CAT 3 Typhoon 14W(KOINU) to peak within 24h while approaching TAIWAN// TS 17L(PHILIPPE)//TD 18L(RINA)//0209utc

JTWC IS ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON TY 14W(KOINU).

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SLIGHTLY ASYMMETRIC TYPHOON STRENGTH CIRCULATION WITH A RAGED 5-10NM EYE. EQUATORWARD OUTFLOW IS DRIVING INCREASED CONVECTION TO THE SOUTH OF THE LLCC WHILE INCREASING MID-LEVEL VWS AND DRY AIR ENTRAINMENT ARE PUTTING PRESSURE ON THE NORTHERN QUADRANT, RESULTING IN THIS ASYMMETRIC APPEARANCE. THE SSMIS IMAGERY ALSO INDICATES AN EYE WALL HAS FORMED AND THE BEGINNINGS OF A MOAT BEYOND THAT. THOUGH CIMSS M-PERC VALUES HAVE CLIMBING TO ROUGHLY 30 PERCENT, IT IS UNLIKELY THE SYSTEM WILL REMAIN IN THE REQUISITE INTENSITY BAND TO PROGRESS THOUGH AN ERC. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON MSI AND SSMIS IMAGERY. THE INITIAL INTENSITY OF 105 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE MAJORITY OF INTENSITY ESTIMATES INCLUDING AGENCY DVORAK AND CIMSS AUTOMATED ESTIMATES INDICATING 105KTS WITH MINIMAL DEVIATION.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TYPHOON 14W (KOINU) IS FORECAST TO CONTINUE ON A GENERALLY NORTHWESTWARD TRACK UNDER THE STEERING INFLUENCE OF THE DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE EAST. AS EVIDENCED BY THE ASYMMETRIC APPEARANCE IN MSI AND MICROWAVE IMAGERY, 14W IS EXPERIENCING INCREASED MID-LEVEL VERTICAL WIND SHEAR AND DRY AIR ENTRAINMENT. OVER THE NEXT 12 HOURS, THESE NEGATIVE FACTORS ARE GENERALLY NEGATED BY FAVORABLE OUTFLOW ALOFT WHICH IS FORECAST TO ALLOW FOR ADDITIONAL INTENSIFICATION. BY TAU 24 HOWEVER, AFTER REACHING A PEAK INTENSITY NEAR 110KTS, FAVORABLE EQUATORWARD OUTFLOW IS LOST WHICH WHEN COUPLED WITH INCREASING MID-LEVEL VWS AND DRY AIR ENTRAINMENT, THE SYSTEM WILL BEGIN TO GRADUALLY WEAKEN. AS THE STR TO THE EAST BUILDS WESTWARD, 14W WILL BE FORCED TOWARDS THE SOUTHERN TIP OF TAIWAN AS IT CONTINUES TO SLOWLY WEAKEN. AFTER MAKING LANDFALL NEAR TAU 60, THE MOUNTAINOUS EASTERN COAST OF TAIWAN WILL QUICKLY WEAKEN 14W TO 80KTS BY TAU 72. IN THE EXTENDED TRACK, 14W IS FORECAST TO SLOWLY TRANSIT THE TAIWAN STRAIT AS MORE COOL DRY AIR STEAMS INTO THE SYSTEM FROM THE NORTH, RESULTING IN CONTINUED WEAKENING THROUGH TAU 120 AS THE SYSTEM APPROACHES MAINLAND CHINA.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH ALL MEMBERS CLOSELY FOLLOWING THE JTWC FORECAST TRACK THROUGH TAU 36. BY TAU 72, MEMBER GUIDANCE REMAINS IN FAIR AGREEMENT WITH A 150NM SPREAD IN SOLUTIONS. FOR THIS REASON THE JTWC FORECAST TRACK IS PLACED INITIALLY WITH HIGH CONFIDENCE AND WITH MEDIUM CONFIDENCE THEREAFTER. RELIABLE MODEL INTENSITY GUIDANCE IS IN GOOD AGREEMENT WITH MOST MEMBERS INDICATING LIMITED INTENSIFICATION THROUGH TAU 24, AFTER WHICH CONTINUOUS WEAKENING THROUGH THE FORECAST PERIOD. THE ONE EXCEPTION TO THIS HAPPY STORY IS COAMPS-TC (GFS VERSION), WHICH IS THE ONLY MEMBERS TO NOT MAKE LANDFALL OVER TAIWAN AND AS A RESULT SHOWS CONTINUOUS INTENSIFICATION THROUGH TAU 120. DESPITE THIS HOLDOUT, THE JTWC INTENSITY FORECAST IS PLACED WITH OVERALL MEDIUM CONFIDENCE.