WDXS32 PGTW 260300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 22S (HALIMA) WARNING 
NR 
006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.3S 73.3E
   INITIAL INTENSITY: 110 KTS
   GEOGRAPHIC REFERENCE: 494 NM SOUTH OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 33 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
COMPACT SYSTEM WITH MODERATE CONVECTION WRAPPING AROUND A LOW-LEVEL
CIRCULATION (LLC). THE MINIMAL MOTION TO THE SOUTH AND CONSTANT
UPWELLING NEAR THE CIRCULATION CENTER OVER THE LAST TWELVE HOURS
HAS CAUSED THE EYE TO FILL. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE USING THE EMBEDDED CENTER METHOD, A NOTCH APPEARING
ON THE EIR LOOP, AND A 252336Z SSMIS 91GHZ IMAGE. THE INITIAL
INTENSITY OF 110 KTS IS ASSESSED WITH MEDIUM CONFIDENCE USING
MULTIPLE AGENCY DVORAK ESTIMATES AND IS HELD SLIGHTLY LOWER THAN
PGTW FIX, BOUND BY CONSTRAINTS. THE INTENSITY IS A BLEND OF THE
MULTIPLE AGENCY FIX ESTIMATES, WHICH IS SLIGHTLY HIGHER THAN THE
260015Z ADT ESTIMATE OF 107KTS, AI-ENHANCED ADT (AIDT) 103KTS, AND
THE 252345Z SATELLITE CONSENSUS (SATCON) OF 99KTS, WHICH ARE NOT
BOUND BY THE SAME CONSTRAINTS. ANALYSIS INDICATES A FAVORABLE
ENVIRONMENT, WITH MODERATE POLEWARD AND EQUATORWARD OUTFLOW,
MODERATE VERTICAL WIND SHEAR, AND WARM SST THAT IS NOW TEMPORARILY
IMPACTED BY UPWELLING.

INITIAL WIND RADII BASIS: PERSISTENCE

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: T5.5 - 102 KTS
   FIMP: T5.5 - 102 KTS
   CIMSS SATCON: 99 KTS AT 252245Z
   CIMSS ADT: 107 KTS AT 260015Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD
   OTHER FACTORS: UPWELLING COOLER WATER

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE OVERALL FORECAST PHILOSOPHY HAS
NOT CHANGED IN TERMS OF THE TRACK, BUT THE PEAK INTENSITY HAS
DECREASED BY 15 KNOTS TO REFLECT THE LATEST GUIDANCE DUE TO
EXCESSIVE UPWELLING.

FORECAST DISCUSSION: TC 22S WILL CONTINUE ON A SOUTHERLY TRACK
ALONG THE WESTERN PERIPHERY OF THE NORTH-SOUTH ORIENTED STEERING
RIDGE THROUGH TAU 24. DUE TO HIGHLY FAVORABLE CONDITIONS, THE
SYSTEM WILL SLIGHTLY INTENSIFY ONCE IT BEGINS MOVING FURTHER SOUTH
AND REGAINS THE WARMER SSTS TO A PEAK INTENSITY OF 115 KNOTS AT TAU
12. THERE IS SLIGHT POTENTIAL FOR THE SYSTEM TO PEAK HIGHER WITHIN
THE NEXT 24 HOURS AS ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE. TC
HALIMA WILL WEAKEN QUICKLY IN THE NEAR TAUS AS IT BEGINS 
ENCOUNTERING A HIGHER VERTICAL WIND SHEAR (VWS) ENVIRONMENT TO THE
SOUTH. VWS APPEARS TO INCREASE TO 20-25 KNOTS WITH THE APPROACHING
UPPER-LEVEL TROUGH MIGRATING IN FROM THE WEST. TC 22S WILL TURN
SOUTHEASTWARD THEN EASTWARD THROUGH TAU 96 AS IT CONTINUES TO BE
IMPACTED BY THE COMPLEX STEERING OF THE UPPER-LEVEL TROUGH TO THE
WEST AND THE NORTH-SOUTH ORIENTED RIDGE TO THE EAST. THE RIDGE TO
THE EAST WILL SLIGHTLY BUILD WEST, FORCING TC HALIMA TO TURN
EQUATORWARD BEGINNING AT TAU 96. AT THIS TIME, TC HALIMA WILL HAVE
A SMALL WINDOW WHEREBY THE POLEWARD OUTFLOW WILL INCREASE AND
DEEPEN THE SYSTEM BACK TO TYPHOON STRENGTH FOR THE EXTENDED
TIMEFRAME.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 72, EXCEPT FOR NAVGEM. HOWEVER, THE TRACK GUIDANCE
WEAKENS IN THE LATER TAUS. BOTH THE DETERMINISTIC AND PROBABILISTIC
GUIDANCE ARE IN POOR AGREEMENT AS THE STEERING HIGH TO THE EAST
BEGINS BUILDING BACK TOWARDS THE WEST AND TURNS TC 22S EQUATORWARD.
INTENSITY GUIDANCE NO LONGER INDICATES RAPID INTENSIFICATION, AND
HWRF CONTINUES TO WEAKEN THE SYSTEM THROUGH THE NEXT 12 HOURS DUE
TO COOL WATER UPWELLING, INDICATED IN THE HWRF SST FIELDS. THE
GUIDANCE CONTINUES TO INDICATE A STEADY WEAKENING TREND IN THE
LATER FORECAST PERIOD, EXCEPT FOR HWRF, WHICH INDICATES A RAPID
INTENSIFICATION AT TAU 96. THIS SCENARIO IS UNLIKELY, HOWEVER,
PLAUSIBLE AS THE SYSTEM HAS A SMALL WINDOW TO GAIN THE ROBUST
POLEWARD OUTFLOW CHANNEL BEFORE THE UPWELLING DECREASES THE SYSTEM.
THEREFORE, THE OVERALL JTWC TRACK AND INTENSITY GUIDANCE IS MEDIUM
UP TO TAU 72 AND LOW THEREAFTER.

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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