late season tropical cyclone forms- the 21st WTPS31 PGTW 291500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 21P (TWENTYONE) WARNING NR 001//
RMKS/
1. TROPICAL CYCLONE 21P (TWENTYONE) WARNING NR 001
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
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WARNING POSITION:
291200Z --- NEAR 12.2S 154.8E
MOVEMENT PAST SIX HOURS - 165 DEGREES AT 04 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
REPEAT POSIT: 12.2S 154.8E
---
FORECASTS:
12 HRS, VALID AT:
300000Z --- 12.6S 154.8E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT
035 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 225 DEG/ 03 KTS
---
24 HRS, VALID AT:
301200Z --- 13.1S 154.3E
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
VECTOR TO 36 HR POSIT: 245 DEG/ 07 KTS
---
36 HRS, VALID AT:
010000Z --- 13.7S 152.9E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
---
REMARKS:
291500Z POSITION NEAR 12.3S 154.8E.
TROPICAL CYCLONE 21P, LOCATED APPROXIMATELY 475 NM EAST-SOUTHEAST OF
PORT MORESBY, PAPUA NEW GUINEA, HAS TRACKED SOUTH-SOUTHEASTWARD AT 04
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY SHOWS THE COLD DENSE OVERCAST HAS COOLED AS THE CYCLONE
SLOWED ITS FORWARD MOTION. THE INITIAL POSITION WAS EXTRAPOLATED FROM
A 290816Z TRMM MICROWAVE IMAGE WITH POOR CONFIDENCE. THE INITIAL
INTENSITY WAS BASED ON THE DVORAK ESTIMATE FROM PGTW AND FROM A
291057Z ASCAT PASS THAT SHOWS 25-30 KNOT WIND BARBS FEEDING INTO THE
LOW LEVEL CIRCULATION CENTER. UPPER LEVEL ANALYSIS INDICATES THE
CYCLONE IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF A SHALLOW NEAR
EQUATORIAL RIDGE. HOWEVER, A LOW- TO MID-LAYERED SUBTROPICAL RIDGE TO
THE SOUTH IS EXPECTED TO ASSUME STEERING OVER THE NEXT 12-24 HOURS
AND DEFLECT THE SYSTEM WESTWARD. THE VERTICAL WIND SHEAR (VWS) WILL
SIGNIFICANTLY INCREASE AS THE UPPER LEVEL WINDS BECOME OUT-OF-PHASE
WITH LOW-LEVEL WINDS AND STORM MOTION. DURING THE TRANSITION IN THE
STEERING PATTERN, THE SYSTEM MAY SLIGHTLY INTENSIFY BEFORE THE STRONG
VWS DISSIPATES IT BY TAU 36. THE AVAILABLE NUMERICAL GUIDANCE IS
WIDELY SPREAD, THEREFORE, THERE IS POOR CONFIDENCE IN THE TRACK
FORECAST. THIS WARNING SUPERSEDES AND CANCELS REF A, JOINT TYPHOON
WRNCEN PEARL HARBOR HI 291000Z JUN 12 TROPICAL CYCLONE FORMATION
ALERT (WTPS21 PGTW 291000) MAXIMUM SIGNIFICANT WAVE HEIGHT AT 291200Z
IS 11 FEET. NEXT WARNINGS AT 300300Z AND 301500Z. //
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