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Tropical Cyclone JONI : JTWC Advisories
Season 2008-2009 Summaries (Operational Data): [AU] [SIO] [SPAC] [SH]
---> Tropical Cyclone JONI Track Map and Data

WTPS21 PGTW 20090311 02:00z COR
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE FORMATION ALERT REISSUED CORRECTED//
REF/A/MSG/NAVMARFCSTCEN PEARL HARBOR HI/100153ZMAR2009//
NARR/REF A IS A TROPICAL CYCLONE FORMATION ALERT.//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 19.8S 158.2W TO 25.6S 157.9W
WITHIN THE NEXT 12 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 IM-
AGERY AT 110130Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 20.8S 158.1W. THE SYSTEM IS MOVING SOUTHWARD AT 05 KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 18.7S
156.4W, IS NOW LOCATED NEAR 20.8S 158.1W, APPROXIMATELY 100 NM EAST
OF RAROTONGA. RECENT ANIMATED MULTISPECTRAL IMAGERY SHOWS FORMATIVE
CONVECTIVE BANDING BEGINNING TO WRAP INTO A LOOSELY-DEFINED LOW
LEVEL CIRCULATION CENTER (LLCC). THIS LLCC IS CONFIRMED BY A 101652Z
QUIKSCAT PASS SHOWING WINDS OF 25 TO 30 KNOTS NEAR THE CENTER WITH
EVEN STRONGER FLOW LOCATED 60 TO 80 NM NORTH OF THE SYSTEM CENTER.
AN ANTI-CYCLONE ALOFT IS PROVIDING AMPLE RADIAL OUTFLOW FOR
DEVELOPMENT, AND THE SYSTEM LIES IN A REGION OF WEAK VERTICAL WIND
SHEAR, WARM SST (>26C) AND SIGNIFICANT OCEAN HEAT CONTENT. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1002 MB. THE DISTURBANCE IS
TRACKING SOUTH ALONG THE NORTHWESTERN PERIPHERY OF A LOW- TO MID-
LEVEL RIDGE LOCATED EAST-SOUTHEAST OF THE SYSTEM. ALTHOUGH
ORGANIZATION HAS IMPROVED OVER THE PAST 24 HOURS, THIS DISTURBANCE
REMAINS FAIRLY WEAK AND STILL LACKS SIGNIFICANT SURFACE DEVELOPMENT
NEAR THE LLCC TO WARRANT UPGRADE TO TROPICAL CYCLONE STATUS AT THIS
TIME. DUE TO THE IMPROVING SURFACE CONDITIONS AS WELL AS FAVORABLE
CONDITIONS ALOFT, HOWEVER, THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS GOOD.
THIS SUPERSEDES REF A.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
120200Z.
4. JUSTIFICATION FOR CORRECTION: CORRECTED LOCATION RELATIVE TO
RAROTONGA FROM WEST TO EAST.//
=========================================================================
WTPS32 PGTW 20090311 09:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ: TROPICAL CYCLONE 20P (TWENTY) WARNING NR 001
REF/A/NAVMARFCSTCEN/110152Z MAR 09//
AMPN/TROPICAL CYCLONE FORMATION ALERT//
1. TROPICAL CYCLONE 20P (TWENTY) WARNING NR 001
   02 ACTIVE TROPICAL CYCLONES IN SOUTHPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   110600Z --- NEAR 21.2S 158.1W
     MOVEMENT PAST SIX HOURS - 190 DEGREES AT 06 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: 21.2S 158.1W
    ---
   FORECASTS:
   12 HRS, VALID AT:
   111800Z --- 23.0S 158.6W
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 180 DEG/ 09 KTS
    ---
   24 HRS, VALID AT:
   120600Z --- 24.7S 158.6W
   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: 175 DEG/ 09 KTS
    ---
   36 HRS, VALID AT:
   121800Z --- 26.5S 158.5W
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 48 HR POSIT: 170 DEG/ 09 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   130600Z --- 28.3S 158.2W
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
110900Z POSITION NEAR 21.6S 158.2W.
TROPICAL CYCLONE (TC) 20P, LOCATED APPROXIMATELY 95 NM EAST OF RARO-
TONGA, COOK ISLANDS, HAS TRACKED SOUTHWARD AT 06 KNOTS OVER THE PAST
06 HOURS. ANIMATED INFRARED SATELLITE IMAGERY AND AN 110513Z SSMI
IMAGE INDICATE A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC)
WITH IMPROVED CONVECTIVE BANDING WRAPPING INTO THE SOUTHEAST QUADRANT
OF THE SYSTEM. THE SSMI 37 GHZ IMAGE SUPPORTS A DEVELOPING LLCC
WITH A MORE DEFINED CENTER. RECENT SCATTEROMETER, IN GENERAL, SHOWED
25-30 KNOT UNFLAGGED WINDS. HOWEVER, DVORAK ESTIMATES HAVE INCREASED
TO 30-35 KNOTS BASED ON THE IMPROVED STRUCTURE NEAR THE CENTER. THE
LLCC IS SITUATED UNDER AN UPPER-LEVEL ANTICYCLONE WITH GOOD POLEWARD
OUTFLOW ENHANCED BY A DEEP SHORTWAVE TROUGH WEST OF THE SYSTEM (ALONG
165W) AND AN ANTICYCLONE NEAR 28S 147W. THE SYSTEM IS TRACKING ALONG
THE WESTERN PERIPHERY OF A POLEWARD ORIENTED LOW-LEVEL SUBTROPICAL
RIDGE AND IS FORECAST TO CONTINUE TRACKING SOUTHWARD THROUGH THE
FORECAST PERIOD. THE AVAILABLE MODEL GUIDANCE IS IN VERY GOOD AGREE-
MENT WITH THE OFFICIAL FORECAST. TC 20P IS EXPECTED TO INTENSIFY
SLIGHTLY OVER THE NEXT 12 HOURS BUT SHOULD WEAKEN QUICKLY AS THE
AFOREMENTIONED UPPER-LEVEL TROUGH SHIFTS EAST AND DISRUPTS OUTFLOW.
ADDITIONALLY, COOLER SST WILL WEAKEN THE SYSTEM BELOW 35 KNOTS
AFTER TAU 36 LEADING TO DISSIPATION OVER WATER. THIS WARNING
SUPERSEDES AND CANCELS REF A, NAVMARFCSTCEN 110152Z MAR 09 TROPICAL
CYCLONE FORMATION ALERT (WTPS22 PGTW 110200). MAXIMUM SIGNIFICANT
WAVE HEIGHT AT 110600Z IS 8 FEET. NEXT WARNINGS AT 112100Z AND
120900Z. REFER TO TROPICAL CYCLONE 18P (HAMISH) WARNINGS (WTPS31
PGTW) FOR TWELVE-HOURLY UPDATES.//
=========================================================================
WTPS32 PGTW 20090311 21:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 20P (JONI) WARNING NR 002//
RMKS/
1. TROPICAL CYCLONE 20P (JONI) WARNING NR 02
   02 ACTIVE TROPICAL CYCLONES IN SOUTHPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   111800Z --- NEAR 22.2S 158.4W
     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 - 055 KT, GUSTS 070 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 010 NM NORTHEAST QUADRANT
                            010 NM SOUTHEAST QUADRANT
                            010 NM SOUTHWEST QUADRANT
                            010 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 035 NM NORTHEAST QUADRANT
                            035 NM SOUTHEAST QUADRANT
                            030 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   REPEAT POSIT: 22.2S 158.4W
    ---
   FORECASTS:
   12 HRS, VALID AT:
   120600Z --- 23.3S 158.7W
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 010 NM NORTHEAST QUADRANT
                            010 NM SOUTHEAST QUADRANT
                            010 NM SOUTHWEST QUADRANT
                            010 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 190 DEG/ 08 KTS
    ---
   24 HRS, VALID AT:
   121800Z --- 24.8S 159.0W
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 185 DEG/ 12 KTS
    ---
   36 HRS, VALID AT:
   130600Z --- 27.1S 159.3W
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 034 KT WINDS - 035 NM NORTHEAST QUADRANT
                            030 NM SOUTHEAST QUADRANT
                            025 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 180 DEG/ 12 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   131800Z --- 29.4S 159.4W
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
112100Z POSITION NEAR 22.5S 158.5W.
TROPICAL CYCLONE (TC) 20P, LOCATED APPROXIMATELY 95 NM SOUTHEAST OF
RAROTONGA, COOK ISLANDS, HAS TRACKED SOUTH-SOUTHEASTWARD AT 04 KNOTS
OVER THE PAST 06 HOURS. ANIMATED INFRARED SATELLITE IMAGERY AND AN
111806Z SSMIS IMAGE INDICATE A RAPID CONSOLIDATION OF THE LOW-LEVEL
CIRCULATION CENTER (LLCC) WITH INCREASED BANDING AND CONVECTION NEAR
THE LLCC. A RECENT MULTISPECTRAL IMAGE SUPPORTS THE POSITION OF THE
LLCC IN INFRARED AND MICROWAVE IMAGERY. OVER THE PAST 12 HOURS DVORAK
ESTIMATES HAVE INCREASED TO 50-55 KNOTS BASED ON INCREASED ORGANI-
ZATION OF THE LLCC. THE LLCC IS SITUATED UNDER AN UPPER-LEVEL ANTI-
CYCLONE WITH GOOD POLEWARD OUTFLOW ENHANCED BY A DEEP SHORTWAVE
TROUGH WEST OF THE SYSTEM (ALONG 165W), AN ANTICYCLONE TO THE
SOUTHEAST (NEAR 30S 144W), AND AN UPPER LEVEL LOW (NEAR 20S 140W).
THE SYSTEM IS TRACKING ALONG THE WESTERN PERIPHERY OF A POLEWARD
ORIENTED LOW TO MID-LEVEL SUBTROPICAL RIDGE AND IS FORECAST TO
CONTINUE TRACKING SOUTHWARD THROUGH THE FORECAST PERIOD. THE
AVAILABLE MODEL GUIDANCE IS IN VERY GOOD AGREEMENT WITH THE OFFICIAL
FORECAST. TC 20P IS EXPECTED MAINTAIN ITS CURRENT INTENSITY OVER THE
NEXT 12 HOURS BUT SHOULD WEAKEN QUICKLY AS THE AFOREMENTIONED UPPER-
LEVEL TROUGH SHIFTS EAST AND DISRUPTS OUTFLOW. ADDITIONALLY, COOLER
SST AND INCREASING VERTICAL WIND SHEAR WILL WEAKEN THE SYSTEM
LEADING TO DISSIPATION BY TAU 48. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
111800Z IS 11 FEET. NEXT WARNINGS AT 120900Z AND 122100Z. REFER TO
TROPICAL CYCLONE 18P (HAMISH) WARNINGS (WTPS31 PGTW) FOR TWELVE-
HOURLY UPDATES.//
=========================================================================
SUBJ: TROPICAL CYCLONE 20P (JONI) WARNING NR 003    
WTPS32 PGTW 20090312 09:00z    
1. TROPICAL CYCLONE 20P (JONI) WARNING NR 003    
   02 ACTIVE TROPICAL CYCLONES IN SOUTHPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   120600Z --- NEAR 23.2S 158.7W
     MOVEMENT PAST SIX HOURS - 180 DEGREES AT 05 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT
                            070 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   REPEAT POSIT: 23.2S 158.7W
    ---
   FORECASTS:
   12 HRS, VALID AT:
   121800Z --- 25.0S 158.9W
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT
                            070 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 185 DEG/ 12 KTS
    ---
   24 HRS, VALID AT:
   130600Z --- 27.4S 159.1W
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 180 DEG/ 14 KTS
    ---
   36 HRS, VALID AT:
   131800Z --- 30.2S 159.2W
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
120900Z POSITION NEAR 23.6S 158.7W.
TROPICAL CYCLONE (TC) 20P (JONI), LOCATED APPROXIMATELY 130 NM SOUTH-
SOUTHEAST OF RAROTONGA, COOK ISLANDS, HAS TRACKED SOUTHWARD AT 05 
KNOTS OVER THE PAST 06 HOURS. JONI WILL CONTINUE TO TRACK SOUTHWARD
ALONG THE WESTERN PERIPHERY OF THE MID-LEVEL STEERING RIDGE TOWARDS 
COOLER WATER AND INCREASED VERTICAL WIND SHEAR. THE SYSTEM HAS 
CONTINUED TO BENEFIT FROM DUAL OUTFLOW CHANNELS ALOFT - ONE AHEAD OF 
A TROUGH ADVANCING FROM THE WEST, AND ANOTHER INTO AN UPPER LEVEL 
LOW TO THE EAST - IN ADDITION TO LOW VERTICAL WIND SHEAR (VWS) AND 
FAVORABLE SEA SURFACE TEMPERATURES. THE INITIAL INTENSITY IS BASED 
ON DVORAK SATELLITE INTENSITY ESTIMATES FROM PGTW, NFFN, ABRF AND 
PHFO, RANGING FROM 45 TO 55 KNOTS, AND THE INITIAL POSITION IS BASED 
ON A 120458Z SSMI 37H MICROWAVE IMAGE. THE UPPER LEVEL ENVIRONMENT 
IS FORECAST TO DEGRADE AS THE TROUGH, AND A STRONG JET MAX, ADVANCE 
CLOSER TO THE TC FROM THE WEST, AND THE UPPER LEVEL LOW MOVES CLOSER 
FROM THE EAST, LIMITING CONVECTION WITHIN THE EASTERN SEMICIRCLE. 
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 120600Z IS 11 FEET. NEXT WARNINGS 
AT 122100Z AND 130900Z. REFER TO TROPICAL CYCLONE 18P (HAMISH) 
WARNINGS (WTPS31 PGTW) FOR TWELVE-HOURLY UPDATES.
=========================================================================
WTPS32 PGTW 20090312 21:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 20P (JONI) WARNING NR 004//
RMKS/
1. TROPICAL CYCLONE 20P (JONI) WARNING NR 004
   02 ACTIVE TROPICAL CYCLONES IN SOUTHPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   121800Z --- NEAR 24.9S 159.3W
     MOVEMENT PAST SIX HOURS - 190 DEGREES AT 11 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 010 NM NORTHEAST QUADRANT
                            010 NM SOUTHEAST QUADRANT
                            010 NM SOUTHWEST QUADRANT
                            010 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT
                            085 NM SOUTHEAST QUADRANT
                            085 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   REPEAT POSIT: 24.9S 159.3W
    ---
   FORECASTS:
   12 HRS, VALID AT:
   130600Z --- 27.4S 159.7W
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT
                            080 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 185 DEG/ 16 KTS
    ---
   24 HRS, VALID AT:
   131800Z --- 30.6S 159.9W
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            065 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 160 DEG/ 21 KTS
    ---
   36 HRS, VALID AT:
   140600Z --- 34.5S 158.3W
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
122100Z POSITION NEAR 25.5S 159.4W.
TROPICAL CYCLONE (TC) 20P (JONI), LOCATED APPROXIMATELY 220 NM SOUTH
OF RAROTONGA, COOK ISLANDS, HAS TRACKED SOUTHWARD AT 11 KNOTS OVER
THE PAST 06 HOURS. TRACK SPEED HAS INCREASED OVER THE PAST 12 HOURS
AND IS DUE TO AN INCREASE IN THE GRADIENT FLOW AT THE LOW TO MID-
LEVELS AS THE LARGE WAVE TROUGH TO THE SOUTHWEST TRACKS EASTWARD
INTO THE RIDGING EAST AND SOUTHEAST OF JONI. TC 20P WILL CONTINUE TO
TRACK SOUTHWARD THROUGH TAU 24 BUT WILL TURN TO THE SOUTHEAST AS
THE GRADIENT FLOW SHIFTS TO THE SOUTHEAST. UPPER LEVEL ANALYSIS
INDICATES THAT JONI HAS BENEFITTED OVER THE PAST 24 HOURS FROM DUAL
OUTFLOW CHANNELS ASSOCIATED WITH THE TROUGH TO THE SOUTHWEST AND AN
UPPER LEVEL LOW TO THE EAST. HOWEVER, THE UPPER LEVEL LOW IS QUICKLY
TRACKING WESTWARD TOWARD JONI AND WILL BEGIN TO HINDER OUTFLOW IN
THE NEXT 12 TO 24 HOURS. ADDITIONALLY, THE TROUGH WILL CONTINUE TO
TRACK EASTWARD OVER TC 20P LEADING TO INCREASED VERTICAL WIND SHEAR
AND DECREASING POLEWARD OUTFLOW. CURRENTLY JONI IS IN FAVORABLE SEA
SURFACE TEMPERATURES BUT WITHIN THE NEXT 12 TO 24 HOURS WILL TRACK
INTO MUCH COOLER, LESS FAVORABLE WATERS FURTHER HINDERING
DEVELOPMENT AND ULTIMATELY LEADING TO SYSTEM DISSIPATION. THE
AVAILABLE MODEL GUIDANCE IS IN VERY GOOD AGREEMENT WITH THE OFFICIAL
FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 121800Z IS 14 FEET.
NEXT WARNINGS AT 130900Z AND 132100Z.//
=========================================================================
WTPS32 PGTW 20090313 09:00z
1. TROPICAL CYCLONE 20P (JONI) WARNING NR 005
   01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   130600Z --- NEAR 27.7S 159.2W
     MOVEMENT PAST SIX HOURS - 175 DEGREES AT 16 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT
                            045 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT
                            110 NM SOUTHEAST QUADRANT
                            080 NM SOUTHWEST QUADRANT
                            055 NM NORTHWEST QUADRANT
   REPEAT POSIT: 27.7S 159.2W
    ---
   FORECASTS:
   12 HRS, VALID AT:
   131800Z --- 30.7S 158.8W
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT
                            080 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 165 DEG/ 19 KTS
    ---
   24 HRS, VALID AT:
   140600Z --- 34.4S 157.5W
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
130900Z POSITION NEAR 28.5S 159.1W.
TROPICAL CYCLONE (TC) 20P (JONI), LOCATED APPROXIMATELY 390 NM SOUTH
OF RAROTONGA, COOK ISLANDS, HAS TRACKED SOUTHWARD AT 16 KNOTS OVER
THE PAST 06 HOURS. JONI HAS MAINTAINED AN INITIAL INTENSITY OF 55
KNOTS DESPITE GRADUALLY DEGRADING UPPER LEVEL CONDITIONS AND
DECREASED SEA SURFACE TEMPERATURES. DVORAK SATELLITE INTENSITY
ESTIMATES ARE AT 3.5 OR 55 KNOTS FROM PGTW AND KNES. THE INITIAL
POSITION IS BASED ON A SERIES OF MICROWAVE IMAGES, INCLUDING A
130458Z CORIOLIS AND 130624Z SSMI, WHICH BOTH SUGGEST THAT THE LLCC
IS TUCKED IN UNDER THE WESTERN EDGE OF THE REMAINING DEEP
CONVECTION. EQUATORWARD OUTFLOW HAS WEAKENED OVER THE PAST 12 HOURS
AS THE UPPER LEVEL LOW TO THE EAST MOVED CLOSER TO THE SYSTEM. THIS
LOW IS EXPECTED TO CUT OFF EQUATORWARD OUTFLOW ALL TOGETHER WITHIN
THE NEXT 12 HOURS AS IT MOVES EVEN CLOSER. FROM THE WEST A LONGWAVE
TROUGH WILL BRING HEIGHTENED VERTICAL WIND SHEAR AND DRIER AIR, AND
THE MID-LEVEL REFLECTION WILL ACCELERATE THE TC POLEWARD. SEA SURFACE
TEMPERATURES WILL CONTINUE TO DROP BELOW SUSTAINABLE LEVELS. ALL OF
THESE FACTORS WILL RAPIDLY WEAKEN THE TC OVER THE NEXT DAY. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 130600Z IS 12 FEET. NEXT WARNINGS AT
132100Z.
=========================================================================
WTPS32 PGTW 20090313 21:00z
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 20P (JONI) WARNING NR 006//
RMKS/
1. TROPICAL CYCLONE 20P (JONI) WARNING NR 006
   01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   131800Z --- NEAR 31.4S 159.0W
     MOVEMENT PAST SIX HOURS - 175 DEGREES AT 19 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: 31.4S 159.0W
    ---
   FORECASTS:
   12 HRS, VALID AT:
   140600Z --- 35.5S 157.3W
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
   VECTOR TO 24 HR POSIT: 135 DEG/ 23 KTS
    ---
   24 HRS, VALID AT:
   141800Z --- 38.7S 153.1W
   MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
132100Z POSITION NEAR 32.4S 158.6W.
TROPICAL CYCLONE (TC) 20P (JONI), LOCATED APPROXIMATELY 336 NM SOUTH
OF RAROTONGA, HAS TRACKED RAPIDLY SOUTHWARD AT 19 KNOTS OVER THE PAST
SIX HOURS. ANIMATED WATER VAPOR IMAGERY SHOWS OUTFLOW OVER THE SYSTEM
HAS SIGNIFICANTLY DIMINISHED AS THE UPPER LEVEL CYCLONE TO THE EAST,
PREVIOUSLY AIDING WITH DIFFLUENCE, HAS CLOSED IN AND  PINCHED THE
OUTFLOW CHANNEL. CONVECTION AROUND THE LOW LEVEL CIRCULATION CENTER
IS GREATLY REDUCED AND HAS BECOME ASYMMETRICAL. UPPER LEVEL ANALYSIS
INDICATES TC 20P IS FAST APPROACHING THE BAROCLINIC ZONE AND VERTICAL
WIND SHEAR HAS INCREASED TO 30-40 KNOTS. THE SYSTEM IS EXPECTED TO
QUICKLY DISSIPATE OVER THE NEXT 24 HOURS. THIS IS THE FINAL WARNING
ON THIS SYSTEM BY THE JOINT TYPHOON
WARNING CENTER (NAVMARFCSTCEN).  THE SYSTEM WILL BE CLOSELY MONITORED
FOR SIGNS OF REGENERATION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 131800Z
IS 12 FEET.//

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


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Document: tropical_cyclone_joni_jtwc_advisories.htm Updated: 2 May 2017