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RECAP: The *perfect* storm #DENNIS – one of the most intense extratropical cyclones on record (North Atlantic)

The extra-tropical storm Dennis was a remarkable system. This extremely deep low-pressure system over the North Atlantic bottomed at near 920hPa on Saturday evening, located just south of Iceland. Dennis has become one of the most intense extratropical cyclones on record. Its behavior and stunning imagery rival the famous ‘Braer storm’ – the most intense / deepest North Atlantic storm on record. During its mature stage, Dennis has grown bigger than the whole European continent, dominating the whole North Atlantic and indeed our European weather as well. It pushed a severe wind storm into western Europe and very warm air mass further east.


NEW UPDATE: Another intense North Atlantic cyclone – explosive development underway!

*Update* on the new intense North Atlantic cyclone – explosive development underway!


The event started on Thursday when a new upper wave appeared along the northeast US and southeast Canada while there was already an intense and very deep extra-tropical cyclone ongoing in the North Atlantic. This first system was soon followed by another extremely rapidly intensifying cyclone – a featured cyclone #Dennis. That is really a remarkable strengthening, more than a double threshold for the system to be classified as a bomb cyclone. Dennis’s behavior was likely led by the remnants of the previous system leaving a very favorable baroclinic environment in its wake. Resulting in an explosive development – bombogenesis.

Here are the final, official minimum central pressure values by NOAA analysis since the cyclone’s Dennis birth along the northeast US on Thursday, Feb 13th afternoon and over the weekend until its dissipating stage on Monday, Feb 17th morning near Scandinavia (Norwegian Sea). Cyclone went into a rapid intensification soon after its birth, then also into an explosive deepening, taking the bombogenesis phase. As it has happened several times this winter season, a bomb cyclone was on its way towards Europe. The rate of its intensification and deepening central pressure was beyond exceptional from Friday to late Saturday, for quite some time there was a rate of 45-55 mbar per 24-hour period!