WDIO31 PGTW 102100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02A (BIPARJOY) WARNING 
NR 019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.4N 67.5E
   INITIAL INTENSITY: 105 KTS
   GEOGRAPHIC REFERENCE: 445 NM SOUTH OF KARACHI, PAKISTAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 33 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TC 02A HAS RATHER UNEXPECTEDLY RAPIDLY INTENSIFIED BASED ON A
SERIES OF RELIABLE AND HIGH CONFIDENCE INTENSITY MEASUREMENTS OVER
THE PAST 24 HOURS. WHILE THE DEPICTION IN THE ENHANCED INFRARED
(EIR) IMAGERY HAS BEEN LACKLUSTER FOR THE MOST PART, WITH NO
SUSTAINED EYE AND MODESTLY COLD CLOUD TOPS, THE LOW LEVEL WIND
STRUCTURE IS IMPRESSIVE. THE FIRST HINT THAT THE SYSTEM WAS
SIGNIFICANTLY STRONGER THAN THE DVORAK-BASED INTENSITY ESTIMATES
WOULD SUGGEST CAME VIA A 100125Z RCM-3 SAR PASS SHOWING A MAXIMUM
WIND OF 106 KNOTS. TWELVE HOURS LATER A COINCIDENT 101325Z AND
101352Z RCM-3 SAR PASS BOTH INDICATED WINDS IN THE NEIGHBORHOOD OF
95-105 KNOTS. WHILE DIFFICULT TO RECONCILE THE 30-PLUS KNOT
DIFFERENCES BETWEEN THE SMAP, SAR AND THE SUBJECTIVE AND
ESPECIALLY OBJECTIVE DVORAK-BASED ESTIMATES, THE AGREEMENT OF THREE 
RELIABLE SENSORS ACROSS A TWELVE-HOUR PERIOD LENDS HIGH CONFIDENCE TO 
THE BOTH THE INITIAL POSITION AND INTENSITY ESTIMATES. THE SYSTEM HAS
CLEARLY BEEN ABLE TO ORGANIZE A STRONG INNER CORE OF DEEP
CONVECTION AS ESTABLISHED BY THE SAR DATA, AND PUSH BACK AGAINST
THE MODERATE (20 KNOTS OR MORE) OF ENVIRONMENTAL SHEAR AND TAKE
ADVANTAGE OF THE ZESTY SSTS, HIGH OHC AND MODERATE WESTWARD AND
EQUATORWARD OUTFLOW. THE SYSTEM IS MOVING VERY SLOWLY TOWARDS THE
NORTH ALONG THE WEST SIDE OF A DEEP SUBTROPICAL RIDGE (STR)
CENTERED OVER INDIA.

INITIAL WIND RADII BASIS: SAR DATA 

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


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   KNES: T4.5 - 77 KTS
   DEMS: T4.5 - 77 KTS
   CIMSS SATCON: 61 KTS AT 101402Z
   CIMSS ADT: 55 KTS AT 101800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 30+ KTS
   SST: 31-32 CELSIUS
   OUTFLOW: MODERATE WESTWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 02A CONTINUES TO DRIFT RATHER SLOWLY
TOWARDS THE NORTH AS THE STR TO THE EAST REMAINS RELATIVELY WEAK.
THE RIDGE IS FORECAST TO BUILD OVER THE NEXT 12 TO 24 HOURS AND TC
02A IS FORECAST TO SLOWLY PICK UP SOME SPEED WHILE STILL TRAVELING
GENERALLY NORTHWARD. SOME SINUSOIDAL MOTION EAST AND WEST OF THE
MEAN NORTHWARD VECTOR IS EXPECTED THROUGH TAU 72 AS SLIGHT CHANGES
IN THE POSITION AND ORIENTATION OF THE STEERING RIDGE ARE
ANTICIPATED. IN THE LATER TAUS IT APPEARS THAT THE ECMWF HAS WON
OVER THE BULK OF THE OTHER MODELS IN DEPICTING A BUILDING RIDGE
DEVELOPING OVER SOUTHERN IRAN AFTER TAU 72, AND RIDGING OVER
SOUTHERN PAKISTAN, WHICH WILL PUSH TC 02A ONTO A NORTHEASTWARD
TRACK THROUGH THE END OF THE FORECAST, WITH LANDFALL EXPECTED JUST
EAST OF THE PAKISTAN-INDIA BORDER PRIOR TO TAU 120. AFTER
UNEXPECTEDLY RAPIDLY INTENSIFYING TO 105 KNOTS OVER THE PAST 24
HOURS, TC 02A HAS LIKELY REACHED ITS PEAK. WESTERLY SHEAR AROUND
20 KNOTS CONTINUES TO PRESSURE THE EAST SIDE OF THE CIRCULATION AND
AS CONVECTION STARTS TO WEAKEN, THIS SHOULD BEGIN TO TILT THE VORTEX
EVER MORE, AND DISRUPT THE CORE ENOUGH TO AT LEAST ARREST THE
INTENSIFICATION TREND. INTENSITY IS EXPECTED TO REMAIN STEADY
THROUGH TAU 12, BUT THEN AS THE SYSTEM MOVES NORTH INTO A HIGHER
SHEAR ENVIRONMENT WITH CONVERGENT EASTERLY FLOW ALOFT, IT IS
EXPECTED TO STEADILY WEAKEN THROUGH LANDFALL, WITH RAPID
DISSIPATION ONCE ASHORE.

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE HAS COME INTO MUCH
BETTER AGREEMENT OVER THE PAST COUPLE OF RUNS. WITH THIS RUN, ALL
BUT THE NAVGEM AND THE NAVGEM VERSION OF COAMPS-TC, HAVE COME INTO
AGREEMENT ON A NORTHWARD TRACK TO TAU 72, FOLLOWED BY A FAIRLY
SHARP TURN TO THE NORTHEAST. SPREAD AT LANDFALL COVERS ROUGHLY
FROM THE PAKISTAN-INDIA BORDER TO THE GUJARAT PENINSULA, OR
APPROXIMATELY 160NM BETWEEN HWRF ON THE LEFT AND UKMET ON THE
RIGHT. THE MULTI-MODEL ENSEMBLE MEAN SPREAD HAS ALSO DECREASED
SIGNIFICANTLY AS THE ENSEMBLES HAVE ALSO COME INTO AGREEMENT ON
THE OVERALL TRACK SCENARIO. IN LIGHT OF THE IMPROVED AGREEMENT IN THE
GUIDANCE, CONFIDENCE IN THE TRACK FORECAST HAS INCREASED TO HIGH
TRENDING TO MEDIUM IN THE LATER TAUS. INTENSITY GUIDANCE IS IN
RELATIVELY GOOD AGREEMENT, THOUGH THE HWRF IS AN OUTLIER SHOWING
NEAR-TERM WEAKENING FOLLOWED BY ADDITIONAL INTENSIFICATION AFTER
TAU 36. THE JTWC FORECAST LIES CLOSE TO THE CONSENSUS MEAN THROUGH
THE MAJORITY OF THE FORECAST, WITH MEDIUM TO LOW CONFIDENCE. 

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