WDXS31 PGTW 112100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 04S (CHIDO) WARNING NR 005// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 10.4S 56.7E INITIAL INTENSITY: 120 KTS GEOGRAPHIC REFERENCE: 583 NM NORTH OF PORT LOUIS, MAURITIUS MOVEMENT PAST 6 HOURS: WESTWARD AT 08 KTS SIGNIFICANT WAVE HEIGHT: 48 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL CYCLONE (TC) 04S (CHIDO) HAS UNDERGONE EXTREMELY RAPID INTENSIFICATION OVER THE PAST DAY, INCREASING FROM 60 KNOTS TO 120 KNOTS IN JUST 24 HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A COMPACT SYSTEM, WITH A 6NM WIDE EYE, SURROUNDED BY DEEP CONVECTION, PASSING OVER THE ISLAND OF VINGT CINQ AT 1800Z. BETWEEN 1800Z-1900Z, EIR IMAGERY SUGGESTED AN EROSION OF THE EASTERN EYEWALL, HOWEVER THE EIR UP TO 2000Z SHOWS THE CONVECTION REFORMING UPSHEAR TO THE EAST AND REESTABLISHING THE EYEWALL ON THE NORTHEASTERN SIDE. CLOUD TOP TEMPERATURES REMAIN RELATIVELY WARM AT JUST -68C, AND THE EYE TEMPERATURE HAS RETURNED TO NEGATIVE TERRITORY AFTER REACHING A MAXIMUM OF 15C AT 1600Z. A 111402Z SSMIS 91GHZ MICROWAVE IMAGE REVEALED A VERY COMPACT INNER CORE OF DEEP CONVECTION FORMING A CONTINUOUS EYEWALL SURROUNDING A TINY, VERTICALLY ALIGNED EYE FEATURE. HOWEVER, THE EYEWALL WAS THINNEST ON THE EASTERN SIDE, CONSISTENT WITH THE MODERATE EASTERLY SHEAR STILL IMPACTING THE SYSTEM. THE INITIAL POSITION WAS ASSESSED WITH HIGH CONFIDENCE BASED ON THE 6NM EYE FEATURE IN THE EIR NOTED ABOVE. THE INITIAL INTENSITY WAS ASSESSED WITH MEDIUM CONFIDENCE, HEDGED HIGHER THAN SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES NOTED ABOVE, IN LIGHT OF THE FACT THAT THE DVORAK-BASED TECHNIQUES ARE LIKELY BIASED LOW DUE TO THE EXTREMELY SMALL EYE AND COMPACT NATURE OF THE STORM AS A WHOLE. IN THE AGGREGATE, THE ENVIRONMENT REMAINS FAVORABLE, WITH STRONG RADIAL OUTFLOW BEING HELPED BY A WEAK OUTFLOW CHANNEL TO POLEWARD AND WARM SSTS. THE MAIN QUESTIONABLE FACTOR IS THE EASTERLY SHEAR, WHICH IS STILL RUNNING IN THE MODERATE RANGE, BUT SO FAR HAS NOT BEEN A HINDERANCE TO THE RAPID INTENSIFICATION OF TC 04S. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: NORTHERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE SOUTH. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T5.5 - 102 KTS KNES: T5.5 - 102 KTS DEMS: T5.5 - 102 KTS FMEE: T5.5 - 102 KTS FIMP: T6.0 - 115 KTS CIMSS SATCON: 102 KTS AT 111729Z CIMSS ADT: 97 KTS AT 111800Z CIMSS AIDT: 111 KTS AT 111700Z CIMSS D-MINT: 103 KTS AT 111405Z CIMSS D-PRINT: 108 KTS AT 111800Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 15-20 KTS SST: 27-28 CELSIUS OUTFLOW: STRONG RADIAL ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: WITH THE EXCEPTION OF THE CURRENT INTENSITY EXCEEDING THE PREVIOUSLY EXPECTED INTENSITY BY 10 KNOTS, THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 04S WILL CONTINUE TO TRACK WESTWARD FOR THE NEXT 12 TO 18 HOURS, ALONG THE NORTHERN SIDE OF THE LARGE STR TO THE SOUTH. THE RIDGE CENTER IS FORECAST TO SLIDE EASTWARD DURING THE SAME TIMEFRAME, SUCH THAT BY TAU 24, TC 04S WILL LIE ALONG THE NORTHWESTERN SIDE OF THE STEERING RIDGE AND BEGIN TO TURN ONTO A SOUTHWESTWARD TRACK. BY TAU 36, TC 04S WILL BE FIRMLY ENTRENCHED ON A DIRECTLY SOUTHWESTWARD TRACK, AND IS EXPECTED TO CONTINUE ON THIS TRAJECTORY THROUGH THE REMAINDER OF THE FORECAST PERIOD. THE SYSTEM IS FORECASTED TO CLIP THE NORTHERN TIP OF MADAGASCAR AROUND TAU 48, BEFORE MOVING CLOSE TO, OR DIRECTLY OVER, MAYOTTE IN THE NORTHERN MOZAMBIQUE CHANNEL AROUND TAU 72. LANDFALL ALONG THE NORTHEASTERN COAST OF MOZAMBIQUE IS ANTICIPATED AROUND TAU 96, MOST LIKELY JUST NORTH OF NACALA. IN TERMS OF INTENSITY, THE SYSTEM LIKELY PEAKED AROUND 111600Z BASED OFF THE RAW ADT VALUES EXCEEDING T6.2 AND THE EYE REACHING ITS WARMEST POINT. HOWEVER, AS DISCUSSED ABOVE, THE LATEST EIR IMAGERY SUGGESTS THE REFORMATION OF THE EYEWALL AS DEEP CONVECTION IS DEVELOPING ON THE UPSHEAR SIDE OF THE EYE. SO ANOTHER ROUND OF INTENSIFICATION MAY BE IN THE OFFING IN THE NEAR TERM, WITH THE FORECAST CALLING FOR A PEAK OF 125 KNOTS WITHIN THE NEXT 12 HOURS. THE SYSTEM WILL MAINTAIN PEAK INTENSITY FOR A PERIOD OF TIME, THEN BEGIN TO SLOWLY WEAKEN AS IT APPROACHES THE NORTHERN TIP OF MADAGASCAR AS IT WILL BE ENTERING RELATIVELY COOLER WATERS AND COULD FACE AN EYEWALL REPLACEMENT CYCLE (EWRC). CLOSE PASSAGE TO MADAGASCAR WILL INDUCE SOME DISRUPTION OF THE LOW-LEVEL INFLOW, AND ACCOMPANIED BY AN EXPECTED INCREASE IN SHEAR VALUES, WILL RESULT IN A MORE RAPID WEAKENING PHASE AFTER TAU 48. HOWEVER, THE SYSTEM IS EXPECTED TO REMAIN A STRONG TROPICAL CYCLONE AS IT PASSES MAYOTTE. BY THE TIME THE SYSTEM APPROACHES MOZAMBIQUE, IT WILL LIKELY STILL BE A RELATIVELY STRONG TC, WITH AN INTENSITY BETWEEN 70-80 KNOTS. AFTER LANDFALL, THE SYSTEM WILL RAPIDLY WEAKEN AND DISSIPATE BY TAU 120. MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH THE FORECAST PERIOD, WITH NAVGEM BEING THE ONLY OUTLIER DEVIATING FROM THE TIGHT TRACK ENVELOPE AND TAKING THE SYSTEM POLEWARD INTO THE MOZAMBIQUE CHANNEL. THE REMAINDER OF THE CONSENSUS MEMBERS ARE CONFINED TO AN ENVELOPE OF 75NM AT TAU 48 (CPA TO MADAGASCAR), 95NM AT TAU 72 (CPA TO MAYOTTE) AND 155NM AT TAU 96 (LANDFALL IN MOZAMBIQUE). THE ECMWF IS LIES ON THE NORTHERN EDGE OF THE GUIDANCE ENVELOPE THROUGH THE ENTIRE FORECAST PERIOD, WHILE THE GALWEM IS SITUATED ON THE SOUTHERN SIDE THROUGH THE FORECAST. THE JTWC FORECAST TRACK IS CLOSE TO, BUT JUST NORTH OF, THE MULTIMODEL CONSENSUS WITH HIGH CONFIDENCE. LIMITED INTENSITY GUIDANCE IS STRONGLY MIXED, WITH THE HAFS-A INDICATING NEAR-TERM INTENSIFICATION TO 130 KNOTS, WHERE IT SITS UNTIL TAU 36, BEFORE STEADY TO RAPID WEAKENING THROUGH THE REMAINDER OF THE FORECAST. HWRF SHOWS THE OPPOSITE TREND, WEAKENING THE SYSTEM FROM THE BEGINNING OF THE FORECAST ALL THE WAY TO THE END. THIS LEADS TO A MAXIMUM SPREAD OF OVER 80 KNOTS AT TAU 72, THOUGH THE CONSENSUS LIES AT THE HIGHER END OF THE GUIDANCE PACKAGE. THE JTWC FORECAST IN GENERAL FOLLOWS THE CONSENSUS MEAN THROUGH THE FORECAST PERIOD, BUT CONFIDENCE REMAINS LOW DUE TO THE EXTREMELY LARGE SPREAD IN THE AVAILABLE GUIDANCE. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: LOW INTENSITY 72-120 HR: LOW// NNNN