Interesting Science Of How Snow Accumulates

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28 cm of lying snow in Tallaght on December 2nd, 2010. Image: Author

Snow is an extremely complicated form of precipitation, and as such leads to a very tricky time for a forecaster. A fraction of a degree either way can tip the balance between a proper snowflake and a more melted form, especially here in Ireland. There is a whole lot of physics going on there, much of which is still poorly understood, but let’s take a look at the stuff we do understand.

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Storm Abigail and Ex-hurricane Kate To Set Stormy Scene

Over the past week or so we have fallen into a warm Atlantic conveyor-belt pattern of weather which has brought rain band after rain band but very mild temperatures. The reason is a persistent low south of Iceland and a persistent high over the continent, we being stuck in between. It’s about to crank up a notch or two, however, as two named storms enter the party. Step up Abigail and Kate.
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Blast From The Past: Hurricane Debbie (1961)

Hurricane Debbie over the Atlantic on September 13th, 1961. Image from Wikiwand
Hurricane Debbie over the Atlantic on September 13th, 1961. Image from Wikiwand

Of all the Irish windstorms in living memory, Debbie in September 1961 set many records that still stand to this day. With a total death-toll of 78 (18 in Ireland and 60 in a plane crash in Cape Verde), it left a path of destruction in its wake. It has been claimed that this storm was the only true hurricane to survive as far north as Ireland, but this is not the case. Hurricanes, in the true sense of the word, simply cannot hold onto their tropical characteristics throughout the long trek this far north, and Debbie was no different. It is possible for us to get regular storms with hurricane-force winds, but they are a different beast altogether. So what was Debbie then?

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Layer Of High Cloud All We Got From Joaquin

Altostratus cloud from ex-hurricane Joaquin partially blocks out the sun over Kildare on Saturday morning. Image: Author

For a week we had been wondering if hurricane Joaquin would send anything our way as it died a death somewhere over Europe this weekend. As it turns out, the main depression is filling off the northwest coast of Iberia, but one fragment of upper moisture from the former Category 4 hurricane has made it north and is doing its best to block out the sun.
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Will We Get Joaquin’s Remnants?

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As of 2100 GMT today Joaquin is still a Category 1 hurricane of 70 knots, racing east-northeastwards towards cooler waters below the 26 °C threshold. These cooler waters and increased shear should cause Joaquin to lose tropical characteristics during Wednesday and become an extratropical depression as it passes near to the Azores Friday and continues towards mainland Europe. The question is, where in Europe will it end up, if at all? The signals are still very mixed!
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