Tropical Cyclones [Index]

Tropical Cyclone 201708 Southern Hemisphere Summary

WTPS31 PGTW 20170222 03:00z
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 08P (EIGHT) WARNING NR 001//
RMKS/
1. TROPICAL CYCLONE 08P (EIGHT) WARNING NR 001
   02 ACTIVE TROPICAL CYCLONES IN SOUTHPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   220000Z --- NEAR 21.2S 172.8W
     MOVEMENT PAST SIX HOURS - 115 DEGREES AT 30 KTS
     POSITION ACCURATE TO WITHIN 060 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
   RADIUS OF 034 KT WINDS - 225 NM NORTHEAST QUADRANT
                            140 NM SOUTHEAST QUADRANT
                            075 NM SOUTHWEST QUADRANT
                            200 NM NORTHWEST QUADRANT
   REPEAT POSIT: 21.2S 172.8W
    ---
   FORECASTS:
   12 HRS, VALID AT:
   221200Z --- 24.2S 167.4W
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   BECOMING EXTRATROPICAL
   RADIUS OF 034 KT WINDS - 215 NM NORTHEAST QUADRANT
                            090 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            190 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 130 DEG/ 24 KTS
    ---
   24 HRS, VALID AT:
   230000Z --- 27.1S 163.1W
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   EXTRATROPICAL
   RADIUS OF 034 KT WINDS - 195 NM NORTHEAST QUADRANT
                            075 NM SOUTHEAST QUADRANT
                            045 NM SOUTHWEST QUADRANT
                            150 NM NORTHWEST QUADRANT
    ---
REMARKS:
220300Z POSITION NEAR 22.0S 171.4W.
TROPICAL CYCLONE 08P (EIGHT), LOCATED APPROXIMATELY 431 NM SOUTH-
SOUTHWEST OF PAGO PAGO, HAS TRACKED EAST-SOUTHEASTWARD AT 30 KNOTS
OVER THE PAST SIX HOURS. RECENT ANIMATED MULTISPECTRAL SATELLITE
IMAGERY AND A 212113Z ASCAT PASS INDICATE THAT TROPICAL CYCLONE
FORMATION HAS OCCURRED DURING THE PAST SEVERAL HOURS. THE INITIAL
POSITION IS BASED ON THE ASCAT DATA AND RECENT FIXES FROM KNES AND
PGTW. THE INTENSITY ESTIMATE OF 40 KNOTS IS CONSISTENT WITH MULTIPLE
AGENCY DVORAK SATELLITE INTENSITY ESTIMATES AND ASCAT WIND
OBSERVATIONS OF 35-40 KNOTS NEAR THE CIRCULATION CENTER. STRONGER
LOW LEVEL WINDS, UP TO 45 KNOTS, ARE PRESENT ALONG THE NORTHEASTERN
PERIPHERY OF THE CIRCULATION. TC 08P IS TRACKING RAPIDLY
SOUTHEASTWARD IN THE GRADIENT BETWEEN AN EXTENSION OF A SUBTROPICAL
RIDGE THE NORTHEAST AND A DEEP-LAYERED MID-LATITUDE TROUGH SITUATED
TO THE SOUTHWEST. PERSISTENT NORTHWESTERLY UPPER-LEVEL FLOW IS
INDUCING STRONG POLEWARD OUTFLOW, WHILE STORM MOTION IN THE
DIRECTION OF THIS FLOW IS MINIMIZING VERTICAL WIND SHEAR OVER THE
CIRCULATION CENTER. HOWEVER, SHEAR HAS BEEN SUFFICIENT TO DISPLACE A
LARGE PORTION OF THE DEEP CONVECTION ASSOCIATED WITH THIS SYSTEM TO
THE SOUTHEAST OF THE CENTER. TC 08P IS EXPECTED TO CONTINUE TRACKING
RAPIDLY SOUTHEASTWARD WITHIN THE CURRENT STEERING ENVIRONMENT FOR
THE NEXT SEVERAL DAYS. THE SYSTEM WILL INTERACT WITH THE BAROCLINIC
ZONE AND BEGIN EXTRATROPICAL TRANSITION BY TAU 12, AND COMPLETE THE
TRANSITION TO A FULLY EXTRATROPICAL LOW BY TAU 24. INTENSITY SHOULD
REMAIN APPROXIMATELY STEADY DURING THE TRANSITION DUE TO A FAVORABLE
UPPER-LEVEL DIFFLUENCE PATTERN. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
220000Z IS 16 FEET. NEXT WARNINGS AT 221500Z. REFER TO TROPICAL
CYCLONE 07P (BART) WARNINGS (WTPS32 PGTW) FOR SIX-HOURLY UPDATES.//
=========================================================================
WTPS31 PGTW 20170222 15:00z
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 08P (EIGHT) WARNING NR 002//
RMKS/
1. TROPICAL CYCLONE 08P (EIGHT) 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:
   221200Z --- NEAR 24.7S 166.9W
     MOVEMENT PAST SIX HOURS - 130 DEGREES AT 33 KTS
     POSITION ACCURATE TO WITHIN 045 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
   BECOMING EXTRATROPICAL
   RADIUS OF 034 KT WINDS - 180 NM NORTHEAST QUADRANT
                            145 NM SOUTHEAST QUADRANT
                            075 NM SOUTHWEST QUADRANT
                            175 NM NORTHWEST QUADRANT
   REPEAT POSIT: 24.7S 166.9W
    ---
   FORECASTS:
   12 HRS, VALID AT:
   230000Z --- 27.6S 162.6W
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   BECOMING EXTRATROPICAL
   RADIUS OF 034 KT WINDS - 175 NM NORTHEAST QUADRANT
                            095 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            135 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 130 DEG/ 22 KTS
    ---
   24 HRS, VALID AT:
   231200Z --- 30.4S 158.8W
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   EXTRATROPICAL
   RADIUS OF 034 KT WINDS - 155 NM NORTHEAST QUADRANT
                            075 NM SOUTHEAST QUADRANT
                            035 NM SOUTHWEST QUADRANT
                            120 NM NORTHWEST QUADRANT
    ---
REMARKS:
221500Z POSITION NEAR 25.4S 165.8W.
TROPICAL CYCLONE 08P (EIGHT), LOCATED APPROXIMATELY 660 NM SOUTH-
SOUTHEAST OF PAGO PAGO, AMERICAN SAMOA HAS TRACKED SOUTHEASTWARD
AT 33 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY DEPICTS AN ELONGATED SYSTEM WITH THE BULK OF DEEP
CONVECTION SHEARED JUST SOUTHEAST OF THE PARTIALLY EXPOSED LOW LEVEL
CIRCULATION CENTER. THE CYCLONE IS TRACKING RAPIDLY SOUTHEASTWARD IN
A TIGHT GRADIENT BETWEEN AN EXTENSION OF A SUBTROPICAL RIDGE TO THE
NORTHEAST AND A DEEP-LAYERED MID-LATITUDE TROUGH SITUATED TO THE
SOUTHWEST. A SERIES OF MICROWAVE IMAGES AND THE TOTAL PRECIPITABLE
WATER LOOP SHOW DRY AIR ASSOCIATED WITH THE AFOREMENTIONED TROUGH
BEGINNING TO WRAP AROUND THE NORTHERN PERIPHERY OF THE CYCLONE. THIS
INTERACTION HAS STARTED THE EXTRA-TROPICAL TRANSITION PROCESS WHICH
IS EXPECTED TO BE COMPLETE IN THE NEXT 24 HOURS. ENVIRONMENTAL
CONDITIONS WILL CONTINUE TO DETERIORATE AS THE CYCLONE FULLY EMBEDS
WITHIN THE BAROCLINIC ZONE AND MOVES INTO COOLER SEA SURFACE
TEMPERATURES. HOWEVER, STRONG UPPER LEVEL DIVERGENCE WILL ALLOW THE
SYSTEM TO MAINTAIN ITS CURRENT INTENSITY. DYNAMIC MODEL GUIDANCE IS
IN VERY TIGHT AGREEMENT DUE TO THE STRAIGHT FORWARD STEERING
SCENARIO WHICH LEADS TO HIGH CONFIDENCE IN THE JTWC FORECAST.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 221200Z IS 15 FEET. NEXT
WARNINGS AT 230300Z.//
=========================================================================
WTPS31 PGTW 20170222 21:00z
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 08P (EIGHT) WARNING NR 003//
RMKS/
1. TROPICAL CYCLONE 08P (EIGHT) WARNING NR 003
   01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   221800Z --- NEAR 26.6S 163.7W
     MOVEMENT PAST SIX HOURS - 125 DEGREES AT 35 KTS
     POSITION ACCURATE TO WITHIN 015 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
   EXTRATROPICAL
   RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT
                            180 NM SOUTHEAST QUADRANT
                            075 NM SOUTHWEST QUADRANT
                            175 NM NORTHWEST QUADRANT
   REPEAT POSIT: 26.6S 163.7W
    ---
   FORECASTS:
   12 HRS, VALID AT:
   230600Z --- 31.1S 157.1W
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   EXTRATROPICAL
   RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT
                            180 NM SOUTHEAST QUADRANT
                            075 NM SOUTHWEST QUADRANT
                            175 NM NORTHWEST QUADRANT
    ---
REMARKS:
222100Z POSITION NEAR 27.7S 162.1W.
TROPICAL CYCLONE (TC) 08P (EIGHT), LOCATED APPROXIMATELY 388 NM
SOUTH-SOUTHWEST OF TONGA, HAS TRACKED SOUTHEASTWARD AT 35 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
SHOWS THE ASSOCIATED CONVECTION HAS BECOME SEVERELY SHEARED, EXPOSING
A RAGGED AND ELONGATED LOW LEVEL CIRCULATION. THE INITIAL POSITION IS
BASED ON AN ELLIPTICAL LOW REFLECTIVITY CIRCULATION FEATURE ON THE
221700Z SSMIS MICROWAVE PASS WITH HIGH CONFIDENCE. THE INITIAL
INTENSITY IS BASED ON AN OVERALL ASSESSMENT OF OBJECTIVE AND
SUBJECTIVE DVORAK ESTIMATES AND FROM RECENT SCATTEROMETRY DATA.
ANALYSES INDICATE TC 08P HAS BECOME EXTRA-TROPICAL, CORROBORATED BY
THE CIRA/RAMMB AMSU RADIAL/HEIGHT CROSS-SECTION PRODUCT AND THE FSU
CYCLONE PHASE DIAGRAM SHOWING AN ASYMMETRIC COLD-CORE LOW PRESSURE
SYSTEM. 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 221800Z IS
15 FEET.//