Chesapeake Bay Climate Impacts Summary and Outlook

Chesapeake Bay Watershed Climate Impacts Summary and Outlook: Winter 2019-2020

Highlights

  • The region experienced an unusually mild winter, which ranked among the ten warmest on record for many sites.
  • The coldest temperature observed this winter in Washington, D.C. was the warmest minimum temperature for winter on record.
  • This winter was also among the ten least snowy on record.
  • Six tornadoes touched down in Maryland and northern Virginia on February 7, 2020. The Mid-Atlantic averages about one tornado per winter.
  • It was the first time in Baltimore, Maryland’s 128 years of recordkeeping that the city saw no snow during February.
  • In both low and high emission futures, the southeastern Mid-Atlantic is projected by an ensemble of climate models to experience significant decreases in freeze-thaw days by mid- to late-century.

Part 1: Significant Weather Events and Impacts

Winter Weather

From December 1 to 3, a significant storm brought snow, ice, and rain to the region. Central New York and northern Pennsylvania had the greatest storm snow totals of up to 14 inches.1 Binghamton, NY received 9.6 inches of snow on December 2, which made it their eighth snowiest December day on record.2 Western Maryland and central Pennsylvania experienced freezing rain and had ice accumulations of up to 0.40 inches.3

This winter storm severely impacted post-Thanksgiving travel. More than 50 vehicles were involved in a series of crashes that shut down Interstate 68 in Garrett County, Maryland for four hours, while icy conditions in central New York caused sections of some major roads to be closed.4 Air travel was also affected, with hundreds of flights cancelled and thousands delayed.5

Another storm system dropped mixed precipitation on the region from December 16 to 17. Portions of central Pennsylvania, western Maryland, and the eastern panhandle of West Virginia saw 0.50 to 0.68 inches of ice accumulation, which downed tree limbs and wires and led to power outages.6 Behind the storm, an Arctic front brought intense snow squalls and strong winds and ushered colder air into the region. The squalls likely contributed to a pileup involving nearly 60 vehicles on Interstate 80 in Union County in central Pennsylvania that resulted in two deaths, sent dozens of people to the hospital, and caused the westbound lanes to be closed for more than a day.7

On December 22, dense fog and icy roads were blamed for a pileup involving 75 vehicles on Interstate 64 near Williamsburg in eastern Virginia.8 Around 50 people were taken to hospital and the interstate was shut down for several hours.9

On January 7 and 8, a fast-moving storm and snow squalls produced as much as 6 inches of snow across the region.10 The greatest snow totals were reported in central and southern Pennsylvania, northern and western Maryland, the Eastern Panhandle of West Virginia, and western Virginia.11 Washington Dulles International Airport received 2 inches of snow from the storm, but Washington, D.C. only received traces of snow from snow squalls.12 Snow squall warnings were issued for Washington, D.C. suburbs.13 Schools and federal workers were dismissed early on January 7.14 The increased volume of commuters across the Washington, D.C. metro area snarled traffic, created train delays and cancellations, and caused tolls on the I-395/95 Express Lanes from Washington, D.C., to Stafford, VA to jump to more than $60, which is about twice the usual maximum rush hour toll for these lanes.15

On January 11 and 12, severe thunderstorms downed trees and power lines in Virginia.16

A rare tornado outbreak occurred on February 7 when six tornadoes, two Enhanced Fujita Scale (EF)-0s and four EF-1s, touched down in Maryland and northern Virginia.17 These were the first February tornadoes since records began in 1950 for Loudoun County, Virginia, and Cecil, Montgomery, and Carroll counties in Maryland.18 Previously, there had only been four February tornadoes in Maryland between 1950 and 2019.19 The Mid-Atlantic averages about one tornado per winter, and no other winter severe weather has produced more than a single tornado in either Maryland or Virginia.20 Additionally, these tornadoes are the earliest tornadoes in a calendar year for Carroll, Montgomery, Frederick, and Cecil Counties in Maryland and Loudoun County, Virginia. In fact, this beat the Loudoun County record by more than two months.21 The tornadoes uprooted trees, destroyed outbuildings, and damaged roofs and siding on several buildings.22 Damaging severe thunderstorms also downed trees and wires in Delaware, southern Pennsylvania, and other parts of Maryland and Virginia.23 These areas also saw up to 3 inches of rain, resulting in some minor flooding in Virginia and erasing the abnormal dryness in eastern Maryland and southern Delaware that had been lingering since July 2019.24 The same storm system brought up to 12 inches of snow and some ice accumulation to northern Pennsylvania and central New York.25 Thundersnow and snowfall rates of 2 to 3 inches per hour were reported, and several roads were shut down due to accidents.26 Across the watershed, the storm also produced wind gusts (not associated with thunderstorms) of up to 63 mph on land and up to 73 mph at maritime stations.27

Southeastern Virginia received up to 5 inches of snow from February 20 to 21, which was the largest snowfall of the winter season for many sites in that area.28 Several school districts and government offices were closed or delayed opening.29

Temperature

Unusually mild temperatures that ranged from 60 degrees Fahrenheit (F) to over 70 degrees F set numerous daily temperature records across the region on January 11 and 12 with temperatures around 35 degrees above average.30 In fact, both days ranked among the ten all-time warmest January days on record for Binghamton, NY, and for Scranton, PA.31 The warm weather mid-month helped make this January one of the ten warmest on record for Washington Dulles International Airport, Harrisburg, PA, and Binghamton, NY.32

This February ranked among the ten warmest Februarys on record for many areas including Richmond, VA, Washington, D.C., Washington Dulles International Airport, Baltimore, MD, and Harrisburg and Scranton, PA.33 The warmth contributed to low February snowfall totals in southern parts of the watershed.34 This February was the least snowy on record for Washington Dulles International Airport, Baltimore, MD and Harrisburg, PA and the second least snowy for Washington, D.C.35 It was the first time in Baltimore, MD’s 128 years of recordkeeping that the city saw no snow during February.36 With the warm, snowless weather, leaves started to emerge on trees and plants weeks earlier than usual in southern areas.37 The pollen count was also unusually high several days during February.38

The entire region experienced an unusually mild winter, which ranked among the ten warmest on record for many sites, including Richmond and Norfolk, VA, Washington, D.C., Washington Dulles International Airport, Baltimore, MD, and Harrisburg and Scranton, PA.39 The coldest temperature observed this winter in Washington, D.C. was 22 degrees F and at Washington Dulles International Airport was 15 degrees F, which are the warmest minimum temperatures for winter on record.40 The mild winter enabled transportation departments to save money but led to decreased revenue for snow removal businesses.41

Part 2: Seasonal Temperature and Precipitation

Temperature

Figure 1 shows Winter 2019–2020 (December 2019 – February 2020) average temperature compared to the climate normal—the average temperature from 1981 to 2010.42 This figure indicates that above-average temperatures were experienced for all of the Chesapeake Bay watershed. Areas in Pennsylvania, Virginia and Maryland experienced temperatures that were 4–6 degrees above normal.

Figure 1. December 1, 2019 – February 29, 2020 Departure from Normal Temperature (°F)

Note: Normal temperature is based on winter seasonal average temperature data from 1981-2010. Yellow, orange, and red indicate above-average temperatures. Average departures from normal temperature are based on station-specific normal temperature for the winter compared to the same station’s winter 2019-2020 average temperature. Station-level departures from normal are then spatially interpolated to form the figure above.

Source: Northeast Regional Climate Center, 2020.

Precipitation

From December 1, 2019 through February 29, 2020, precipitation departures from normal, seen in Figure 2, show that the Chesapeake Bay watershed experienced both more and less precipitation than historical averages. Parts of eastern Pennsylvania and Virginia experienced 75-100% of their normal precipitation for the period, and areas in West Virginia, southwestern Virginia, and western Pennsylvania saw precipitation at 125-150% of normal.

Figure 2. December 1, 2020 – February 29, 2020 Percent of Normal Precipitation

Note: Normal seasonal precipitation is based on precipitation data from 1981-2010. Browns indicate below-average seasonal precipitation. Average departures from normal precipitation are based on gridded precipitation datasets (with a spatial resolution of approximately 5 kilometers by 5 kilometers) that contain precipitation data from the normal time period and the current winter 2019-2020 period. Both are produced by the Northeast Regional Climate Center. These can be accessed at: http://www.rcc-acis.org/docs_gridded.html

Source: Northeast Regional Climate Center, 2020.

From December 1, 2019 through February 29, 2020, winter snowfall throughout the majority of the Chesapeake Bay Watershed was below the 1981–2010 normal. Figure 3 shows the southern portion of Pennsylvania saw 25–75% of normal snowfall for the winter season, while the majority of Virginia and Maryland experienced less than 25% of normal snowfall.

Figure 3. December 1, 2020 – February 29, 2020 Percent of Normal Snowfall

Note: Normal seasonal snowfall is based on snowfall data from 1981-2010. Browns indicate below-average seasonal snowfall. Percentages of normal seasonal snowfall are based on station-specific normal seasonal snowfall for the winter compared to the same station’s winter 2019-2020 seasonal snowfall. Station-level percentages of normal are then spatially interpolated to form the figure above.

Source: Northeast Regional Climate Center, 2020.

More information on how recent precipitation and temperature compares to historical trends for the East Coast, including the Mid-Atlantic region, can be found using the Southeast Regional Climate Center’s Climate Perspectives tool.43

The impacts of seasonal temperature and precipitation are discussed in Part 1.

Part 3: Spring 2020 Outlook

Temperature and Precipitation

As of February 20, 2020, NOAA’s Climate Prediction Center forecasted a 40–50% chance of above normal precipitation for April 2020 – June 2020 for much of the Mid-Atlantic region. They predicted a 40–50% chance of temperatures above normal for the northern half of the Chesapeake Bay Watershed and greater than 50% chance of temperatures above normal for the southern half.44

Drought Incidence

The United States Seasonal Drought Outlook predicts how drought may change across the United States, categorizing areas by whether drought could develop or become more or less intense. As of February 20, 2020, the outlook indicated no tendency for drought conditions in the region through May 2020.45

Climate Circulation Patterns

NOAA’s Climate Prediction Center, which monitors the likelihood of occurrence of El Niño and La Niña climate phenomena, had no alerts or warnings active as of March 12, 2020, and predicted neutral conditions in the Pacific Ocean, rather than either El Niño or La Niña.46

Part 4: Freeze-Thaw Cycles in a Changing Climate

Freeze and thaw days occur when temperatures swing above and below freezing in a single day. Because these changes in temperature affect the freezing and melting of water in soils, roadways, and on crops, freeze-thaw cycles can affect crop yields, runoff and erosion, and roadway conditions.47 Examples of the impacts of freeze-thaw cycles include pavement damage and potholes, as well as the indirect costs associated with accidents due to less safe driving conditions.48 Freeze-thaw cycles are most prevalent during winter months, yet warming minimum temperatures, which have increased over the last century, could change the frequency, timing, and location of these events.49

Trends in Freeze-Thaw Days in the Mid-Atlantic

Figure 4 shows modeled historic and projected percent changes in freeze-thaw days across the Mid-Atlantic region. This interactive tool can be utilized to generate local and regional insights. Four illustrative examples include:

  • In both low and high emission futures, the southeastern Mid-Atlantic is projected by an ensemble of climate models to experience significant decreases in freeze-thaw days by mid- to late-century.
  • In high emissions futures, parts of eastern Virginia could see fewer than ten freeze-thaw days per year by late-century.
  • The northern reaches and northwestern portions of the Chesapeake Bay watershed could see similar levels of freeze-thaw days in low emissions futures by mid-century.
  • In both low and high emission futures, nearly all regions within the watershed may see a 20-50% decrease in freeze-thaw cycles by 2099.

When examining the data in the tool, it is important to keep in mind the regional context of winter temperatures throughout the Mid-Atlantic. For example, in the southernmost regions of the watershed, we would expect to see few changes in freeze-thaw days in future climate. This is likely due to the low frequency of freeze-thaw days in current climate. Warmer winter temperatures in the future would therefore not change the number of freeze-thaw days.

How to Use the Tool

Selecting time periods and future emissions scenarios: To view percent changes in freeze-thaw days for select 30-year time increments and future greenhouse gas emissions scenarios, users can use the 30-year period slider bar and future emissions scenario options (Low and High Emissions) to the right of the map. Users can also hover over a location on the map to see a pop-up window of annual freeze-thaw days for a given location from 1981-2099.

Technical Notes

LOCA or Localized Constructed Analogs is a downscaled climate data product available at 1/16th degree (6 km) resolution over the continental United States. LOCA datasets50 include the 32 climate models available in the Coupled Model Intercomparison Project 5 (CMIP5) archive, for two future greenhouse gas concentration trajectories—a low emissions future, RCP 4.5,51 and a high emissions future, RCP 8.5.52 For this study, we utilized LOCA data over the Chesapeake Bay watershed from 1981–2100 (or 2099 for some models). Access LOCA datasets and learn more about the methodology.

Freeze-thaw days were calculated as those with a maximum temperature greater than or equal to 32 degrees F and a minimum temperature less than or equal to 28 degrees F in the same day. We averaged values across 30-year periods—1981–2010, 2011–2040, 2041–2070, 2071–2099 for LOCA data53 for a low emissions future (RCP 4.5)54 and a high emissions future (RCP 8.5).55 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.56 The LOCA datasets were masked to the boundaries of the Chesapeake Bay watershed.

Back to top

The MARISA Seasonal Climate Impacts Summary and Outlook is a quarterly series produced by the Mid-Atlantic Regional Integrated Sciences and Assessments (MARISA) program, a collaboration funded by NOAA through RAND and researchers at Pennsylvania State University, Johns Hopkins University, Cornell University, and the Virginia Institute of Marine Science. This series draws information from regional climate centers, news and weather information, and regional-specific climate datasets for the benefit of policymakers, practitioners, residents, and community leaders in the Chesapeake Bay Watershed. Projections of weather and climate variability and change in the Chesapeake Bay Watershed come from the best available scientific information. For any questions or comments, please contact Krista Romita Grocholski at Krista_Romita_Grocholski@rand.org.

This edition of the MARISA Seasonal Climate Impacts Summary and Outlook was authored by Michelle E. Miro (RAND Corporation), Krista Romita Grocholski (RAND Corporation), Samantha Borisoff (Cornell University), Jessica Spaccio (Cornell University), Arthur T. DeGaetano (Cornell University), Jordan R. Fischbach (RAND Corporation), and Kyle Haak (RAND Corporation).

Help us improve this climate summaryTake the Survey

Footnotes

  1. https://twitter.com/NWSBinghamton/status/1201904044274417664 Return to text ⤴

  2. http://climod2.nrcc.cornell.edu/ Return to text ⤴

  3. Ice accumulation totals were the greatest amounts reported in western Maryland and central Pennsylvania. https://www.wpc.ncep.noaa.gov/storm_summaries/2019/storm26/stormsum_26.html Return to text ⤴

  4. https://www.wvnews.com/news/wvnews/vehicles-crashes-injuries-sunday-on-i/article_4a471228-193b-5d0e-a89c-fd6194245885.html; https://www.mytwintiers.com/news-cat/top-stories/top-stories-2/major-roadways-closed-in-tioga-and-broome-counties/ Return to text ⤴

  5. https://www.cnbc.com/2019/12/01/winter-storm-snarls-post-thanksgiving-flights-airlines-waive-change-fees.html Return to text ⤴

  6. https://www.wpc.ncep.noaa.gov/storm_summaries/2019/storm27/stormsum_10.html; https://www.times-news.com/news/ice-storm-leaves-thousands-without-electricity-across-region/article_46d8d128-20d5-11ea-9b1a-9baefd810fa8.html Return to text ⤴

  7. https://www.northcentralpa.com/news/psp-i--crash-in-white-deer-township-involved-cars/article_c522067c-2278-11ea-b857-f7c5651239cb.html Return to text ⤴

  8. https://www.13newsnow.com/article/traffic/investigation-continues-in-massive-i-64-pileup/291-0ebfbe70-015b-4924-84c0-625a4f80d73c Return to text ⤴

  9. https://www.13newsnow.com/article/traffic/investigation-continues-in-massive-i-64-pileup/291-0ebfbe70-015b-4924-84c0-625a4f80d73c Return to text ⤴

  10. https://twitter.com/NWS_BaltWash/status/1215254627001753600 Return to text ⤴

  11. https://www.washingtonpost.com/weather/2020/01/08/first-snow-2020-drops-coating-few-inches-dc-region/ Return to text ⤴

  12. https://www.washingtonpost.com/weather/2020/01/08/first-snow-2020-drops-coating-few-inches-dc-region/ Return to text ⤴

  13. https://www.washingtonpost.com/weather/2020/01/08/first-snow-2020-drops-coating-few-inches-dc-region/ Return to text ⤴

  14. https://patch.com/district-columbia/washingtondc/dc-nova-area-federal-offices-closing-1-pm-due-weather Return to text ⤴

  15. https://www.wusa9.com/article/traffic/i-270-backed-up-during-winter-weather/65-4203e6c7-e635-44e8-8cd1-04d20b7f4074; https://www.wusa9.com/article/traffic/tolls-jumped-to-higher-prices/65-9bf815e7-5a5b-4dbb-9457-152c328842da; https://www.washingtonpost.com/local/trafficandcommuting/tolling-on-395-express-lanes-starts-sunday-heres-what-you-need-to-know/2019/11/16/07742088-07d4-11ea-818c-fcc65139e8c2_story.html Return to text ⤴

  16. https://www.spc.noaa.gov/climo/reports/200111_rpts.html Return to text ⤴

  17. https://www.weather.gov/lwx/2020Feb07_Tornadoes Return to text ⤴

  18. https://www.ncdc.noaa.gov/stormevents/ Return to text ⤴

  19. https://www.ncdc.noaa.gov/stormevents/ Return to text ⤴

  20. https://www.washingtonpost.com/weather/2020/02/07/virginia-maryland-tornadoes-confirmed/ Return to text ⤴

  21. https://www.washingtonpost.com/weather/2020/02/07/virginia-maryland-tornadoes-confirmed/ Return to text ⤴

  22. https://www.weather.gov/lwx/2020Feb07_Tornadoes Return to text ⤴

  23. https://www.spc.noaa.gov/climo/reports/200207_rpts.html Return to text ⤴

  24. https://twitter.com/NWSWakefieldVA/status/1225955812301918208; https://droughtmonitor.unl.edu/ Return to text ⤴

  25. https://twitter.com/NWSEastern/status/1226218333118377985/photo/1 Return to text ⤴

  26. https://twitter.com/NWSBinghamton/status/1225804947922419713; https://twitter.com/NWSBinghamton/status/1225805196975955969 Return to text ⤴

  27. https://www.wpc.ncep.noaa.gov/storm_summaries/storm3/stormsum_19.html; https://twitter.com/NWSWakefieldVA/status/1225845782588182528 Return to text ⤴

  28. https://www.weather.gov/akq/SnowEventFeb21-2020 Return to text ⤴

  29. https://www.wavy.com/weather/possible-winter-weather-school-impacts-in-virginia-north-carolina/ Return to text ⤴

  30. https://twitter.com/NWS_BaltWash/status/1215254627001753600 Return to text ⤴

  31. https://twitter.com/NWSBinghamton/status/1216413262591299584 Return to text ⤴

  32. http://www.nrcc.cornell.edu/services/blog/2020/02/03/index.html Return to text ⤴

  33. http://www.nrcc.cornell.edu/services/blog/2020/03/02/index.html Return to text ⤴

  34. http://www.nrcc.cornell.edu/services/blog/2020/03/02/index.html Return to text ⤴

  35. http://www.nrcc.cornell.edu/services/blog/2020/03/02/index.html Return to text ⤴

  36. These data were obtained from both the Baltimore Customs House and Baltimore/Washington International Thurgood Marshall Airport (BWI); data prior to 1893 were not included. https://www.weather.gov/media/lwx/climate/bwisnow.pdf; https://twitter.com/NWSEastern/status/1234173182187393024 Return to text ⤴

  37. https://www.usanpn.org/news/spring Return to text ⤴

  38. https://www.washingtonpost.com/weather/2020/02/21/indicators-early-spring-are-fluorishing-all-around-washington/ Return to text ⤴

  39. http://www.nrcc.cornell.edu/services/blog/2020/03/02/index.html Return to text ⤴

  40. https://twitter.com/NWS_BaltWash/status/1233936939721474048 Return to text ⤴

  41. https://www.abc27.com/news/local/plowing-through-winter-how-mild-weather-is-impacting-penndot-private-plow-drivers/ Return to text ⤴

  42. Climate normals, as defined by the National Oceanic and Atmospheric Administration (NOAA), are “three-decade averages of climatological variables including temperature and precipitation.” The latest climate normal released by NOAA is the 1981-2010 average. Return to text ⤴

  43. https://sercc.com/perspectivesmap?var=avgt&period=MTD&date=2019-11-24&type=value; http://www.nrcc.cornell.edu/wxstation/perspectives/perspectives.html Return to text ⤴

  44. https://www.cpc.ncep.noaa.gov/products/predictions/long_range/seasonal.php?lead=2 Return to text ⤴

  45. https://www.cpc.ncep.noaa.gov/products/expert_assessment/season_drought.png Return to text ⤴

  46. https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.html Return to text ⤴

  47. https://www.jstor.org/stable/26183173?seq=1 Return to text ⤴

  48. https://ascelibrary.org/doi/abs/10.1061/(ASCE)CR.1943-5495.0000161 Return to text ⤴

  49. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012GL052483; https://journals.ametsoc.org/doi/full/10.1175/2010JCLI3363.1; https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-13-00750.1; https://link.springer.com/article/10.1007/s10584-014-1257-2; https://nca2018.globalchange.gov/downloads/NCA4_Ch12_Transportation_Full.pdf Return to text ⤴

  50. http://loca.ucsd.edu Return to text ⤴

  51. 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 ⤴

  52. 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-y Return to text ⤴

  53. http://loca.ucsd.edu Return to text ⤴

  54. 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 ⤴

  55. 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-y Return to text ⤴

  56. http://www.nrcc.cornell.edu Return to text ⤴

Back to top