WDPN31 PGTW 022100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (KOINU) WARNING NR 014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.0N 125.4E
   INITIAL INTENSITY: 110 KTS
   GEOGRAPHIC REFERENCE: 375 NM SOUTHEAST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: WESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 36 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A RAGGED
EYE AND AN ASYMMETRIC CONVECTIVE STRUCTURE DUE TO INCREASING
MID-LEVEL NORTHEASTERLY VERTICAL WIND SHEAR (VWS) AND DRY AIR
ENTRAINMENT. EIR ALSO INDICATES A SOMEWHAT ERRATIC TRACK MOTION
WITH A SHORT-LIVED DIP TO THE SOUTHWEST NEAR 021600Z AND SUBSEQUENT
RETURN TO A NORTHWESTWARD TRAJECTORY BY 021800Z. A 021703Z GMI 89
GHZ MICROWAVE IMAGE REVEALS A 20 TO 25 NM DIAMETER EYE WITH A BREAK
IN THE EYEWALL OVER THE EASTERN QUADRANT. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON THE EIR IMAGERY AND THE GMI
IMAGE. DESPITE THE RECENT DEGRADATION OF THE CONVECTIVE STRUCTURE,
THE INITIAL INTENSITY REMAINS ASSESSED AT 110 KTS WITH MEDIUM
CONFIDENCE BASED ON THE DVORAK CURRENT INTENSITY ESTIMATES AND A
021701Z DMINT ESTIMATE OF 109 KNOTS. UW-CIMSS ADT AND AIDT
ESTIMATES REMAIN UNREALISTICALLY HIGH.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE EAST AND NORTHEAST WITH A BREAK TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T6.0 - 115 KTS
   KNES: T6.0 - 115 KTS
   CIMSS SATCON: 122 KTS AT 021728Z
   CIMSS ADT: 132 KTS AT 021730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG EQUATORWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

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: TYPHOON (TY) 14W IS FORECAST TO TRACK
NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE STR THROUGH
TAU 12 TOWARD A BREAK IN THE STR ASSOCIATED WITH A MIDLATITUDE
SHORTWAVE TROUGH. AFTER TAU 12, THE TROUGH WILL PROPAGATE EASTWARD
ALLOWING THE STR TO REBUILD TO THE NORTH, WHICH WILL TURN THE
SYSTEM ON A WEST-NORTHWESTWARD TO WESTWARD TRAJECTORY THROUGH TAU
120. TY 14W SHOULD WEAKEN STEADILY DUE TO THE PERSISTENT VWS AS IT
APPROACHES AND TRACKS OVER SOUTHERN TAIWAN WITH FURTHER WEAKENING
AS IT TRACKS OVER THE SOUTH CHINA SEA, TAIWAN STRAIT REGION. A WEAK
NORTHEAST SURGE IS EXPECTED TO BUILD INTO THE TAIWAN STRAIT WITH
EXPANSIVE GALE-FORCE WINDS.        

MODEL DISCUSSION: THROUGH TAU 72, NUMERICAL MODEL GUIDANCE IS IN
TIGHT AGREEMENT WITH AN 87 NM CROSS-TRACK SPREAD IN SOLUTIONS
LENDING HIGH CONFIDENCE TO THE JTWC TRACK FORECAST THROUGH TAU 72.
AFTER TAU 72, THERE IS INCREASING SPREAD AND UNCERTAINTY DUE TO THE
NORTHEAST SURGE THROUGH THE TAIWAN STRAIT AND ITS INFLUENCE ON A
WEAKENING, SHALLOWER SYSTEM. MUCH OF THE DETERMINISTIC GUIDANCE IS
TURNING THE SYSTEM WEST-SOUTHWESTWARD TO SOUTHWESTWARD NEAR TAU
120. BOTH THE GEFS AND EPS ENSEMBLES INDICATE RAPID WEAKENING NEAR 
THE SOUTHEAST COAST OF CHINA WITH INCREASING POTENTIAL FOR A SLOW,
ERRATIC TRACK AND A SHARP SOUTHWESTWARD TURN NEAR OR JUST SOUTHEAST
OF HONG KONG. AS A RESULT OF THIS COMPLEX SCENARIO, THERE IS LOW
CONFIDENCE IN THE JTWC FORECAST TRACK AFTER TAU 72. OVERALL, THERE
IS MEDIUM CONFIDENCE IN THE JTWC INTENSITY FORECAST.         

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