WDXS32 PGTW 130900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 25S (JUDE) 
WARNING NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.6S 37.4E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 221 NM NORTHWEST OF EUROPA ISLAND
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RAPIDLY 
CONSOLIDATING LOW-LEVEL CIRCULATION (LLC), WITH FORMATIVE BANDING AND 
A LARGE CLUSTER OF DEEP CONVECTION OVER THE EASTERN SEMICIRCLE. 
VISIBLE IMAGERY SHOWS A PARTIALLY-EXPOSED, TIGHTLY-WRAPPED LOW-LEVEL 
CIRCULATION CENTER POSITIONED ON THE NORTHWESTERN EDGE OF THE DEEP 
CONVECTIVE CLUSTER, WHICH SUPPORTS THE INITIAL POSITION WITH MEDIUM 
CONFIDENCE. MICROWAVE IMAGERY HAS BEEN SPARSE, HOWEVER, A 130318Z 
SSMIS 91GHZ MICROWAVE IMAGE SHOWED THE BULK OF THE DEEP CONVECTION 
CONFINED TO THE SOUTHERN SEMICIRCLE, FRAGMENTED BANDING OVER THE 
WESTERN QUADRANT, AND NO DEFINED LLCC. A 130300Z SMAP WINDSPEED IMAGE 
AND PARTIAL ASCAT IMAGERY REVEAL A FAIRLY EXTENSIVE SWATH OF 35-45 
KNOT WINDS OVER THE SOUTHERN SEMICIRCLE, WITH WEAKER WINDS OVER THE 
NORTHERN SEMICIRCLE. THE INITIAL INTENSITY IS ASSESSED AT 40 KNOTS 
BASED ON THE SMAP AND ASCAT DATA, WITH SUBJECTIVE DVORAK ESTIMATES 
RANGING FROM 35 TO 45 KNOTS. ENVIRONMENTAL CONDITIONS ARE FAVORABLE, 
WITH RADIAL OUTFLOW, LOW VERTICAL WIND SHEAR (VWS) AND WARM SST 
VALUES.
          
INITIAL WIND RADII BASIS: SMAP DATA 

CURRENT STEERING MECHANISM: LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR) 
POSITIONED TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS (130830Z)
   KNES: T2.5 - 35 KTS
   FMEE: T3.0 - 45 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 25S WILL TRACK EAST-
SOUTHEASTWARD TO EASTWARD ALONG THE SOUTHERN PERIPHERY OF THE STR 
THROUGH TAU 72. ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE FOR THE NEXT 
24 HOURS. THUS, TC 25S SHOULD INTENSIFY TO A PEAK INTENSITY OF 50 
KNOTS BY TAU 24. AFTER TAU 24, THE SYSTEM WILL WEAKEN AS IT TRACKS 
UNDER AN APPROACHING SUBTROPICAL MAJOR SHORTWAVE TROUGH, WHICH WILL 
INTRODUCE INCREASING VWS (20-35 KNOTS) AND CONVERGENCE ALOFT BEFORE 
THE SYSTEM MAKES LANDFALL OVER SOUTHWEST MADAGASCAR NEAR TAU 36. AFTER 
TAU 36, TC 25S WILL WEAKEN RAPIDLY DUE TO LAND INTERACTION AND STRONG 
VWS (40-60 KNOTS), EMERGING OVER WATER EAST OF MADAGASCAR EMBEDDED 
WITHIN THE NORTHERN PERIPHERY OF THE SUBTROPICAL TROUGH. CONSEQUENTLY, 
THE SYSTEM IS EXPECTED TO TRANSITION INTO A SUBTROPICAL CYCLONE. 
HOWEVER, DISSIPATION IS POSSIBLE AS WELL.

MODEL DISCUSSION: NUMERICAL TRACK GUIDANCE IS IN TIGHT AGREEMENT ONLY 
THROUGH TAU 36, WITH A 30NM CROSS-TRACK SPREAD AT TAU 36. AFTER TAU 
36, MODEL GUIDANCE DIVERGES SIGNIFICANTLY LENDING LOW OVERALL 
CONFIDENCE TO THE JTWC TRACK FORECAST. BOTH THE GEFS AND EPS ENSEMBLES 
INDICATE INCREASING PROBABILITIES (40 PERCENT) FOR A STRONG (50-63 
KNOTS) TROPICAL STORM STRENGTH SYSTEM TO IMPACT SOUTHWESTERN 
MADAGASCAR PRIOR TO LANDFALL. DETERMINISTIC INTENSITY GUIDANCE SHOWS A 
LARGE SPREAD OF PEAK INTENSITIES FROM TAU 24 TO TAU 36 RANGING FROM 37 
TO 57 KNOTS.       

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