Tropical Cyclone CHIDO (04S)

WTXS31 PGTW 150900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 04S (CHIDO) WARNING NR 017//
RMKS/
1. TROPICAL CYCLONE 04S (CHIDO) WARNING NR 017    
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   150600Z --- NEAR 13.3S 40.2E
     MOVEMENT PAST SIX HOURS - 270 DEGREES AT 12 KTS
     POSITION ACCURATE TO WITHIN 030 NM
     POSITION BASED ON EYE FIXED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT
                            025 NM SOUTHEAST QUADRANT
                            025 NM SOUTHWEST QUADRANT
                            020 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 035 NM NORTHEAST QUADRANT
                            045 NM SOUTHEAST QUADRANT
                            045 NM SOUTHWEST QUADRANT
                            035 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT
                            070 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   REPEAT POSIT: 13.3S 40.2E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   151800Z --- 13.9S 37.5E
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
   VECTOR TO 24 HR POSIT: 240 DEG/ 13 KTS
    ---
   24 HRS, VALID AT:
   160600Z --- 15.1S 35.1E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
   VECTOR TO 36 HR POSIT: 240 DEG/ 11 KTS
    ---
   36 HRS, VALID AT:
   161800Z --- 16.1S 33.1E
   MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
    ---
REMARKS:
150900Z POSITION NEAR 13.4S 39.5E.
15DEC24. TROPICAL CYCLONE 04S (CHIDO), LOCATED APPROXIMATELY 83
NM NORTH-NORTHWEST OF NACALA, MOZAMBIQUE, HAS TRACKED WESTWARD AT
12 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
(MSI) DEPICTS TROPICAL CYCLONE 04S AS HAVING MADE LANDFALL ABOUT 15
NM SOUTH OF PEMBA, MOZAMBIQUE AT 0400Z. THE SYSTEM, AT THE TIME OF
LANDFALL, HAD A PINHOLE EYE AND A 150253Z RCM-1 SAR IMAGE SHOWED A
VMAX OF AROUND 120 KTS IN A CONCENTRIC RING 10 NM OUT FROM THE
CENTER. THE SYSTEM HAS VERY RAPIDLY ERODED AS IT MOVES INLAND DUE TO
TERRAIN INTERACTION AND THE COMPACT SIZE OF THE SYSTEM. 04S IS
FORECAST TO TRACK GENERALLY WEST-SOUTHWESTWARD AND CONTINUE RAPIDLY
WEAKENING OVER THE NEXT 12 HOURS WITH MORE GRADUAL WEAKENING
THEREAFTER. DISSIPATION IS FORECAST TO OCCUR NO LATER THAN TAU 36,
AND POSSIBLY SOONER. NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT
ON THE TRACK OF 04S, LENDING HIGH CONFIDENCE TO THE JTWC TRACK
FORECAST. THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT
TYPHOON WRNCEN PEARL HARBOR HI. THE SYSTEM WILL BE CLOSELY MONITORED
FOR SIGNS OF REGENERATION. MINIMUM CENTRAL PRESSURE AT 150600Z IS 966
MB.//
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WDXS31 PGTW 102100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 04S (CHIDO) WARNING NR 
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 10.6S 59.6E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 585 NM NORTH-NORTHEAST OF PORT LOUIS,
MAURITIUS
   MOVEMENT PAST 6 HOURS: WESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 21 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN
ASYMMETRIC DEEP CONVECTION PERSISTING OVER A LOW-LEVEL CIRCULATION
CENTER EVIDENT IN A 101653Z METOP-B ASCAT PASS. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON MULTI-AGENCY
SATELLITE FIXES AND THE AFOREMENTIONED ASCAT DATA. THE INITIAL
INTENSITY OF 60 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON
AVAILABLE AUTOMATED AND SUBJECTIVE ESTIMATES RANGING FROM 48 KNOTS
TO 65 KNOTS. TC 04S IS SLOWLY INTENSIFYING UNDER THE INFLUENCES OF
MODERATE EASTERLY VERTICAL WIND SHEAR, RADIAL OUTFLOW ALOFT, AND
PASSAGE OVER VERY WARM WATER.

INITIAL WIND RADII BASIS: 101653Z METOP-B ASCAT PASS

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE SOUTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   DEMS: T3.5 - 55 KTS
   CIMSS SATCON: 48 KTS AT 101418Z
   CIMSS ADT: 53 KTS AT 101500Z
   CIMSS AIDT: 60 KTS AT 101700Z
   CIMSS D-MINT: 54 KTS AT 101439Z
   CIMSS D-PRINT: 53 KTS AT 101900Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: FORECAST INTENSITIES HAVE INCREASED
FROM THE PREVIOUS WARNING BASED ON EXPECTATIONS OF FAVORABLE
ENVIRONMENTAL SUPPORT. OTHERWISE, THERE ARE NO MAJOR CHANGES.

FORECAST DISCUSSION: TC 04S WILL CONTINUE TRACKING WESTWARD TO
WEST-SOUTHWESTWARD THROUGHOUT THE FORECAST PERIOD DUE TO PERSISTENT
RIDGING TO THE SOUTH OF THE SYSTEM. ENVIRONMENTAL CONDITIONS TO
THIS POINT HAVE FAVORED SLOW DEVELOPMENT, BUT OVER THE NEXT 12 TO
24 HOURS, VERTICAL WIND SHEAR IS EXPECTED TO DECREASE AND UPPER-LEVEL
OUTFLOW IS EXPECTED TO IMPROVE MARKEDLY, WITH LIKELY DEVELOPMENT OF
A POLEWARD OUTFLOW CHANNEL ENHANCED TOWARD AN UPPER-LEVEL SHORTWAVE
TROUGH PASSING TO THE SOUTH. TC 04S IS EXPECTED TO STEADILY
INTENSIFY, PERHAPS RAPIDLY, THROUGH TAU 36 UNDER THESE FAVORABLE
CONDITIONS. THEREAFTER, EASTERLY VERTICAL WIND SHEAR IS EXPECTED TO
INCREASE AND OUTFLOW DIMINISH AS THE FLOW ASSOCIATED WITH A
BUILDING DEEP-LAYER RIDGE TO THE SOUTH IMPACTS THE SYSTEM.
INTERACTION WITH THE NORTHERN PORTION OF MADAGASCAR WILL ACCELERATE
WEAKENING AROUND TAU 72 AND THE SYSTEM IS LIKELY TO WEAKEN ONLY
SLOWLY THEREAFTER AS IT MOVES WEST-SOUTHWARD TOWARD LANDFALL IN
MOZAMBIQUE NEAR THE END OF THE FORECAST PERIOD.

MODEL DISCUSSION: NUMERICAL MODELS GUIDANCE IS IN GOOD AGREEMENT
REGARDING THE TRACK OF 04S THROUGH TAU 72, WITH SPREAD INCREASING
IN THE EXTENDED TAUS. ALL DETERMINISTIC AND ENSEMBLE MEAN
TRACKERS, ASIDE FROM NAVGEM, DEPICT A CONTINUOUS WESTWARD TO
WEST-SOUTHWESTWARD TRACK THROUGH THE ENTIRETY OF THE FORECAST
PERIOD. NAVGEM DEPICTS RECURVATURE OVER MADAGASCAR, WHICH IS ASSESSED 
AS A VERY UNLIKELY SCENARIO THAT NONE OF THE GEFS OR ECMWF MEDIUM-
RANGE ENSEMBLE SOLUTIONS SUPPORT. INTENSITY MODELS ARE IN GOOD 
AGREEMENT REGARDING THE TREND TOWARD A PEAK INTENSITY AT TAU 36 WITH A 
SLOW TO STEADY WEAKENING THEREAFTER. HOWEVER, SOLUTIONS FOR PEAK 
INTENSITY RANGE FROM 90 TO AS HIGH AS 140 KTS (HAFS). THE CURRENT 
INTENSITY FORECAST IS CONSISTENT WITH THE MULTI-MODEL CONSENSUS.

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