WDXS31 PGTW 011500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 04S (ALVARO)     
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.5S 42.7E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 145 NM EAST-NORTHEAST OF EUROPA ISLAND
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 19 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 04S HAS CONSOLIDATED STEADILY OVER THE PAST
12 HOURS, FLIRTING WITH A RAGGED, FORMATIVE EYE AT TIMES. RECENT
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A CENTRAL 
DENSE OVERCAST BUILDING OVER AND OBSCURING THE CENTER. FORTUNATELY, A 
011026Z AMSR2 37 GHZ COLOR COMPOSITE MICROWAVE IMAGE DEPICTS A CYAN 
RING SURROUNDING A ROUND, WELL-DEFINED MICROWAVE EYE FEATURE, WHICH 
SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE. THE INITIAL 
INTENSITY IS ASSESSED AT 60 KNOTS BASED ON AN AVERAGE OF THE 
SUBJECTIVE DVORAK ESTIMATES (55-65 KNOTS) AND A 011029Z DMINT ESTIMATE 
OF 57 KNOTS. ADDITIONALLY, A 010253Z SENTINEL-1A SAR PASS INDICATED 
MAXIMUM WINDS OF 59 KNOTS AND A 011026Z AMSR2 WINDSPEED IMAGE REVEALED 
A SWATH OF 50-62 KNOTS WINDS OVER THE EASTERN SEMICIRCLE WITH SOME 
HIGHER WINDS ALONG THE COAST. THE INITIAL INTENSITY ASSESSMENT IS 
CONSISTENT WITH THE STRONG MICROWAVE EYE FEATURE AND SHORT-LIVED 
VISIBLE EYE. 

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: NEAR EQUATORIAL RIDGE POSITIONED TO THE
NORTH STEERING THE SYSTEM GENERALLY EASTWARD.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   FMEE: T4.0 - 65 KTS
   CIMSS SATCON: 45 KTS AT 011230Z
   CIMSS ADT: 49 KTS AT 011200Z
   CIMSS DMINT: 57 KTS AT 011029Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: MID- TO UPPER-LEVEL DRY AIR ENTRAINMENT

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: DUE TO RAPID CONSOLIDATION OF THE
SYSTEM'S CORE, THE INITIAL INTENSITY IS SIGNIFICANTLY HIGHER THAN
THE PREVIOUS JTWC WARNING. ADDITIONALLY, INITIAL INTENSITIES FROM
311800Z TO 010600Z HAVE BEEN RE-EVALUATED AND REVISED HIGHER. 

FORECAST DISCUSSION: TC 04S IS FORECAST TO WEAKEN AS IT TRACKS
EASTWARD AND APPROACHES THE COAST OF MADAGASCAR, WITH LANDFALL
ANTICIPATED NEAR TAU 06. AFTER TAU 06, THE SYSTEM WILL WEAKEN
RAPIDLY AND DISSIPATE AS IT TRACKS EASTWARD ACROSS THE MOUNTAINOUS
TERRAIN OF SOUTHERN MADAGASCAR. TC 04S WILL RE-EMERGE OVER THE
INDIAN OCEAN NEAR TAU 36 WITH A BRIEF PERIOD OF REINTENSIFICATION
TO ABOUT 40 KNOTS BY TAU 48. AFTER TAU 48, TC 04S WILL TURN
EAST-SOUTHEASTWARD AS IT TRANSITIONS TO THE STEERING INFLUENCE OF A
SUBTROPICAL RIDGE POSITIONED TO THE NORTHEAST. THE SYSTEM IS
EXPECTED TO WEAKEN STEADILY AS IT INTERACTS WITH STRENGTHENING
SUBTROPICAL WESTERLIES AND ENCOUNTERS STRONG VERTICAL WIND SHEAR
(40 TO 55 KNOTS) AND COOLING SEA SURFACE TEMPERATURES (26 TO 25 C).
TC 04S WILL DISSIPATE NO LATER THAN TAU 96.   

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT
LENDING MEDIUM CONFIDENCE TO THE JTWC TRACK FORECAST THROUGH TAU
96. THE 010000Z ECMWF ENSEMBLE (EPS) AND THE 010600Z GFS ENSEMBLE 
(GEFS) GENERALLY INDICATE A LOW TO MODERATE PROBABILITY OF 
REINTENSIFICATION TO 35-49 KNOTS EAST OF MADAGASCAR. HOWEVER, THERE IS 
HIGH UNCERTAINTY DUE TO THE MARGINAL CONDITIONS FORECAST DURING THIS 
PHASE OF THE JTWC FORECAST.    

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