A rapidly intensifying low pressure system made its way into the Atlantic on Tuesday, 11 February 2020 and quickly grew into a powerful extratropical cyclone producing hurricane force winds by Thursday, 13 February 2020. By 0600 UTC on 14 February 2020, the low bottomed out with a minimum low pressure of 929mb. This system deepened by more than 40 mb in 24 hours during its rapid intensification phase, classifying it as a “bomb” cyclone. It tracked north towards Iceland where it caused hurricane force wind gusts, the highest gust, although terrain enhanced, reached 159 mph (https://www.severe-weather.eu/recent-events/near-record-wind-gusts-255kmh-hafnarfjall-iceland-mk/). These gusts were recorded on the leading edge of the cyclone where the cold conveyor belt north of the occluded front in the N-NE quadrants played a role.
This intense extratropical cyclone was closely followed by another cyclone (named Dennis by the UKMet office) rapidly intensified during the day on 14 February 2020 deepening by 40 mb in 24 hours, classifying it as another bomb cyclone. This system is following a similar path as the previous cyclone, capitalizing on the favorable baroclinic environment left in the wake of the first cyclone.
In the RGB Airmass imagery (above) from GOES-16, it is clear that there is also a large potential vorticity anomaly (red shading) upstream of the system, originating from a trough over the eastern United States. This inflow of potential vorticity into the storm is aiding the rapid intensification of the system. This system deepened to 920 mb as of the Ocean Prediction Center (OPC) 1800 UTC analysis on 15 February 2020. Hurricane force winds have been sampled by ASCAT scatterometers and by aircraft in the early morning hours of 15 February 2020 with maximum winds of 94 kt!
The above ASCAT and Altimeter images from ~1700-1745 UTC on 15 February 2020 show winds in the primary 920 mb low (south of Iceland) still at hurricane-force (>65 kt) with significant wave heights near 42 ft in the southeast quadrant. Meanwhile the older, lee-side low that was part of the 13 February 2020 storm is still exhibiting winds of 50-60 kt, aided by a barrier jet in eastern Greenland and a tip jet near the southern tip of Greenland. The altimeter readings near this latter storm were 30-42 ft (note that it’s possible higher waves (~50+ ft) were in the vicinity of both storms at this time).
These latest ASCAT and Altimeter passes show the 922 mb low (as of the 0000 UTC 16 February 2020 OPC analysis) has started to fill (weaken slightly) with plenty of storm-force wind barbs and significant waves still over 40+ ft, though higher winds of 65+ kt and waves over 50 ft are most likely not sampled.
We will have a more detailed recap of this past week’s stormy north Atlantic in the coming days, so please stay tuned.
Thank you for reading!
Michael Folmer (OPC) and Deirdre Dolan (UMD)