURS DUE TO COOL
UPWELLING WATER EVIDENT IN THE HWRF SST FIELDS, HOWEVER, THIS
SCENARIO APPEARS UNLIKELY AS THE SYSTEM IS ON THE CUSP OF
INTENSIFYING FURTHER AND THERE HAS BEEN NO APPARENT WEAKENING
THUS FAR. THE BULK OF THE GUIDANCE SUPPORTS THE STEADY WEAKENING
TREND IN THE LATER TAUS WITH THE EXCEPTION OF HWRF WHICH TRACKS THE
SYSTEM EQUATORWARD EARLIER AND REINTENSIFIES THE SYSEM TO 100+
KNOTS BY TAU 120.       

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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