Probable Maximum Precipitation Project Progressing

Probable maximum precipitation (PMP) estimates are used by engineers to design large, critical facilities like dams and nuclear power plants. These estimates help them gauge the “worst-case scenario” precipitation for the area, ensuring the facility can withstand such an event, reducing the risk of a catastrophe.

The NOAA-wide effort led by PSL to modernize PMP estimates has made great strides over the past several months. This includes:

• development of Extreme Precipitation Event Case Study webpages which will host analyses of many past events relevant for updating PMP;
• authorship of several research papers documenting the representation of extreme precipitation in key NOAA datasets; and
• development and evaluation of new experimental high-resolution, rapidly updating NOAA models that will also be leveraged for producing extended reforecast datasets.

More information on this important progress, other successes, and the project timeline for the remainder of the year can be found on the PSL PMP project page.

In brief: What is a ‘thirstwave’?

A new term for prolonged periods of atmospheric thirst has been coined: thirstwaves.

Meetpal Kukal, a research hydrologist at the University of Idaho, and Mike Hobbins, a CIRES researcher at PSL, describe the new term and examine past United States thirstwaves in a new paper published in Earth’s Future.

PSL does extensive research into the Madden-Julian Oscillation (MJO), a mode of sub-seasonal atmospheric variability over the Indian Ocean that influences the location and strength of tropical precipitation. The MJO can impact extreme weather throughout the globe, including in the United States. PSL has a recently redesigned MJO page dedicated to the latest info and research into this phenomenon.

Most recently, a new study by PSL’s Lisa Bengtsson in collaboration with other PSL researchers published in the Geophysical Research Letters has made a key discovery related to the impact of a forecast model’s starting state on the accuracy of Madden-Julian Oscillation prediction.

PSL’s atmospheric river observatories: serving up data rain or shine

Did you know PSL operates nine (9) atmospheric river observatories at sites distributed along the coast from Washington to Southern California? These unmanned weather stations send round-the-clock observations back to the laboratory, which analyzes and displays the data publicly on its Atmospheric River Portal.

The National Weather Service utilizes this data portal to produce forecasts and weather warnings. State and local agencies also use the portal for creating water management strategies and emergency response planning.

Interested in seeing all of PSL’s observation sites? Check out the PSL Observation Network interactive tool.

Jacox, Alexander, Amaya honored with NOAA Research Outstanding Scientific Paper of the Year Award

Michael Jacox (NOAA Fisheries/PSL), Michael Alexander (PSL, retired), and Dillon Amaya (PSL) recently won the NOAA Research Outstanding Scientific Paper of the Year award for their paper ‘Global seasonal forecasts of marine heatwaves’.

Their groundbreaking work used “climate forecast systems to develop global predictions of MHWs [marine heatwaves] and evaluate their skill over the past three decades…highlight[ing] the feasibility of predicting MHWs and provid[ing] a foundation for a much-needed operational MHW forecast system.”

PSL mentors high school student; wins NASA science award

PSL’s Andrew Hoell, Rochelle Worsnop, Melissa Breeden, and Ryan Harp mentored a Broomfield (Colorado) High School student earlier this year who won the NASA Earth System Science Project Award and placed second place at the Boulder Valley School District Science Fair. The presentation was on conditions related to area burned by wildfire in Colorado and qualified to present at the Colorado Science Fair.

Publication Report - 1st Half of 2025

See a list of peer-reviewed products from lead and contributing PSL authors from January through June 2025.

For a full list of PSL publications from this and past years, visit the PSL Publications database.