WDPN31 PGTW 161500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 28W (RAI) WARNING NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 10.1N 124.3E
   INITIAL INTENSITY: 115 KTS
   GEOGRAPHIC REFERENCE: 332 NM SOUTHEAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WESTWARD AT 17 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN
EMBEDDED CENTER WITH A SLIGHTLY WEAKENING SYSTEM MOVING QUICKLY
OVER MULTIPLE PHILIPPINE ISLANDS. THE INITIAL POSITION IS ASSESSED
WITH MEDIUM CONFIDENCE BASED ON THE EMBEDDED CENTER AND A 161254Z
ASCAT METOP-B 25KM IMAGE. THE INITIAL INTENSITY IS ASSESSED WITH
LOW CONFIDENCE AT 115 KNOTS, BASED LOWER THAN THE ADVANCED DVORAK
TECHNIQUE (ADT), WHICH IS HELD BY CONSTRAINTS OF 135 KNOTS, THE
SATELLITE CONSENSUS (SATCON) OF 143 KNOTS, AND MULTIPLE AGENCY FIXES
LISTED BELOW. THE ENVIRONMENT REMAINS FAVORABLE OVERALL, WITH VERY
WARM SSTS, HIGH OHC, GOOD POLEWARD AND EQUATORWARD OUTFLOW, BEING
SLIGHTLY OFFSET BY MODERATE TO STRONG EASTERLY VWS.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA, BASED UPON THE
161254Z ASCAT METOP-B 25KM IMAGE.

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   RJTD: T6.0 - 115 KTS
   KNES: T6.5 - 127 KTS
   CIMSS SATCON: 143 KTS AT 161216Z
   CIMSS ADT: 135 KTS AT 161310Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 20-25 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY 28W WILL CONTINUE TRACKING WEST-NORTHWEST
OVER MULTIPLE PHILIPPINE ISLANDS AND THE ISLAND OF PALAWAN THROUGH
THE NEXT 24 HOURS AND SLIGHTLY DECREASE INTENSITY AS IT INTERACTS
WITH THE ISLANDS. HOWEVER, ONCE THE STORM MOVES WEST OF PALAWAN, IT
WILL BEGIN TO TAP INTO A STRONGER POLEWARD OUTFLOW CHANNEL AND 
REACH A PEAK INTENSITY OF 105 KNOTS BY TAU 48 JUST AS IT BEGINS TO
TURN NORTH. BY TAU 72 TY RAI WILL ENCOUNTER A NORTHEAST SURGE,
ROUND THE RIDGE AXIS AND INDUCT COLD AIR INTO THE SYSTEM. THE COLD
DRY AIR AND HIGHER VWS WILL RAPIDLY ERODE THE CORE OF THE SYSTEM
THROUGH THE END OF THE FORECAST PERIOD. 

MODEL DISCUSSION: TRACK GUIDANCE REMAINS IN TIGHT AGREEMENT,
WITH A MERE SPREAD OF ONLY 100NM AT TAU 72. THE CROSS-TRACK SPREAD 
INCREASES TO 270NM BY TAU 120 BETWEEN THE GFS ON THE RIGHT AND AFUM
ON THE LEFT OF THE GUIDANCE ENVELOPE. THE JTWC FORECAST REMAINS 
CONSISTENT WITH THE PREVIOUS FORECAST AND CLOSELY TRACKS THE 
CONSENSUS MEAN THROUGH TAU 36, THEN SLIGHTLY TO THE LEFT OF THE MEAN 
THROUGH TAU 120. INTENSITY GUIDANCE IS IN FAIR AGREEMENT AS WELL, 
WITH ALL MEMBERS INDICATING IMMEDIATE WEAKENING FROM STARTING TAU 
WITH HWRF REMAINING THE MOST SUBDUED, REDUCING THE SYSTEM DOWN TO 70 
KNOTS BY TAU 24, WHILE COAMPS-TC BOLSTERS THE SYSTEM TO A SECOND 
PEAK OF 110 KNOTS IN THE SOUTH CHINA SEA. THE JTWC FORECAST REMAINS 
10 KNOTS ABOVE THE CONSENSUS MEAN, BUT LOWER THAN THE COAMPS-TC 
THROUGH TAU 36, THEN SLIGHTLY BELOW THE COAMPS-TC BUT ABOVE THE 
REMAINDER OF THE GUIDANCE THROUGH TAU 120. CONFIDENCE IN THE TRACK 
REMAINS HIGH FOR THE BEGINNING OF THE TRACK, THEN TRENDS TOWARDS 
MEDIUM IN THE LONG-RANGE AS THE ALONG TRACK SPEED CHANGES AFTER THE 
SYSTEM ENCOUNTERS THE COLD DRY AIR AND ROUNDS THE RIDGE AXIS. 
CONFIDENCE IN THE INTENSITY IS LOW DUE TO UNCERTAINTIES OF THE 
IMPACT OF THE LAND INTERACTION AND WHETHER THE SYSTEM WILL QUICKLY 
INTENSIFY IN THE SOUTH CHINA SEA.   

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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