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WeatherMatrix (Jesse Ferrell)

Models on UK / Ireland Big Christmas Storm

By Jesse Ferrell, Meteorologist/Community Director
12/30/2013, 8:30:05 AM

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UPDATE 12/22/2013: It just keeps getting deeper. This morning's model graphics show a 928mb low on Christmas Eve with another 938 low pressure at the end of the week. The storm may be only the fourth in history to pass under 930mb, at least in this area.


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The storm is being powered by a 275-mph jetstream!!


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Wind gusts, however, are predicted to be less than one would expect with a storm this strong -- widespread 60 knots or higher over much of the country on Monday, increasing to 70-80 knots over parts of the South and English channel.


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UPDATE 12/20/2013: Capital Weather Gang has more information on this storm, and Mark Vogan will compare this system to historic storms later today.

UPDATE 12/20/2013: The Euro now has a sub-930mb low pressure system (equivalent to a strong Category 4 hurricane on the SS scale!)* on Christmas Eve morning:


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This morning, the Euro is showing a swath of 70- to 80-knot winds swinging north of Ireland into northernmost Great Britain:


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UPDATE 12/19/2013: The latest Euro model run (update) has 80- to 90-knot (148-167 km/hr or 92-104 mph) winds in southern Britain and northern France on Christmas night. This is a far cry from what it predicted yesterday, when the winds were offshore and never made it through the English Channel.


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I'd like to see this happen consistently from run to run before I'd be convinced that it's a threat.... even with only a week to go, the models have not been able to pin down the area of high winds yet, because they can't decided if there will be one or two low pressure systems in the area.

ORIGINAL BLOG 12/18/2013: I've been playing around with the new Model Animator on our Professional site (30-day free trial) this week. We've written a story saying that the United Kingdom and Ireland will suffer five major storms over the next week, before Christmas. The models show this well, with the European (ECMWF) model showing an extremely strong 936 mb (Category 4 hurricane equivalent)* low pressure system poised just northwest of the islands on Christmas Eve:


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The U.S. (GFS) model splits the low pressure into two, with a (slightly more moderate) 944 mb low - with 948 mb on land in the northern U.K. But blog reader Louise asked: So what does this all mean for wind speeds?


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*Fortunately, although the pressures correspond to a Category 4 hurricane on the Saffir-Simpson scale, winds aren't worst near the center of these winter storms, and deep pressure systems don't typically contain hurricane-force winds in this area of the world. However, wind gusts can be expected over 50 knots (58 mph or 93 km/hr) in much of the U.K. between now and Christmas Day, with gusts over 60 knots being the worst, according to these two forecast models. The worst winds will actually be in the northwest islands this Thursday, where gusts could top 80 knots (92 mph or 148 km/hr), shown above.

Next up... In the Middle East, there have recently been some unusually early and potent snowstorms, centered around the Dec. 10-15 period. Although we may never know how much snow fell where, I was able to catch the results of the storm on the Euro model's snow cover charts yesterday:


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The wind Thursday can also be visualized on the NullSchool worldwide streaming wind map:


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The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com

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WeatherMatrix (Jesse Ferrell)