Storm Dennis is forecast to track to the north of Ireland and the UK over the weekend. It will likely bring periods of very wet and windy weather, with some stormy conditions possible, particularly later Sunday into Monday.

The Meteorological Situation

Cold air is forecast to exit Canada and enter the North Atlantic Ocean over the next few days, creating a sharp temperature gradient in the atmosphere. This will result in an intensification of the jet stream, shown in the graphics below, which will direct low pressure systems towards Ireland.

Gales are likely in coastal areas on Saturday with fresh to strong winds inland. Winds could increase further on Sunday, possibly becoming stormy, particularly along western coasts. It will be very gusty too over the weekend, with some damaging gusts possible.

Flooding issues

We are entering into 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 perhaps stormy conditions, may increase the possibility of coastal flooding especially along western and southern coasts due to wave transformation.

Storm Dennis may also bring very wet conditions with localised flooding possible. River levels are elevated across much of the midlands so any heavy rainfall would cause issues here.

Storm Naming

Storm Dennis is the fourth named storm of the season. The naming convention now also includes the Dutch meteorological service, KNMI as well as our existing partner UKMO. 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.

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.

Related content

• Storm Dennis to hit Britain and Europe with very strong winds this weekend

https://www.windy.com/-Wind-accumulation-gustAccu?gustAccu,51.598,-11.777,6,internal

National Warnings

Status: Orange

(Severe) Wind warning for Galway, Mayo, Clare, Kerry and Limerick

Southwesterly winds veering westerly will reach mean speeds 65 to 80km/h with gusts generally of 100 to 130km/h, higher in some coastal regions.

Storm surges will produce coastal flooding and damage.

Valid: Thursday 03 October 2019 18:00 to Friday 04 October 2019 06:00

Status: Yellow

(Moderate) Wind warning for Ireland

Southeasterly winds will reach mean speeds 50 to 65km/h with gusts 90 to 100km/h resulting in some disruptive impacts.

Valid: Thursday 03 October 2019 09:00 to Thursday 03 October 2019 18:00

Status: Yellow

(Moderate) Rainfall warning for Connacht, Leinster, Cavan, Monaghan and Donegal
Status Yellow - Rainfall warning for Connacht, Leinster, Cavan, Monaghan and Donegal

Spells of heavy rain at times today and tonight will result in some flooding.

Valid: Thursday 03 October 2019 09:00 to Friday 04 October 2019 06:00

Status: Yellow

(Moderate) Wind warning for Leitrim and Sligo

West veering northwest winds of mean speeds of 50 to 65km/h with gusts of 90 to 100km/h.

Valid: Thursday 03 October 2019 18:00 to Friday 04 October 2019 06:00

Marine Warnings

Status: Orange

(Severe) Gale Warning

South to southwest gales or strong gales on all Irish Coastal Waters and on the Irish Sea, reaching storm force 10 this evening and for a time tonight from Loop Head to Erris Head to Rossan Point.

Issued: Thursday 03 October 2019 17:00

Advisories

Status: Yellow

The effects of Storm Lorenzo will begin to be felt across Ireland this morning.
In early October, trees are mostly in full leaf with a large surface area, so even moderate strength winds can bring down weakened trees and/or tree limbs.

In addition, some trees may be compromised due to saturated soils at the moment, and with more rain likely some disruption due to falling trees/branches is likely. The rain, coupled with falling leaves may block drains and gullies, leading to surface flooding.

Coastal

Storm Lorenzo will produce significant swell, high waves and sizeable storm surges. This will lead to wave overtopping, some coastal flooding and damage.

Surface Flooding

Saturated soils and the expected heavy rainfall may lead to surface flooding.

River

River levels are currently elevated across the country and the rainfall may lead to river flooding in parts of the midlands, west and northwest. River levels will continue to rise after Storm Lorenzo has passed.

Valid: Thursday 03 October 2019 09:00 to Friday 04 October 2019 06:00

https://www.windy.com/-Weather-warnings-capAlerts?capAlerts,53.531,-8.119,7,internal

As the Post-Tropical Cyclone Lorenzo is heading towards Ireland (and United Kingdom), Met Éireann, the national meteorological service in Ireland, has issued several warnings. The Met Éireann's warnings are available directly on Windy, specifically on our Weather Warnings map.

National Warnings

Status Orange - (Severe) Wind warning for Galway, Mayo, Clare, Cork, Kerry and Limerick

Southwesterly winds veering westerly will reach mean speeds 65 to 80km/h with gusts generally of 100 to 130km/h, higher in coastal regions.

Storm surges will produce coastal flooding and damage.

Valid: Thursday 03 October 2019 18:00 to Friday 04 October 2019 03:00

Status Yellow - (Moderate) Wind warning for Ireland

Southeasterly winds later veering southwesterly will reach mean speeds 50 to 65km/h with gusts to 100km/h resulting in some disruptive impacts.

Valid: Thursday 03 October 2019 09:00 to Friday 04 October 2019 06:00

Status Yellow - (Moderate) Rainfall warning for Ireland

Spells of heavy rain (in excess of 50mm in parts of the west and northwest) will result in some flooding.

Valid: Thursday 03 October 2019 09:00 to Friday 04 October 2019 09:00

Marine Warnings

Status Orange - (Severe) Gale Warning

Southeast gales or strong gales on Thursday morning on all Irish Coastal Waters and on the Irish Sea, veering southwest and reaching storm force at times in the west.

Issued: Wednesday 02 October 2019 15:00

Advisories

Status: Yellow (Moderate)

The effects of Storm Lorenzo will begin to be felt across Ireland from Thursday morning, easing Friday morning. The main impacts will include disruptive winds, falling trees and flooding.

In early October, trees are mostly in full leaf with a large surface area, so even moderate strength winds can bring down weakened trees and/or tree limbs. In addition, some trees may be compromised due to saturated soils at the moment, and with more rain forecast with Storm Lorenzo some disruption due to falling trees/branches is likely. Heavy rain, coupled with falling leaves may block drains and gullies, leading to surface flooding.

Coastal

Storm Lorenzo will produce significant swell, high waves and sizeable storm surges. This will lead to wave overtopping, some coastal flooding and damage, especially along western and southern coasts.

Surface Flooding

Saturated soils and the expected heavy/thundery rainfall may lead to surface flooding.

River

River levels are currently elevated across the country and the rainfall may lead to river flooding, especially in parts of the midlands and west. River levels will continue to rise after Storm Lorenzo has passed

Valid: Thursday 03 October 2019 09:00 to Friday 04 October 2019 09:00

Related content

• The latest Lorenzo updates and forecast

https://www.windy.com/-Weather-warnings-capAlerts?capAlerts,53.531,-8.119,7,internal

• A level 1 and 2 were issued across western France and southern UK mainly for severe wind gust, large hail and tornado chances, and in Ireland for spout-type tornadoes.

• A level 1 was issued across southeastern Europe mainly for large hail and extreme rainfall.

SYNOPSIS

The strong southerly flow east of an Atlantic low has advected a layer with steep low to mid level lapse rates out of the Sahara and Spain northward into central France, where high low level moisture converges in a thermal trough. Meanwhile, southeastern Europe continues to be under influence of an upper cold pool, with relatively weak flow but significant CAPE.

DISCUSSION

Western Europe

A level 1 over central France illustrates mainly the uncertainty of storm initiation, where MUCAPE over 1000 J/kg meets 500 m2/s2 0-3 km SREH and 20-25 m/s DLS. Td2m forecast to be 19-21C. Across western France and southeastern UK various models produce precipitation likely from elevated convection along the cold front, with weaker CAPE. The lifting action of shortwave troughs also reaches central France, and relatively weak CIN is calculated on the convergence line. However, models hesitate producing any storm in the otherwise severe weather supportive environment, except for an evening/night MCS developing most likely over Normandy, moving NNE-ward.

Initially convection will start as clusters of cells including rotating ones (supercells) even if elevated base, which can produce very large hail and severe gusts. If rooted in the boundary layer of the surface convergence line, then with 0-1 km shear exceeding 10 m/s and the strong SREH also tornadoes are possible. However, such collocation is not what COSMO model suggests, which keeps nocturnal development west of the line. But if indeed clustering into an MCS over the late evening, a squall line may form with the potential of organized severe wind gusts.

Southeastern Europe

An upper low moving towards Greece will trigger numerous thunderstorms in the weakly capped environment with locally 1000-2000 J/kg MLCAPE. Weak shear and slow storm motion can create excessive precipitation sums in little time, while also large hail can be produced by strong updrafts, mainly across Bulgaria and E Romania.

The ESTOFEX forecasts are published under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 license

Stay safe!

https://www.windy.com/annotation/5cc3628ac12ac2001cce6601