WDXS31 PGTW 120900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 07S (DIKELEDI) WARNING 
NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.6S 46.2E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 326 NM EAST OF NACALA, MOZAMBIQUE
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 27 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS LOW-LEVEL
BANDING WRAPPING INTO A LOW-LEVEL CIRCULATION CENTER (LLCC)
OBSCURED BY AN IRREGULARLY SHAPED CENTRAL DENSE OVERCAST
CONVECTION. WATER VAPOR IMAGERY REVEALS STRONG RADIAL OUTFLOW WITH
NO DISCRETE CLOUD EDGES. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON A 120548Z GPM GMI 89HBT MICROWAVE IMAGE
REVEALING IRREGULAR AND ASYMMETRIC DEEP CONVECTION WHICH PARTIALLY
EXPOSES THE LOW-LEVEL CLOUD BANDING TO THE SOUTH. THE INITIAL
INTENSITY OF 65 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON AN
EARLIER 120221Z RCM-3 SYNTHETIC APERTURE RADAR (SAR) IMAGE
REVEALING 60KTS OF WIND, AND A 120620Z METOP-B ASCAT IMAGE
DEPICITNG 65KTS TO THE NORTH AND NORTHWEST OF THE LLCC.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   KNES: T4.0 - 65 KTS
   DEMS: T4.5 - 77 KTS
   CIMSS ADT: 59 KTS AT 120600Z
   CIMSS AIDT: 58 KTS AT 120600Z
   CIMSS D-PRINT: 52 KTS AT 120600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 07S IS FORECAST TO TRACK
SOUTHWESTWARD OVER THE MOZAMBIQUE CHANNEL FOR THE NEXT 48 HOURS
WHILE APPROACHING THE STR AXIS. AFTER TAU 48, THE SYSTEM WILL ALTER
COURSE SOUTHEASTWARD, CONTINUING TO ROUND THE RIDGE. THE INTENSITY
OF TC 07S WILL STAGNATE FOR THE FIRST 12 HOURS WHILE AN UPPER-LEVEL
CYCLONE TO THE SOUTH MOVES OUTBOUND EASTWARD. AN UPPER-LEVEL
ANTICYCLONE WILL MOVE IN, ALLOWING FOR A POLEWARD OUTFLOW CHANNEL
TO FORM BETWEEN TAU 24-72, IMPROVING UPPER-LEVEL DIVERGENCE.
VERTICAL WIND SHEAR (VWS) WILL REMAIN LOW TO MODERATE UNTIL TAU 72.
THE INCREASINGLY FAVORABLE ENVIRONMENT FOR THE FIRST 72 HOURS WILL
LEAD TO A PEAK INTENSITY OF 100KTS BY TAU 72. BY TAU 96, AN
UPPER-LEVEL JET MAXIMUM WILL BEGIN TO INDUCE HIGH VERTICAL WIND
SHEAR AND BAROCLINIC FORCING, INITIATING EXTRATROPICAL TRANSITION.
WEAKENING WILL CONTINUE THROUGH THE END OF THE FORECAST AND
EXTRATROPICAL TRANSITION WILL COMPLETE. 

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN TIGHT
AGREEMENT THAT THE SYSTEM WILL TRACK CLOSELY TO THE COAST OF
MOZAMBIQUE WITHIN THE FIRST 48 HOURS, BUT GFS AND ECMWF DIFFER AS
TO WHETHER THE SYSTEM WILL TRACK OVER LAND OR NOT. GFS DEPICTS THE
SYSTEM SKIRTING THE COAST OF MOZAMBIQUE, BUT ECMWF KEEPS TC 07S
OVER WATER. HOWEVER, THE ENSEMBLE GUIDANCE FOR BOTH GEFS AND EC-EPS
DEPICT MOST MEMBERS KEEPING THE SYSTEM OVER WATER. THE INTENSITY
GUIDANCE IS HIGHLY DEPENDENT ON WHETHER OR NOT THE TRACK MOVES OVER
LAND OR NOT, THUS GFS AND HWRF GUIDANCE DEPICT A SLOWER RATE OF
INTENSIFICATION WHILE COAMPS-TC AND HAFS-A INDICATE RAPID
INTENSIFICATION WITHIN THE FIRST 72 HOURS.

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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