WDIO31 PGTW 112100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02A (BIPARJOY) 
WARNING NR 023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.1N 67.8E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 345 NM SOUTH OF KARACHI, PAKISTAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TC 02A
CONTINUING ITS DAILY CYCLING OF DEEP CONVECTION, ALMOST AS IF IT IS
BREATHING. IMAGERY FROM THE PAST 12 HOURS SHOWED A DECREASE IN THE
AREAL EXTENT AND WARMING OF THE CONVECTIVE CLOUD TOPS. BUT THE
LATEST EIR IMAGERY SHOWS DEEP CONVECTION WITH VERY COLD CLOUD TOPS
ONCE MORE FIRING OFF ALL ALONG THE SOUTHERN PERIPHERY AND BEGINNING
TO WRAP UPSHEAR TOWARDS THE EAST. THE INITIAL POSITION IS ASSESSED
WITH LOW CONFIDENCE DUE TO A LACK OF RECENT HIGH-RESOLUTION
MICROWAVE IMAGERY. EXTRAPOLATION OF A LOW-RESOLUTION AMSU-B 89GHZ
IMAGE WHICH SHOWED DEVELOPING BANDS OF CURVED CONVECTION WRAPPING
UP THE EAST SIDE AND A SIMILAR PATTERN IN THE EIR PROVIDED MINIMAL
SUPPORT TO THE INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED
WITH LOW CONFIDENCE DUE TO THE CONTINUED WIDE SPREAD IN THE
AVAILABLE INTENSITY ESTIMATES. THE CURRENT ASSESSMENT IS BROUGHT
DOWN TO ALIGN MORE WITH THE AGENCY DVORAK CURRENT INTENSITY
ESTIMATES OF T5.0 (90 KNOTS) FROM BOTH PGTW AND KNES, WHILE ALL OF
THE OBJECTIVE ESTIMATES REMAIN AT 75 KNOTS OR BELOW. THE OVERALL
ENVIRONMENT REMAINS MARGINALLY FAVORABLE WITH VERY WARM SSTS, HIGH
OHC AND GOOD POLEWARD AND WESTWARD OUTFLOW OFFSET BY PERSISTENT
MODERATE EASTERLY SHEAR AND CONVERGENCE ALOFT BETWEEN THE SYSTEM
AND THE INDIAN COASTLINE. HOWEVER, THE SYSTEM HAS DEMONSTRATED AN
UNCANNY ABILITY TO PUSH BACK AGAINST THE ENVIRONMENTAL SHEAR AND
MAKE ITS OWN MORE FAVORABLE ENVIRONMENT.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED OVER INDIA. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   KNES: T5.0 - 90 KTS
   DEMS: T4.5 - 77 KTS
   CIMSS SATCON: 72 KTS AT 111550Z
   CIMSS ADT: 74 KTS AT 111500Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   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: BASED ON THE RELATIVELY LOW CONFIDENCE
POSITION AT 18Z AND THE MOST RECENT ANIMATED EIR, IT APPEARS THAT
TC 02A HAS STARTED TO TRACK MORE NORTH-NORTHWESTWARD AS THE RIDGE
OVER INDIA HAS CONTINUED TO BUILD. A GENERAL NORTH-NORTHWEST
TRAJECTORY IS FORECAST THROUGH THE NEXT 48 HOURS AS THE STEERING
PATTERN REMAINS RELATIVELY UNCHANGED. BY TAU 36 A NEW RIDGE CENTER
IS EXPECTED TO DEVELOP OVER THE STRAIT OF HORMUZ REGION, AND
GRADUALLY BUILD TOWARDS THE EAST. BY TAU 72, PARTICULARLY IN THE
ECMWF FIELDS, A SHARP BUT NARROW RIDGE IS FORECAST TO DEVELOP
ACROSS SOUTHERN PAKISTAN WHICH WILL PUSH TC 02A ONTO A MORE
EAST-NORTHEASTWARD PATH AFTER TAU 72 AND CONTINUING THROUGH
LANDFALL. LANDFALL IS CURRENTLY FORECAST TO OCCUR BETWEEN TAU 72
AND TAU 96 SOUTHWEST OF THE RANN OF KUTCH IN THE VICINITY OF
SUTHRI, INDIA. AS HAS OCCURRED EACH DAY FOR THE PAST SEVERAL DAYS,
CYCLING CONVECTION IS ALREADY STARTING TO REDEVELOP AND ROTATE
UPSHEAR, INDICATING ANOTHER ROUND OF INTENSIFICATION MAY BE IN THE
OFFING. THE JTWC FORECAST CALLS FOR ABOUT 10 KNOTS OF
INTENSIFICATION THROUGH TAU 12, FOLLOWED BY A MORE PRONOUNCED
WEAKENING PHASE AS THE SYSTEM MOVES NORTHWARD INTO A LESS FAVORABLE
OUTFLOW ENVIRONMENT WITH CONVERGENT FLOW ALOFT EXPECTED TO INCREASE
IN ADDITION TO THE PERSISTENT EASTERLY SHEAR. AS THE SYSTEM
APPROACHES LAND, IT WILL INGEST DRY AIR FLOWING SOUTH FROM THE
INTERIOR OF PAKISTAN, WHICH WILL HELP PRECIPITATE ADDITIONAL
WEAKENING. ONCE ASHORE, THE SYSTEM WILL RAPIDLY DISSIPATE NO LATER
TAU 120 OVER WESTERN INDIA. 

MODEL DISCUSSION: TRACK GUIDANCE REMAINS CONSISTENT WITH SEVERAL
PREVIOUS MODEL RUNS, WITH NAVGEM REMAINING THE SOLE OUTLIER TAKING
THE SYSTEM TOWARDS A LANDFALL IN THE VICINITY OF KARACHI. THE
REMAINDER OF THE CONSENSUS MEMBERS SHOW A TRACK TO THE
NORTH-NORTHEAST FOLLOWED BY A SHARP TURN EASTWARD AFTER TAU 48.
TRACK SPREAD AT LANDFALL IS 130NM, BASICALLY STRETCHING FROM THE
PAKISTAN-INDIA BORDER (GFS) TO THE GULF OF KUTCH (ECMWF ENSEMBLE
MEAN). THE JTWC FORECAST LIES JUST WEST OF THE CONSENSUS MEAN, WITH
MEDIUM CONFIDENCE THROUGH THE FORECAST PERIOD. INTENSITY GUIDANCE
CONTINUES THE SAME TREND SEEN OVER THE PAST COUPLE OF DAYS, WITH
HWRF CONTINUING TO INSIST ON RAPID INTENSIFICATION (TO 125 KNOTS)
THROUGH TAU 12 FOLLOWED BY STEADY WEAKENING. MEANWHILE THE
COAMPS-TC MODELS SHOW NEAR-TERM WEAKENING FOLLOWED BY RAPID
INTENSIFICATION BETWEEN TAU 24 AND TAU 60, WHICH SEEMS UNLIKELY
GIVEN THE OVERALL MODEL TRENDS. THE JTWC FORECAST BREAKS WITH THE
BULK OF THE GUIDANCE IN CALLING FOR SOME INTENSIFICATION THROUGH
TAU 12, THEN GENERALLY FOLLOWS THE TREND OF THE CONSENSUS MEAN
THROUGH THE REST OF THE FORECAST. CONFIDENCE REMAINS LOW HOWEVER
DUE TO THE EXTREME UNCERTAINTY IN THE GUIDANCE AND DEMONSTRATED
INABILITY OF THE MODELS TO EFFECTIVELY HANDLE THE INTENSITY OF THIS
SYSTEM. 

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