WDIO31 PGTW 131500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 01B (MOCHA) WARNING NR 
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.9N 90.8E
   INITIAL INTENSITY: 130 KTS
   GEOGRAPHIC REFERENCE: 329 NM SOUTH OF CHITTAGONG
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 50 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 01B (MOCHA) HAS RAPIDLY INTENSIFIED OVER THE
PAST SIX HOURS, HAVING CONSOLIDATED A TIGHT INNER-CORE OF
CONVECTION AND ESTABLISHED A WELL-DEFINED EYEWALL. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A 19-NM WIDE EYE
FEATURE, WITH CENTER TEMPERATURES APPROACHING -10C AND DEEP
CONVECTIVE BANDS COMPLETELY SURROUNDING THE INNER CORE. THE 131226Z
GMI AND 131156Z SSMIS 89GHZ MICROWAVE IMAGES DEPICTED A SOLID INNER
EYEWALL, AS WELL AS A STATIONARY BANDING COMPLEX (SBC) TO THE SOUTH, 
WHICH IN THE GMI PASS HAS NOW BECOME SEPARATED FROM THE PRIMARY 
EYEWALL, WHICH MAY HAVE SOME IMPACTS DOWN THE ROAD.  ANIMATED WATER 
VAPOR IMAGERY AND THE CIRA ADVECTED LAYER PRECIPITABLE WATER PRODUCT 
CONFIRM THE SIGNIFICANT MOISTENING OF THE ENVIRONMENT ON THE NORTH 
SIDE OF THE SYSTEM, AND THE DRASTIC IMPROVEMENT IN POLEWARD OUTFLOW, 
AS THE SYSTEM IS NOW SOLIDLY CONNECTED TO OUTFLOW CHANNEL INTO THE 
RIGHT ENTRANCE REGION OF THE JET MAX OVER SOUTHERN CHINA. THE INITIAL
POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE RECENT
MICROWAVE IMAGES NOTED ABOVE. THE INITIAL INTENSITY IS ASSESSED
WITH HIGH CONFIDENCE BASED ON A BLEND OF THE AGENCY CURRENT
INTENSITY ESTIMATES, ALONG WITH THE DEEP MICRONET (DMN) AND
OPEN-AIIR ESTIMATES OF 127 KNOTS AND 132 KNOTS RESPECTIVELY. THE
SYSTEM CONTINUES TO TRACK NORTHEASTWARD ALONG THE NORTHWEST SIDE OF
THE SUBTROPICAL RIDGE (STR) AND IS PICKING UP SPEED. CONDITIONS
REMAIN FAVORABLE FOR INTENSIFICATION, WITH LOW (5-10 KTS) VWS, WARM
(30-31C) SSTS AND ROBUST OUTFLOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: NORTHWEST PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED OVER THE NORTHERN PHILIPPINES. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T7.0 - 140 KTS 
   KNES: T6.0 - 115 KTS
   DEMS: T5.5 - 102 KTS
   CIMSS ADT: 109 KTS AT 130900Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: THERE IS NO SIGNIFICANT CHANGE IN THE TRACK
FORECAST, WITH THE SYSTEM EXPECTED TO TRACK NORTHEASTWARD THROUGH
THE FORECAST PERIOD. DUE AN INCREASE IN TRACK SPEED, LANDFALL IS
EXPECTED SLIGHTLY EARLIER THAN PREVIOUSLY FORECAST, BUT WILL STILL
BETWEEN TAUS 12 AND 18 ALONG THE COAST OF MYANMAR, NEAR SITWE.
AFTER LANDFALL, THE SYSTEM WILL CONTINUE TO ACCELERATE TOWARDS THE
NORTHEAST ALONG THE TIGHT STEERING GRADIENT. IN TERMS OF INTENSITY,
THE SYSTEM STILL HAS SOME TIME UNDER NEAR-OPTIMAL CONDITIONS, WHICH
WILL SUPPORT ADDITIONAL INTENSIFICATION. SHEAR IS VERY LOW AT
PRESENT, ESTIMATED AT BETWEEN 5-10 KNOTS AT BEST. COMBINED WITH THE
ZESTY WATERS BELOW AND THE ROBUST OUTFLOW ALOFT, THE SYSTEM IS
LIKELY TO MAKE A RUN AT 140 KNOTS OR A BIT HIGHER WITHIN THE NEXT 6
TO 12 HOURS. THE CIMSS M-PERC EYEWALL REPLACEMENT CYCLE (ERC)
PREDICTION TOOL IS INDICATING A MODERATE PROBABILITY OF AN ERC AND
THE PRESENCE OF THE AFOREMENTIONED SBC FEATURE IN THE MICROWAVE
IMAGERY PROVIDES ANOTHER HINT THAT AN ERC COULD BE IN THE OFFING,
THOUGH THE EXACT TIMING OF ONSET IS DIFFICULT TO PREDICT. THE
FORECAST CALLS FOR A PEAK NEAR 140 KNOTS OR ABOVE AROUND TAU 6,
FOLLOWED BY THE ONSET OF ERC WHICH WILL LEAD TO A SLOW WEAKENING BY
TAU 12, BACK TO 130 KNOTS. THEREAFTER THE SYSTEM WILL FEEL THE
EFFECTS OF SLIGHTLY COOLER SSTS ALONG THE COAST, AS WELL AS AN
INCREASE IN MID-LEVEL SHEAR WHICH WILL LEAD TO GENERAL WEAKENING
PRIOR TO LANDFALL, THOUGH THE SYSTEM WILL STILL BE AT OR ABOVE 115
KNOTS AT LANDFALL. AFTER LANDFALL THE SYSTEM WILL RAPIDLY WEAKEN
DUE TO VERY HIGH SHEAR AND TERRAIN INTERACTION, FULLY DISSIPATING
NO LATER THAN TAU 48 OVER NORTHERN MYANMAR. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN VERY GOOD
AGREEMENT ON THE NORTHEAST TRACK THROUGH THE FORECAST PERIOD, WITH
LESS THAN 50NM SPREAD AT LANDFALL, LENDING HIGH CONFIDENCE TO THE
JTWC FORECAST TRACK. INTENSITY GUIDANCE IS ALSO IN GOOD OVERALL
AGREEMENT, WITH THE MAJORITY OF THE CONSENSUS MEMBERS INDICATING A
FLAT INTENSITY THROUGH TAU 12, FOLLOWED BY GRADUAL WEAKENING
THROUGH LANDFALL AND THEN DRASTIC WEAKENING THROUGH DISSIPATION.
THE COAMPS-TC (BOTH NAVGEM AND GFS VERSIONS) ARE THE ONLY MODELS
SUGGESTING INTENSIFICATION IN THE NEAR-TERM, THROUGH ABOUT TAU 12,
AFTER WHICH THEY REJOIN THE PACK. THE JTWC FORECAST FOLLOWS THE
CONSENSUS MEAN, THOUGH AS MENTIONED ABOVE, THE SYSTEM IS LIKELY TO
EXPERIENCE SOME ADDITIONAL INTENSIFICATION, AS DEPICTED BY THE
COAMPS-TC, IN THE TIMEFRAME BETWEEN THE TAU 00 AND TAU 12 FORECAST
POINTS. OVERALL CONFIDENCE IN THE JTWC FORECAST INTENSITY IS HIGH. 


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