WDIO31 PGTW 122100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 01B (MOCHA) WARNING NR 
008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.0N 88.7E
   INITIAL INTENSITY: 110 KTS
   GEOGRAPHIC REFERENCE: 456 NM SOUTH OF KOLKATA, INDIA
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 48 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR) DEPICTS A BROAD,
WELL ORGANIZED SYSTEM WITH A RAGGED EYE SURROUNDED BY BANDS OF DEEP
CONVECTION IN ALL QUADRANTS WRAPPING INTO THE LOW LEVEL CIRCULATION
CENTER (LLCC). ANALYSIS OF MULTI-AGENCY 121800Z POSITIONS COMPARED
TO PREVIOUS POSITIONS SUGGESTS THE SYSTEM HAS WOBBLED NORTHWARD.
THIS BEHAVIOR IS USUALLY INDICATIVE OF A RAPIDLY STRENGTHENING
SYSTEM. IN ADDITION, ANALYSIS OF THE M-PERC EYEWALL REPLACEMENT
TOOL SUGGESTS AN EYEWALL REPLACEMENT CYCLE (ERC) IS UNDERWAY. ONE
MAJOR CONTRIBUTING FACTOR TO THE RAPID INTENSIFICATION IS AN
INTENSE POOL OF OCEAN HEAT CONTENT (OHC) THAT HAS DOMINATED THE
CENTRAL BAY OF BENGAL OVER THE PAST SEVERAL DAYS. TC MOCHA IS IN A
MARGINALLY FAVORABLE ENVIRONMENT FOR FURTHER TROPICAL DEVELOPMENT.
THESE CONDITIONS ARE CHARACTERIZED BY STRONG POLEWARD AND
EQUATORWARD OUTFLOW ALOFT, A STRONG 850 MB VORTICITY SIGNATURE,
MODERATE (15-20 KTS) VERTICAL WIND SHEAR (VWS), AND VERY WARM
(30-31 C) SEA SURFACE TEMPERATURES (SST). THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON MULTI-AGENCY FIXES, AS WELL AS
THE AFOREMENTIONED EIR IMAGERY. THE INITIAL INTENSITY OF 110 KNOTS
IS ASSESSED WITH MEDIUM CONFIDENCE BASED OFF A BLEND OF
MULTI-AGENCY DVORAKS ESTIMATES AND THE ABOVEMENTIONED RAPID
INTENSIFICATION EXAMINATION.

INITIAL WIND RADII BASIS: PERSISTENCE AND ANALYSIS OF A PARTIAL
121536Z ASCAT-C PASS.

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   KNES: T6.5 - 127 KTS
   DEMS: T5.5 - 102 KTS
   CIMSS SATCON: 102 KTS AT 121533Z
   CIMSS ADT: 112 KTS AT 121800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 31-32 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD
   OTHER FACTORS: HIGH OCEAN HEAT CONTENT (OHC) AND RAPID
INTENSIFICATION (RI)

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: INCREASE OF INITIAL INTENSITY DUE TO
RI.

FORECAST DISCUSSION: TC 01B (MOCHA) IS RIDING THE WESTERN PERIPHERY
OF THE STR TO THE EAST. AS PREVIOUSLY MENTIONED, TC MOCHA HAS
RAPIDLY INTENSIFIED OVER THE PAST 6 HOURS. BETWEEN TAUS 12 AND 24,
TC 01B WILL TRACK NORTHEASTWARD AND CONTINUE TO INTENSIFY TO 115
KTS AND 120 KTS RESPECTIVELY AS THE SYSTEM WILL CONTINUE TO
STRENGTHEN. BY TAU 36, PRIOR TO LANDFALL JUST SOUTH OF THE
BANGLADESH AND MYANMAR BORDER, TC MOCHA WILL DECREASE IN INTENSITY
TO 100 KNOTS AS THE ENVIRONMENT WILL BECOME LESS FAVORABLE. THESE
LESS FAVORABLE CONDITIONS ARE DEFINED BY AN INCREASE IN VWS, DRY
AIR ENTRAINMENT WRAPPING INTO THE LLCC FROM THE SOUTHERN PERIPHERY,
THE ONSET OF LAND INTERACTION, AND COOLER (28-29 C) SST. BY TAU 42,
TC 01B WILL MAKE LANDFALL AND BEGIN ITS DISSIPATION PHASE. BETWEEN
TAUS 48 AND 72, TC MOCHA WILL DISSIPATE DUE TO LAND INTERACTION
OVER NORTHWEST MYANMAR.  

MODEL DISCUSSION: THE DETERMINISTIC AND ENSEMBLE MODELS ALL AGREE
THAT TC 01B WILL CONTINUE TO INTENSIFY AS IT TRANSITS NORTHEASTWARD
THROUGH TAU 24, THEN WEAKEN ON OR BEFORE TAU 36 AS IT CONTINUES THE
SAME TRAJECTORY. THE JTWC FORECAST TRACK CONSENSUS MEMBERS ARE IN
TIGHT AGREEMENT WITH A 21 NM SPREAD AT TAU 12 THAT GRADUALLY
INCREASES TO 94 NM JUST BEFORE LANDFALL. THE GFS, ECMWF AND NAVGEM
TRACKS ARE ON THE POLEWARD SIDE OF THE CONSENSUS ENVELOPE, WHEREAS
THE UK AND AFUM SOLUTIONS ARE ON THE EQUATORWARD SIDE. DUE TO THIS,
THE JTWC TRACK IS PLACED SLIGHTLY LEFT OF CONSENSUS WITH HIGH 
CONFIDENCE THROUGHOUT THE FORECAST PERIOD. THE JTWC INTENSITY
CONSENSUS IS ALSO IN GOOD AGREEMENT WITH ALL SOLUTIONS INDICATING A
DECREASE IN INTENSITY PRIOR TO LANDFALL. THE GFS INTENSITY GUIDANCE
IS THE OUTLIER SHOWING LOWER VALUES THROUGHOUT THE FORECAST PERIOD.
THE JTWC INTENSITY FORECAST IS SET WITH MEDIUM CONFIDENCE DUE TO
THE SPREAD IN THE CONSENSUS MEMBERS AND THE RAPID INTENSIFICATION
SCENARIO.

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