WDPN32 PGTW 060900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 05W (DANAS) WARNING NR 010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.2N 118.8E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 229 NM SOUTHWEST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RECENTLY
DEVELOPED IRREGULAR EYE FEATURE OF TYPHOON (TY) 05W (DANAS). THE
INITIAL POSITION IS THEREFORE PLACED WITH HIGH CONFIDENCE BASED ON
THE VISIBLE SATELLITE IMAGERY. TY 05W IS CURRENTLY TRACKING
NORTHEASTWARD TOWARD THE WESTERN COAST OF TAIWAN. DRIVEN BY HIGHLY
FAVORABLE ENVIRONMENTAL CONDITIONS, THE SYSTEM HAS INTENSIFIED 25
KTS OVER THE LAST 24 HOURS AND EXHIBITS WELL DEVELOPED SPIRAL BANDS
OF DEEP CONVECTION, WITH THE BANDING OVER SOUTHERN SEMICIRCLE
EXTENDING AS FAR AS EAST OF TAIWAN. THE RAGGED EYE FEATURE HAS
TEMPERATURE OF ABOUT -8 C, WHILE THE COLDEST CLOUD TOPS ARE ESTIMATED 
AT -83 C. ADDITIONAL ENVIRONMENTAL ANALYSIS INDICATES THAT TY 05W IS 
IN A HIGHLY FAVORABLE ENVIRONMENT IDENTIFIED BY LOW (5-10 KTS) 
VERTICAL WIND SHEAR (VWS), WARM (29-30 C) SEA SURFACE TEMPERATURES 
(SST) AND STRONG RADIAL OUTFLOW. THE INITIAL INTENSITY OF 80 KTS IS 
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK AND 
OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: 060052Z METOP-B AND 060143 METOP-C ASCAT
PASSES

CURRENT STEERING MECHANISM: DEEP LAYER NEAR-EQUATORIAL RIDGE (NER)
TO THE SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T5.0 - 90 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 84 KTS AT 060530Z
   CIMSS ADT: 63 KTS AT 060600Z
   CIMSS AIDT: 67 KTS AT 060600Z
   CIMSS D-MINT: 74 KTS AT 060455Z
   CIMSS D-PRINT: 76 KTS AT 060600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: TY 05W IS NOW FORECAST TO PASS
DIRECTLY OVER WESTERN AND NORTHERN TAIWAN

FORECAST DISCUSSION: TY 05W IS FORECAST TO TRACK NORTHEASTWARD
UNDER THE INFLUENCE OF A NER TO THE SOUTHEAST THROUGH TAU 36,
HOWEVER RECENT NUMERICAL MODEL GUIDANCE INDICATES THAT THE RIDGE IS
BEGINNING TO REALIGN ALONG A SOUTHWEST-NORTHEAST AXIS AND THEREFORE
LEADING TO THE TRACK SHIFTING SLIGHTLY EASTWARD. AS A RESULTS, TY
05W IS NOW EXPECTED TO MAKE LANDFALL OVER SOUTHWESTERN TAIWAN, NEAR 
QIGU DISTRICT, WITHIN THE NEXT 6 TO 12 HOURS. PRIOR TO THAT, THE 
SYSTEM IS EXPECTED TO INTENSIFY FURTHER, POTENTIALLY UP TO 90-95 KTS, 
BEFORE THE WIND FIELD IS EXPOSED TO THE MOUNTAIN RANGES OF TAIWAN. THE 
WESTERN FOOTHILLS, AS WELL AS THE XUESHAN RANGE ARE EXPECTED TO HAVE A 
SIGNIFICANT IMPACT ON WEAKENING OF THE SYSTEM. AFTER CROSSING THE 
ISLAND, TY DANAS IS FORECAST TO WEAKEN TO APPROXIMATELY 60 KTS AND 
CONTINUE TRACKING NORTHEASTWARD UNTIL AROUND TAU 36. AT THAT TIME, A 
SUBTROPICAL RIDGE (STR) TO THE NORTH WILL ASSUME STEERING AND PUSH THE 
SYSTEM WESTWARD. ANOTHER LANDFALL, OVER MAINLAND CHINA, IS EXPECTED 
BETWEEN TAUS 48 AND 72. AFTER THAT, TY 05W IS EXPECTED TO BEGIN 
DISSIPATING, WHICH IS FORECAST TO BE COMPLETED AT OR BEFORE TAU 96. 
INTENSITY, PARTICULARLY DURING THE UPCOMING 24-36 HOURS, IS ASSESSED 
WITH LOW CONFIDENCE, DUE TO SIGNIFICANT UNCERTAINTY ASSOCIATED WITH 
THE TRACK OF THE SYSTEM, AND THEREFORE IMPACTS OF THE TERRAIN 
INTERACTION ON INTENSIFICATION OR WEAKENING. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT THROUGH TAU 24, AS WITNESSED BY A CROSS-TRACK SPREAD OF
70 NM. MAJORITY OF THE MODEL GUIDANCE, INCLUDING THE MULTI-MODEL
CONSENSUS ARE NOW INDICATING LANDFALL OVER WESTERN TAIWAN, WITH
JUST ECMWF ENSEMBLE, JGSM AND UKMET ENSEMBLE KEEPING THE TRACK
ENTIRELY OVER THE TAIWAN STRAIT. ADDITIONALLY, TRACK FORECAST
UNCERTAINTY INCREASES IN REGARD TO THE TIMELINE OF THE WESTWARD
TURN, AND THE SUBSEQUENT LANDFALL OVER MAINLAND CHINA, AS WITNESSED
BY A 155 NM CROSS-TRACK SPREAD AT LANDFALL. INTENSITY GUIDANCE IS
IN FAIR AGREEMENT AS WELL, WITH ALL GUIDANCE INDICATING THAT TY 05W
HAS ALREADY OR WILL SOON REACH PEAK INTENSITY AND INDICATING 
CONSISTENT WEAKENING THROUGHOUT THE FORECAST PERIOD. JTWC INTENSITY 
FORECAST IS ASSESSED WITH ONLY MEDIUM CONFIDENCE, DUE TO THE 
POSSIBILITY OF THE STORM STAYING OVER WARM WATERS OF TAIWAN STRAIT AND 
THEREFORE BEING ABLE TO MAINTAIN STRUCTURAL INTEGRITY OF THE VORTEX 
AND CONVECTIVE BENDING, DESPITE THE DETRIMENTAL IMPACTS OF LAND 
INTERACTION.

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