But operating weather-monitoring instruments in the ocean takes a lot of work, because the conditions on the open sea are so harsh. The federal government maintains about 200 ocean buoys, as well as gliders and other instruments that can measure what's happening below the surface of the ocean. Research ships, military vessels and some cargo ships also contribute weather data for the public.
"Obviously we cannot cover the entire globe, the entire surface of the Earth, with all these instruments, so we have to be smart," says Vijay Tallapragada, a weather modeling expert for NOAA's Environmental Modeling Center. For example, weather sensors are strategically located in parts of the ocean where severe weather is more likely to form.
The last, and arguably most crucial, piece of the puzzle is information about the atmosphere. Every day, employees at the National Weather Service launch weather balloons with sensors attached to them. Until recently, that was happening at least twice a day at 90 locations across the country, and more often in places that were expecting severe weather such as tornadoes.
But multiple National Weather Service offices have cut back on balloon launches this spring because of staffing shortages. The Trump administration has moved to lay off hundreds of weather workers and left hundreds of other critical forecasting positions vacant after workers retired.
The weather service addressed such disruptions in a written statement. "The National Weather Service is adjusting some services due to temporary staffing changes at our local forecast offices throughout the country in order to best meet the needs of the public, our partners and stakeholders in each office's local area," the statement says. "These adjustments are also temporary and we will continue to fulfill our core mission of providing life-saving forecasts, warnings, and decision support services."
Tallapragada says balloon data, and other aerial measurements from planes, are the single most impactful source of data for weather forecasting computer models. In addition to providing real-time information about what's happening in the atmosphere, forecasters rely on balloon measurements to calibrate satellite data. So, without balloon measurements, satellite measurements are less useful.