Advisories

WDIO31 PGTW 030300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 04B (MURASU) WARNING NR 
009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.5N 80.3E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 626 NM SOUTHWEST OF KOLKATA, INDIA
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS VORTICAL
HOT TOWERS CONTINUING TO FIRE WITHIN THE COMPACT CENTRAL DENSE
OVERCAST (CDO), WITH CONVECTIVE BANDING FORMING NORTHEAST OF THE
CDO. RADAR IMAGERY INDICATES THAT THE EYE IS JUST OFFSHORE, WITH
THE WESTERN SIDE OF THE EYEWALL SCRAPING THE NORTHERN COROMANDEL
COAST. AN EARLIER 021939Z AMSR3 PASS REVEALED AN UPPER-LEVEL EYE
MEASURING JUST 7 NM IN DIAMETER. SEA SURFACE TEMPERATURES ARE 28-29
DEGREES CELSIUS, AND MODERATE VERTICAL WIND SHEAR PERSISTS.
HOWEVER, THE SYSTEM IS EXPERIENCING INCREASING LAND INTERACTION.
BECAUSE THE OVERALL CONVECTIVE STRUCTURE HAS NOT CHANGED
SIGNIFICANTLY DURING THE PAST SIX HOURS, THE INITIAL INTENSITY IS
HELD AT AN UNCERTAIN 85 KTS WITH LOW CONFIDENCE. THIS ASSESSMENT IS
HIGHER THAN THE SUBJECTIVE AND OBJECTIVE ESTIMATES, WHICH MAY
UNDERESTIMATE THE INTENSITY OF TC 04B DUE TO ITS EXTREMELY COMPACT
INNER-CORE STRUCTURE. THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON RADAR IMAGERY.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WESTERN FLANK OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED NEAR 18N 91E

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   DEMS: T3.5 - 55 KTS
   CIMSS SATCON: 59 KTS AT 022024Z
   CIMSS ADT: 72 KTS AT 022100Z
   CIMSS AIDT: 47 KTS AT 022300Z
   CIMSS D-MINT: 68 KTS AT 022025Z
   CIMSS D-PRINT: 62 KTS AT 022300Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: LAND INTERACTION

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 04B IS LOCATED ALONG THE WESTERN PERIPHERY
OF THE STR AND IS TURNING MORE SHARPLY POLEWARD. THIS GENERALLY
POLEWARD MOTION WILL CONTINUE THROUGH TAU 24 AS THE SYSTEM MOVES
INLAND AND RAPIDLY WEAKENS DUE TO LAND INTERACTION. AFTER TAU 24,
THE SHALLOWER VORTEX SHOULD BEGIN TO TURN WESTWARD AS LOWER-LEVEL
EASTERLY FLOW BECOMES THE DOMINANT STEERING MECHANISM. DISSIPATION
IS PREDICTED BY TAU 36.

MODEL DISCUSSION: SOME SPREAD EXISTS AMONG THE TRACK GUIDANCE. MOST
DYNAMICAL MODELS FAVOR AN EARLIER WESTWARD TURN, WHILE GFS AND
GOOGLE DEEPMIND DEPICT A MORE POLEWARD TRACK. THE JTWC FORECAST
TRACK IS POSITIONED NEAR THE GOOGLE DEEPMIND SOLUTION THROUGH TAU
24, THEN SHIFTS TOWARD THE MULTI-MODEL CONSENSUS BY TAU 36. ALL
INTENSITY AIDS INDICATE IMMINENT RAPID WEAKENING AS THE SYSTEM
MOVES INLAND. THE JTWC INTENSITY FORECAST IS ALIGNED WITH THE
INTENSITY AIDS THROUGH TAU 36.

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