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![]() Tropical Cyclone 201221 Southern Hemisphere Summary |
WTPS21 PGTW 20120629 10:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE FORMATION ALERT// RMKS/ 1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN A 160 NM RADIUS OF 13.2S 154.0E WITHIN THE NEXT 06 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME. WINDS IN THE AREA ARE ESTIMATED TO BE 25 TO 30 KNOTS. METSAT IMAGERY AT 290930Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 11.8S 154.7E. THE SYSTEM IS MOVING SOUTHEASTWARD AT 08 KNOTS. 2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 11.2S 154.2E, IS NOW NEAR 11.7S 154.7E, APPROXIMATELY 465 NM EAST-SOUTHEAST OF PORT MORESBY, PAPUA NEW GUINEA. RECENT ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS PERSISTENT DEEP CENTRAL CONVECTION OVER A WELL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC). ALSO, A 290527Z AMSU-B MICROWAVE IMAGE SHOWS VERY TIGHT SPIRAL BANDING FEEDING INTO THE LLCC. A 290142Z SCATTEROMETRY PASS SHOWS 25-30 KNOT WIND BARBS IN THE LLCC. THE CYCLONE IS CURRENTLY 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 VWS WILL SIGNIFICANTLY INCREASE AS THE UPPER LEVEL WINDS BECOME OUT-OF-PHASE WITH LOW-LEVEL WINDS AND STORM MOTION. IT IS DURING THE TRANSITION IN THE STEERING THAT THE SYSTEM MAY REACH WARNING CRITERIA, HOWEVER BRIEF, BEFORE THE STRONG VWS DISSIPATES IT. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO HIGH. 3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 301000Z. // ========================================================================= WTPS31 PGTW 20120629 15:00z 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 --- 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. // ========================================================================= WTPS31 PGTW 20120630 03:00z MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21P (TWENTYONE) WARNING NR 002// RMKS/ 1. TROPICAL CYCLONE 21P (TWENTYONE) WARNING NR 002 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 300000Z --- NEAR 11.0S 154.8E MOVEMENT PAST SIX HOURS - 335 DEGREES AT 04 KTS POSITION ACCURATE TO WITHIN 030 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER REPEAT POSIT: 11.0S 154.8E --- FORECASTS: 12 HRS, VALID AT: 301200Z --- 10.6S 154.4E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 300300Z POSITION NEAR 10.9S 154.7E. TROPICAL CYCLONE (TC) 21P, LOCATED APPROXIMATELY 320 NM WEST- SOUTHWEST OF HONIARA, SOLOMON ISLANDS, HAS TRACKED NORTH- NORTHWESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY-EXPOSED, WEAKENING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH RAPIDLY DECAYING DEEP CONVECTION SHEARED SOUTHEAST OF THE SYSTEM A 292323Z ASCAT IMAGE INDICATES NUMEROUS 20-25 KNOT WINDS WITH AN ISOLATED 30 KNOT WIND OVER THE WEST QUADRANT. THE ASCAT DATA AS WELL AS THE LATEST DVORAK ESTIMATES OF 25-30 KNOTS FROM PGTW AND KNES SUPPORT THE INITIAL INTENSITY ASSESSMENT OF 30 KNOTS. MSI AND MICROWAVE IMAGERY SHOW THAT THE LOW-LEVEL CIRCULATION CENTER (LLCC) DECOUPLED FROM THE DEEP CONVECTION APPROXIMATELY 12 HOURS AGO AND BEGAN TO TRACK EQUATORWARD UNDER THE STEERING INFLUENCE OF THE LOW- LEVEL SOUTHERLY FLOW ASSOCIATED WITH THE STRENGTHENING SUBTROPICAL RIDGE POSITION OVER THE CORAL SEA. 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. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 300000Z IS 10 FEET.//
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Document: tropical_cyclone_201221.htm | Updated: 2 July 2012 |