WDPN31 PGTW 160300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 28W (RAI) WARNING NR 
013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 9.7N 127.5E
   INITIAL INTENSITY: 140 KTS
   GEOGRAPHIC REFERENCE: 481 NM SOUTHEAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 48 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
STY 28W HAS UNDERGONE AN IMPRESSIVE RAPID INTENSIFICATION,
INCREASING FROM 65 TO 140 KNOTS IN THE LAST 24 HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A COMPACT, 6NM EYE,
SURROUNDED BY DEEP CYCLING CONVECTION. CLOUD TOPS HAVE WARMED
SLIGHTLY OVER THE LAST COUPLE OF HOURS, BUT THE HIGH RESOLUTION EIR
AND MSI SHOW IMPRESSIVE GRAVITY WAVES EMANATING OUT FROM THE
EYEWALL CONVECTION. A 152204Z SSMIS 91GHZ IMAGE SHOWED AN INNER
EYEWALL WITH A NASCENT SECONDARY EYEWALL BEGINNING TO EMERGE,
PARTICULARLY ON THE SOUTH AND EASTERN FLANKS, INDICATING AN
IMMINENT EYEWALL REPLACEMENT CYCLE (EWRC). THE INITIAL POSITION IS
ASSESSED WITH HIGH CONFIDENCE BASED ON THE 6NM EYE IN THE VISIBLE
AND INFRARED IMAGERY AS WELL AS EXTRAPOLATION OF THE MICROWAVE EYE
IN THE AFOREMENTIONED MICROWAVE IMAGE. THE INITIAL INTENSITY IS
ASSESSED AT A SOMEWHAT GENEROUS 140 KNOTS, ON THE HIGHER END OF THE
AGENCY DVORAK CURRENT INTENSITY ESTIMATES, HEDGED HIGHER THAN THE
ADT BASED ON THE RAW ADT WHICH AT THE 0000Z WAS T7.5. THE SYSTEM
HAS LIKELY REACHED PEAK INTENSITY. THE SYSTEM IS MOVING GENERALLY
JUST NORTH OF WEST, BUT THE TROCHOIDAL MOTION ABOUT THE MEAN TRACK
MEANS THAT SOME NEAR-TERM VARIATIONS IN THE TRACK ARE TO BE
EXPECTED. THE ENVIRONMENT REMAINS HIGHLY FAVORABLE OVERALL, WITH
VERY WARM SSTS, HIGH OHC, GOOD WESTWARD AND POLEWARD OUTFLOW AND
MODERATE EASTERLY VWS.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T7.0 - 140 KTS 
   RJTD: T6.5 - 127 KTS
   KNES: T7.0 - 140 KTS 
   CIMSS SATCON: 113 KTS AT 152204Z
   CIMSS ADT: 119 KTS AT 152340Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG WESTWARD
   OTHER FACTORS: EWRC

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: STY 28W IS FORECAST TO CONTINUE TRACKING
WEST-NORTHWESTWARD THROUGH TAU 72, BEFORE TURNING SHARPLY POLEWARD
INTO A BREAK IN THE STR TO THE NORTH THROUGH TAU 120. THE SYSTEM IS
EXPECTED TO MAKE LANDFALL NEAR THE NORTHEAST COAST OF MINDANAO AND
THE SIARGAO AND DINAGAT ISLANDS WITHIN THE NEXT 6-8 HOURS, THEN
CROSS OVER THE VISAYAS AND EMERGE INTO THE SULU SEA BY TAU 24. THE
SYSTEM WILL THEN CROSS THE NORTHERN TIP OF PALAWAN BEFORE ENTERING
THE SOUTH CHINA SEA BY TAU 48. STY 28W HAS LIKELY REACHED PEAK
INTENSITY. CLOUD TOPS HAVE BEEN STEADILY WARMING OVER THE PAST
THREE HOURS. ADDITIONALLY, THE MICROWAVE-BASED PROBABILITY OF
EYEWALL REPLACEMENT CYCLE (M-PERC) FULL-MODEL PREDICTION INDICATED
A 100 PERCENT PROBABILITY OF EWRC, LENDING HIGH CONFIDENCE TO THE
ANALYSIS OF RECENT MICROWAVE IMAGERY AND THE FORECAST OF NEAR-TERM
EWRC. THE FORECAST CALLS FOR WEAKENING TO 125 KNOTS BY TAU 12, DUE
TO THE IMPACT OF THE EWRC AND LAND INTERACTION AS THE SYSTEM
CROSSES THE SURIGAO STRAIT. WHILE THE EWRC APPEARS IMMINENT, THE
LACK OF RECENT MICROWAVE IMAGERY MAKES IT DIFFICULT TO CONFIRM AND
THUS THERE IS HIGH UNCERTAINTY IN THE AMOUNT OF WEAKENING EXPECTED.
IT REMAINS POSSIBLE THAT THE SYSTEM COULD EXPERIENCE SOME SLIGHT
INTENSIFICATION BETWEEN TAU 00 AND TAU 12 THOUGH THIS SEEMS
UNLIKELY. AS THE STORM CROSSES THE PHILIPPINE ISLANDS, DISRUPTION
OF THE LOW LEVEL INFLOW COMBINED WITH INCREASED VWS WILL WEAKEN THE
SYSTEM, AND IT WILL CROSS INTO THE SOUTH CHINA SEA AS A 95 KNOT
TYPHOON. DURING THE 24 PERIOD BETWEEN TAU 48 AND 72, THE SYSTEM
WILL INTENSIFY ONCE MORE AS IT TAPS INTO STRONGLY DIVERGENT
POLEWARD OUTFLOW, WHICH WILL OFFSET MODESTLY INCREASED SOUTHERLY
WIND SHEAR, TO A PEAK OF 110 KNOTS AT TAU 72. AFTER THIS POINT
HOWEVER, AN INFLUX OF COOLER, DRIER AIR FROM A NORTHEAST SURGE, AND
DRAMATICALLY INCREASING VWS WILL SMOTHER AND DECAPITATE THE SYSTEM,
LEADING TO RAPID WEAKENING THROUGH THE END OF THE FORECAST. 

MODEL DISCUSSION: TRACK GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH
TAU 72, WITH A SPREAD OF LESS THAN 100NM AT TAU 72. SPREAD
INCREASED TO 170NM BY TAU 120 BETWEEN THE NAVGEM ON THE RIGHT AND
ECMWF ON THE LEFT OF THE GUIDANCE ENVELOPE. THE JTWC FORECAST
REMAINS CONSISTENT WITH THE PREVIOUS FORECAST AND CLOSELY TRACKS
THE CONSENSUS MEAN THROUGH TAU 48, THEN SLIGHTLY TO THE LEFT OF THE
MEAN THROUGH TAU 120. INTENSITY GUIDANCE IS IN GOOD AGREEMENT AS
WELL, WITH ALL MEMBERS INDICATING IMMEDIATE WEAKENING FROM TAU 00
WITH THE HWRF BEING THE MOST BEARISH, TAKING THE SYSTEM DOWN TO 60
KNOTS WITHIN 24 HOURS, WHILE THE COAMPS-TC IS THE MOST BULLISH,
WITH THE MINIMUM OF 110 KNOTS AS THE SYSTEM CROSSES THE PHILIPPINES
FOLLOWED BY A SECOND PEAK OF 125 KNOTS IN THE SOUTH CHINA SEA. THE
JTWC FORECAST IS ABOUT 15 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 IS HIGH TRENDING MEDIUM IN THE LONG-RANGE,
WHILE CONFIDENCE IN THE INTENSITY IS MEDIUM TRENDING LOW IN THE
LONG-RANGE DUE TO UNCERTAINTIES SURROUNDING THE IMPACT OF THE EWRC
AND TERRAIN INDUCED WEAKENING.   

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