Category Archives: Tropical Cyclones

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

Tropical Cyclone Megh 8/11/2015

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Less than 10 days after Tropical Cyclone Chapala made landfall over coastal Yemen as a Category 1 storm, another tropical cyclone has formed over the Arabian Sea within the same region.

This is unusual because tropical cyclones have less chances of forming over this area due to the effects of dry air and deserts prevailing across the Arabian Peninsula and parts of Eastern Africa.

The latest storm is named Tropical Cyclone Megh and should track towards the Gulf of Aden. The storm is a little further south than the track taken by Tropical Cyclone Chapala.

The storm is currently at Category 2 on the Saffir Simpson Scale with winds of approximately 90 knots (Approximately 167 km/h). According to the CIMSS forecast model, the storm could reach Category 3 on the Saffic Simpson Scale with peak winds of 105 knots (Approximately 194 km/h). However, should it reach Category 3 then it would only be brief. Dry air is expected to impact the intensity of the storm and the storm is expected to weaken. By the time it makes landfall, the named storm should have weakened to a tropical storm.

It's lifespan as a tropical cyclone is expected to be short and a feature of the storm over recent hours is that it is relatively small. Sea surface temperatures are only 27 to 29 degrees across this part of the world and it is hard to see the storm intensifying much further.

At the time the satellite photo was taken on November 6, (Worldview image from NASA) the storm was struggling to form and had no eye. Convection was apparent and there were separate thunderstorms well to the north east of the storm. Since that time, the storm has developed into a small tropical cyclone featuring a small but clearly defined eye.

It was only two days ago that computer models were not sure if the storm would transition into a tropical cyclone greater than Category 1 in strength. That has now occurred and now the storm approaches Yemen.

Tropical Cyclone Chapala

Tropical Cyclone Chapala did cross the coast of Yemen but it did weaken beforehand. Peak wind gusts topped 127 knots or 235 km/h at peak intensity and it reached a Category 4 storm on the Saffir Simpson Scale. Due to the effects of civil unrest and non functioning weather stations, it is difficult to obtain data from the region. It appears it crossed the coast as a Category 1 storm with wind gusts of 90 knots (Approximately 167 km/h) and sustained wind speeds of 75 knots (Approximately 139 km/h).

The storm did produced damaging winds and flooding rain across Socotra Island.

Rainfall can only be estimated with precipitation amounts being approximately 250 mm. According to one estimate, the storm may have brought 1 to 3 years worth of rain to a region that receives such low rainfall and where desert like conditions prevail.


1 - Accuweather (Estimated rainfall from Chapala).
2 - CIMSS (Models of the storm acquired 6 and 8 November 2015).
3 - NASA Worldview (Satellite photo of the storm) dated 6 November 2015.

Tropical Cyclone Chapala 30/10/2015

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A tropical storm has developed rapidly into a small but intense tropical cyclone within an area of the Indian Ocean that receives few such storms per year.

Named Tropical Cyclone Chapala and supported by oceanic temperatures of 29C to 30C the storm is travelling west and is predicted to make landfall on the east coast of Yemen within 72 hours.

The storm appears to have reached Category 4 on the Saffir Simpson Scale with winds according to CIMSS reaching 135 knots (Approximately 250 km/h) at the core. This makes it a significant storm in terms of strength but it is not a large storm. The storm is relatively compact and has a small but well defined eye.

The storm reached Category 4 at latitude 14.2 degrees north and 61.1 degrees east and is forecast to make landfall over the coast of Yemen as a Category 3 or 4 storm. Most of the east coast of Yemen is desert and as such, there are few urban centres threatened by the storm. There is one city that is threatened called Salalah close to the Oman / Yemen border (In Oman) but should the storm follow the path shown, then it would make landfall south of the city.

Using the model, the storm would impact Sayhut, or Ash Shihr or Al Mukalla although they are not major urban centres.

A more recent model is suggesting the storm possibly reaching Category 5 on the Saffir Simpson Scale with winds of 145 knots (Approximately 268 km/h) with stronger peak gusts of 160 knots (Approximately 296 km/h) at peak intensity making it a powerful storm.

The attached Worldview image of the region is showing the storm clearly within the Arabian Sea and the urban extents overlay is showing a region with few major cities that could be impacted should it make landfall.

The tropical cyclone is expected to have a short life span due to its location.


CIMSS - Model plots of the storm acquired 30/10/2015.
NASA - Worldview with overlays of the storm and urban extents.

Hurricane Patricia Wind Details 23/10/2015

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As per a previous post on the Hurricane, Thursday morning of the 22/10/15, the storm was still developing and it was identified that rapid development to a Category 1 storm would occur. However, the forecast models did not at the time reveal that this would become a Category 5 hurricane.

It was also known that the storm would have a short life span given its location and likely path that it would take.

During Thursday, the storm rapidly intensified and by Friday it had developed into a powerful Category 5 storm. The storm made landfall over Colima and Jalisco states of Mexico. It is also known that cities in the area including Puerto Vallanta have escaped a major storm due to the mountainous terrain of the area.

The storm made landfall near Cuixmala and once landfall occurred, the storm rapidly lost its energy.

The eye of the storm made landfall in a sparsely populated area avoiding Puerto Vallanta and Manzonilla. While heavy rain and wind occurred in those centres, the infrastructure suffered relatively little damage.

The storm has passed over a weather station which appears to have survived the onslaught of the storm. Meso West operates a weather station being Station Number ID-CCXJI - Chamela Cuixmala just 10 miles or 16 km north west of where the eye passed over and some of the winds recorded are astounding as follows:-

Station Number CCXJI Latitude 19.49 N and 105.044 west at 90 metres above sea level for the 23 October 2015


6.30 pm 148.5 mph or 238.9 km/h from the north.
6.40 pm 133.4 mph or 214 km/h from the north north west.
6.50 pm 185 mph or 297.66 km/h from the north west.

The wind speed of 297.66 km/h is the highest recorded as sustained winds. It is not known what occurred between 7 pm and 7.30 pm as the station is not showing any wind data.

7.30 pm 162.3 mph or 265.65 km/h from the north north west.
7.38 pm 162.3 mph or 265.65 km/h from the north north west.

There are two other peaks at 162.3 mph at 7.51 pm and 7.57 pm but thereafter, peak sustained winds rapidly drop well below 100 mph and 80 miles per hour.


The station has recorded some powerful peak wind gusts although three of these are suspect and could be disputed as follows.

5.50 pm wind speeds of 49 mph but a gust of of 138.6 mph being 79 km/h and 223 km/h.
6 pm wind speeds of 66.2 mph but a gust of of 160.9 mph being 106.5 km/h and 258.88 km/h.
6.10 pm wind speeds of 89 mph but a gust of of 210.9 mph being 143.2 km/h and 337.89 km/h.

The problem identified is that there are no peak wind gust readings from 6.19 pm to 7.50 pm. There appears to be missing data.

A wind speed plot prepared on the CIMSS site for the particular storm is attached. The plot unlike the observations appears to be complete and it suggests a single peak gust in the order of 185 miles per hour which is just under 298 km/h. The plot then suggests that winds eased back to around 70 miles per hour which is approximately 112 km/h, then increased back to 162 miles per hour (265.65 km/h) before rapidly waning in intensity.

The weather station also recorded a low pressure of 937.5 millibars at 6.40 pm and a minimum temperature of 22 degrees Celsius at 6.50 pm.

Notes for the wind plot:

Blue - Wind direction.
Red - Wind speed.
Green - Wind gusts.

The powerful hurricane at peak intensity off the coast of Mexico is attached taken from NASA (MODIS Worldview) with place names overlaid. A feature of the storm is the tiny eye. The eye is unusually small given the size of the storm although it is visible.

The third image is the MODIS Worldview image showing the population centres along the coastline impacted by the storm. There are population centres along the coastline but it was fortunate that the eye came ashore missing the population centres north and south.


CIMSS (Wind data sets) acquired 24/10/2015.
Meso West - Weather station data from Weather Station CCXJI acquired 24/10/2015.
NASA (MODIS Worldview) images and overlays acquired 24/10/15.