WTXS21 PGTW 20160328 14:30z
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
200 NM EITHER SIDE OF A LINE FROM 13.5S 76.1E TO 22.5S 80.1E WITHIN
THE NEXT 03 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 281400Z
INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 14.4S 76.7E. THE
SYSTEM IS MOVING SOUTH-SOUTHEASTWARD AT 11 KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 14.0S
76.6E IS NOW LOCATED NEAR 14.4S 76.7E, APPROXIMATELY 495 NM SOUTH-
SOUTHEAST OF DIEGO GARCIA. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS A RAPIDLY CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC)
WITH IMPROVED DEEP CONVECTIVE BANDING WRAPPING INTO A WELL-DEFINED
CENTER. A 281101Z SSMIS 91GHZ IMAGE SHOWS A COMPACT SYSTEM,
APPROXIMATELY 120NM DIAMETER, WITH TIGHTLY-CURVED DEEP CONVECTIVE
BANDING. A 280445Z ASCAT IMAGE REVEALS 25 TO 30 KNOT WINDS OVER THE
NORTHEASTERN QUADRANT. UPPER-LEVEL ANALYSIS REVEALS A FAVORABLE
ENVIRONMENT WITH RADIAL OUTFLOW AND LOW VERTICAL WIND SHEAR. DUE TO
THE SMALL SIZE OF THE LLCC, DYNAMIC MODELS ARE POORLY INITIALIZING
THE SYSTEM, HOWEVER, THE SYSTEM IS EXPECTED TO ACCELERATE SOUTHWARD
BETWEEN ENHANCED FLOW BETWEEN A DEEP TROUGH AND A POLEWARD-ORIENTED
SUBTROPICAL RIDGE. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT
25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR
1001 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL
CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
291430Z.//
=========================================================================
WTXS31 PGTW 20160328 21:00z
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 17S (SEVENTEEN) WARNING NR 001//
RMKS/
1. TROPICAL CYCLONE 17S (SEVENTEEN) WARNING NR 001
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   281800Z --- NEAR 15.4S 77.4E
     MOVEMENT PAST SIX HOURS - 145 DEGREES AT 12 KTS
     POSITION ACCURATE TO WITHIN 040 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: 15.4S 77.4E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   290600Z --- 17.6S 78.2E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT
                            070 NM SOUTHEAST QUADRANT
                            070 NM SOUTHWEST QUADRANT
                            060 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 160 DEG/ 15 KTS
    ---
   24 HRS, VALID AT:
   291800Z --- 20.5S 79.3E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT
                            080 NM SOUTHEAST QUADRANT
                            080 NM SOUTHWEST QUADRANT
                            070 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 155 DEG/ 17 KTS
    ---
   36 HRS, VALID AT:
   300600Z --- 23.6S 80.8E
   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 48 HR POSIT: 145 DEG/ 27 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   301800Z --- 28.0S 84.4E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
282100Z POSITION NEAR 16.0S 77.6E.
TROPICAL CYCLONE (TC) 17S (SEVENTEEN), LOCATED APPROXIMATELY 575 NM
SOUTH-SOUTHEAST OF DIEGO GARCIA, HAS TRACKED SOUTHEASTWARD AT 12
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY REVEALS A RAPIDLY CONSOLIDATING LOW LEVEL CIRCULATION CENTER
(LLCC) WITH DEEP CONVECTIVE BANDING WRAPPING INTO A WELL-DEFINED
CENTER. A 281628Z AMSU 89 GHZ IMAGE SHOWS A COMPACT SYSTEM WITH
TIGHTLY-CURVED CONVECTION PRIMARILY ALONG THE SOUTHERN AND EASTERN
PERIPHERIES, WHICH SUPPORTS THE CURRENT POSITION WITH HIGH
CONFIDENCE. THE CURRENT INTENSITY IS ASSESSED AT 35 KNOTS BASED ON
RECENT DVORAK ESTIMATES OF T2.5 (35 KNOTS) FROM PGTW AND KNES. UPPER-
LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH GOOD POLEWARD
OUTFLOW AND LOW (5 TO 10 KNOTS) VERTICAL WIND SHEAR (VWS). TC 17S IS
BEING STEERED SOUTHEASTWARD ALONG THE WESTERN PERIPHERY OF A
SUBTROPICAL RIDGE (STR). THIS SYSTEM IS FORECAST TO CONTINUE
TRACKING SOUTHEASTWARD UNDER THE SAME STEERING INFLUENCE THROUGH THE
FORECAST PERIOD. TC 17S WILL BEGIN TO ACCELERATE THROUGH TAU 48 AS
IT BECOMES FULLY EMBEDDED WITHIN A DEEP UPPER LEVEL TROUGH
APPROACHING FROM THE WEST. THE SYSTEM HAS A SHORT WINDOW FOR
INTENSIFICATION REACHING A PEAK INTENSITY OF 45 KNOTS AT TAU 12
UNDER A FAVORABLE UPPER LEVEL ENVIRONMENT NEAR THE STR AXIS.
HOWEVER, AFTER TAU 12, THE SYSTEM WILL BEGIN TO WEAKEN AS VWS
BECOMES UNFAVORABLE WITHIN THE TROUGH. TC 17S IS FORECAST TO FULLY
DISSPATE BY TAU 48. DYNAMIC MODEL GUIDANCE IS IN TIGHT AGREEMENT
LEADING TO HIGH CONFIDENCE IN THE JTWC FORECAST TRACK. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 281800Z IS 12 FEET. NEXT WARNINGS AT
290900Z AND 292100Z. THIS CANCELS AND SUPERSEDES REF A (WTXS21 PGTW
281430)//
=========================================================================
WTXS31 PGTW 20160329 09:00z
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL CYCLONE 17S (SEVENTEEN) WARNING NR 002
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   290600Z --- NEAR 17.8S 78.3E
     MOVEMENT PAST SIX HOURS - 175 DEGREES AT 15 KTS
     POSITION ACCURATE TO WITHIN 045 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 - 040 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            025 NM SOUTHWEST QUADRANT
                            025 NM NORTHWEST QUADRANT
   REPEAT POSIT: 17.8S 78.3E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   291800Z --- 20.3S 79.1E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
                            045 NM SOUTHEAST QUADRANT
                            025 NM SOUTHWEST QUADRANT
                            025 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 155 DEG/ 16 KTS
    ---
   24 HRS, VALID AT:
   300600Z --- 23.2S 80.5E
   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: 150 DEG/ 15 KTS
    ---
   36 HRS, VALID AT:
   301800Z --- 25.8S 82.2E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
290900Z POSITION NEAR 18.4S 78.5E.
TROPICAL CYCLONE 17S (SEVENTEEN), LOCATED APPROXIMATELY 726 NM
SOUTH-SOUTHEAST OF DIEGO GARCIA, HAS TRACKED SOUTHWARD AT 15
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER
(LLCC) WITH THE FLARING CENTRAL CONVECTION BEING SHEARED AWAY TO THE
SOUTH. RECENT MICROWAVE IMAGERY CONFIRMS THE LOW LEVEL STRUCTURE HAS
IMPROVED OVER THE LAST SIX HOURS AS CONVECTIVE BANDING IS MORE
DEFINED AND IS ROTATING INTO A WELL DEFINED LLCC WITH THE STRONGEST
CONVECTION LOCATED IN THE SOUTHERN PERIPHERY. A 290424Z MHS 89GHZ
IMAGE SHOWS A REGION OF DRY AIR APPROACHING TC 17S FROM THE WEST
WHICH WILL HINDER FUTURE INTENSIFICATION. THE CURRENT INTENSITY IS
ASSESSED AT 40 KNOTS AND IS BASED ON A 290337Z METOP-B ASCAT IMAGE
SHOWING 35 TO 40 KNOT SURFACE WINDS ON THE EASTERN PERIPHERY. THIS
IS IN CONTRAST TO DVORAK ESTIMATES FROM REPORTING AGENCIES
SUGGESTING TC 17S HAS WEAKENED OVER THE LAST SIX HOURS. THIS IS
ATTRIBUTED TO THE RELATIVELY SMALL SIZE AND WANING STRUCTURE OF THE
TC IN WHICH DVORAK TECHNIQUES CAN BE UNREPRESENTATIVE OF TRUE
INTENSITY. CURRENTLY, CONDITIONS ARE MARGINALLY FAVORABLE WITH WARM
(29 CELSIUS) SEA SURFACE TEMPERATURES (SSTS) AND A STRONG POLEWARD
OUTFLOW CHANNEL BEING OFFSET BY HIGH (20 TO 25 KNOTS) VERTICAL WIND
SHEAR. TC 17S IS CURRENTLY POSITIONED BETWEEN A LONG WAVE TROUGH TO
THE WEST AND A SUBTROPICAL RIDGE TO THE EAST STEERING IT ALONG A
SOUTHWARD TRACK. AS THE TROUGH APPROACHES, VERTICAL WIND SHEAR IS
EXPECTED TO INCREASE CONSIDERABLY OVER THE NEXT 12 TO 24 HOURS AND
BY TAU 36 SSTS WILL BE NEAR 26 CELSIUS. DUE TO THE DETERIORATING
ENVIRONMENT TC 17S IS EXPECTED TO FULLY DISSIPATE BY TAU 36 AS IT
GETS FULLY ABSORBED IN THE PASSING TROUGH. DYNAMIC MODEL GUIDANCE IS
IN GOOD AGREEMENT GIVING HIGH CONFIDENCE TO THE FORECAST TRACK.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 290600Z IS 14 FEET. NEXT
WARNINGS AT 292100Z AND 300900Z.
=========================================================================
WTXS31 PGTW 20160329 21:00z
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 17S (SEVENTEEN) WARNING NR 003//
RMKS/
1. TROPICAL CYCLONE 17S (SEVENTEEN) WARNING NR 003
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   291800Z --- NEAR 21.2S 79.6E
     MOVEMENT PAST SIX HOURS - 160 DEGREES AT 21 KTS
     POSITION ACCURATE TO WITHIN 040 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 - 040 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            025 NM SOUTHWEST QUADRANT
                            025 NM NORTHWEST QUADRANT
   REPEAT POSIT: 21.2S 79.6E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   300600Z --- 25.1S 81.8E
   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 24 HR POSIT: 145 DEG/ 25 KTS
    ---
   24 HRS, VALID AT:
   301800Z --- 29.1S 85.2E
   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 22.2S 80.2E.
TROPICAL CYCLONE (TC) 17S (SEVENTEEN), LOCATED APPROXIMATELY 941 NM
SOUTH-SOUTHEAST OF DIEGO GARCIA, HAS TRACKED SOUTH-SOUTHEASTWARD
AT 21 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY AND A 291606Z AMSU IMAGE CONTINUE REVEAL A COMPACT
SYSTEM WITH DEEP CONVECTIVE BANDING WRAPPING TIGHTLY INTO THE LOW-
LEVEL CIRCULATION CENTER. THE CURRENT POSITION AND INTENSITY IS
SUPPORTED WITH HIGH CONFIDENCE BASED ON A 291655Z ASCAT AMBIGUITY
ANALYSIS, AND SCATTEROMETRY DATA DEPICTING A CORE OF 35 TO 40 KNOT
WINDS NEAR THE CENTER. UPPER LEVEL ANALYSIS INDICATES A MARGINALLY
FAVORABLE ENVIRONMENT WITH GOOD POLEWARD OUTFLOW OFFSET BY STRONG
(30 TO 40 KNOTS) VERTICAL WIND SHEAR (VWS). TC 17S IS BEING STEERED
SOUTHEASTWARD BY AN AREA OF ENHANCED POLEWARD FLOW BETWEEN A DEEP
UPPER LEVEL TROUGH AND A SUBTROPICAL RIDGE. THIS SYSTEM IS FORECAST
TO CONTINUE ACCELERATING SOUTHEASTWARD THROUGH THE FORECAST PERIOD
AS IT BECOMES FULLY EMBEDDED WITHIN THE TROUGH. TC 17S IS EXPECTED
TO BEGIN WEAKENING BY TAU 12 AND FULLY DISSIPATE BY TAU 24, AS THE
SYSTEM ENCOUNTERS COLDER SSTS AND UNFAVORABLE VWS VALUES. DYNAMIC
MODEL GUIDANCE IS IN SOLID AGREEMENT ON THE SYNOPTIC STEERING
PATTERN LEADING TO HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 291800Z IS 12 FEET. NEXT WARNINGS
AT 300900Z.//
=========================================================================
WTXS31 PGTW 20160330 09:00z
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL CYCLONE 17S (SEVENTEEN) WARNING NR 004
   01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   300600Z --- NEAR 25.8S 82.9E
     MOVEMENT PAST SIX HOURS - 145 DEGREES AT 31 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
   REPEAT POSIT: 25.8S 82.9E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   301800Z --- 29.2S 85.7E
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
300900Z POSITION NEAR 26.7S 83.6E.
TROPICAL CYCLONE 17S (SEVENTEEN), LOCATED APPROXIMATELY 1270 NM
SOUTH-SOUTHEAST OF DIEGO GARCIA, HAS TRACKED SOUTHEASTWARD AT 31
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A LONGWAVE TROUGH APPROACHING FROM THE WEST THAT HAS
SIGNIFICANTLY DISRUPTED THE TC LEAVING ONLY A BROAD LINE OF
CONVECTION WITH ALMOST NO ORGANIZATION OR ANY VISIBLE LOW LEVEL
CIRCULATION CENTER (LLCC). RECENT MICROWAVE IMAGERY CONFIRMS A
SIGNIFICANT DISORGANIZATION OF TC 17S OVER THE LAST SIX HOURS GIVING
LOW CONFIDENCE TO THE INITIAL POSITION. A 300406Z METOP-A ASCAT
IMAGE SHOWS THAT THE LLCC HAS DETERIORATED SIGNIFICANTLY LEAVING
ONLY A ELONGATED LOW LEVEL TROUGH. THE CURRENT INTENSITY IS ASSESSED
AT 35 KNOTS AND IS BASED ON THE AFOREMENTIONED ASCAT IMAGE. TC 17S
IS EXPECTED TO CONTINUE ITS TRACK SOUTHEAST AND DISSIPATE AS IT GETS
FULLY EMBEDDED IN THE PASSING TROUGH. DYNAMIC MODEL GUIDANCE IS IN
TIGHT AGREEMENT GIVING HIGH CONFIDENCE TO THE FORECAST TRACK. 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 300600Z
IS 12 FEET.

Tropical cyclone tracks developed by Michael Bath using operational warnings and advisories.

Document: tropical_cyclone_201617_jtwc_advisories.htm Updated: 17 June 2020 [Australian Severe Weather index] [Copyright Notice] [Email Contacts] [Search This Site] [Privacy Policy]