WDXS32 PGTW 241500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 22S (HALIMA) WARNING 
NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.1S 74.4E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 377 NM SOUTH-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 21 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN 80NM
DIAMETER CENTRAL DENSE OVERCAST OBSCURING THE LOW-LEVEL CIRCULATION
CENTER (LLCC) WITH SPIRAL BANDING PRIMARILY LOCATED OVER THE
WESTERN SEMICIRCLE. A 241057Z SSMIS 91GHZ MICROWAVE IMAGE SHOWS
TIGHTLY CURVED BANDING WRAPPING INTO THE EYEWALL SURROUNDING A
SMALL 5-10NM MICROWAVE EYE FEATURE, WHICH SUPPORTS THE INITIAL
POSITION WITH HIGH CONFIDENCE. UPPER-LEVEL CONDITIONS REMAIN HIGHLY
FAVORABLE WITH NEAR-RADIAL OUTFLOW AND ROBUST POLEWARD OUTFLOW INTO
THE STRONG WESTERLIES TO THE SOUTH. OUTFLOW OVER THE EASTERN
QUADRANT IS GRADUALLY IMPROVING DESPITE SOME LOW EASTERLY VERTICAL
WIND SHEAR. THERE IS MEDIUM CONFIDENCE IN THE INITIAL INTENSITY OF 
65 KNOTS, WHICH IS BASED ON THE HIGHER END OF THE DVORAK ESTIMATES 
RANGING FROM 55 TO 65 KNOTS AND THE CIMSS ADT ESTIMATE.  

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: WEAK EXTENSION OF THE SUBTROPICAL RIDGE
(STR) POSITIONED TO THE SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   FMEE: T4.0 - 65 KTS
   FIMP: T3.5 - 55 KTS
   CIMSS SATCON: 63 KTS AT 240834Z
   CIMSS ADT: 72 KTS AT 241215Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 22S IS FORECAST TO TRACK GENERALLY
SOUTHWARD ALONG THE WESTERN PERIPHERY OF A NORTH-SOUTH ORIENTED
STEERING RIDGE THROUGH TAU 48. DUE TO HIGHLY FAVORABLE CONDITIONS,
THE SYSTEM IS EXPECTED TO RAPIDLY INTENSIFY THROUGH TAU 36 WITH A
PEAK INTENSITY OF 115 KNOTS AT TAU 36. SLIGHT WEAKENING WILL OCCUR
AFTER TAU 36 AS VERTICAL WIND SHEAR (VWS) INCREASES TO MODERATE
LEVELS WITH THE APPROACH OF A BROAD UPPER-LEVEL TROUGH OVER THE
SYSTEM. AFTER TAU 48, TC 22S WILL TURN SOUTH-SOUTHEASTWARD THEN
EAST-SOUTHEASTWARD 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 96, A STRONG
LOW- TO MID-LEVEL HIGH WILL BUILD TO THE SOUTHEAST EFFECTIVELY
BLOCKING THE EASTWARD PROGRESSION AND PRODUCING A SLOWER, MORE
ERRATIC TRACK. TC HALIMA WILL STEADILY WEAKEN THROUGH THE REMAINDER
OF THE FORECAST AS VWS INCREASES TO HIGH LEVELS (25-35 KNOTS) AND
SEA SURFACE TEMPERATURES COOL TO 26-27C. TC 22S SHOULD GRADUALLY
TRANSITION TO A SUBTROPICAL STORM IN THE EXTENDED PERIOD AS IT
STALLS UNDER THE SUBTROPICAL WESTERLIES.    

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT
THROUGH TAU 72 WITH A 200NM SPREAD IN SOLUTIONS AT TAU 72.
SIGNIFICANT UNCERTAINTY IS PRIMARILY RELATED TO THE COMPLEX,
EVOLVING STEERING PATTERN ASSOCIATED WITH AN APPROACHING
UPPER-LEVEL TROUGH. AFTER TAU 72, BOTH THE DETERMINISTIC AND
PROBABILISTIC MODEL GUIDANCE INDICATE INCREASING UNCERTAINTY (LOW
JTWC TRACK CONFIDENCE) DUE TO A POTENTIAL SLOW-DOWN OR STALL
ASSOCIATED WITH A STRONG HIGH FORECAST TO BUILD IN QUICKLY TO THE
EAST AND SOUTHEAST. INTENSITY GUIDANCE IS FAIRLY UNANIMOUS IN
SUPPORTING RAPID INTENSIFICATION (RI) OVER THE NEXT 36 HOURS WITH
SEVERAL RAPID INTENSIFICATION AIDS TRIGGERED AND THE COAMPS-TC
ENSEMBLE (GFS VERSION) INDICATING A 60 TO 80 PERCENT PROBABILITY OF
RI. IN THE LATER TAUS, THERE IS LOW CONFIDENCE IN THE JTWC
INTENSITY FORECAST WITH POTENTIAL FOR A SIGNIFICANTLY WEAKER
SYSTEM.     

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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