WDIO31 PGTW 110300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02A (BIPARJOY) 
WARNING NR 020//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.9N 67.5E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 415 NM SOUTH OF KARACHI, PAKISTAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 41 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TC 02A HAS WEAKENED EVER SO SLIGHTLY, OFF FROM THE PREVIOUS HIGH OF
105 KNOTS, WHICH WAS BASED ON A SERIES OF SAR PASSES. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A VERY COMPACT
CENTRAL DENSE OVERCAST (CDO) WITH HOT TOWERS WITH CLOUD TOP TEMPS
IN THE OVERSHOOTING TOPS APPROACHING -91C, FIRING OFF IN THE
SOUTHEAST SECTOR. SO IT APPEARS THAT WE MAY BE IN FOR ANOTHER ROUND
OF INTENSIFICATION IN THE NEAR-TERM. AN 110018Z SSMIS 91GHZ IMAGE
SHOWED A SOMEWHAT SURPRISINGLY DISORGANIZED UPPER-LEVEL STRUCTURE,
WHILE THE 37GHZ IMAGE SHOWED MORE ROBUST LOW-LEVEL BANDING FEATURES
SURROUNDING AN ELONGATED MICROWAVE EYE FEATURE. THE INITIAL
POSITION IS ASSESSED WITH MEDIUM CONFIDENCE, BASED ON THE IRREGULAR
SHAPED MICROWAVE EYE FEATURE AND LIES IN THE NORTHEAST PORTION OF
THE CDO. THE INITIAL INTENSITY IS ASSESSED WITH LOW CONFIDENCE AS
IT REMAINS WELL ABOVE NEARLY ALL OF THE AVAILABLE SUBJECTIVE AND
OBJECTIVE INTENSITY ESTIMATES BASED ON THE EARLIER SAR DATA, THE
CLOSEST ESTIMATE BEING THE PGTW T5.0. ENVIRONMENTAL SHEAR REMAINS
STRONG, NEAR 25 KNOTS IN THE LATEST CIMSS ESTIMATES, HOWEVER THE
SYSTEM IS STILL FIRING OFF ENOUGH CONVECTION TO CREATE A MESOSCALE
REGION OF LOWER SHEAR, WHICH IS ALLOWING IT TO INTENSIFY AS MUCH AS
IT HAS. OTHERWISE, THE ENVIRONMENT IS FAVORABLE WITH VERY WARM SSTS,
MODERATELY HIGH OHC AND GOOD WESTWARD OUTFLOW. THE SYSTEM CONTINUES
TO MOVE NORTHWARD ALONG THE WEST SIDE OF THE SUBTROPICAL RIDGE
(STR) OVER INDIA.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF THE DEEP-LAYER STR
TO THE EAST OVER INDIA. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   KNES: T4.5 - 77 KTS
   DEMS: T4.5 - 77 KTS
   CIMSS SATCON: 80 KTS AT 102108Z
   CIMSS ADT: 59 KTS AT 110000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 25-30 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE WESTWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: THERE HAVE BEEN NO MAJOR CHANGES TO THE
OVERALL TRACK SINCE THE PREVIOUS FORECAST. TC 02A IS FORECAST TO
CONTINUE MOVING SLOWLY NORTHWARD THROUGH THE NEXT 12 HOURS, BUT
THEN PICK UP SOME SPEED AFTER TAU 24 AS THE RIDGE TO THE EAST
STRENGTHENS. THE SYSTEM IS FORECAST TO FOLLOW A SINUSOIDAL TRACK
NORTHWARD THROUGH TAU 72 AS SHORT-TERM FLUCTUATIONS IN THE RIDGE
ORIENTATION AND NORTHWESTWARD EXTENT WILL EXERT SOME MINOR STEERING
INFLUENCE ON THE SYSTEM. BY TAU 48, A NEW STR CENTERED OVER
SOUTHERN IRAN IS EXPECTED TO FORM AND BEGIN TO BUILD TOWARDS THE
EAST OVER SOUTHERN PAKISTAN. AS THIS RIDGE STRENGTHENS IT WILL
FORCE TC 02A ONTO A MORE NORTHEASTWARD TRAJECTORY AFTER TAU 72,
TOWARDS THE RANN OF KUTCH REGION. LANDFALL IS EXPECTED ALONG THE
COAST IN THE VICINITY OF SUTHRI, INDIA JUST AFTER TAU 96, AFTER
WHICH THE SYSTEM WILL QUICKLY MOVE INLAND. IN TERMS OF INTENSITY,
AS MENTIONED IN THE FIRST PARAGRAPH, INDICATIONS ARE THAT THE
SYSTEM COULD BE PRIMED FOR ANOTHER BURST OF INTENSIFICATION, AS
DEEP CONVECTION IS FIRING AND WRAPPING UPSHEAR AS OF THE 0100Z HOUR
IN A VERY SIMILAR FASHION TO 24 HOURS AGO. HAVING ALREADY REACHED A
HIGH STARTING POINT OF 100 KNOTS, THERE IS NO REASON NOT TO BELIEVE
THE SYSTEM COULD REACH ANOTHER 105-110KT PEAK IN THE NEXT 12 HOURS
OR SO. AFTER TAU 24 HOWEVER, AS THE SYSTEM MOVES NORTHWARD, IT WILL
BUTT INTO A FAIRLY STRONG 200MB ANTICYCLONE LYING IN WAIT OVER
SOUTHERN PAKISTAN, WHICH WILL IMPART CONVERGENT UPPER-LEVEL FLOW
OVER TOP OF THE SYSTEM. AT THE SAME TIME, THE GENERAL OFFSHORE FLOW
OFF OF PAKISTAN WILL INTRODUCE DRY DESERT AIR INTO THE WESTERN SIDE
OF THE SYSTEM. THE COMBINED EFFECTS OF THESE TWO FACTORS WILL LEAD
TO A SLOW WEAKENING TREND AFTER TAU 48, FOLLOWED BY A RAPID
WEAKENING AFTER MAKING LANDFALL. 

MODEL DISCUSSION: TRACK GUIDANCE REMAINS CONFINED TO A FAIRLY SMALL
ENVELOPE, WITH THE NOTABLE EXCEPTION OF NAVGEM WHICH CONTINUES TO
INSIST ON TAKING THE SYSTEM NORTHWESTWARD INTO THE DEVELOPING RIDGE
OVER IRAN. DISCOUNTING THAT UNREALISTIC SCENARIO, THE REMAINDER OF
THE GUIDANCE SUPPORTS THE JTWC FORECAST, WITH THE CONSENSUS
TRACKERS LYING IN A GRADUALLY EXPANDING ENVELOPE THAT REACHES 120NM
AT TAU 72. SIMILAR TO LAST CYCLE, ALL THE CONSENSUS MEMBERS
CONTINUE TO AGREE ON THE TURN TO THE NORTHEAST AFTER TAU 72, WITH A
SPREAD OF 125NM AT LANDFALL, ROUGHLY FROM THE PAKISTAN-INDIA BORDER
TO THE WESTERN TIP OF THE GUJARAT PENINSULA. THE JTWC TRACK REMAINS
CONSISTENT WITH THE PREVIOUS FORECAST AND LIES SLIGHTLY TO THE LEFT
OF THE CONSENSUS MEAN THROUGH THE FORECAST PERIOD, WITH MEDIUM
CONFIDENCE. INTENSITY GUIDANCE IS MIXED, WITH THE HWRF SHOWING
NEAR-RAPID INTENSIFICATION TO 120 KNOTS BY TAU 12 AND CYCLICAL
PERIODS OF WEAKENING AND INTENSIFICATION THROUGH THE REMAINDER OF
THE FORECAST. THE REMINDER OF THE GUIDANCE PACKAGE SHOWS FAIRLY
STEADY WEAKENING THROUGH THE FORECAST. THE JTWC FORECAST DEVIATES
TOWARDS THE HWRF THROUGH TAU 12, BUT THEN REJOINS THE CONSENSUS
MEAN AFTER TAU 36. DUE TO THE RECENT INTENSITY EVOLUTION, AND THE
HIGHLY CYCLICAL NATURE OF THE SYSTEM, THERE IS LOW CONFIDENCE IN
THE FORECAST INTENSITY. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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