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Coronavirus could disrupt the weather forecast

Cancelled flights kill valuable data for weather models

Flights recording weather data 2 March 2020 (left) and 23 March 2020 (right). Colours indicate the altitude, with red indicating low altitudes. There is a general reduction in report density, particularly over Italy and parts of Eastern Europe.
Flights recording weather data 2 March 2020 (left) and 23 March 2020 (right). Colours indicate the altitude, with red indicating low altitudes. There is a general reduction in report density, particularly over Italy and parts of Eastern Europe. (.)

The spring severe weather season is upon us and the forecast tools used to predict dangerous storms may be less accurate because of the coronavirus.

Fewer planes in the sky has resulted in less aircraft collected weather observations that feed forecast computer models.

The collected data is used for a range of meteorological applications, including, public weather forecasting, climate monitoring and prediction, early warning systems for weather hazards and, importantly, weather monitoring and prediction in support of the aviation industry.

About 40 airlines use onboard weather sensors including FedEX, UPS, and many big international carriers like American, United and Southwest Airlines.

“We are anticipating the substantial reduction in the availability of US AMDAR data to continue over the coming weeks, likely to generate some measure of impact on the output of our numerical weather prediction systems,” says Christopher Hill from the US National Oceanic and Atmospheric Administration (NOAA).

A critical issue is how those numerical weather models interpret smaller localized events like the storms expected to move into southern Georgia Tuesday evening and beyond toward Jacksonville.

Greater detail is shown with WRF regional model. Individual storms shown moving past Jacksonville.
Greater detail is shown with WRF regional model. Individual storms shown moving past Jacksonville. (none)

Regional models like the WRF offer realistic projections of severe weather environments down to a few miles wide. This high resolution is possible by relying on data rich supplemental aircraft data while incorporating the boundary conditions from the global GFS model.

GFS offers better global coverage but without the details in the WRF.
GFS offers better global coverage but without the details in the WRF. (.)

Timing, strength and placement of forecasted individual storms can only be predicted with dense high resolution data. While supplemental data comes from satellites and weather balloon launches, aircraft measurements provide a vital role in filling data gaps.

Regional models that spot small scale high-impact weather, such as thunderstorms, need a snapshot of the vertical structure of the atmosphere which aircraft measurements handle very effectively.

Weather prediction centers around the planet use the information created by global models in making weather predictions including the European Center for Medium Range Forecasting.

The announcement from ECMWF notes, “At ECMWF, aircraft reports are second only to satellite data in their impact on forecasts. However, recently added satellite wind observations will help to mitigate the drop in the number of aircraft-based observations.”

Other types of observations are likely to be less affected by the COVID-19 disruption than aircraft reports, and there may be some additional radiosonde launches to try to mitigate the lack of aircraft data.


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