Critical Hurricane Forecast and Sea Ice Monitoring Tool Abruptly Terminated

Date: June 26, 2025

• Abrupt Termination: The DoD will permanently terminate the processing and transmission of microwave data from its three weather satellites by no later than June 30, 2025. This decision was formalized on June 25, 2025, and communicated to users, including NOAA and the National Hurricane Center, on June 24 and 25, 2025, respectively.
• Severe Impact on Hurricane Forecasts: The discontinuation of SSMIS data will "severely impede and degrade hurricane forecasts for this season and beyond," affecting millions of Americans in hurricane-prone regions. This data is critical for understanding storm structure, estimating intensity, and accurately positioning storm centers, particularly when direct observations are scarce.
• Increased Risk of "Sunrise Surprise": Without SSMIS microwave data, forecasters face an "increased risk of a ‘sunrise surprise,’ the realization from first-light images that a system had become much better organized overnight, but it wasn’t recognized because structural details are so hard to discern from [infrared satellite]."
• Impact on Sea Ice Products: The SSMIS data is also essential for several sea ice products, including the "Near-Real-Time NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration" and the "Sea Ice Index." These products will cease processing after June 30, 2025, leading to a "gap in data availability."
• Rationale Unclear, Security Concerns Suspected: While the exact rationale for the abrupt termination is "not immediately clear," the decision "appears to have stemmed from Department of Defense security concerns."
• Alternative Data Sources Being Explored/Recommended (with caveats):AMSR2: For sea ice products, the AMSR2 instrument is recommended as an alternative, noting it has "better resolution than SSMIS and therefore provides more detailed information." However, AMSR2 data are "prototype and not yet fully intercalibrated with older data," which means "users will notice differences in sea ice extents."
• WSF-M: The DoD successfully launched a follow-on weather satellite, Weather System Follow-on Microwave (WSF-M), in April 2024. However, data from WSF-M is "not currently available to forecasters and it’s not clear if or when data access will be permitted."
• SSMIS Data Proven Critical for Model Simulation: A 2003 study on Hurricane Danny demonstrated that assimilating SSM/I (predecessor to SSMIS) data significantly improved hurricane simulations by "increas[ing] the moisture content over most of the Gulf of Mexico, but also strengthen[ing] the low-level cyclonic circulation, giving a better convergence field and reduced model spin-up time."