Thread by @althecat

#Batsirai #ExtremeWeather Update Thread:

Cyclone Batsirai is weakening and accelerating on its final approach to Madagascar's East Coast. But while lower winds will be helpful - it's primary impact - widespread very heavy rain - is likely to be extreme.

https://twitter.com/althecat/status/1489702852679372808?s=20&t=rA_h3GwjhD6ZTxJgDMWHxg

The official forecast has not been updated, the eyewall landfall (diminished by the filling of the eye) is likely to take place a little later than forecast but wind and rain is already building over the island as is obvious in the satellite imagery.

As of 20 minutes ago the center of the cyclone had roughly 100kms to travel to the shoreline. It will a bring a significant tidal surge with it, especially on the southern side and likely cause significant coastal flooding over a large area of the coastline.

This animation shows satellite estimated rainfall from @Meteoblue over the same 12 hour period as show in the animation in the original post at the top. Rain impacts ahead of the cyclone are already intense.

Here's the latest satellite radar rain image for #Batsirai which shows the leading rain band approaching the capital Antsirabe (population 250k) in which 80 people were killed during Storm Ana by flooding just over a week ago. This storm however is an order of magnitude larger.

In this image its apparent how large the full force wind field will be at landfall. This animation shows 10 wind gust speeds over the coming four days during the course of the cyclone's intense impacts on the Island of nearly 30 million people.

Madagascar is 1000kms long and the most populated areas re forecast to be most effected by the cyclone. The population is mostly rural and agrarian.

The area of most intense heavy rainfall near the coast is roughly 67k km2 - 3/4 the size of the Irish Republic.

This 96 hour animation shows the Euro ECMWF's modelling of the timing of rain. The rain shown in the first frame has already mostly fallen, and the most intense rainfall is forecast to end by midnight Sunday.

Here are the first four frames in that animation (each showing 6 hours of rainfall) taking us to 6pm tomorrow.

These are the next three frames showing that the intense rain part of this will be over by midnight tomorrow.

This animation shows the atmospheric water trail being generated by and accompanying the storm. From the presentation following exit over the Mozambique channel it is apparent only a tiny fraction of this water will fall as rain.

And our final plot shows the latest accumulating rainfall totals. And we can see here that the southern drought effected area is expected to get significant rain, and mostly in quantities that ought not to cayse massive flooding.

To conclude this update yesterday's @UNGeneva briefing began with a briefing from the @WMO #OCHA and @WFP about its preparations to assist Madagascar in the cleanup and humanitarian mission which is expected to follow the storm.

Watch here >> media.un.org/en/asset/k1a/k…

/ENDS

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