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Storm Jorge – Saturday 29th February 2020

Storm Jorge from Space – Saturday 29th of Feb, 2020

By Conor Lally (Meteorologist, Observations Division)

Presented are a series of three satellite images detailing the progression of Storm Jorge (pronounced Hor-hay), the seventh winter storm of the season, as it crossed the country today.

These images are Natural Colour RGB (Red Green Blue) composites courtesy of the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). Composite satellite images combine pictures taken at different visible and infra-red frequencies, each of which contains slightly different information. To highlight each picture’s own particular specialty, that is to say those features that are captured best in that particular frequency, they are tinted a different colour. Then when combined together they reveal more information than they would by themselves.

The centre of the storm Jorge, which developed in the mid-Atlantic and deepened rapidly as it approached Ireland thanks to a strong jet stream aloft, was clearly identifiable as the dark patch to the west of the country in the first of our series of satellite photos, which was taken at 9am. At this stage the pressure in the centre of the storm was predicted to be in the region of 950 hPa and the closest of our stations to the centre of the storm, Belmullet in Co Mayo, recorded a Mean Sea Level pressure of 963 hPa.

Despite the proximity of the storm centre we can also see that Saturday started off as a bright clear day for many with an absence of cloud for much of the eastern half of the country. However, the storm quickly began make its presence felt shortly after sunrise on the west coast, as a swathe of storm force winds began to drive in across the west of the country by which time our station in Mace Head had already recorded a wind gust of 92 km/hr.

We can see in the second image taken at 11 pm the storm’s occluded front, which was visible as the thick band of cloud in the shape of a comma head that is wrapped around the storm’s centre, push its way into to the middle of the country. With the front came heavy rain but also for a short while some sleet and snow along its leading edge. Our station in Knock airport recording 3 cm of snow lying by 11 am. Looking carefully at our composite image we can just discern this band of frozen precipitation as a light blue streak to the right of the thick white and warmer cloud of the front. The tip of the comma head often contains much of the highest winds and this is evident in the winds recorded at this time with Mace Head, Newport, and Athenry recording gusts of 133, 102 and 98 km/hr.

In our third image taken at 1 pm, the front has spread across the whole of the country and ‘Jorge’ now shows signs of a maturing system. What was in our first image the tight core of the storm centre has become elongated as cold air, visible in the picture as the dark clear sector east and south of Ireland, was dragged into the centre. This has the effect of cutting the storm off from the supply of warm air which drives it and thus reducing its intensity.

Table listing the highest ten minute means and gusts observations for each of the weather stations

Storm Jorge: highest ten minute means and gusts

 

Meteorologist’s commentary issued at 6pm Thursday 27th February 2020

by Joan Blackburn (Deputy Head of Forecasting Division), Sinéad Duffy (Meteorologist, Technology Division) and Eoin Sherlock (Head of Flood Forecast Division) on Thursday, 27th February 2020

Storm Jorge (named by AEMET, the Spanish meteorological service) is the latest in a series of Atlantic storms this month and is due to affect Ireland from early Saturday. Rain will extend countrywide from the west tonight, before the storm arrives.

The Meteorological Situation:

Storm Jorge (pronounced Hor-hay) is a storm centre which will undergo rapid cyclogenesis in the mid-Atlantic during Friday 28th February as it tracks northeastwards towards Ireland. It is then expected to fill slowly as it crosses over the north of the country during Saturday 29th February. Figure 1 shows the forecast position of Storm Jorge and its associated fronts at 12 midday on Saturday.

Figure 1. Forecasted position and fronts of Storm Jorge at midday Saturday 29th February.

 

Storm Jorge is forecast to bring severe winds to western and northwestern coastal counties (orange wind warning) and less severe winds to the rest of the country (yellow wind warning) from Saturday morning into early Sunday morning.

Spells of heavy rain associated with Storm Jorge will worsen the flooding situation across the country. A yellow level rainfall warning will come into operation for Munster, Connacht and Donegal from tonight (Thursday night) to late on Saturday evening.

 

The animation in figure 2 below shows the position of the strong Atlantic jet with the corresponding deepening of the storm centre from early Friday morning to early Sunday morning.

 

Figure 2. Forecast position of the Jet stream during Storm Jorge

 

Figure 3 shows the wind field from the Harmonie high-resolution weather model for early Saturday morning, the start of the orange warning for Mayo, Galway, Clare and Kerry.

Figure 3. Wind warning forecast from the Harmonie weather model at 6am Saturday 29th February

 

Storm Jorge is the seventh named storm of the season. It was originally named by AEMET, the Spanish national meteorological service, due to the impact of the storm’s active cold front which is forecast to bring severe gusts and strong waves to the northwest of Spain.

Here’s the list of the winter storms so far this season:

  1. Lorenzo, 4Oct-2019 (Ex-hurricane, named by the NOAA National Hurricane Centre in the USA)
  2. Atiyah, 8-Dec-2019
  3. Elsa, 18-Dec-2019 (named by IPMA, the national meteorological service of Portugal)
  4. Brendan, 13-Jan-2020
  5. Ciara, 9-Feb-2020
  6. Dennis, 16-Feb-2020
  7. Jorge, 29-Feb-2020 (named by AEMET, the national meteorological service of Spain)

Storms are named to aid the communication of approaching severe weather, helping the public to be better placed to keep themselves, their property and businesses safe. Met Éireann are part of a western Europe storm-naming group which includes the Dutch meteorological service, KNMI and the UK’s meteorological service UKMO. The national meteorological services of Spain, Portugal, France (MeteoFrance) and Belgium (RMI) are part of a southwestern Europe storm-naming group which has a separate list of names allocated to the Winter 2019/20 storm season. When a storm has already been officially named by another national meteorological service or the US National Hurricane Centre, that storm name is retained.

Flooding issues

  1. A) Elevated river levels
    Currently river levels are elevated across the country, particularly in the Midlands (Shannon catchment). Levels across the Northern half of the country are also high. Therefore, additional rainfall over the coming days will compound the flooding issues here.
  2. B) Coastal Flooding
    We are in a period of transition between Spring (High) Tides and Neap (Low) Tides. This means there will not be a large variation between high and low tides. The combination of high seas and strong winds or stormy conditions associated with Storm Jorge may increase the possibility of coastal flooding, especially in flood-prone areas along the Atlantic coast on Saturday (particularly when coincident with high tides).

 

 Keep up to date

As forecast confidence improves over the coming days Met Éireann will issue warnings as required. Please check for updates on https://www.met.ie/warnings.

Push notifications for all weather warning levels (yellow, orange and red) for your location are available on the latest version of the Met Éireann App.

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