Category Archives: Tropical Cyclones

A large circulation sproducing heavy rainfall, very strong winds and storm surges

Tropical Storm Uhriah February 14 to 17 2016

Published by:

TCUriah

Uhriah16Feb

NASAUhriah

In a remote area of the Indian Ocean, a tropical storm continues to intensify then weaken only to redevelop making forecasting very challenging.

The named storm is forecast to develop into a weak tropical cyclone over coming days. However only two days ago on February 14, a forecast was made for the storm to develop into a strong Category 3 storm on the Saffir Simpson Scale. That forecast is downgraded significantly and there is even the chance it may not properly transition into a tropical cyclone at all.

The named storm “Uhriah” developed relatively close but south west of Java (Indonesia) and travelled south west but is expected take a more southerly direction over coming days.

The storm has formed over waters of 29C which would support a tropical cyclone however it appears the storm has been significantly affected by sheer which at one stage, almost tore the storm apart. The storm has managed to redevelop after losing much of its structure. It sustains a small but intense core and an eye has been visible in satellite photos.

At the time of writing the storm is situated at latitude 17.9 degrees south and 84.7 degrees east placing it deep within the Indian Ocean with no imminent threat of landfall. It is possible that the storm will not make landfall during its lifespan.

It sustains winds of 55 knots or approximately 102 km/h near the core. It borders on the transition to a tropical cyclone and if it does so, then its maximum strength is expected to be a Category 1 storm throughout its life span with peak winds to 80 knots or 148 km/h.

What makes this storm interesting that despite the sheer that nearly pulls the storm apart, it has maintained some degree of structure over the past 3 or 4 days. Eventually the storm will weaken as it encounters colder waters further south.

CREDITS

1- CIMSS (Forecast plots for Tropical Storm Uhriah) dated 16/2/2016.
2 - NASA (MODIS Worldview satellite image of Uhriah) acquired 16/2/2016.

Tropical Storm Tatiana and Tropical Cyclone Winston 12/2/2016

Published by:

Tatiana1

InfraredTatiana

Winston1

InfraredWinston

WorldviewofWinston

Over the past 24 hours two tropical storms have developed well off the Queensland coast with one of these developing into a Tropical Cyclone and the other one expected to transition into a tropical cyclone shortly.

Both storms have been given names as:-

1 - Tatiana (The westernmost storm closest to the Queensland coastline).
2 - Winston (The easternmost storm south east of Vanuatu.

Both named storms are expected to remain over open ocean for the duration of their life spans.

It is unusual to have two named storms so close to one another as seen on the CIMSS forecast models. Tropical Storm Tatiana is the first storm to form in Australian waters off the Queensland coast for the summer season 2015 / 2016.

Tropical storm / Tropical Cyclone Tatiana

The storm is situated approximately 750 km off the Central Queensland coast at latitude 20.28 degrees south and 158.79 degrees east. The forecast model by CIMSS suggests the storm remaining off the coast and not making landfall. While this is presently a tropical storm, it may transition into a weak Category 1 tropical cyclone. Winds close to the core are estimated at 55 knots (Approximately 102 km/h). Winds may increase to 65 knots or 120 km/h over coming hours. Should the storm transition into a tropical cyclone, then its lifespan as a tropical cyclone may be short lived. The storm does not have a developed eye but it is clear that it has an intense core.

Tropical Cyclone Winston

This is the stronger of the two storms and it is currently positioned south east of Vanuatu. The storm features strong convection and a developed eye. The storm may impact some of the outlying islands of Vanuatu such as Erromango and Lenakel but should remain mostly out to sea.

This is a category 1 storm on the Saffir Simpson Scale and may intensify to a Category 2 storm over coming hours. The storm presently sustains wind speeds of 65 knots or 120 km/h near the core. The storm transitioned into a tropical cyclone at latitude 18 degrees south and 171.6 degrees east.

As seen in the NASA Worldview image, the storm is circular in shape but cumulonimbus clouds are visible as a spiral surrounding the northern and eastern quadrant of the storm. The core is ringed by deep convection and cumulonimbus clouds.

The storm formed over waters of 30C to 31C but likely to weaken as it heads further south towards cooler waters.

CREDITS

1 - CIMSS (Forecast plots and infra red images) acquired 12 February 2016.
2 - NASA (MODIS Worldview of TC Winston ) acquired 12 February 2016.

Tropical Cyclone Stan NW Western Australia 29 to 31 January 2016

Published by:

CloudStan

TCStan

TCStanat landfall

During the period 29 to 31 January, a small Category 1 Tropical Cyclone formed off the coast of the Pilbara region of North West Western Australia. This was a short lived storm because it developed so close to the coastline and its ability to intensify would have been limited.

The storm formed over waters of 29C before moving south east.

This was the first tropical cyclone to form and cross the Australian coastline during the summer of 2015 / 2016. The storm transitioned into a tropical cyclone at latitude 18.7 degrees south and 118.8 degrees east and tracked south east crossing the coast east of Port Headland.

The storm had little impact on Port Headland and only brought 11.2 mm of rain at the local weather station.

While warnings were issued for flooding and gales from the storm, a significant disaster was avoided. The Pilbara is sparsely settled with few towns. If anything, the storm brought beneficial rains including 97 mm at Nullagine, 82 mm at Bonney Downs and 74 mm to Tarina to 9 am 1 February 2016.

The CIMSS weather model suggested a Category 1 Tropical Cyclone to cross the coast with peak wind speed to 65 knots or 120 km/h with possible higher speeds to 70 knots or 130 km/h.

A weather station at Rowley Shoals well north of Port Headland at latitude 17.52 degrees south and 118.95 degrees east which is close to where the storm formed recorded a peak wind gust to 133 km/h at 9.24 am and again at 9.30 am on the morning of the 30/1/2016 from the west which is consistent with the CIMSS Model. This implies the core of the storm was just to the south of the weather station at the time the peak wind gusts were recorded.

This weather station also recorded 100 km/h gales between 4 am to 11 am during the morning of the 30/1/2016. The recordings appear to be the highest wind gusts obtained by a weather station from the event.

There are also peak wind gusts to 89 km/h at Bedout Island at 5.17 am 30/1/2016. Elsewhere wind speeds were lower as the storm passed through including a peak gust of just 67 km/h at Port Headland. It is acknowledged that there are few weather stations within this part of Western Australia and hence there is limited ability to verify accurate wind speeds at landfall.

Once the storm crossed the coast, the storm broke apart but has delivered beneficial rains within an area that is generally arid.

The CIMSS model for the storm is attached and while it is dated the 30 January, it is identified that the storm generally followed the path as shown.

The attached satellite photo of the storm from NASA (MODIS Worldview) acquired 31/1/2016 is showing the storm shortly after landfall.

Credits

Bureau of meteorology for rainfall data dated 1/2/2016.
CIMSS (Satellite photo and plot) dated 30/1/2016.
NASA (MODIS Worldview) satellite image acquired 31/1/2016.

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