Paul Thompson

⚠️ WEATHER WARNINGS LIKELY TO BE ISSUED FOR TONIGHT As mentioned in yesterday's forecast update, weather warnings are likely to be issued early this week due to the risk of fog. Tonight should start with clear skies, but as the night goes on, widespread dense fog will develop across Ulster, Connacht, and North Leinster, with very low visibility, especially by the Tuesday morning commute. Please allow extra time when traveling on Tuesday morning and use appropriate lighting on your vehicle. High pressure often sets the stage for fog development, especially in Ireland during autumn and winter. This occurs because high pressure brings sinking air, light winds, clear skies, and significant overnight cooling. These conditions allow moisture near the ground to condense into tiny water droplets suspended in the air. Under a settled anticyclone, several different scenarios can lead to fog: ▪️ Inland valleys: Radiation fog frequently forms overnight, particularly in sheltered spots where cold air drains and collects. ▪️ Northwest and Donegal: Clear nights can create fog in valleys and low-lying areas. Moist Atlantic air also contributes to mist and low cloud in these regions. ▪️ Eastern Ireland: Sheltered inland locations may experience radiation fog. However, coastal areas can have varying conditions depending on wind direction and sea temperatures. ▪️ Coastal areas: Advection fog can develop when moist air moves over a colder sea surface, even during otherwise settled weather. We see this alot during the summer when we have very warm spell coastal fog can develop. ▪️ Urban areas: Buildings, traffic, and other heat sources can influence local fog formation. Pollution particles can also provide surfaces for water droplets to condense upon. #weatherwarning #Fog #IrelandWeather #HighPressure #WeatherPhenomenon #AtmosphericScience – at Donegal, Ireland