WDIO31 PGTW 052100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02A (SHAKHTI) WARNING 
NR 012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.8N 60.3E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 92 NM EAST-SOUTHEAST OF MASIRAH ISLAND
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 17 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RAPIDLY
DETERIORATING CONVECTIVE STRUCTURE, WITH DEEP CONVECTION SHEARING
WESTWARD AND AN EXPOSED LOW-LEVEL CIRCULATION. ENVIRONMENTAL 
CONDITIONS HAVE DEGRADED, WITH HIGH VERTICAL WIND SHEAR AND EXTENSIVE 
DRY AIR. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED 
ON THE MSI. THE INITIAL INTENSITY OF 55 KTS IS ASSESSED WITH MEDIUM 
CONFIDENCE BASED ON THE CIMSS OBJECTIVE INTENSITY ESTIMATES RANGING 
FROM 49-53 KNOTS.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR) 
TO THE WEST AND BUILDING TO THE SOUTHWEST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   CIMSS ADT: 49 KTS AT 051500Z
   CIMSS AIDT: 53 KTS AT 051700Z
   CIMSS D-PRINT: 53 KTS AT 051730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: TROPICAL CYCLONE (TC) 02A IS SLOWING AND WILL
STALL AND TURN SOUTHWESTWARD TO SOUTHWARD UNDER THE STEERING
INFLUENCE OF THE LOW-LEVEL STEERING RIDGE TO THE WEST AND SOUTH. 
AFTER TAU 12, TC 02A WILL TRACK EAST-SOUTHEASTWARD TO EASTWARD UNDER 
AS THE LOW-LEVEL RIDGE BUILDS TO THE SOUTH, WITH RAPID WEAKENING DUE 
TO EXTENSIVE DRY AIR ENTRAINING INTO THE SYSTEM AT ALL LEVELS. THE
SYSTEM IS EXPECTED TO DISSIPATE BY TAU 36.

MODEL DISCUSSION: DETERMINISTIC AND PROBABILISTIC GUIDANCE IS IN
FAIR AGREEMENT SUPPORTING THE JTWC TRACK FORECAST WITH MEDIUM 
CONFIDENCE. RELIABLE INTENSITY GUIDANCE SUPPORTS THE RAPID WEAKENING 
FORECAST DUE TO THE VERY DRY ENVIRONMENT AND HIGH VERTICAL WIND 
SHEAR.  

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   INTENSITY 00-72 HR: HIGH//
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