Rapid Onset Drought Risk Inclusion in the U.S. Week-2 Hazards Outlook

Introductions

Speakers: Meredith Muth, National Integrated Drought Information System (NIDIS); Jon Gottschalck, National Weather Service Climate Prediction Center (CPC)

• To address the rising interest in rapid-onset droughts (aka ‘flash droughts), NIDIS has  created a list of priorities, based on feedback from the drought community, and actions to be undertaken with partners. This includes tool development, regional dialogues, information sharing, creating guidance documents and an upcoming national workshop. 
  • Flash Drought information page on Drought.gov
  • Compilation of Flash Drought Tools
  • Advantages/Disadvantages of Flash Drought Tools
• The Climate Prediction Center, under NOAA’s National Weather Service, has a mission to deliver real-time products and information that predict and describe climate variations on timescales from weeks out to a year thereby promoting effective management of climate risk and a climate-resilient society. Additional information can be found on the Climate Prediction Center website.

Product Overview and Summer 2022 Case Studies

Speakers: Brad Pugh and Adam Hartman, National Weather Service Climate Prediction Center

• CPC’s Week-2 Hazards product is intended to identify hazardous weather/climate risks (heatwaves, arctic air outbreaks, atmospheric rivers, winter storms) at a week-2 time lead. It is released each weekday afternoon. This includes:
  • Temperature, precipitation, snow, and winds [probabilistic with slight (20%), moderate (40%), and high (60%) risks]
  • Flooding and rapid onset drought (ROD) are categorical
• The motivation to include Rapid Onset Drought Risk into the Week-2 Hazards came from stakeholders that identified a need for more frequent drought prediction in addition to the monthly and seasonal outlook, especially because drought can develop quickly (i.e., in 2–3 weeks or within a month)
• A major event (Southern Plains and Ozarks region) during July 2022 verified well with other skillful forecasts across the Corn Belt and Southeast this past summer.
• There was a higher false alarm rate during May and September; drought was slower to develop (more than 4 weeks).
• This product missed rapid onset drought in the Northeast during late July and early August.
• Rapid onset drought and excessive heat hazards typically coincide.
• View the U.S. Week-2 Hazards Outlook Risk product, which now includes Rapid Onset Drought. Learn more about this product on Drought.gov.

Planned Product Adjustments Based on Public Comment

Speaker: Jon Gottschalck, National Weather Service Climate Prediction Center (CPC)

• As part of the CPC experimental Rapid Onset Drought (ROD) demonstration period during the summer of 2022, users were given the opportunity to provide feedback for improvement.
• Reviewing and summarizing the feedback resulted in the identification of 3 areas requiring improvement or attention:

Improvement Area 1: Day-to-Day inconsistencies in ROD Outlook Areas

• At times, the ROD outlook areas could vary considerably from one day to the next depending on the situation and region during this past summer. Some of the changes were too large to be consistent with typical evolution of slowly varying drought conditions (even in this ROD context).
• To address this issue, CPC will only issue ROD outlook areas on the Week 2 U.S. Hazards Outlook once per week—on Thursday. This will coincide with the routine weekly issuance of the U.S. Drought Monitor. If required due to changing or unforeseen conditions, however, an update will be provided within a 1-week span prior to the next issuance of the U.S. Drought Monitor.

Improvement Area 2: Confusion with Monthly Drought Outlook and/or Relationships with ROD

• The CPC Monthly Drought Outlook is released on the last day of each month, and depicts a forecast for the change in drought conditions in place at the end of the upcoming month.
• With the new ROD outlooks, CPC is trying to better communicate rapid drought development that can sometimes occur between Monthly Drought Outlook releases. Consistency with the Monthly Drought Outlook and Week 2 ROD depictions is and will continue to be a major priority this coming warm season.

Improvement Area 3: Need for Product Verification and Skill Metrics

• With any kind of experimental outlook, it is important to know how the new product performs when compared to observational data. Users requested this information so that they can develop trust in the product and convey forecast reliability to their stakeholders. CPC intends to conduct verification once a sufficient number of data samples existed.
• Verification criteria includes: (1) The U.S. Drought Monitor is the observational data that will be used to verify the ROD outlooks; (2) a correct forecast is counted if at a given location the U.S. Drought Monitor degrades by 2 classes any time within the next 2–4 weeks (as denoted by the U.S. Drought Monitor) and (3) applied to all pixels within the ROD outlook area on the Week-2 U.S. Hazards Outlook.

Question & Answer Session; Closing

Speaker: Meredith Muth, National Integrated Drought Information System (NIDIS) 

For additional information:

• U.S. Week-2 Hazards Outlook
• Contact: Brad Pugh, brad.pugh@noaa.gov
• Contact: Adam Hartman, adam.hartman@noaa.gov