Tropical Cyclone FAIDA (11S)

WTPS33 PGTW 280300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 21P (SERU) WARNING NR 008//
RMKS/
1. TROPICAL CYCLONE 21P (SERU) WARNING NR 008    
   02 ACTIVE TROPICAL CYCLONES IN SOUTHPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   280000Z --- NEAR 23.0S 172.5E
     MOVEMENT PAST SIX HOURS - 090 DEGREES AT 02 KTS
     POSITION ACCURATE TO WITHIN 030 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   SUBTROPICAL
   RADIUS OF 034 KT WINDS - 140 NM NORTHEAST QUADRANT
                            170 NM SOUTHEAST QUADRANT
                            095 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   REPEAT POSIT: 23.0S 172.5E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   281200Z --- 23.1S 173.1E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   SUBTROPICAL
   RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT
                            100 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            020 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 090 DEG/ 03 KTS
    ---
   24 HRS, VALID AT:
   010000Z --- 23.1S 173.7E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   SUBTROPICAL
    ---
REMARKS:
280300Z POSITION NEAR 23.0S 172.7E.
28FEB25. TROPICAL CYCLONE 21P (SERU), LOCATED APPROXIMATELY 359 NM
EAST OF NOUMEA, NEW CALEDONIA, HAS TRACKED EASTWARD AT 02 KNOTS OVER
THE PAST SIX HOURS. SATELLITE ANALYSIS REVEALED A DECOUPLING HAS
OCCURRED DUE TO INCREASINGLY HOSTILE VERTICAL WIND SHEAR (VWS) AND
HAS RESULTED IN A FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC).
THE WIND FIELD REMAINS STRONG DUE TO AN ENHANCED PRESSURE GRADIENT
BUT IS EXPECTED TO CONTINUE WEAKENING AS THE VORTEX STRUCTURE TILTS
BEYOND REPAIR. THE MAJORITY OF THE MOISTURE FIELD IS DISPLACED
ASYMMETRICALLY EAST AND POLEWARD OF CENTER, FURTHER SUPPORTING THE
CLASSIFICATION OF THIS HYBRID SYSTEM AS NOW FULLY SUBTROPICAL.
ADDITIONALLY, THE VORTICITY SIGNATURE IS ASSESSED AS FRONTAL.
THIS SYSTEM IS EXPECTED TO BECOME INCREASINGLY ELONGATED WITH
ASSOCIATED WINDS DECREASING. MODEL GUIDANCE INDICATES IT WILL
EVENTUALLY FILL AND BECOME ABSORBED INTO THE EXISTING SPCZ BOUNDARY
TO WHICH IT REMAINS AFFIXED. 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 280000Z IS 996 MB. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 280000Z IS
18 FEET. REFER TO TROPICAL CYCLONE 18P (ALFRED) WARNINGS (WTPS31 PGTW)
FOR SIX-HOURLY UPDATES.//
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WDPS33 PGTW 271500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 21P (SERU) WARNING NR 
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.9S 171.0E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 273 NM EAST OF NOUMEA, NEW CALEDONIA
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHEASTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 21 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
DEGRADING TROPICAL CYCLONE (TC) WITH DEEP CONVECTION SHEARED TO THE
SOUTHEAST. DISTINCT DRY AIR IS IMPINGING ON THE CIRCULATION FROM
THE WESTERN PERIPHERY. THE INITIAL POSITION IS PLACED WITH LOW
CONFIDENCE BASED ON THE AFOREMENTIONED EIR IMAGERY AND DEGRADATION
TO HIMAWARI-9 DATA. THE INITIAL INTENSITY OF 45 KTS IS ASSESSED
WITH MEDIUM CONFIDENCE BASED ON A 270936Z METOP-B ASCAT IMAGERY
REVEALING AN ELONGATED CIRCULATION WITH A SWATH OF 45KT WINDS TO
THE SOUTH AND SOUTHWEST.

INITIAL WIND RADII BASIS: 270936Z METOP-B ASCAT IMAGERY

CURRENT STEERING MECHANISM: A COMPETING STEERING ENVIRONMENT
BETWEEN TWO WEAK RIDGES TO THE EAST AND WEST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   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: TROPICAL CYCLONE (TC) 21P WILL SLOWLY CURVE
SOUTHEASTWARD FOR THE REMAINDER OF THE FORECAST PERIOD. THE
COMPETING ENVIRONMENT WILL LEAD TO SLOW TRACK MOVEMENT, AND
POTENTIAL QUASI-STATIONARY PERIODS. THE SYSTEM IS EXPECTED TO
CONTINUALLY WEAKEN IN AN ENVIRONMENT OF HIGH VERTICAL WIND SHEAR,
COOL SEA SURFACE TEMPERATURES, AND UPWELLING FROM SLOW TRACK
MOVEMENT. BY THE END OF THE FORECAST PERIOD, THE SYSTEM WILL HAVE
WEAKENED BELOW THE 35KT WARNING THRESHOLD AND HAVE REACHED
DISSIPATION.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE HAS THE RESEMBLANCE
OF WHAT WE CALL A 'SQUASHED SPIDER' - SPREAD IN MULTIPLE DIRECTIONS
AND THEREBY IN POOR AGREEMENT. THIS IS DUE TO THE UNCERTAINTY OF
THE STEERING INFLUENCE BETWEEN THE TWO RIDGES AS THE SYSTEM WINDS
DOWN. THE INTENSITY GUIDANCE IS IN GOOD AGREEMENT THAT TC 21S WILL
DISSIPATE IN 36 HOURS.

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