The island of Madagascar is facing a risk of severe flooding this week. Severe Tropical Storm Cheneso made landfall across north-eastern Madagascar on 19 January, with maximum sustained winds of 65mph. The storm has since weakened to become a non-tropical depression, and was centred just west of central Madagascar early on 23 January. Cheneso brought strong winds to coastal regions, while heavy rain brought significant flooding to northern parts of the country.
The remnants of Cheneso will now remain essentially stationary just west of central Madagascar for about four days. On 22 January, Météo-France Réunion issued a 30-60% chance of Cheneso regaining tropical characteristics during this period – dependent upon the system moving sufficiently far offshore across the Mozambique Channel. Regardless of tropical redevelopment, Cheneso’s remnants bring a significant threat of flooding through Thursday, with western areas most at risk. Rainfall totals of 75-100mm are expected each day, bringing storm totals in excess of 500mm – approaching the average annual rainfall in the west coast town of Morondava of 764mm.
Active weather is expected in the US this week. Low pressure will strengthen across southern Texas on Tuesday, tracking north-eastwards. Severe thunderstorms are expected on Tuesday in parts of Texas, Louisiana, Mississippi, Alabama and Florida, with tornadoes, large hail and damaging straight-line winds all possible. Later in the week, this system will bring widespread snowfall across the eastern midwest and the Great Lakes, spreading into New England and parts of south-eastern Canada.
Low pressure will rapidly deepen to the east of Japan on Tuesday, building a sharp pressure gradient across the Sea of Japan due to strong high pressure across eastern China. The resultant northerly winds across the Sea of Japan will tap into the cold air mass across eastern Asia, bringing a strong push of Arctic air to Japan. Although surface temperatures will moderate across the ocean, upper-air temperatures will be significantly colder than normal. This will create a very unstable atmosphere, and generate frequent heavy snow showers. These showers will primarily affect the mountainous north coast, but will be strong enough to push a significant distance inland towards the Pacific coast at times. Snowfall totals of more than 100cm are expected in the mountains exposed to the heaviest and most frequent showers.