Newsletter Issue 43 (May 2024)

The Weather of April 2024 – The warmest April

Mainly attributing to the warmer than normal sea surface temperature and stronger than usual southerly flow in the lower atmosphere over the northern part of the South China Sea, April 2024 was much warmer than usual. The monthly mean maximum temperature of 28.9 oC, monthly mean temperature of 26.4 oC and monthly mean minimum temperature of 24.5 oC were 3.3 oC, 3.4 oC and 3.4 oC above their corresponding normals and all of them were the highest on record for April.

April 2024 – 11th consecutive warmest month globally

The global average surface air temperature last month was warmer than in any previous April in the ERA5 reanalysis dataset, going back to 1940. April 2024 is the eleventh consecutive month being the warmest for the respective month of the year. It is unusual, but a similar streak of monthly global temperature records happened already in 2015/2016. The month was 1.58°C warmer than an estimate of the April average for the pre-industrial reference period (1850-1900).

Global temperature record streak continues, as climate change makes heatwaves more extreme

It was the warmest April on record – the eleventh month in a row of record global temperatures. Sea surface temperatures have been record high for the past 13 months. The monthly reports from C3S, NOAA, NASA and JMA highlight the extraordinary duration of record temperatures fuelled by the naturally occurring El Niño event and the additional energy trapped in the atmosphere and ocean by greenhouse gases from human activities.

Deep green sea? The oceans are changing colour

The balance of phytoplankton populations in the sea is shifting as a result of human-induced climate change, altering the oceans in profound ways. When you picture the ocean you might imagine sparkling turquoise waters – but recent research suggests swathes of our world’s oceans may in fact be turning greener. And the leading culprit might be climate change. And while some waters are becoming more green, particularly in low latitudes near the equator, others are growing more blue as global temperatures rise.

How ‘tornado alley’ is changing

Scientists from the City University of New York announced an unexpected development. Tornado alley, with its dubious geographical perimeter, has been migrating. Between the 1950s and the 1980s, the corridor’s classically accepted boundaries were broadly respected by these weather events. But in the last three decades the country has been experiencing a radical shift with a higher frequency hundreds of miles away, in the southeast and “Dixie Alley” – a region of the southern US with a history of particularly violent tornadoes.

Geomagnetic storm shows need for space weather forecasts

One of the largest geomagnetic storms in several decades has caused a spectacular light show in skies around the world and highlighted the importance of forecasts of potentially disruptive space weather events – one of the agenda items on WMO forthcoming Executive Council. From 10-13 May, aurorae could be seen at unusually low latitudes. This was the result of an extreme geomagnetic storm from a series of coronal mass ejections – clouds of plasma material that are expelled from the Sun with high velocity into the interplanetary space.

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