Hurricane season is here and meteorologists are losing a vital tool for forecasting them

Meteorologists are losing a sophisticated tool that many say has proved invaluable when monitoring and forecasting hurricanes.

The National Oceanic and Atmospheric Administration (NOAA) announced in a service change notice this week that it would be ending the importing, processing and distribution of data from the Special Sensor Microwave Imager Sounder (SSMIS).

"This service change and termination will be permanent," wrote NOAA.

The SSMIS instruments are part of three weather satellites in low-Earth orbit and are maintained by NOAA in cooperation with the United States Department of Defense. The SSMIS provides critical weather information that can't yet be replaced by other satellites and weather instruments, according to NOAA.

The tool offers forecasters the ability to examine the inner workings of active tropical systems and understand their behavior. Specifically, SSMIS uses microwaves to penetrate clouds and obtain a clearer picture of the inner structure of a tropical cyclone, including its exact center.

Other weather satellites use visible and infrared imagery, which can only capture surface-level details of the cloud tops rather than what's happening inside the cyclone. These satellites are also ineffective after sunset when it's too dark to see and when direct observations over open water are scarce. Forecasters, therefore, rely on the data collected from the SSMIS system during these periods.

The SSMIS data not only allows forecasters to better monitor the current progress of a tropical cyclone but also to identify the center of the system for weather forecast models.

Weather forecast models are sensitive to initial weather conditions and rely on multiple sources of accurate weather data for forecasting. Any degradation or discontinuity in the data, whether in terms of quality or quantity, could negatively affect the model's forecasting skill, scientists warn.

While there is other microwave data available to forecasters, SSMIS accounts for almost half of all microwave instruments, which would dramatically reduce the data available to forecasters. In a worst-case scenario, forecasters say it could lead to missing a tropical system that intensifies overnight, which would not be apparent from using infrared satellite imagery alone.

The SSMIS system is part of the Defense Meteorological Satellite Program (DMSP), which is operated by NOAA on behalf of the Defense Department's Space Force, which has satellite control authority.

The DMSP program focuses on the design, development, launch, and maintenance of satellites that track weather patterns, oceanic conditions and solar-terrestrial physics.

A Space Force official told ABC News the U.S. Navy is responsible for processing the SSMIS data and providing it to NOAA and they are referring all questions about the decision to the Navy.

In a statement, a Space Force official wrote that "satellites and instruments are still functional." The official added that Department of Defense users, including the Navy, "will continue to receive and operationally use DMSP data sent to weather satellite direct readout terminals across the DoD."

On Monday, the Navy told ABC News in a statement that "We can confirm that the Navy's Fleet Numerical Meteorology and Oceanography Center will no longer contribute to processing and disseminating Defense Meteorological Satellite Program data on July 31, 2025, in accordance with Department of Defense policy. DMSP is a joint program owned by the U.S. Space Force and scheduled for discontinuation in September 2026. The Navy is discontinuing contributions to DMSP given the program no longer meets our information technology modernization requirements."

In an update posted on NOAA's Office of Satellite and Product Operations on Monday stated that the cutoff would be delayed for a month and that the data would continue to be available until July 31, 2025, at the request of NASA. The notice also cited "a significant cybersecurity risk" as the reason for decommissioning the system.

And in a statement to ABC News, NOAA's communications director, Kim Doster, explained that "The DMSP is a single dataset in a robust suite of hurricane forecasting and modeling tools in the NWS portfolio, which also includes microwave sensing data via the recently launched USSF WSF-M satellite, which was the planned replacement of the DPSM program." Doster wrote that these changes are part of the "routine process of data rotation and replacement."

She added that another satellite, the Advanced Technology Microwave Sounder, "provides the richest, most accurate satellite weather observations available" and said that "NOAA's data sources are fully capable of providing a complete suite of cutting-edge data and models that ensure the gold-standard weather forecasting the American people deserve"

But the retired head of the National Hurricane Center's Hurricane Specialist Unit, James Franklin, wrote on Substack that "While forecasters have access to a wide array of data, there is currently no practical substitute for the SSMIS." He estimates that the microwave data passes will be cut by nearly 50 percent and that the remaining information will be less detailed than what was previously provided by SSMIS.

He added that he expects the loss of the SSMIS data to result in less accurate estimates and forecasts for weaker storms, delays in updating the strength of hurricanes for storms not being monitored by aircraft and "abrupt changes to the National Hurricane Center track and intensity forecasts."

Other scientists from around the country are also expressing their concerns about the decision, stating that it will negatively impact the weather community's capabilities and accuracy in tracking life-threatening cyclones.

Matthew Cappucci, an atmospheric scientist and senior meteorologist at @MyRadarWX wrote on X, "Please be aware that this change can and will have a negative impact on the forecasts relied upon by Americans living in hurricane-prone areas."

Michael Lowry, a hurricane specialist at ABC affiliate WPLG in Miami, wrote on his Substack blog, "The permanent discontinuation of data from the Special Sensor Microwave Imager Sounder (SSMIS) will severely impede and degrade hurricane forecasts for this season and beyond, affecting tens of millions of Americans who live along its hurricane-prone shorelines."

And Brian McNoldy, a hurricane researcher at the University of Miami, wrote on Bluesky that "For anyone near a hurricane-prone area, this is alarmingly bad news."

Space Force told ABC News that while the U.S. Navy's Fleet Numerical Meteorology and Oceanography Center (FNMOC) "is making a change on their end, the posture on sharing DMSP data has not changed," noting that NOAA has been making DMSP data publicly available, and that many non-Defense Department entities use this data.

Editor's note: This story has been updated with statements from the Navy and NOAA on the Defense Meteorological Satellite Program.