WDXS31 PGTW 141500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 04S (CHIDO) WARNING NR 
014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.1S 44.1E
   INITIAL INTENSITY: 120 KTS
   GEOGRAPHIC REFERENCE: 399 NM NORTH-NORTHWEST OF ANTANANARIVO,
MADAGASCAR
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE (TC) 04S (CHIDO) WITH AN IMPRESSIVE APPEARANCE FROM 0900Z
TO 1100Z WITH A SYMMETRICAL EYE AND VERY COLD CLOUD TOPS COMPLETELY
SURROUNDING THE EYEWALL. THE APPEARANCE AS OF 1200Z HAS SLIGHTLY
WORSENED THOUGH, WITH A DIMPLE EYE NOW AND A MORE RAGGED CENTRAL
DENSE OVERCAST. THE POLEWARD OUTFLOW HAS IMPROVED OVER THE PAST 6
HOURS AS SEEN IN THE SOUTHWESTERN QUADRANT OF THE SYSTEM IN
ANIMATED WATER VAPOR IMAGERY. THE ENVIRONMENT IS CURRENTLY ANALYZED
TO BE FAVORABLE WITH STRONG RADIAL OUTFLOW ALOFT, LOW TO MODERATE
(15-20 KTS) VERTICAL WIND SHEAR, AND WARM (29-30 C) SEA SURFACE
TEMPERATURES. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON THE DIMPLE EYE IN THE ANIMATED MSI. THE INITIAL INTENSITY
OF 120 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE HIGH END
OF AGENCY DVORAK AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW. IT
IS HEDGED HIGHER DUE TO THE COMPACT SIZE OF THE SYSTEM CAUSING THE
POTENTIAL FOR UNDERESTIMATION IN INTENSITY. ADDITIONALLY, A 141045Z
AMSR2 WIND SPEED IMAGE DEPICTED A MAX OF 115 KTS TO FURTHER SUPPORT
THE INITIAL INTENSITY.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: THE NORTHWESTERN PERIPHERY OF A
DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   KNES: T5.5 - 102 KTS
   DEMS: T6.0 - 115 KTS
   FMEE: T6.0 - 115 KTS
   CIMSS ADT: 102 KTS AT 141200Z
   CIMSS AIDT: 106 KTS AT 141200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 04S IS FORECAST TO CONTINUE TRACKING
GENERALLY WEST-SOUTHWESTWARD ALONG THE NORTHWESTERN PERIPHERY OF
THE STR CENTERED TO THE SOUTHEAST THROUGH THE REMAINDER OF THE
FORECAST PERIOD. LANDFALL ALONG THE NORTHERN COAST OF MOZAMBIQUE,
ABOUT 35 NM SOUTH OF PEMBA BAY, IS EXPECTED IN AROUND 18 HOURS.
AFTER MAKING LANDFALL, THE SYSTEM IS FORECAST TO CONTINUE TRACKING
INLAND TOWARD THE SOUTHERN TIP OF LAKE MALAWI AS IT DISSIPATES.
REGARDING INTENSITY, 04S IS EXPECTED TO MAINTAIN ITS CURRENT
INTENSITY OVER THE NEXT 12 HOURS, AND POSSIBLY SLIGHTLY INTENSIFY,
AS IT APPROACHES THE COAST DUE TO THE STRONG OUTFLOW AND VERY WARM
SEA SURFACE TEMPERATURES. AFTER LANDFALL, TERRAIN INTERACTION WILL
QUICKLY ERODE THE VORTEX CAUSING RAPID WEAKENING. WEAKENING BELOW
35 KTS IS EXPECTED TO OCCUR AROUND TAU 36 AS THE SYSTEM CONTINUES
TO DRIFT WEST-SOUTHWESTWARD.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT ON
THE TRACK OF 04S WITH A 39 NM CROSS-TRACK SPREAD AT THE TIME OF
LANDFALL. AS A RESULT, THE JTWC TRACK FORECAST IS PLACED CLOSE TO
CONSENSUS WITH HIGH CONFIDENCE. INTENSITY GUIDANCE IS IN GOOD
AGREEMENT, WITH THE EXCEPTION OF GFS, WHICH CONTINUES TO SUGGEST A
MUCH WEAKER SYSTEM THAN THE MESOSCALE MODELS. INTENSITY GUIDANCE AS
A WHOLE ALSO SUGGESTS SLIGHT WEAKENING OVER THE NEXT 12 HOURS,
HOWEVER THE JTWC INTENSITY FORECAST KEEPS THE INTENSITY CONSTANT
DUE TO THE FAVORABLE ENVIRONMENT. AFTER TAU 12, THE JTWC INTENSITY
FORECAST FOLLOWS CLOSELY TO CONSENSUS WITH MEDIUM CONFIDENCE.

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