WDXS31 PGTW 211500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 24S (IALY) WARNING NR 
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 4.7S 42.2E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 214 NM NORTHEAST OF DAR ES SALAAM,
TANZANIA
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 21 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE 24S (IALY) TRACKING WEST-NORTHWESTWARD OFF OF THE COAST OF
KENYA INTO AN AREA OF INCREASING NORTHEASTERLY VERTICAL WIND SHEAR,
WHICH HAS CAUSED THE EYE THAT DEVELOPED OVER THE LAST 12 HOURS TO
BECOME DISORGANIZED AND CLOUD-FILLED OVER THE PAST FEW HOURS. A
211117Z ATMS 88GHZ MICROWAVE IMAGE DEPICTS CONVECTIVE BANDING
WRAPPING ALONG THE SOUTHERN AND WESTERN PERIPHERIES, WITH AN
OPENING TO THE NORTHEAST OF THE CIRCULATION CENTER. AN EARLIER
210656Z METOP-C ASCAT IMAGE DEPICTS A DISTINCT LOW-LEVEL
CIRCULATION CENTER WITH ASSOCIATED WIND SPEEDS REACHING 55KTS. THE
INITIAL POSITION IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON
ANIMATED MSI. THE INITIAL INTENSITY OF 60 KTS IS ASSESSED WITH
MEDIUM CONFIDENCE BASED THE PREVIOUSLY MENTIONED METOP-C ASCAT
IMAGE AND THE AGENCY AND OBJECTIVE FIXES BELOW.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA AND OBJECTIVE BEST
TRACK 

CURRENT STEERING MECHANISM: NEAR-EQUATORIAL RIDGE OVER TANZANIA

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   KNES: T4.0 - 65 KTS
   DEMS: T4.5 - 77 KTS
   FMEE: T4.5 - 77 KTS
   CIMSS SATCON: 58 KTS AT 211200Z
   CIMSS ADT: 53 KTS AT 211200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE FORECAST TRACK HAS SHIFTED
SLIGHTLY TO THE WEST FROM THE PREVIOUS WARNING, BUT OTHERWISE THERE
ARE NO SIGNIFICANT CHANGES TO THE FORECAST.

FORECAST DISCUSSION: TC 24S IS FORECAST TO CURVE TO THE
NORTH-NORTHWEST OVER THE NEXT TWELVE HOURS AS THE SYSTEM WEAKENS
UNDER PERSISTENT VERTICAL WIND SHEAR AND COMES UNDER THE STEERING
INFLUENCE OF STRONG SOUTHWESTERLY LOW-LEVEL FLOW PARALLELING THE
EASTERN COAST OF THE AFRICAN CONTINENT. AS THE SYSTEM CONTINUES TO
ERODE, IT WILL CONTINUE TRACKING IN A NORTHEASTERLY DIRECTION AND
DISSIPATE BY TAU 24. NEAR-TERM MOVEMENT A BIT FARTHER TO THE WEST
IS POSSIBLE IF THE VORTEX RESISTS INCREASING SHEAR FOR LONGER THAN
ANTICIPATED.

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK FORECAST GUIDANCE IS
SCANT, WITH SEVERAL MODEL TRACKS UNABLE TO LOCATE THE VORTEX AS
ANTICIPATED RAPID WEAKENING OCCURS OVER THE NEXT 12 TO 24 HOURS.
HOWEVER, AVAILABLE TRACK GUIDANCE DOES GENERALLY AGREE ON A NEARLY
NORTHWARD TRACK THROUGH TAU 12 TURNING TO PARALLEL THE COAST KENYA
AND SOUTHERN SOMALIA THEREAFTER FOLLOWING THE LOW-LEVEL FLOW.
MESOSCALE MODEL INTENSITY FORECAST GUIDANCE IS IN AGREEMENT THAT
THE SYSTEM WILL WEAKEN RAPIDLY UNDER PERSISTENT SHEAR, PARTICULARLY
AFTER TAU 12.

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