Changes in Future Seasonal Total Precipitation

This tool is excerpted from Chesapeake Bay Watershed Climate Impacts Summary and Outlook for Winter 2018-2019.

Key Findings

  • All future time periods and emissions scenarios show increases in seasonal total precipitation in the winter and spring across the Chesapeake Bay watershed. This is consistent with increases in precipitation seen in the Winter 2018-2019 season.
  • Winter precipitation could increase by as much as 30 percent in the northwestern region of the Chesapeake Bay Watershed by the end of the century. Combined with projected changes in spring precipitation, heightened winter precipitation could lead to more dramatic spring flooding as snow melts and spring precipitation increase simultaneously.

How To Use the Tool

Selecting future time periods and emissions scenarios:
The slider bar to the right of the figure under Time Period allows the user to adjust the future time period used to calculate the projected change in precipitation. For each time period, the user can also select a future greenhouse gas emissions scenario under Future Emissions Scenario by selecting Moderate Emissions future, Representative Concentration Pathway (RCP) 4.51, or a High Emissions future, RCP 8.5.2

Viewing individual locations trends over time:
By holding your mouse over an individual grid cell, a window that shows trends in the seasonal total precipitation will pop up. This data was calculated for each year of the analysis, for each grid cell and will change as you select different metrics, years and future emissions scenarios using the instructions above.

Filtering by geography:
Using the dropdown menu, users should first select a geographic level—the entire watershed, state, county or municipality. A list of states, counties or municipalities will appear, and individual locations can then be selected.

Technical Notes

LOCA or Localized Constructed Analogs is a downscaled climate data product available at 1/16thdegree (6 km) resolution over the continental United States. LOCA datasets include the 32 climate models available in the CMIP5 archive, for two future greenhouse gas concentration trajectories – RCP 4.5 and RCP8.5. For this study, we utilized LOCA data over the Chesapeake Bay watershed from 1976-2095. Access LOCA datasets and learn more about the methodology.

Seasonal total precipitation was determined for each season by summing all daily precipitation events that occurred for each three-month season. We calculated seasonal total precipitation for each season for each year and the averaged values for each season across 30-year periods – 1976-2005, 2006-2035, 2036-2065, 2066-2095 for LOCA data for both RCP 4.5 and RCP 8.5 and 1976-2005, 2006-2017 for ChesWx data. To average across climate models for each grid cell in the LOCA dataset, we employed a weighted average provided by the Northeast Regional Climate Center. Both LOCA and ChesWx datasets were masked to the boundaries of the Chesapeake Bay watershed before calculating seasonal precipitation values and the spatial resolution of each dataset was preserved. Winter is defined as December, January and February. Spring is defined as March, April and May. Summer is defined as June, July and August. Fall is defined as September, October and November.

Footnotes

  1. More information on RCP 4.5 can be found in: Thomson, A.M., Calvin, K.V., Smith, S.J. et al. Climatic Change (2011) 109: 77. https://doi.org/10.1007/s10584-011-0151-4 Return to text ⤴

  2. More information on RCP 8.5 can be found in: Riahi, K., Rao, S., Krey, V. et al. Climatic Change (2011) 109: 33. https://doi.org/10.1007/s10584-011-0149-yReturn to text ⤴

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