U.S. Department of Defense announced Tuesday it would no longer process and deliver data essential to most hurricane forecasts

On Monday, the U.S. Department of Defense announced it would immediately stop ingesting, processing, and transmitting data essential to most hurricane forecasts.

The announcement was formalized on Tuesday when NOAA distributed a service change notice to all users, including the National Hurricane Center, that by next Monday, June 30th, they would no longer receive real-time microwave data collected aboard three weather satellites jointly run by NOAA and the U.S. Department of Defense.

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.

The news on Tuesday sent users across the weather and climate community – including those monitoring changes to sea ice extent in the polar regions – scrambling to understand the rationale behind the abrupt termination. Though not immediately clear why the real-time data was suddenly discontinued, the decision appears to have stemmed from Department of Defense security concerns.

Officials at the National Hurricane Center were also caught off guard by the announcement and are preparing their team for the loss of critical forecast data for the rest of the hurricane season.