Flash floods give people very little time, and the people watching for them are often staring at radar that can’t see everything. That’s the gap the National Weather Service (NWS) wants TACLS to help fill. The NWS is reported to be rolling out an upgraded version of the tool, a flash flood decision aid, to all of its forecast offices in the second half of October 2026. TACLS stands for Transient Artifact and Continuous Learning System, and it helps forecasters. It does not issue warnings on its own.
NASA’s Jet Propulsion Laboratory (JPL), the University of California San Diego (UCSD) and NOAA’s National Weather Service built it. UCSD Scripps scientist Yehuda Bock leads the project, and NASA’s Earth Science Technology Office funded it. The idea starts with satellites. TACLS uses signals from Global Navigation Satellite System (GNSS) satellites, the family that includes GPS. Water vapor in the lower atmosphere delays those signals, and the delay can be used to estimate moisture over a location.
A machine learning model trained on more than 30 years of GNSS data then classifies each unusual moisture signal. It’s either an artifact, meaning a data distortion, or a transient, meaning a real, time-sensitive event such as heavy rain. Transients go to a visualization tool called MGViz, where an analyst reviews them and decides whether to issue a warning. NASA says forecasts are produced “in as little as fifteen minutes.” That describes how fast the system processes data. It isn’t a promise of 15 minutes of extra warning for the public.
NWS meteorologist Ivory Small compared TACLS to automatic braking in a car. As NASA’s technology office quotes her, such systems activate and say “hey, pay attention to this.”
Where it stands, and who has it
NASA’s June 2026 article says NWS meteorologists were working to fold TACLS into their flash flood systems for Southern California, and it gave no timeline for other offices. A summary of The Verge’s reporting, republished by Zetik on September 18, 2026, says the Los Angeles and San Diego offices already use TACLS. It also says an upgraded version with improved graphics will reach all 122 NWS forecast offices in the back half of October. The 122-office and October details are second-hand, relayed through an aggregator rather than an NWS announcement. NASA also says the software and its training data will be open source, so other scientists can adapt the model.
Why It Matters to You
You won’t see TACLS directly. It works behind the scenes to help forecasters notice flash flood conditions, and your alerts still come through the normal NWS channels. If the rollout happens as reported, forecasters in more places would have the tool, and people in flood-prone areas would be the first to feel any difference.
Reading the numbers carefully
- NASA reports that in simulations using severe weather from 2017 to 2023, TACLS captured 93% of the flash flood warnings the NWS had issued. NASA does not say how many warnings were tested, how “captured” was measured or how often TACLS flagged floods that never happened.
- That test compares TACLS with warnings forecasters already issued. It does not show TACLS would have warned earlier than forecasters did.
- No source gives a typical lead time, and the claim of about 15 minutes of extra warning is not supported.
- The 122-office rollout and the late-October timing come from an aggregator’s summary of another outlet’s report, not from the NWS.
- The Joint Economic Committee’s Democratic staff estimated in June 2024 that flooding costs the United States between $179.8 billion and $496.0 billion a year in 2023 dollars. The largest share is the cost of infrastructure upgrades to protect against floods. The authors call the range a likely undercount and note significant uncertainty. It’s a staff estimate, and most of it is not the kind of loss a warning tool would prevent.
Quick answers
Will TACLS send alerts to my phone, and should I still turn on emergency alerts?
No to the first. TACLS flags conditions for NWS analysts, who decide whether to issue a warning. Yes to the second: a better forecaster tool does not replace having alerts enabled on your phone and a plan for where to go.
What does the 93% figure mean?
In NASA’s simulations, TACLS captured 93% of the flash flood warnings the NWS had actually issued. It is not a measure of how often it predicts floods correctly.
Sources
- NASA Science: NASA Uses Machine Learning to Enhance Flash Flood Warnings (Jun 23, 2026)
- NASA ESTO: NASA TACLS software helps provide quick warnings for flash floods (Mar 30, 2026)
- Zetik: NWS Deploys Improved TACLS to 122 Offices for Earlier Flash Flood Warnings (Sep 18, 2026; summary of a story from The Verge)
- NewsBytes: New TACLS system helps NWS issue faster flash flood alerts (Sep 18, 2026)
- Joint Economic Committee Democrats: Flooding Costs the U.S. Between $179.8 and $496.0 Billion Each Year (Jun 10, 2024)