MTSAT « CIMSS Satellite Blog

Occluding cyclone south of Australia

January 8th, 2012

MTSAT-2 6.75 µm water vapor channel images (click image to play animation)

A large area of low pressure over the Southern Ocean between Australia and Antarctica on 07 January – 08 January 2012 (surface analyses) exhibited a beautiful signature of an occluding cyclone on 5-km ressolution MTSAT-2 6.75 µm water vapor channel imagery (above; click image to play animation). This storm prompted the issuance of Gale Warnings for widespread areas of winds of 30-45 knots producing high seas.

A closer view of the MTSAT-2 water vapor imagery (below) revealed very intricate detail to the plume of dry air wrapping into the ceter of the storm, along with several small vortices of dry air that became cut off and isolated along the periphery of the system as it began to decay just southwest of the island of Tasmania.

MTSAT-2 6.75 µm water vapor channel images

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Tropical Storm Thane (06B) in the Bay of Bengal, and Tropical Storm Benilde (04S) in the South Indian Ocan

December 28th, 2011

MTSAT-1R 10.8 µm IR channel images

MTSAT-1R 10.8 µm IR channel images from the CIMSS Tropical Cyclones site (above) showed Category 1 Tropical Storm Thane (06B) in the Bay of Bengal, moving toward the east coast of India on 28 December 2011.

Contours of 850-200 hPa satellite-derived deep layer wind shear overlaid on MTSAT-1R 6.75 µm water vapor channel images (below) indicated that Thane was in an environment of low wind shear, which favored some intensification prior to making landfall.

MTSAT-1R 6.75 µm water vapor channel images + Deep layer wind shear

It is interesting to note that the MIMIC Total Precipitable Water product (below) showed the northern counterclockwise circulation of Tropical Storm Thane and the southern clockwise circulation of Tropical Storm Four (04S) — each drawing moisture from the Inter-Tropical Convergence Zone (ITCZ).

MIMIC Total Precipitable Water product

===== 30 December Update =====

Tropical Storm 04 S intensified in a similar low wind shear environment, becoming Tropical Cyclone Benilde in the South Indian Ocean. Benilde was forecast to intensify, with wind gusts up to 140 knots. Meteosat-7 visible/shortwave IR images with an overlay of ASCAT scatterometer surface winds (below) showed the structure of Benilde.

Meteosat-7 visble/shortwave IR imagery + ASCAT surface winds

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Tropical Storm Washi (27W) strikes the Philippines

December 17th, 2011

MTSAT-1R 10.8 µm IR images (click image to play animation)

MTSAT-1R 10.8 µm IR images from the CIMSS Tropical Cyclones site (above; click image to play animation) showed a fairly compact cluster of cold convective cloud tops associated with Tropical Storm Washi as it moved westward toward the Philippines during the 15-16 December 2011 period.

A closer view using MIMIC microwave imagery (below) also showed a relatively small area of enhanced brightness temperatures (representing heavy precipitation) crossing Mindanao Island in the southern Philippines on 16 December.

MIMIC microwave imagery

However, AWIPS images of the MIMIC Total Precipitable Water (TPW) product (below; click image to play animation) revealed that Tropical Storm Washi was embedded within a long fetch of very rich tropical moisture, with TPW values in excess of 60 mm or 2.4 inches (darker red color enhancement). This abundance of moisture helped to fuel over 10 hours of heavy rainfall, which resulted in widespread flash flooding and reports of over 900 deaths in the Philippines.