WDPN31 PGTW 070300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (KOINU) WARNING NR 031//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.1N 115.4E
   INITIAL INTENSITY: 105 KTS
   GEOGRAPHIC REFERENCE: 98 NM SOUTHEAST OF HONG KONG
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 29 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (MSI) SHOWS TYPHOON
14W (KOINU) MAINTAINING A RELATIVELY SYMMETRIC STRUCTURE
WITH A WELL-DEFINED EYE WITH DEEP CONVECTION COMPLETELY SURROUNDING
THE EYE FEATURE. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE WARM AND CLEAR EYE IN VISIBLE IMAGERY IN
ADDITION TO A MICROWAVE EYE, AS SEEN IN THE 062319Z SSMIS 91GHZ
MICROWAVE IMAGE. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON AN OVERALL ASSESSMENT OF MULTIPLE AGENCY
CURRENT INTENSITY ESTIMATES IN THE T5.5-6.0 RANGE IN COMBINATION
WITH ADT AND SATCON ESTIMATES OF 87 AND 86 KNOTS, RESPECTIVELY.
RECENT DPRINT AND DMINT ESTIMATES RANGE FROM 104 TO 97 KNOTS.
INCLUDING A 062202Z SAR, WHICH SHOWED 105 KNOTS. ANALYSIS INDICATES
A FAVORABLE ENVIRONMENT WITH MODERATE RADIAL OUTFLOW, WARM SSTS,
AND FAVORABLE (05-10 KNOTS) VERTICAL WIND.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTHWEST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   DEMS: T6.0 - 115 KTS
   CIMSS ADT: 84 KTS AT 062330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TYPHOON 14W (KOINU) IS TRACKING GENERALLY
WEST-SOUTHWESTWARD AT A SLOW FORWARD MOTION ALONG THE SOUTHERN
PERIPHERY OF THE STR TO THE NORTHWEST AS THE STEERING ENVIRONMENT
REMAINS FAIRLY WEAK. AFTER TAU 48, A TURN TOWARD THE SOUTHWEST AND
AN INCREASE IN FORWARD MOTION IS FORECAST AS THE SYSTEM IS DRIVEN
TOWARD HAINAN BY A SUBTROPICAL RIDGE BUILDING IN FROM THE
EAST-NORTHEAST. A FINAL LANDFALL OVER VIETNAM IS EXPECTED BY TAU
120. IN TERMS OF INTENSITY, TYPHOON 14W WILL GRADUALLY WEAKEN DUE
TO THE UPWELLING OF COOLER WATER AND THE INCREASE OF DRY AIR
ENTRAINMENT THROUGH TAU 48. BETWEEN TAU 48 AND TAU 72, FURTHER
WEAKENING IS EXPECTED AS THE SYSTEM TRACKS OVER HAINAN. BY TAU 120,
DISSIPATION IS EXPECTED AS THE SYSTEM TRACKS OVER VIETNAM.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH A
SLOW WESTWARD TRACK IN THE NEAR TERM, FOLLOWED BY AN ACCELERATION
TOWARD THE SOUTHWEST BEYOND TAU 48. CROSS-TRACK SPREAD INCREASE
AFTER TAU 48 THROUGH TAU 120. THEREFORE, THE JTWC TRACK FORECAST IS
PLACED WITH HIGH CONFIDENCE IN THE NEAR-TERM TRACK FORECAST AND
MEDIUM CONFIDENCE THEREAFTER. THE INTENSITY GUIDANCE IS IN GOOD
AGREEMENT, ALL SHOWING A STEADY WEAKENING TREND THROUGHOUT THE
FORECAST PERIOD, SO THE OFFICIAL FORECAST FOLLOWS THE INTENSITY
CONSENSUS AND IS PLACED WITH HIGH CONFIDENCE THROUGH TAU 72 AND
MEDIUM THEREAFTER, DUE TO UNCERTAINTY ASSOCIATED WITH THE TIMING OF
THE POTENTIAL LAND INTERACTION WITH HAINAN ISLAND.


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