Preparing for the Season Ahead

Spring and summer forecasts help prepare road managers in Europe

Knowing what the weather could be in the coming months is essential for planning and preparation for the European transportation sector, especially with the COVID-19 pandemic Being aware of potential weather risks, such as high winds, extreme temperatures and flooding, can help managers schedule crews and road maintenance work, as well as prepare for potential emergency responses. A DTN European Transportation webcast provides a valuable weather outlook for the rest of April and the summer season, including the impact on road surface temperatures.


Looking back at Winter 2019 – 2020 
Winter 2019

This winter, the frost frequency on UK roads was often low but and sporadic. Fewer than 40% of monitored road sites saw temperatures fall below 0ºC and of those sites less than 10% of the nights fell below 0ºC during that time. This scenario is not surprising, considering the season was dominated by predominantly mild westerly wind flows.The four-month period between November 2019 and February 2020 was the fifth wettest season since 1950.


The Weather Outlook and Impact on Transportation

Temperature & Precipitation Anomaly Outlook April through June

A wet February over England and Wales is rarely followed by a wet March and April. So far this pattern is holding, with the country seeing relief from the sustained heavy rain and flooding with higher pressure and drier weather.

The pattern for April is becoming more defined, with a dry and cold late March and early April. This will then dramatically flip to a much warmer pattern with it being driest in the south and east of the UK. The north and west of the UK will tend to be wettest. Another short cold spell may occur in the second half of April or early May. A look back at the past six years reveals a tendency for April temperatures to be extremely fickle and a cold spell in late April has been a regular occurrence.

This means frost and road surfaces temperatures may still fall below 0C into early May and parts of the road network may require gritting. A hyperlocal road weather forecast at that point can be beneficial to make critical decisions on where to grit –on a select gritting route or cold spots – or whether it is necessary.

For May, while the model guidance offers weak and conflicting signals, our research suggests the strong possibility for a change back to a more regular wetter and windier pattern across all parts of the UK. A repeat of dry, hot and sunny May 2018 is unlikely and we expect dry and hot spells to be fleeting. A slight threat of some colder weather with wintry showers over northern areas in early May.


Temperature & Precipitation Anomaly Outlook June through August

For summer, there are still conflicting patterns. Normally by late April, we tend to see a clearer signal emerging, as influential factors like the state of El  Niño become more obvious. Current data suggests that summer could be  cool and unsettled over northern areas, with brisk westerly winds at times. Extreme winds and storms may cause downed trees in the road, or impair scheduled road maintenance. Monitoring forecasts can help road maintenance mangers prepare and schedule crews.

It is more likely that dry and hot spells will be short and sharp like last summer, rather than the prolonged heat and drought of summer 2018. Extreme heat can be a concern for road surface temperatures. Intense heat, even in short cycles, can cause roads to soften, or “melt.” Gritters may be necessary for some sections of the road network.


Considering the Impact of COVID-19 on the Outlook

Some studies suggest that cool and dry conditions help COVID-19 to thrive and spread. Summer in Europe, U.S., and northern Asia will be warmer and more humid than it is now, which could  limit the spread rate and virulence of the virus. But it’s a complex web of factors that  influence the spread rate of the virus, not just weather. The combination of social isolation, plus the spring and summer warmth, could give the impression that the virus is fading, with the risk of new peaks occurring winter 2020. But in reality, there are still lots of unknowns.

Also, COVID-19 does have some effect on forecasting data due to the reduced number of upper air observations from global passenger flights, but the effect is low. In addition to multiple global models and proprietary surface observation networks, and a combination of increased weather balloon ascents and sophisticated new satellites the impact on forecast quality isn’t expected to be significant.


Keeping your weather data in hand

Having a long-range forecast helps the transportation industry plan and prepare, but the volatility of weather requires carefully monitoring daily forecasts. The DTN RoadMaster mobile app provides key decision makers and crews with relevant information – even when you’re away from your desk, or on the road. For more detailed insight on the spring and summer outlook, watch the European Transportation webcast.