WDPN33 PGTW 020900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 10W (HAIKUI) WARNING NR 020//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.4N 125.4E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 269 NM SOUTHEAST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: WESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) INDICATES THAT
TYPHOON (TY) 10W (HAIKUI) CONTINUES TO STRUGGLE IN FACE OF
PERSISTENT NORTHEASTERLY MID-LEVEL SHEAR. A RAGGED EYEWALL POPPED
OUT AROUND 0300Z BUT QUICKLY FADED AWAY AS THE VORTICAL HOT TOWERS
(VHTS) THAT WERE FIRING ON THE SOUTHERN PERIPHERY FAILED TO WRAP
UPSHEAR AND CLOSE OFF THE EYEWALL. THE SAME OVERALL PATTERN HAS
CONTINUED UP TO THE PRESENT HOUR, WITH DISORGANIZED VHTS CONTINUING
TO FIRE ALONG THE ENTIRE SOUTHERN SIDE OF THE LOW LEVEL CIRCULATION
CENTER (LLCC) BUT UNABLE TO WRAP UPSHEAR AND THUS THE SYSTEM
REMAINS WITHOUT AN EYE. HOWEVER, RADAR DATA FROM BOTH JAPAN AND
TAIWAN SHOW AN EYE FEATURE WITH A STRONG SOUTHERN EYEWALL. THE MOST
RECENT HIGH RESOLUTION MICROWAVE IMAGERY FROM 020136Z SHOWED AN
ELONGATED LOW-LEVEL EYE FEATURE IN THE 37GHZ BAND, WITH A STRONG
BAND OF CONVECTION ALONG THE SOUTHERN PERIPHERY. THE INITIAL
POSITION IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE EYE
FEATURE IN THE LONG-RANGE RADAR DATA AND AMONGST THE GROUPING OF
AGENCY FIX POSITIONS. THE INITIAL INTENSITY IS SET AT 85 KNOTS WITH
MEDIUM CONFIDENCE BASED ON AN AVERAGE OF THE AGENCY INTENSITY
ESTIMATES AND THE CIMSS SATCON ESTIMATE. ANALYSIS REVEALS A
GENERALLY FAVORABLE ENVIRONMENT WITH WARM SSTS AND DECENT
EQUATORWARD OUTFLOW INHIBITED BY MODERATE NORTHEASTERLY SHEAR,
PARTICULARLY IN THE MID-LEVELS AND LIMITED OUTFLOW TO THE POLEWARD
SIDE.

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: T5.0 - 90 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T5.5 - 102 KTS
   KNES: T4.5 - 77 KTS
   CIMSS SATCON: 84 KTS AT 020450Z
   CIMSS ADT: 74 KTS AT 020530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY 10W IS FORECAST TO CONTINUE TRACKING
WEST-NORTHWESTWARD ALONG THE SOUTHERN SIDE OF THE STRONG STR TO THE
NORTH, FOR THE DURATION OF THE FORECAST PERIOD. SOME WOBBLING IS TO
BE EXPECTED AS THE SYSTEM APPROACHES THE TAIWAN COASTLINE BUT THE
GENERAL TRACK MOTION WILL BE RELATIVELY STEADY THROUGH THE NEXT 24
HOURS. THE SYSTEM WILL LIKELY SLOW DOWN AS IT NEARS LANDFALL,
CURRENTLY EXPECTED JUST AFTER TAU 24, ALONG THE SOUTHEASTERN COAST
OF TAIWAN. AS IT MAKES LANDFALL, THE TRACK WILL BECOME HIGHLY
INFLUENCED BY THE TERRAIN OF TAIWAN AND THE CENTER OF THE SYSTEM
WILL SHIFT SOUTHWESTWARD AS IT MOVES ACROSS THE ISLAND. BY TAU 36
THE SYSTEM WILL CROSS THE WESTERN COAST BETWEEN KAOHSIUNG AND
TAINAN AND EMERGE BACK OVER THE SOUTHERN PORTION OF THE SOUTH CHINA
SEA. ONCE BACK OVER WATER THE SYSTEM WILL RESUME ITS NORTHWEST
TRACK, MAKING A SECOND LANDFALL IN SOUTHERN FUJIAN PROVINCE OF
EASTERN CHINA AROUND TAU 72. THE SYSTEM IS CURRENTLY STRUGGLING IN
THE FACE OF PERSISTENT NORTH-NORTHEASTERLY SHEAR AS A RESULT OF AN
UPPER-LEVEL ANTICYCLONE SITTING IN THE EAST CHINA SEA. GLOBAL
MODELS SUGGEST THIS ANTICYCLONE WILL SHIFT EASTWARD AT A RAPID CLIP
THROUGH THE NEXT 24 HOURS AND AS IT DOES SO, THE SHEAR VECTOR
SHIFTS EAST WHILE SHEAR GENERALLY EASES. AT THE SAME TIME THE
SYSTEM WILL MOVE OVER A POCKET OF VERY WARM SSTS THAT LIES EAST OF
TAIWAN, PROVIDING THE FUEL NEEDED TO FEED A PERIOD OF
INTENSIFICATION WHICH PEAKS AT 110 KNOTS JUST PRIOR TO LANDFALL.
THE SYSTEM WILL RAPIDLY WEAKEN DUE TO TERRAIN EFFECTS AS IT CROSSES
TAIWAN, THEN CONTINUE TO WEAKEN THROUGH THE SECOND LANDFALL DUE TO
MODERATE SHEAR, WEAKENED OUTFLOW ALOFT AND DISRUPTION OF THE LLCC
DUE TO FRICTIONAL EFFECTS. THE SYSTEM WILL WEAKEN TO JUST 25 KNOTS
BY THE END OF THE FORECAST PERIOD. 

MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN
GOOD AGREEMENT THROUGH THE MAJORITY OF THE FORECAST PERIOD, WITH A
45NM SPREAD AT LANDFALL. THE ENVELOPE WIDENS TO 260NM BY THE END OF
THE FORECAST PERIOD PRIMARILY AS A RESULT OF GFS, UKMET AND ECMWF
ENSEMBLE MEAN WHICH TURN THE SYSTEM TO THE SOUTH AND BACK OVER THE
SOUTH CHINA SEA, WHILE THE EGRR, GALWEM AND JGSM MODELS CONTINUE
TRACKING THE SYSTEM NORTHWEST INTO CENTRAL CHINA. OF NOTE, WHILE
NOT MEMBERS OF THE TRACK CONSENSUS, THE MESOSCALE MODELS SHOW THE
SYSTEM TURNING NORTHWARD INTO THE TAIWAN STRAIT AFTER LANDFALL, OR
EVEN IN THE CASE OF HAFS-A, TRACKING BACK ACROSS TAIWAN AND INTO
THE EAST CHINA SEA. AT PRESENT, THESE SCENARIOS ARE CONSIDERED
HIGHLY UNLIKELY. INTENSITY GUIDANCE IS MIXED, WITH THE SHIPS
GUIDANCE AND THE CMC INDICATING LITTLE IN THE WAY OF
INTENSIFICATION PRIOR TO LANDFALL. ON THE OTHER EXTREME SIT NEARLY
ALL OF THE AVAILABLE RAPID INTENSIFICATION (RI) GUIDANCE, ALL OF
WHICH ARE TRIGGERED, AS WELL AS THE HAFS-A, WHICH PEAK THE SYSTEM
BETWEEN 110-125 KNOTS. THE JTWC FORECAST LIES ABOVE THE MEAN, BUT
BELOW THE MOST AGGRESSIVE MODELS IN LIGHT OF THE RECENT EVOLUTION
OF THE SYSTEM. 

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