Tropical Depression USAGI (27W)

WTPN34 PGTW 160900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL DEPRESSION 27W (USAGI) WARNING NR 022//
RMKS/
1. TROPICAL DEPRESSION 27W (USAGI) WARNING NR 022    
   02 ACTIVE TROPICAL CYCLONES IN NORTHWESTPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   160600Z --- NEAR 22.2N 120.6E
     MOVEMENT PAST SIX HOURS - 125 DEGREES AT 03 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY A COMBINATION OF 
     SATELLITE, RADAR AND SYNOPTIC DATA
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   REPEAT POSIT: 22.2N 120.6E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   161800Z --- 22.5N 121.1E
   MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 24 HR POSIT: 040 DEG/ 04 KTS
    ---
   24 HRS, VALID AT:
   170600Z --- 23.2N 121.7E
   MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
160900Z POSITION NEAR 22.3N 120.7E.
16NOV24. TROPICAL DEPRESSION 27W (USAGI), LOCATED APPROXIMATELY
181 NM SOUTH-SOUTHWEST OF TAIPEI, TAIWAN, HAS TRACKED
SOUTHEASTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED 
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A DISORGANIZED ROTATION 
SLOW SPINNING JUST OFFSHORE OF SOUTHWESTERN TAIWAN. SURFACE 
OBSERVATIONS FROM HENGCHUN SHOW SOUTH-SOUTHWESTERLY WINDS OF 10 KNOTS, 
WHICH HAVE STEADILY VEERED FROM THE SOUTH, INDICATING THE CENTER OF TD 
27W LIES JUST TO THE NORTHWEST OF THE STATION. THE INITIAL POSITION IS 
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE SURFACE OBS AND MSI. THE 
INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE 
OVERALL DEGRADED STRUCTURE AND SURFACE OBS. THE SYSTEM IS DRIFTING TO 
THE EAST BASED ON THE ANIMATED RADAR AND MSI DATA, AND IS EXPECTED TO 
CROSS THE NARROW SOUTHERN TIP OF TAIWAN OVER THE NEXT FEW HOURS AND 
THEN MOVE OFF THE EASTERN COAST OF THE ISLAND. THE SYSTEM WILL 
CONTINUE TO WEAKEN AND DISSIPATE OVER THE NEXT 12 HOURS, BUT THE 
REMNANT VORTEX WILL CONTINUE TO TRACK UP THE EAST COAST OF TAIWAN 
THROUGH AND LIKELY AFTER TAU 24.
THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT TYPHOON
WRNCEN PEARL HARBOR HI. THE SYSTEM WILL BE CLOSELY MONITORED FOR
SIGNS OF REGENERATION. MINIMUM CENTRAL PRESSURE AT 160600Z IS
1006 MB. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 160600Z IS 10 FEET.
REFER TO SUPER TYPHOON 25W (MAN-YI) WARNINGS (WTPN32 PGTW)
FOR SIX-HOURLY UPDATES.//
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WDPN34 PGTW 160300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 27W (USAGI) WARNING 
NR 021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.5N 120.3E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 169 NM SOUTH-SOUTHWEST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
DEPRESSION 27W (USAGI) WITH A PARTIALLY EXPOSED LOW-LEVEL
CIRCULATION CENTER (LLCC) AND SPARSE CONVECTION THAT IS BEING
SHEARED OFF TO THE NORTHEAST. ENVIRONMENTAL ANALYSIS INDICATES THAT
27W IS IN AN UNFAVORABLE ENVIRONMENT CHARACTERIZED BY WEAK POLEWARD
OUTFLOW ALOFT, MODERATE TO HIGH (20-25 KTS) VERTICAL WIND SHEAR,
WARMISH (26-27 C) SEA SURFACE TEMPERATURES, AND TERRAIN
INTERACTION. THE INITIAL POSITION IS PLACED WITH LOW CONFIDENCE
BASED ON THE RAGGED APPEARANCE IN THE ANIMATED MSI. THE INITIAL
INTENSITY OF 30 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE
AGENCY DVORAK AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: LOW TO MID-LEVEL SUBTROPICAL RIDGE
(STR) POSITIONED TO THE EAST, WITH A WEAK EXTENSION TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T2.5 - 35 KTS
   RCTP: T2.0 - 30 KTS
   DEMS: T3.0 - 45 KTS
   CIMSS DPRINT: 28 KTS AT 160000Z
   CIMSS DMINT: 37 KTS AT 152230Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: WEAK POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT TO THE WEST AND TERRAIN
INTERACTION WITH SOUTHWESTERN TAIWAN.

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: 27W IS FORECAST TO TRACK NORTHEASTWARD AS IT
MOVES INLAND IN TAIWAN AND CONTINUES TO WEAKEN. INCREASING TERRAIN
INTERACTION, HIGH VERTICAL WIND SHEAR, AND DRY AIR WILL ALL CONTRIBUTE 
TO DEGRADING THE VORTEX. DISSIPATION OVER LAND IN TAIWAN NEAR TAU 24 
IS CURRENTLY FORECASTED, HOWEVER, THERE IS LARGE UNCERTAINTY IN THE 
ACTUAL TRACK 27W TAKES.    

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN EXTREMELY POOR
AGREEMENT, ESPECIALLY AFTER TAU 12 AS MODELS FAN OUT NEARLY IN
EVERY DIRECTION DUE TO THE DISSIPATING VORTEX. THE JTWC TRACK
FORECAST IS PLACED WITH VERY LOW CONFIDENCE AS A RESULT. INTENSITY 
GUIDANCE IS IN BETTER AGREEMENT, SUGGESTING CONTINUED WEAKENING AS 
MODELS QUICKLY LOSE THE VORTEX. THE JTWC INTENSITY FORECAST IS PLACED 
WITH MEDIUM CONFIDENCE DUE TO THIS.

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