Tropical Cyclone 18P (18P)

WTPS31 PGTW 292100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 18P (EIGHTEEN) WARNING NR 007//
RMKS/
1. TROPICAL CYCLONE 18P (EIGHTEEN) WARNING NR 007    
   01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   291800Z --- NEAR 26.9S 171.9E
     MOVEMENT PAST SIX HOURS - 215 DEGREES AT 12 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT
                            120 NM SOUTHEAST QUADRANT
                            100 NM SOUTHWEST QUADRANT
                            000 NM NORTHWEST QUADRANT
   REPEAT POSIT: 26.9S 171.9E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   300600Z --- 28.0S 170.6E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
292100Z POSITION NEAR 27.2S 171.6E.
29JAN26. TROPICAL CYCLONE 18P (EIGHTEEN), LOCATED APPROXIMATELY
262 NM NORTHEAST OF KINGSTON IS., HAS TRACKED SOUTHWESTWARD AT 12
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTI-SPECTRAL IMAGERY (MSI)
DEPICTS TROPICAL CYCLONE 18P AS A FULLY EXPOSED AND SHALLOW VORTEX
BEING STEERED BY THE LOWER LEVEL EASTERLIES. IT IS COMPLETELY DEVOID
OF CONVECTION AND UPPER-LEVEL STRUCTURE AS IT TRACKS FARTHER
SOUTHWESTWARD INTO A HOSTILE ENVIRONMENT CHARACTERIZED BY HIGH
(30+ KTS) VERTICAL WIND SHEAR, DRY AIR, AND COOL (25-26 C) SEA
SURFACE TEMPERATURES. MODEL GUIDANCE IS IN STRONG AGREEMENT IN BOTH
TRACK AND INTENSITY, LENDING HIGH CONFIDENCE TO THE JTWC FORECAST.
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 291800Z IS 997 MB. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 291800Z IS 18 FEET.//
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WDPS31 PGTW 291500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 18P (EIGHTEEN) WARNING 
NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.2S 172.5E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 428 NM SOUTHEAST OF NOUMEA, NEW CALEDONIA
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHWESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
CYCLONE (TC) 18P WITH A PARTIALLY EXPOSED LOW-LEVEL CIRCULATION
CENTER (LLCC) THAT IS NOW VOID OF DEEP CONVECTION. STRONG NORTHERLY
SHEAR AND DRY AIR ENTRAINMENT CONTINUE TO ACT ON THE VORTEX,
INHIBITING THE DEVELOPMENT OF CONVECTION. THE INITIAL POSITION IS
PLACED WITH LOW CONFIDENCE DUE TO THE CENTER BEING SOMEWHAT
OBSCURED BY THE CIRRUS CLOUDS FLOWING OVER THE SYSTEM IN ANIMATED
EIR IMAGERY. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND OBJECTIVE
INTENSITY ESTIMATES LISTED BELOW. THE STRONGEST WINDS ARE CONFINED
TO THE EASTERLIES THAT MAKE UP THE SOUTHERN SEMICIRCLE OF THE
CIRCULATION. ENVIRONMENTAL ANALYSIS INDICATES THAT 18P REMAINS IN
AN UNFAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG POLEWARD OUTFLOW
ALOFT GREATLY OFFSET BY SIGNIFICANT DRY AIR ENTRAINMENT, HIGH
(30-35 KTS) NORTHERLY VERTICAL WIND SHEAR, AND MARGINAL (25-26 C)
SEA SURFACE TEMPERATURES.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE (STR) POSITIONED TO
THE EAST


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   CIMSS ADT: 32 KTS AT 291210Z
   CIMSS AIDT: 38 KTS AT 291140Z
   CIMSS D-PRINT: 41 KTS AT 291210Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 30-35 KTS
   SST: 25-26 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: SIGNIFICANT DRY AIR ENTRAINMENT FROM THE NORTH

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: TC 18P IS FORECAST TO TRACK GENERALLY
SOUTHWESTWARD OVER THE NEXT 24 HOURS AS AN EXTENSION OF THE STR TO
THE EAST JUTS UNDERNEATH THE VORTEX. THE UNFAVORABLE ENVIRONMENT IS
EXPECTED TO PERSIST OVER THE NEXT 24 HOURS WITH STRONG NORTHERLY
SHEAR AND SIGNIFICANT DRY AIR ENTRAINMENT FROM THE NORTH. THESE TWO
FACTORS WILL CONTRIBUTE TO A CONTINUED WEAKENING TREND. 18P IS
FORECAST TO WEAKEN BELOW TC STRENGTH NEAR TAU 12 AS THE SHALLOW
VORTEX DRIFTS OFF TO THE SOUTHWEST. 18P IS ANALYZED TO BE
SIMULTANEOUSLY GOING THROUGH SUBTROPICAL TRANSITION AS IT
DISSIPATES. 18P IS FORECAST TO COMPLETE SUBTROPICAL TRANSITION AT
AROUND THE SAME TIME THAT IT WEAKENS BELOW TC STRENGTH.  

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT WITH NO NOTABLE OUTLIERS. THE SHORT JTWC TRACK FORECAST
IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE.
INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT WITH ALL MODEL SHOWING
WEAKENING OVER THE NEXT 24 HOURS. THE JTWC INTENSITY FORECAST IS
ALSO PLACED NEAR THE CONSENSUS WITH HIGH CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: HIGH//
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