Advisories

WDIO31 PGTW 270300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02B (ARNAB) WARNING NR 
005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.0N 84.8E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 445 NM SOUTH-SOUTHWEST OF KOLKATA, INDIA
   MOVEMENT PAST 6 HOURS: WESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 29 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE (TC) 02B WITH A WELL-DEVELOPED AND SYMMETRICAL EYE
SURROUNDED BY A COMPACT AND SYMMETRICAL CENTRAL DENSE OVERCAST.
CLOUD TOPS HAVE BEEN WARMING OVER THE PAST FEW HOURS IN ENHANCED
INFRARED IMAGERY BUT THE EXCELLENT SATELLITE PRESENTATION SUGGESTS
THAT INTENSIFICATION IS STILL ONGOING. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON THE EYE IN MSI. THE INITIAL
INTENSITY OF 90 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE
WIDE SPREAD BETWEEN THE AGENCY DVORAK FIXES AND CIMSS OBJECTIVE
INTENSITY ESTIMATES. 90 KTS IS PROBABLY ON THE CONSERVATIVE SIDE
BASED ON THE SATELLITE PRESENTATION. THE ENVIRONMENT IS
CHARACTERIZED AS HIGHLY FAVORABLE, WITH GOOD RADIAL OUTFLOW, WARM
SEA SURFACE TEMPERATURES, AND LOW VERTICAL WIND SHEAR (VWS).

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHWESTERN FLANK OF A SUBTROPICAL
RIDGE (STR) CENTERED OVER SOUTHERN CHINA

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   DEMS: T4.0 - 65 KTS
   CIMSS SATCON: 84 KTS AT 262012Z
   CIMSS ADT: 90 KTS AT 270000Z
   CIMSS AIDT: 97 KTS AT 270000Z
   CIMSS D-MINT: 95 KTS AT 270029Z
   CIMSS D-PRINT: 95 KTS AT 262330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: TC 02B CONTINUES ON A WESTWARD TRACK PRIMARILY
UNDER THE STEERING INFLUENCE OF THE STR POSITIONED TO THE
NORTHEAST. THE STEERING RIDGE IS EXPECTED TO WEAKEN SLIGHTLY AND
SHIFT EASTWARD OVER THE NEXT 24 HOURS, INDUCING A NORTHWARD TURN OF
THE SYSTEM AS IT MAKES LANDFALL JUST AFTER TAU 24. THE TRACK
RETAINS ITS NORTHWARD TRAJECTORY FOR THE REMAINDER OF THE FORECAST
PERIOD. THE INTENSITY FORECAST CALLS FOR CONTINUED INTENSIFICATION
OVER THE NEXT 12 HOURS IN A HIGHLY FAVORABLE ENVIRONMENT. A
WEAKENING TREND BEGINS AROUND TAU 24 AS THE OUTER PERIPHERY OF THE
COMPACT SYSTEM BEGINS TO INTERACT WITH THE INDIAN COAST. RAPID
DECAY OVER LAND WILL BRING DISSIPATION BY TAU 60.

MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT ABOUT
THE WESTWARD TRACK OVER THE BAY OF BENGAL FOLLOWED BY A SHARP
POLEWARD TURN. THE JTWC TRACK FORECAST FOLLOWS THE MULTI-MODEL
CONSENSUS, WHICH IS ALSO TIGHTLY GROUPED WITH THE GOOGLE DEEPMIND
MODELS. A FEW RAPID INTENSITY (RI) AIDS UNSURPRISINGLY TRIGGERED
THIS CYCLE AND THE JTWC INTENSITY FORECAST IS PLACED SLIGHTLY ABOVE
THE CONSENSUS THROUGH TAU 12 IN RESPONSE, THEN FOLLOWS THE
CONSENSUS FOR THE REMAINDER OF THE FORECAST PERIOD. THERE IS SOME
UNCERTAINTY ABOUT JUST HOW HIGH THE INTENSITY CAN CLIMB BEFORE LAND
INTERACTION CAPS IT.

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