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Monthly Global Tropical Cyclone Summary January 2007
[Summaries and Track Data] [Prepared by Gary Padgett]


                               JANUARY, 2007

  (For general comments about the nature of these summaries, as well as
  information on how to download the tabular cyclone track files, see
  the Author's Note at the end of this summary.)

  SPECIAL NOTE:  Very happily, John Diebolt of Tucson, Arizona, now has his
  tropical cyclone website up and running again and has begun once more to
  produce graphic images depicting the tracks of all tropical systems for
  which I prepare a tabular track in the companion cyclone tracks file.
  These can be accessed at the following URL:>

  Scroll down the chart to the month of interest and click on the green
  bar under "Operational Track Image" for the desired system.

  The tabular track of positions and intensities may also be obtained
  from the above website, or from the other archival sites listed in
  the Author's Note in the closing section of this summary.


                            JANUARY HIGHLIGHTS

   --> Southwest Indian Ocean activity picks up late in month
   --> Two short-lived tropical cyclones form in South Pacific Ocean



     Beginning in May, 2000, I began including with each monthly summary
  an extra feature which I called the Feature of the Month.   Beginning
  with July, 2005, I suspended these as a regular monthly item, but have
  since included some extra features as time permits.  Following is an
  index to the Extra Features for 2006.


                     AND THE SAFFIR/SIMPSON SCALE


  APR - none

  MAY - none


  JUL - ADDENDUM TO JUNE SUMMARY - East Coast LOW of 27 June

  AUG - ADDENDUM TO JULY SUMMARY - System South of Nova Scotia on 17 July

                   2006 - 2007 SEASON

  NOV - none


                            ACTIVITY BY BASINS

  ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico

  Activity for January:  No tropical cyclones


  NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180

  Activity for January:  No tropical cyclones


  NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180

  Activity for January:  1 tropical depression **

  ** - classified as a tropical depression by JMA only

               Northwest Pacific Tropical Activity for January

     No tropical storms or typhoons formed in the Northwest Pacific basin
  during the first month of 2007.  However, there was an interesting
  system followed during the first week of the month in the South China
  Sea north of Borneo and far to the southeast of southern Vietnam.
  According to C. P. Chang, Naval Post-graduate School, Monterrey, the
  well-defined vortex was induced by horizontal shear and terrain effects.
  These are typically weak with only moderate vorticity.  There was enough
  convection associated with the vortex that at 0000 UTC on 5 January, JMA
  classified the system as a weak tropical depression near 5.0N/111.0E.
  By 1800 UTC the system had moved westward to near 6.0N/108.0E.  Six
  hours later JMA reduced the system to a low-pressure area, still moving
  slowly westward.  The final reference to the LOW was at 07/1200 UTC
  when it was placed near 4.0N/105.0E.  No wind estimates were given, but
  peak winds likely did not exceed 20 kts.  This system was not referenced
  in any STWOs issued by JTWC.  


  NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea

  Activity for January:  No tropical cyclones


  SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E

  Activity for January:  1 tropical disturbance
                         1 severe tropical storm **
                         1 intense tropical cyclone ++

  ** - system formed late in December and continued on into January

  ++ - system formed late in January and continued on into February

                          Sources of Information

     The primary sources of tracking and intensity information for
  Southwest Indian Ocean tropical cyclones are the warnings issued by
  the Tropical Cyclone Warning Centre on La Reunion Island, part of
  Meteo France (MFR), and the Regional Specialised Meteorological Centre
  for the basin.    However, tropical cyclones in this region are named 
  by the Sub-regional Tropical Cyclone Advisory Centres in Mauritius and 
  Madagascar with longitude 55E being the demarcation line between their 
  respective areas of naming responsibility.  The La Reunion centre only 
  advises these agencies regarding the intensity of tropical systems.  
  References to sustained winds imply a 10-minute averaging period unless
  otherwise stated.

     In the companion tropical cyclone tracks file, I occasionally
  annotate positions from warnings issued by the Joint Typhoon Warning
  Center (JTWC) of the U. S. Air Force and Navy, located at Pearl
  Harbor, Hawaii, when they differ from MFR's coordinates by usually
  40-50 nm or more.  The JTWC warnings are also the source of the
  1-minute average maximum sustained wind values included in the
  tracks file.    Additionally, information describing details of
  satellite imagery and atmospheric circulation features included in
  the narratives is often gleaned from the JTWC warnings.

           Southwest Indian Ocean Tropical Activity for January

     As the month opened Tropical Storm Clovis was gathering strength
  as it passed just east of Ile Tromelin on its way to a rendezvous with
  the eastern coast of Madagascar on 4 January.  The report on Severe
  Tropical Storm Clovis may be found in the December, 2006, summary.

     Bulletins were issued for two numbered disturbances in the Southwest
  Indian Ocean during January.  Early in the month (6 January) a LLCC with
  some associated deep convection formed in the central Mozambique Channel
  off the west coast of Madagascar a few hundred miles west of the city of
  Antananarivo.  Outflow was favorable but shear was high due to an upper-
  level trough to the southwest impinging on the disturbance.  The LOW
  drifted erratically southward through the Channel without significant
  development.   At 08/0600 UTC MFR issued the first of only two warnings
  for Tropical Disturbance 06 with 10-min avg winds estimated at 25 kts,
  locally reaching 30 kts in the eastern part of the system.  The final
  bulletin at 08/1200 UTC noted that intensification was not expected
  due to an unfavorable environment and that the system was forecast to
  make landfall as a weak disturbance between Toliara and Itempolo in
  southwestern Madagascar within the next 12 to 24 hours.  Dvorak estimates
  from JTWC peaked at only T1.5/1.5, but SAB did return a T2.0/2.0 rating
  at 07/2030 UTC, suggesting that 1-min avg winds could have been 30 kts,
  in agreement with MFR's classifications of T2.0/2.0.  A track for this
  system was included in the companion cyclone tracks file and a graphic
  is available on John Diebolt's website.

     Late in the month another tropical cyclone began to take shape over
  the west-central South Indian Ocean west of Diego Garcia and developed
  into the rather intense Tropical Cyclone Dora.  A report on Dora follows.

                        INTENSE TROPICAL CYCLONE DORA
                              (MFR-07 / TC-10S)
                          28 January - 12 February

  A. Introduction and Storm Origins

     Forming at the end of January and operating until nearly the middle
  of February, the long-lived Dora was the herald of a rather significant
  outbreak of tropical cyclones across the Southwest Indian Ocean.  Four
  named storms were to follow during February with three reaching tropical
  cyclone (i.e., hurricane) intensity and two of those becoming intense
  tropical cyclones (10-min avg winds of 90 kts or higher).  Dora followed
  a rather zigzagging south-southwesterly track from deep in the tropics
  to the west of Diego Garcia to extratropical transition far to the south
  of the Mascarenes.  Winds peaked at 100 kts on 4 February while the storm
  was centered more than 200 nm northeast of tiny Rodrigues Island, but
  had weakened to about 50 kts by the time Dora made its closest approach
  to the island, lying 90 nm to the east at 0000 UTC on 6 February.

     A graphic displaying the track of Intense Tropical Cyclone Dora may
  be found at the following link:>

  Scroll down to the chart for January, 2007, and click on the green bar
  under "Operational Track Image" on the line for Dora (10S). 

     In the daily STWO for the Southwest Indian basin on 26 January, JTWC
  noted that an area of convection had persisted approximately 235 nm west
  of Diego Garcia.  Weak convective banding was present on the northeastern
  and southwestern peripheries of the LLCC.  The disturbance was located
  in a region of low vertical shear and favorable diffluence aloft, so the
  potential for development was upped to 'fair' on the 27th.   At 0600 UTC
  on the 28th MFR issued their first bulletin for Tropical Disturbance 07,
  located about 350 nm west of Diego Garcia.  Deep convection was flaring
  over a well-defined LLCC and bands of convection were wrapping into the
  southern semicircle of the disturbance; hence, JTWC upped the development
  potential to 'good'.   By 28/1800 UTC Tropical Disturbance 07 was located
  about 340 nm west-southwest of Diego Garcia and tracking slightly east of
  due south at 6 kts.  MFR estimated the winds at 25 kts, locally reaching
  30 kts, but JTWC issued their first warning on TC-10S, estimating the
  1-min avg MSW at 40 kts.

     Equatorward outflow was excellent, and by early on the 29th a poleward
  outflow channel was developing and the system began to show signs of
  further intensification.    MFR upgraded the disturbance to a 30-kt
  tropical depression at 29/0600 UTC, and six hours later Mauritius
  christened the developing system Tropical Storm Dora--a name contributed
  to the regional list by Mozambique.   Dora was then located about 500 nm
  southwest of Diego Garcia, and moving steadily to the south-southwest
  along the southwestern periphery of a near-equatorial ridge to the

  B. Synoptic History

     After earning a name, Dora intensified rather quickly to a severe
  tropical storm, reaching 50 kts by 0000 UTC on 30 January, but then the
  system intensified more slowly, not reaching tropical cyclone intensity
  until 0600 UTC on 1 February.  (JTWC had upgraded Dora to hurricane
  intensity at 1800 UTC on 30 January.)   The storm was then located
  approximately 375 nm northeast of Rodrigues Island and moving southeast-
  ward at 5 kts.  Dora was caught in a weak steering environment between
  a mid-level ridge to the northeast and another ridge to the south.  After
  reaching tropical cyclone status, Dora's intensity increased only slowly,
  possibly due to stable air introduced by a trough passing to the south.
  Dora's track turned to the south-southwest on 2 February due to the
  influence of a competing subtropical steering ridge anchored over
  Madagascar and extending eastward to the south of the storm.  Around
  this time Dora underwent an eyewall replacement cycle, resulting in a
  large eye and an "annular" appearance.

     Outflow was good and Dora continued to slowly strengthen, reaching a
  peak intensity of 100 kts (10-min avg) with an estimated CP of 930 hPa
  at 03/1200 UTC while centered about 250 nm east-northeast of Rodrigues
  Island.  (JTWC's peak 1-min avg MSW of 115 kts is in good agreement with
  MFR's.)  The storm's motion became westerly at a slow crawl on the 3rd
  as the battle between the near-equatorial ridge and the subtropical ridge
  continued.    After peaking in intensity Dora began to weaken rather
  quickly as a building anticyclone to the southeast began to inject cooler
  and drier air into the cyclone's center.  At 03/1800 UTC the estimated
  MSW was 100 kts--twenty-four hours later Dora was a minimal 65-kt
  tropical cyclone and was downgraded to a 60-kt severe tropical storm at
  05/0000 UTC.

     However, after this point the intensity leveled off and Dora's MSW
  hovered around 50-55 kts for another day and a half.  The very slow
  westerly motion continued and the tropical storm reached its closest
  point of approach to Rodrigues Island around 0000 UTC on 6 February when
  the center lay about 90 nm to the east of the island.  The MSW at this
  time was estimated at 50 kts.   Following its CPA to Rodrigues, Dora's
  track became generally southwesterly for the remainder of its life,
  although still with a few wobbles.   The primary steering mechanism
  became a subtropical ridge situated to the southeast of the tropical
  storm.  As Dora tracked into higher latitudes it encountered increasing
  vertical shear and drier air and had weakened to a 40-kt tropical storm
  by 06/1800 UTC.   JTWC continued to weaken the system, but MFR bumped
  the winds back to 45 kts at 08/0600 UTC.  The storm by this time was
  beginning extratropical transition and the slight intensification was
  likely due to baroclinic influences.

     JTWC issued their final warning on Dora at 09/0600 UTC, noting that
  a well-defined LLCC remained but the system had lost all its deep
  convection.  At the same time MFR classified Dora as an extratropical
  gale with the strongest winds (locally up to 50 kts) occurring far to
  the south of the center due to a gradient with the subtropical HIGH.
  Dora at this time was located approximately 400 nm south-southwest of
  Rodrigues Island and moving southwestward at 5 kts.   RSMC La Reunion
  continued to issue warnings on the extratropical system for another
  three days as it accelerated southwestward, gradually curving to the
  south.  The final reference by MFR was at 1800 UTC on 12 February when
  the weakening gale was located over 1000 nm to the southwest of Reunion

  C. Damage and Casualties

     No reports of damage or casualties are known to have resulted from
  Intense Tropical Cyclone Dora.

  (Report written by Gary Padgett)



  Activity for January:  1 tropical cyclone of gale intensity
                         1 monsoon LOW ("landphoon")

                          Sources of Information

     The primary sources of tracking and intensity information for
  Northwest Australia/Southeast Indian Ocean tropical cyclones are 
  the warnings and advices issued by the Tropical Cyclone Warning
  Centres at Perth, Western Australia, and Darwin, Northern Territory. 
  References to sustained winds imply a 10-minute averaging period
  unless otherwise stated.

     In the companion tropical cyclone tracks file, I occasionally
  annotate positions from warnings issued by the Joint Typhoon Warning
  Center (JTWC) of the U. S. Air Force and Navy, located at Pearl
  Harbor, Hawaii, when they differ from the Australian centres' coor-
  dinates by usually 40-50 nm or more.  The JTWC warnings are also the
  source of the 1-minute average maximum sustained wind values included
  in the tracks file.   Additionally, information describing details of
  satellite imagery and atmospheric circulation features included in
  the narratives is often gleaned from the JTWC warnings.

                Northwest Australia/Southeast Indian Ocean
                      Tropical Activity for January

     A tropical LOW formed south of Indonesia at the end of December and
  remained quasi-stationary for a couple of days.  Some gales on the
  northern periphery were noted on 1 January, and by the next day had
  increased in coverage to the point that the system was named Tropical
  Cyclone Isobel.  Isobel tracked generally southward and inland near Port
  Hedland on the 3rd.   During a post-storm review it was determined that
  Isobel had not met all the criteria for an official tropical cyclone
  as practiced by the Australian TCWCs.   By the definition used by the
  BoM warning centers, a system has to have gales wrapped around more than
  50% of the center for at least 6 hours to qualify as a tropical cyclone.
  This information came from Andrew Burton of BoM Perth, and he notes that
  such hair-splitting is not normally employed in operations, but comes
  into play during preparation of "best tracks" and official post-storm
  summaries.  (Thanks to Andrew for the enlightenment on this issue.)

     A report follows on "Tropical Cyclone" Isobel, and another on a very
  interesting and significant over land monsoon LOW which wandered about
  central Australia for well over a week, bringing heavy rains and gale-
  force winds to some areas.  Both reports were authored by Simon Clarke.

                         TROPICAL CYCLONE ISOBEL
                         31 December � 3 January

  A. Storm Origins

     The fleeting life of Isobel can be traced back to a concentrated 
  cluster of thunderstorm activity located approximately 180 nm S of 
  Bali, Indonesia, and 550 nm NNW of Port Hedland, Western Australia, 
  as early as 29 December 2006.  This thunderstorm activity struggled to 
  consolidate, being affected by strong upper-level westerly winds. 
  However, by 1 January 2007, it was clear to BoM Perth that there was 
  the potential for the tropical LOW to consolidate and develop further,
  with a track forecast to take the system southward toward the Pilbara
  coast of Western Australia. 

  B. Synoptic History
     As the system commenced its rapid path to the SSE, the Perth TCWC 
  noted within its advisories and warnings that the system consisted of 
  multiple low-level circulations and was therefore basing its advices 
  on the projected location of the consolidating centre of organising 
  thunderstorm activity.  The system was named Isobel at 02/0600 UTC when 
  located near 15.0S/119.3E (approximately 310 nm N of Port Hedland) as
  convection consolidated close to the most dominant LLCC.  Development 
  of the overall system was further enhanced by a strong poleward outflow 
  channel.  The system accelerated on a S to SSE path, reaching 13 kts 
  just prior to landfall as a result of a strengthening southerly 
  steering current on the northwestern periphery of a high-amplitude 
  trough situated off the western coast of Australia.

     The system may have achieved its peak intensity of 982 hPa and 45 kts 
  (10 min-avg) at 02/1200 UTC while located approximately 250 nm N of 
  Port Hedland.  However, this figure may be re-examined in further 
  post-analysis scrutiny.    

     Isobel eventually crossed the coast to the north of Pardoo 
  (approximately 20.0S/119.3E) at 12 noon WST (03/0400 UTC), and at   
  this time possessed little more than a weak, ill-defined centre with 
  the central pressure estimated to be 990 hPa.  For that reason the 
  strong squally winds and heavy rains normally associated with a 
  typical tropical cyclone were not reported close to the centre.  The 
  highest winds associated with Isobel were actually reported at Barrow 
  Island: some 230 nm to the west of the landfall location.  Isobel was 
  downgraded 3 hours after landfall as the overall system became 
  embedded and absorbed into the developing deep trough that was forming
  over the southwestern part of Western Australia at the time.  

  C. Storm Effects

     Isobel was responsible for shutting down offshore oil production for 
  a period prior to landfall.  However, the disruption was short-lived. 
  Localised and highly variable rain totals were recorded, including a 
  6-hour total of 141 mm at Mandora, just to the east of the landfall 
  location (up to 3:00 pm on the 3rd).  However, aside from this there 
  were no significant direct impacts associated with the system. 

     Isobel will probably be better remembered for injecting a significant 
  slug of tropical moisture to fuel the developing deep trough /low- 
  pressure system over the eastern Goldfields of Western Australia. 
  Eventually this new mid-latitude LOW pressure system (988 hPA) went 
  on to produce severe gales and significant rainfalls in what was 
  described in the local media as "once-in-a-generation" storm over 
  parts of southern Western Australia. 

     The damage bill from the collision of the moisture slug from �ex-
  Isobel� and the deep trough is estimated to be in the tens of 
  millions (AUD), primarily concentrated in the Esperance to 
  Ravensthorpe area.  More than 100 homes were damaged, several boats 
  were destroyed, trees were felled and 35 metres of bridge on the 
  South Coast Highway, the main road linking Esperance to Perth, was 
  washed away.  A Department of Agriculture and Food spokesman said an 
  estimated 20,000 head of sheep and cattle had died from exposure and 
  drowning in the wild weather.  Mining activities in the south were 
  also severely disrupted.  A region around the West Australian coastal 
  town of Esperance was declared a Natural Disaster Area.

     Some long standing one-day rainfall records fell and a comprehensive 
  summary of the event can be found at the following link:>

     The low-pressure system eventually tracked to the SE, passing over 
  Tasmania on 6�7 January, producing strong winds and useful rain. 
  There were no reports of human injuries or deaths associated with the 
  combined system.

  D. Additional Discussion

     Post-analysis of the tropical system that was named Isobel reveals
  that it really never was a tropical cyclone at all.   The system 
  consisted of a series of multi-centred low-pressure circulations that 
  never had the opportunity to consolidate into a central dominant 
  cyclonic core prior to landfall.  Therefore, it seems that Isobel's
  demotion was predicated upon a structural issue and not a wind speed 
  issue.  (See basin introductory paragraph above for some late-received
  information clarifying this matter.)

     It should be noted that Dvorak classifications from SAB and AFWA
  reached T3.0/3.0 on 2 January, and JTWC's rating at 02/1730 UTC 
  reached as high as T3.5/3.5.  JTWC's peak 1-min avg MSW for Isobel was 
  40 kts, but no warning was issued at the synoptic hour nearest their 
  peak Dvorak numbers, i.e., 02/1800 UTC.

  (Report written by Simon Clarke; last paragraph added by Gary Padgett)

                               MONSOON LOW
                             12 - 22 January

     A persistent monsoon LOW developed from a surge in the monsoon that 
  had become established over the Kimberley/Top End region of Australia by
  12 January.  On 13 January a weak tropical LOW developed overland in the
  Kimberley region of Western Australia and tracked slowly to the
  southwest.  Tropical cyclone advisories were issued as the LOW approached
  the western Kimberley Coastline.  However, by 14 January the LOW switched
  to an east-southeasterly path, taking the system inland into central 
  Australia while it continued to deepen over land.   The monsoon LOW 
  proved to be particularly resilient as it tracked into the Northern 
  Territory late on 16 January, subsequently moving through the central/
  southern half of the Northern Territory to the north of Alice Springs 
  (17 � 20 January) before eventually entering far western Queensland near
  Bedourie, and thence turning onto a north-northeasterly track toward the
  inland region to the south of Mount Isa (20 � 21 January).  The LOW 
  thereafter curved back to the west and quickly dispersed upon 
  re-entering the Northern Territory.   The entire lifespan of the system
  was in excess of ten days.

     The Australian continent experiences such persistent summer monsoonal
  low-pressure systems from time to time and the term �landphoon� has been
  unofficially coined for these weather systems.  The LOW, for all intents
  and purposes, appeared to have the cloud structure of a tropical cyclone
  in satellite imagery and produced areas of strong to gale force winds.  
  However, it did not develop a tight inner core or eye wall.  The movement
  of the LOW could be tracked in radar imagery as it passed to the north of
  Alice Springs where it reached its minimum estimated CP of 995 hPa.

     On 19 January, Birdsville Airport AWS recorded 340/37-kt to 42-kt 
  gusts (QNH 1001.7 hPa) while the LOW was centered about 220 km away.  
  Even farther out from the centre, Ballera Gas Field AWS recorded 
  350/33 kts sustained, probably as a consequence of thunderstorm activity.
     The LOW drew in significant tropical moisture initially though the 
  Kimberley region and the adjacent areas of the northwestern Northern 
  Territory before it swept into the southern half of the Territory, much 
  of South Australia, western parts of Victoria and the far west of 
  Queensland.   During the period 18�21 January most of these areas 
  recorded monthly rainfall in the highest decile, although the BoM notes 
  that few records were set.

     Through South Australia and western Victoria the rains were enhanced 
  by the slow approach of a frontal system which generated a broad area of
  slow moving thunderstorms.  Localised flash flooding occurred at several 
  locations in the Pastoral Districts and northern Agricultural Districts 
  as a result.  Some notable rainfall totals in South Australia included 
  Hawker:  125.4 mm to 9 am on 20 January and 173 mm for the week ending
  9 am Monday 22 January.  Corny Point: 107 mm to 9 am on 20 January and 
  Parawa: 105.4 mm to 9 am also on 20 January.  Arcoona homestead, near 
  Woomera, recorded 143 mm in the 24 hours to 9 am on 20 January, with much
  of this falling in a 4-hour period from 11 am to 3 pm on 19 January. 
  Arcoona had accumulated a total of 190 mm for the week ending 9 am Monday
  22 January.    South Australia had its ninth-wettest January on record 
  (73% above normal). 

     The LOW eventually dumped much-needed rainfall into the Channel 
  Country, Warrego and Central West of Queensland, causing flooding in 
  many inland river systems.  In Queensland, Bedourie's January total of 
  296.4 mm is the highest monthly total recorded in its 61 years of record,
  (January average:  32.1 mm).  Cluny received a monthly total of 483 mm, 
  the highest in its 68 years of record (January average:  37.2 mm). 
  Bedourie, with 169.1 mm, and Cluny, with 229 mm, also reported their 
  highest daily rainfall totals on record.  A number of stations had more 
  rain during this event than they received in all of 2006.

  (Report written by Simon Clarke, with significant statistical information
  provided by BoM)



  Activity for January:  1 tropical LOW **

  ** - system eventually became a tropical cyclone in early February

                      Northeast Australia/Coral Sea
                      Tropical Activity for January

     Much of the southern Northern Territory and western Queensland were
  under the influence of a persistent and well-organized monsoon LOW for
  several days around mid-month.  The LOW, however, formed in the Kimberley
  region of Western Australia and a report on the system, written by Simon
  Clarke, may be found in the above section of this summary covering the
  Western Australian region.  At the end of the month a tropical LOW began
  to take shape just north of the eastern Top End.  During the first week
  of February this system was seen to wander aimlessly around over the
  Gulf of Carpentaria for several days.  By the 5th the LOW was headed
  eastward toward the southern Cape York Peninsula when it began to
  strengthen and was named Tropical Cyclone Nelson.  A report on Nelson
  will be included in the February summary.


  SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E

  Activity for January:  1 tropical depression
                         2 tropical cyclones of storm intensity

                          Sources of Information

     The primary sources of tracking and intensity information for
  South Pacific tropical cyclones are the warnings and advisories
  issued by the Tropical Cyclone Warning Centres at Nadi, Fiji (for
  waters north of latitude 25S), and Wellington, New Zealand (for
  waters south of latitude 25S).  References to sustained winds imply
  a 10-minute averaging period unless otherwise stated.

     In the companion tropical cyclone tracks file, I occasionally
  annotate positions from warnings issued by the Joint Typhoon Warning
  Center (JTWC) of the U. S. Air Force and Navy, located at Pearl
  Harbor, Hawaii, when they differ from the Southern Hemisphere
  centres' coordinates by usually 40-50 nm or more.  The JTWC warnings
  are also the source of the 1-minute average maximum sustained wind
  values included in the tracks file.    Additionally, information
  describing details of satellite imagery and atmospheric circulation
  features included in the narratives is often gleaned from the JTWC

                 South Pacific Tropical Activity for January

     RSMC Nadi, Fiji, issued warnings on three tropical systems during the
  month of January following a month-long quiet period in the tropical
  South Pacific.  Two of the three systems became named cyclones of near
  hurricane intensity.  The first, a non-developing system, is described
  here--reports follow on Tropical Cyclones Zita and Arthur, written by
  Simon Clarke.  Track graphics for all three disturbances may be found 
  on John Diebolt's website.

     Tropical Depression 06F formed on 9 January a couple hundred miles
  east of the Samoan Islands.  For a few days the depression remained
  quasi-stationary and meandered about aimlessly in the same region.  By
  the 14th a decided motion toward the south and east had become apparent
  with the center passing very near Palmerston Island on the 14th while
  moving eastward.  By the 15th the depression accelerated off to the
  southeast but became quasi-stationary again the next day near the Austral
  Islands, where it meandered around for another couple of days before
  weakening.  Deep convection was associated with TD-06F, but the system
  remained in a highly-sheared environment throughout its lifetime.  Gale
  warnings were issued by Nadi for a week-long period from the 10th through
  the 17th for a band of peripheral gales which accompanied the depression,
  mainly to the north and east of the center.   By 15 January northwesterly
  shear had increased to 35-40 kts and the convection had become removed
  far to the north and east of the center--at this juncture RSMC Nadi
  classified the system as an extratropical depression.   It seems highly
  likely that much of the apparent erratic motion of this depression was
  due to relocations of the diffuse LLCC.   Interestingly, both of the
  cyclones which followed during the latter week of January pursued similar
  tracks to TD-06F, forming in the vicinity of Samoa and moving initially
  eastward, then curving southward west of French Polynesia to the vicinity
  of the Austral Islands.

                          TROPICAL CYCLONE ZITA
                            (TD-07F / TC-08P)
                             17 � 26 January

  A. Storm Origins

     Tropical Cyclone Zita (TD-07F/TC-08P) was the third tropical cyclone 
  to form in the South Pacific for the 2005/06 season, developing after
  a nearly two month-long hiatus in tropical cyclone activity in that

     Zita was first identified as a slow-moving and poorly-organised 
  tropical depression (TD-07F) as early as 17 January near 12.0S/174.0W 
  (approximately 130 nm NW of Savai�i Island, Western Samoa).  TD-07F 
  was centrally located along an active ITCZ which had been established 
  across the central South Pacific for several days prior.  Two other 
  clearly identifiable depressions developed at about the same time as 
  pre-Zita, including TD-06F to the west which slid away rapidly to the 
  SSE as a highly sheared extratropical system, and TD-08F to the east 
  which later developed into Cyclone Arthur soon after Zita�s demise 
  (see separate report).

  B. Synoptic History

     Initially TD-07F was in a favourable environment for further 
  development with upper-level divergence persisting at 250 hPa with 
  minimal shear.  At 22/2100 UTC the depression was upgraded to cyclone 
  status near 14.4S/156.7 (approximately 275 nm WNW of Bora Bora, 
  Tahiti) and named Zita.  The cyclone moved to the SE at 14 kts on an 
  accelerating path through a weakness in the subtropical ridge opened 
  up by TD-06 to its SSE.  Zita initially gained strength at a rapid 
  pace with a CDO developing over the LLCC and cold convective bands 
  wrapping tightly around the centre.  Zita reached a peak intensity of 
  maximum 10 min-avg winds of 60 kts and a CP of 975 hPa at 23/1200 UTC 
  near 17.3S/153.8W, or about 250 nm WNW of Papeete, Tahiti, close to 
  Maupihaa Atoll.  However, the cyclone soon entered a region of cool 
  SSTs and high vertical wind shear and its convective top was soon 
  drawn to the SE away from the LLCC. 

     Zita passed close to the North Austral Group of islands while 
  weakening, eventually crossing 25S and entering the open southern 
  ocean and Wellington�s AOR.  Zita was downgraded at 25/0000 UTC near 
  29.0S/150.0W (approximately 780 nm S of Papeete) as it transformed 
  into an extratropical storm.  The remnant storm persisted for another 
  24 hours while moving rapidly to the SSW. 

     The peak 1-min avg MSW estimated by JTWC during Zita's lifetime was
  60 kts at 0600 UTC 23 January.

  C. Storm Effects

     There were no significant reports of damage associated with Zita 
  despite passing through a series of small island groups along its 
  path.  Some localised light damage was reported on Rurutu and 
  Rimatara including several trees uprooted and flooding along coastal 

  (Report written by Simon Clarke)

                         TROPICAL CYCLONE ARTHUR
                            (TD-08F / TC-09P)
                             21 � 28 January

  A. Introduction and Storm Origins

     Tropical Cyclone Arthur (TD-08F/TC-09P) was the fourth tropical 
  cyclone to form in the Southwest Pacific for the 2005/06 season, and 
  like its predecessor, Zita, was a short-lived storm that essentially 
  followed the same track that Zita had taken a few days earlier.

     The pre-Arthur disturbance was first identified as a tropical 
  depression (TD-08F) on 21 January near 11.9S/176.4W (approximately 
  235 nm WNW of Savai�i Island, Western Samoa), moving to the ESE at
  5 kts.  Initial development was hindered by diurnal variations and 
  strong upper-level wind shear which produced an elongated pattern of 
  convection.  The depression gradually accelerated to the ESE, passing 
  to the north of the main Samoan islands.  By 24/0000 UTC convection 
  had begun to organise around the LLCC with convective tops cooling 
  and upper-level outflow improving.  Gale-force winds initially 
  developed in the NE quadrant (between 30 to 90 nm from the centre) 
  and these slowly wrapped in toward the centre. 

  B. Synoptic History

     The depression was upgraded to cyclone status and named Arthur at 
  24/1200 UTC.  At this time Arthur was located near 14.7S/165.6W 
  (approximately 300 nm E of Pago Pago, American Samoa), moving to the 
  ESE at 21 kts under the influence of a westerly steering field. 
  Arthur intensified rapidly under a CVA region with strong divergence 
  and minimal shear.  Cold convective bands wrapped tightly into the 
  centre as outflow developed in all quadrants.  A banding eye formed 
  and was observed to contract in satellite imagery.

     Peak intensity was attained at 25/0000 UTC (maximum 10-min avg winds 
  of 60 kts and a CP of 975 hPa) near 15.7S/160.8W, or about 520 nm WNW 
  of Bora Bora, Tahiti.  The peak intensity was sustained for little 
  more than 6 hours as increasing upper-level northwesterly wind shear 
  began to displace the CDO away to the SE of the LLCC.  Before reaching
  Tahiti, the weakening cyclone veered away from its east-southeasterly 
  track and onto a southeasterly path and into Wellington's AOR.  The 
  combined effects of cooler SSTs and strong upper-level wind shear put 
  an end to Arthur as a tropical cyclone at 27/1200 UTC near 31.0S/145.0W 
  (approximately 820 nm SSE of Papeete, Tahiti).   The remnant storm 
  continued to accelerate toward the SE at 25 kts and was last referenced 
  in Wellington�s warnings near 40.0S/130.0W at 1800 UTC on 28 January.  

     The peak 1-min avg MSW estimated for Arthur by JTWC was 65 kts, in 
  good agreement with Nadi�s 10-min avg estimate of 60 kts.  All the 
  satellite agencies except for AFWA peaked at T4.0/4.0, while AFWA 
  reached T5.0/5.0 at 1730 UTC on the 24th.

  C. Storm Effects

     There were no significant reports of damage as a result of Arthur. 
  However, in tandem with Zita, the cyclone produced a prolonged period 
  of heavy rain in parts of French Polynesia, causing a number of 
  landslides and some associated damage to houses on the main island of 
  Tahiti and neighbouring Moorea.  Gusty winds and heavy sea swells 
  were reported as the cyclone passed through the Austral Islands and 
  into the open southern ocean. 

  (Report written by Simon Clarke)



     The purpose of this section is to list some websites where many and
  varied types of tropical cyclone information are archived.  Many readers
  will know about these already, but for the benefit of those who don't,
  I wanted to include them. 

  (1) Aircraft Reconnaissance Information

     Various types of messages from reconnaissance aircraft may be
  retrieved from the following FTP site:>

     Information regarding how to interpret the coded reconnaissance
  messages may be found at the following URL:>

  Links are also included to websites with further information about the
  U. S. Air Force 53rd Weather Reconnaissance Squadron and the NOAA Air-
  craft Operations Center.

  (2) Archived Advisories

     All the advisory products (public advisories, forecast/advisories,
  strike probabilities, discussions, various graphics) issued by TPC/NHC
  are archived on TPC's website.  For the current year (using 2004 as an
  example), the archived products can be found at:>

  Links to tropical products archives for earlier years are available at
  the following URL:>

  JTWC warnings for past storms are archived on the NRL Monterrey website:>

  On the NRL site, the link to past years can be found in the upper left 
  corner of the screen.

     I am not aware at the moment of any other TCWC which archives all
  its tropical cyclone warning/advisory products for public access, but
  if I learn of any, I will add them to this list.

  (3) Satellite Imagery

     Satellite images of tropical cyclones in various sensor bands are
  available on the NRL Monterrey and University of Wisconsin websites,
  courtesy of Jeff Hawkins and Chris Velden and their associates.  The
  links are:>>

  On the NRL site, the link to past years can be found in the upper left 
  corner of the screen.  For the CIMSS site, a link to data archives is 
  located in the lower left portion of the screen.

     Additional tropical satellite imagery, along with looping ability for
  composite microwave imagery for the Western Hemisphere north of the
  equator, can be found at:

  (1) For the Eastern North Pacific:>

  (2) For the Atlantic, Gulf of Mexico and Caribbean Sea:>

     I'm sure there are other sites with available imagery available, and
  as I learn of them, I will add the links to this list.


                               EXTRA FEATURE

     In order to shorten the amount of typing in preparing the narrative
  material, I have been in the habit of freely using abbreviations and
  acronyms.   I have tried to define most of these with the first usage
  in a given summary, but I may have missed one now and then.  Most of
  these are probably understood by a majority of readers but perhaps a
  few aren't clear to some.  To remedy this I developed a Glossary of
  Abbreviations and Acronyms which I first included in the August, 1998
  summary.  I don't normally include the Glossary in most months in
  order to help keep them from being too long.  If anyone would like to
  receive a copy of the Glossary, please e-mail me and I'll be happy
  to send them a copy.


  AUTHOR'S NOTE:  This summary should be considered a very preliminary 
  overview of the tropical cyclones that occur in each month. The cyclone
  tracks (provided separately) will generally be based upon operational
  warnings issued by the various tropical cyclone warning centers.  The
  information contained therein may differ somewhat from the tracking and
  intensity information obtained from a "best-track" file which is based
  on a detailed post-seasonal analysis of all available data. Information
  on where to find official "best-track" files from the various warning
  centers will be passed along from time to time.

    The track files are not being sent via e-mail.  They can be retrieved
  from the archive sites listed below.  (Note: I do have a limited e-mail
  distribution list for the track files.    If anyone wishes to receive
  these via e-mail, please send me a message.)

    Both the summaries and the track files are standard text files
  created in DOS editor.  Download to disk and use a viewer such as
  Notepad or DOS editor to view the files.

     The first summary in this series covered the month of October,
  1997.   Back issues can be obtained from the following websites
  (courtesy of Michael Bath, Michael V. Padua, Michael Pitt, Chris
  Landsea, and John Diebolt):>>>>>

     Another website where much information about tropical cyclones may
  be found is the website for the UK Meteorological Office.  Their site
  contains a lot of statistical information about tropical cyclones
  globally on a monthly basis.  The URL is:>


     JTWC now has available on its website the Annual Tropical Cyclone
  Report (ATCR) for 2005 (2004-2005 season for the Southern Hemisphere).
  ATCRs for earlier years are available also.

     The URL is:>

     Also, TPC/NHC has available on its webpage nice "technicolor"
  tracking charts for the 2006 Atlantic and Eastern North Pacific
  tropical cyclones; also, storm reports for all the 2006 Atlantic
  and Eastern North Pacific cyclones are now available, as well as
  track charts and reports on storms from earlier years. 

     The URL is:>

     A special thanks to Michael Bath of McLeans Ridges, New South Wales,
  Australia, for assisting me with proofreading the summaries.


  Gary Padgett
  E-mail:  [email protected]
  Phone:  334-222-5327

  Kevin Boyle  (Northwest Pacific)
  E-mail:  [email protected]

  Simon Clarke  (Northeast Australia/Coral Sea, South Pacific)
  E-mail:  [email protected]


Document: summ0701.htm
Updated: 14th March 2007

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