Advisories

WDIO31 PGTW 280300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02B (ARNAB) WARNING NR 
009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.2N 81.6E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 543 NM SOUTHWEST OF KOLKATA, INDIA
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: 
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A MASS OF 
CONVECTION ALONG THE COAST OF SOUTHEASTERN INDIA FULLY OBSCURING THE 
LOW-LEVEL CIRCULATION (LLCC) OF TROPICAL CYCLONE (TC) 02B. A 
FORTUITOUS 280030 SENTINEL-1D SAR PASS CAPTURED THE COMPACT LLCC JUST 
OFFSHORE. THE SAME SAR PASS REVEALED A PEAK VMAX OF 67 KTS IN THE 
SOUTHEAST QUADRANT. THE INITIAL POSITION IS PLACED WITH HIGH 
CONFIDENCE BASED ON THE SAR DATA. THE INITIAL INTENSITY OF 65 KTS IS 
ASSESSED WITH HIGH CONFIDENCE BASED ON THE SAME DATA. THE ENVIRONMENT 
IS UNFAVORABLE FOR FURTHER DEVELOPMENT WITH MODERATE TO HIGH VERTICAL 
WIND SHEAR AND THE PROXIMITY TO LAND.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: WEAK STEERING ENVIRONMENT CHARACTERIZED
BY A WEAK DISTURBANCE (INVEST 90B) TEMPORARILY IMPEDING THE
INFLUENCE OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED OVER
EXTREME SOUTHERN CHINA.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   DEMS: T4.0 - 65 KTS
   CIMSS AIDT: 88 KTS AT 272300Z
   CIMSS D-MINT: 79 KTS AT 272321Z
   CIMSS D-PRINT: 69 KTS AT 280000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: LAND INTERACTION

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 02B MANAGED TO WANDER BACK OFFSHORE OVER THE 
PAST 6 HOURS AS A WEAK DISTURBANCE (INVEST 90B) IMPEDED THE STEERING 
INFLUENCE OF THE STR TO ITS NORTHEAST. THE DISTURBANCE IS EXPECTED TO 
TRANSIT INLAND IMMINENTLY, WHICH SHOULD ALLOW THE STEERING RIDGE TO 
INDUCE A NORTHWARD TRAJECTORY TO 02B OVER THE NEXT 12 HOURS. THE 
NORTHWARD TRACK OVER LAND WILL RESULT IN RAPID DECAY OF THE SYSTEM, 
WITH DISSIPATION BY TAU 36. 

MODEL DISCUSSION: MODEL TRACK GUIDANCE HAS BEEN INSISTENT ABOUT THE
NORTHWARD TURN AND CONTINUES TO DEPICT A DIRECT NORTHWARD TRACK. 
SURFACE FIELDS IN GFS AND ECMWF HAVE CORRECTLY DEPICTED A QUASI-
STATIONARY PERIOD NEAR THE INDIAN COAST. THE JTWC TRACK FORECAST 
BLENDS THE TWO MODEL SOLUTIONS WITH A SLIGHTLY SLOWER TRACK THROUGH 
TAU 12, THEN FOLLOWS THE CONSENSUS. THE INTENSITY GUIDANCE IS IN 
UNANIMOUS AGREEMENT ABOUT THE RAPID DECAY OVER LAND.

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