Chesapeake Bay Climate Impacts Summary and Outlook

Mid-Atlantic Regional Climate Impacts Summary and Outlook: Summer 2021

Highlights

  • The majority of the Mid-Atlantic experienced temperatures 1-2 degrees Fahrenheit (F) above normal and some sites had among one of their warmest summers on record.
  • This summer, the Mid-Atlantic saw generally above normal precipitation, notably in southern New York and northern Pennsylvania, while some areas in Maryland, Virginia, and the panhandle of West Virginia experienced below normal precipitation.
  • The Mid-Atlantic saw a large number of severe weather events, including strong thunderstorms, tornadoes, and flash flooding.
  • Four tropical storms impacted the region, generally bringing heavy rain and flash flooding.
  • An analysis of historic and future projected growing degree days (GDDs) shows that the average annual number of GDDs from 1981 to 2020 has already increased, and the region may experience future increases in average annual GDDs greater than 40 percent.

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Part 1: Significant Weather Events and Impacts

Severe Weather

There were numerous days this summer with severe weather (e.g., thunderstorms, tornadoes) or flash flooding. Several noteworthy examples are discussed below.

Select June Severe Weather Events

On June 3, an Enhanced Fujita Scale 1 (EF-1) tornado carved a two-mile path through Baltimore County, Maryland, snapping or uprooting more than 100 trees.1 Flash flooding from the accompanying storm inundated roads, leading to water rescues in Harford County, Maryland, where Bynum Run in Bel Air rose over eight feet in two hours.2

From June 9 to 11, a slow-moving storm system dropped heavy rain on the watershed. Portions of Virginia saw up to 9.58 inches of rain, with the greatest amounts falling in the Northern Neck of Virginia (Lancaster, Northumberland, Richmond, and Westmoreland counties).3,4 The heavy rain caused a partial dam failure at Chandlers Mill Pond near Montross, Virginia.5 Central and southern Maryland also received as much as 9.19 inches of rain, with the greatest amounts falling in Charles County, Maryland.6 Many of these areas in both Virginia and Maryland experienced flash flooding, making roads impassable and stranding vehicles. For example, dozens of streets were closed on the northeast side of Baltimore, Maryland, and there were more than twenty water rescues in Richmond, Virginia.7,8

On June 30, severe thunderstorms produced wind damage in areas from south-central New York to northern Virginia. A few buildings were damages in central Pennsylvania and Loudon County, Virginia.9 A wind gust of 67 miles per hour (mph) was measured in Cecil County, Maryland.10

Select July Severe Weather Events

On July 1, southern portions of the watershed experienced severe storms, including two tornadoes. An EF-1 tornado traveled nearly four-and-a-half miles from Arlington, Virginia, to Washington, D.C., downing and snapping trees, including some on the National Mall.11 Straight-line winds near the path of the tornado caused a tree and some limbs to fall onto a house, injuring a person, while also downing trees near the Lincoln Memorial.12 Another tornado, an EF-0, also briefly touched down in Washington, D.C.13 In addition, straight-line winds of up to 80 mph downed dozens of trees and power lines and damaged crops in Prince Georges, Anne Arundel, and Dorchester counties in Maryland.14,15 Five people were injured when strong thunderstorm winds caused a building under construction to collapse in Washington, D.C.16

Figure 1. Tornado damage in Arlington, Virginia on July 1, 2021

A brick house with damage to the front facade due to a fallen tree.

SOURCE: Michelle Basch / WTOP Radio

From July 11 through July 17 a series of storm systems brought flash flooding and high wind events to the region. Straight-line winds of up to 95-110 mph snapped and uprooted trees in Clinton, Lycoming and Centre counties in Pennsylvania, as well as damaged several campsites and some vehicles in Centre County.17,18 Flash flooding occurred in Broome County, New York; Bradford County, Pennsylvania; and Baltimore, Maryland, causing a State of Emergency declaration, road closures and washed out roads, building damage, evacuations and water rescues.19,20,21

On July 26, severe thunderstorms moved through Maryland and Virginia. A wind gust of 67 mph was recorded in Washington, D.C., where winds downed at least 100 trees.22 In Henrico County, Virginia, a gas station canopy collapsed, injuring a person.23 Several roads in Petersburg and Prince George’s counties in Virginia were closed due to high water.24 Ping pong ball-sized hail fell in Augusta County, Virginia, while lightning sparked several fires in Hanover County, Virginia.25,26

On July 28, severe thunderstorms produced tennis ball-sized hail and wind gusts of up to 75 mph in Albemarle County, Virginia.27 The large hail and high winds damaged vehicles, buildings, trees, and power lines.28

On July 29, severe thunderstorms produced two tornadoes in the watershed, an EF-0 in Lebanon County, Pennsylvania, and an EF-0 in Howard County, Maryland.29,30 Both tornadoes damaged trees and the Maryland tornado damaged a building and lofted several shopping carts.31,32 These tornadoes were part of a larger outbreak of at least 17 tornadoes that mostly struck Pennsylvania and New Jersey.33 Straight-line winds of up to 90 mph in Stafford County, Virginia, snapped or downed at least 100 trees, with ten houses damaged and one destroyed by fallen trees.34 Straight-line winds of up to 80 mph produced a track of widespread tree damage from central to southeastern Virginia.35

Select August Severe Weather Events

Between August 10-15, severe thunderstorms or flash flooding occurred in at least one part of the Chesapeake Bay Watershed each day.36 Strong thunderstorm winds damaged roofs, blew shingles and siding off of houses, snapped power poles, and downed powerlines and hundreds of trees.37,38 Lightning started several structure fires, including one in a condominium in Germantown, Maryland, that caused an estimated $2.5 million in damage and displaced dozens of residents.39,40 Localized flash flooding closes roads and left vehicles stranded.41 A storm produced as much as 3 inches of rain in 30 minutes in Fairfax, Virginia, and neighboring counties in northern Virginia, sending floodwaters into homes and causing Backlick Run in Alexandria, Virginia, to rise more than six feet in under 30 minutes.42,43

On August 27, severe thunderstorms in Maryland and northern Virginia downed numerous trees and wires, some of which fell onto a car and injured three people in Montgomery County, Maryland.44 In Dauphin County, Pennsylvania, several outbuildings collapsed.45 The next day, on August 28, southern parts of the watershed again saw severe storms.46 A person was injured by lightning in Charlottesville, Virginia. 47 Localized flash flooding was reported on both August 27 and 28.48,49

Tropical Storms

On June 21, Tropical Storm Claudette tracked south and east of Virginia, dropping heavy rain on the Hampton Roads area.50,51, The storm had little impact on the Mid-Atlantic region beyond the occurrence of heavy rainfall.

From July 8 to 9, Tropical Storm Elsa moved through Virginia and across the Delmarva Peninsula.52 The greatest rain totals of three to five inches occurred in central Virginia and southern Maryland, where flash flooding led to closed roads and stranded vehicles.53 Petersburg, Virginia, experienced such significant flash flooding that the National Weather Service reported that due to flooding “70% of all roads in the City of Petersburg were closed at the height of the event”.54 Maryland and Virginia also experienced wind gusts up to 60 mph.55 Elsa also spawned three EF-0 tornadoes in southeastern Virginia, two in the City of Suffolk and one in Isle of Wight County, which caused tree damage.56

From August 18–19, the remnants of Tropical Storm Fred made their way through the region. The combination of these tropical storm remnants and a frontal system dropped as much as five inches of rain on central Pennsylvania and south-central New York.57 A rare Flash Flood Emergency was declared for part of Steuben County, New York, where roads were washed out, homes were flooded, and as many as 100 people were evacuated.58 The remnants of Tropical Storm Fred also produced seven weak (EF-0 or EF-1) tornadoes in central and eastern Pennsylvania, with damage mostly consisting of snapped and uprooted trees and minor siding and roof damage to several structures.59

From August 21-23, Tropical Storm Henri brought as much as three inches of rain to portions of northeastern Pennsylvania and south-central New York, resulting in basement flooding, impassable roads, and stranded vehicles.60,61

Drought

In early June, much of Virginia was experiencing abnormally dry or moderate drought conditions.62 Enough precipitation fell during June and the first half of July to ease the moderate drought across the state but did not remove it entirely. As a result, abnormal dryness persisted in portions of western, central, and southern Virginia.63

During the second half of July, below-normal precipitation and above-normal temperatures caused the areas classified as abnormally dry to expand, while moderate drought conditions developed in portions of western and central Virginia.64

During the first half of August, moderate drought and abnormal dryness expanded in the southern parts of the region, including portions of Virginia, eastern West Virginia, western and central Maryland, and south-central Pennsylvania.65 Farmers in Virginia’s Shenandoah Valley reported poor pasture conditions, reduced crop yields, and concerns about low well levels.66 In Harrisonburg, Virginia, officials encouraged residents to conserve water due to drought conditions.67

During the second half of August, increased rainfall allowed moderate drought and abnormal dryness to ease in much of southern Pennsylvania, central and western Maryland, and eastern West Virginia.68 However, in western Virginia, moderate drought and abnormal dryness coverage contracted, but persisted.69

Part 2: Seasonal Temperature and Precipitation

Temperature

Figure 2 shows the June through August 2021 average temperature compared with the climate normal—i.e., the average temperature from 1991 to 2020.70 The figure shows that temperatures were generally above normal across the region, with the majority of the Mid-Atlantic experiencing temperatures 1-2 degrees Fahrenheit (F) above normal, and with portions of central Pennsylvania and southern New York experiencing particularly warmer than normal temperatures. Southern Virginia and southern Maryland experienced temperatures that were within a degree of normal and only a small portion of southwestern Virginia experienced temperatures below normal. This follows a similar pattern to the spring 2021 season (March-May), but with generally warmer than average temperatures in this summer season.

During June, July, and August several sites in the region experienced a high number of warm nighttime lows (low temperatures at or above 70 degrees F) and days with high temperatures at or above 90 degrees F. These included Lynchburg, Virginia, which saw nine days in June, 21 days in July and 19 days in August with temperatures at or above 90 degrees F. Richmond, Virginia, experienced 12 nights in June, 20 nights in July and 24 nights in August with nighttime lows at or above 70 degrees F.

Figure 2. June 1 – August 31, 2021, Departure from Normal Temperature (degrees Fahrenheit)

Heat map showing departure from normal temperature (degrees Fahrenheit) in the Mid-Atlantic region.

SOURCE: Northeast Regional Climate Center, 2021 (https://www.nrcc.cornell.edu). Used with permission.

NOTE: Normal temperature is based on the summer season’s average temperature data from 1991–2020. Yellow, orange, and red indicate above-normal temperatures. Blue indicates below-normal temperatures. The boundaries of the Chesapeake Bay watershed are outlined in bold black. Average departure from normal temperature is based on a station’s normal temperature for summer compared with the same station’s summer 2021 average temperature. Station-level departures from normal are spatially interpolated across the region. Both are produced by the Northeast Regional Climate Center. These can be found at https://www.rcc-acis.org/docs_gridded.html.

Twelve sites in the Mid-Atlantic experienced average seasonal summer temperatures that ranked their top 20 on record. The locations and ranks are reported in Table 1.

Table 1. Summer Temperature Rankings

Station Name Avg. Temp
(degrees F)		 Normal Temp
(degrees F)		Rank
(warmest)
Charlottesville, Virginia 78.3 76.9 3
Harrisburg, Pennsylvania 77.1 75.0 4
Lynchburg, Virginia 77.4 74.1 5
Baltimore, Maryland 78.6 76.0 5
Dulles Airport, Virginia 77.1 75.2 5
Salisbury, Maryland 77.4 75.5 6
Scranton, Pennsylvania 72.8 71.5 6
Norfolk, Virginia 79.7 79.0 6
Washington National, DC 79.5 78.9 8
Williamsport, Pennsylvania 73.7 71.7 9
Binghamton, New York 68.8 66.9 10
Richmond, Virginia 78.5 77.3 10

SOURCE: Northeast Regional Climate Center, 2021 (http://www.nrcc.cornell.edu). Used with permission.

Monthly Temperature Rankings

In June, July, and August, sites across the Mid-Atlantic experienced average monthly temperatures that ranked in the top 20 on record. Locations and ranks are reported in Table 2. In addition, Dulles Airport, Virginia, and Harrisburg, Pennsylvania, tied their daily warmest minimum temperatures for the month of June on June 28 and June 29, respectively.

Table 2. Monthly Temperature Rankings

June Temperature Rankings
Station Name Avg. Temp
(degrees F)		 Normal Temp
(degrees F)		 Rank
(warmest)
Binghamton, New York 67.8 64.4 3
Harrisburg, Pennsylvania 75.5 72.5 3
Dulles Airport, Virginia 74.4 72.5 4
Scranton, Pennsylvania 71.0 69.0 8
Baltimore, Maryland 75.9 73.5 9
Charlottesville, Virginia 75.9 74.8 9
Norfolk, Virginia 78.1 76.7 13
Williamsport, Pennsylvania 71.5 69.4 15
Salisbury, Maryland 74.4 72.7 17
Lynchburg, Virginia 74.7 72.0 20
July Temperature Rankings
Station Name Avg. Temp
(degrees F)		 Normal Temp
(degrees F)		 Rank
(warmest)
Dulles Airport, Virginia 78.3 77.2 14
Charlottesville, Virginia 79.5 79.0 15
Baltimore, Maryland 80.2 78.3 17
Norfolk, Virginia 81.7 81.1 20
August Temperature Rankings
Station Name Avg. Temp
(degrees F)		 Normal Temp
(degrees F)		 Rank
(warmest)
Harrisburg, Pennsylvania 78.3 75.2 2
Lynchburg, Virginia 79.2 74.5 2
Williamsport, Pennsylvania 75.6 72.0 3
Scranton, Pennsylvania 74.7 71.8 3
Dulles Airport, Virginia 78.6 75.7 3
Charlottesville, Virginia 79.4 76.9 3
Salisbury, Maryland 78.8 75.8 4
Baltimore, Maryland 79.7 76.2 5
Binghamton, New York 70.6 67.3 7
Richmond, Virginia 79.9 77.5 8
Washington National, DC 80.9 79.4 9
Martinsburg, West Virginia 76.7 73.8 15

Source: Northeast Regional Climate Center, 2021 (http://www.nrcc.cornell.edu). Used with permission.

Precipitation

Precipitation departures from normal for June 1 through August 31, 2021 are shown in Figure 3. Departures from normal indicate where this summer season’s average daily precipitation was above or below the climate normal—i.e., the average temperature from 1991 to 2020. Figure 3 shows that the region largely experienced above normal precipitation. The wettest portions of the region were in southern New York and northern Pennsylvania, where they received 150% of normal precipitation or more. In contrast, some areas in Maryland, Virginia, and the panhandle of West Virginia experienced below normal precipitation (75-100%). This is a significant change from the generally dry spring 2021 season, however portions of western Virginia experienced dry conditions in both the spring and summer 2021 seasons.

Figure 3. June 1 – August 31, 2021, Percentage of Normal Precipitation

Heat map showing percentage of normal precipitation for the Mid-Atlantic region.

SOURCE: Northeast Regional Climate Center, 2021 (https://www.nrcc.cornell.edu). Used with permission.

NOTE: Normal seasonal precipitation is based on precipitation data from 1991–2020. Brown shades indicate below normal seasonal precipitation. Green shades indicate above normal seasonal precipitation. The boundaries of the Chesapeake Bay watershed are outlined in bold black. Average departures from normal precipitation are based on a station’s normal precipitation for spring compared with the same station’s summer 2021 average amount of precipitation. Station-level departures from normal are spatially interpolated across the region. Both are produced by the Northeast Regional Climate Center. These can be found at https://www.rcc-acis.org/docs_gridded.html.

Three sites in the Mid-Atlantic region saw summer precipitation amounts that ranked in their top twenty on record. The locations and ranks are provided in Table 3.

Notably, Binghamton, New York, received 6.75 inches more rain than normal, making this summer its second wettest summer on record. This follows a top twenty wettest spring season and a top ten wettest winter season.

Table 3. Summer Precipitation Rankings

Station Name Precipitation
(inches)		 Normal Precip
(inches)		 Rank
(wettest)
Binghamton, New York 19.34 12.59 2
Washington National, DC 18.82 11.78 11
Harrisburg, Pennsylvania 15.99 12.49 17

SOURCE: Northeast Regional Climate Center, 2021 (http://www.nrcc.cornell.edu). Used with permission.

Monthly Precipitation Rankings

In July, sites in the Mid-Atlantic saw monthly precipitation totals that ranked amongst the top 20 on record. Locations and ranks for these records are reported in Table 4.

Binghamton, New York, experienced its wettest July on record, which was also its third all-time wettest month on record. Binghamton also experienced 18 days with measurable precipitation in July, tying the record for July. Scranton, Pennsylvania, also had 18 days with measurable precipitation in July, which ranked second for months of July in their records.

Table 4. Monthly Precipitation Rankings

June Temperature Rankings (wettest and driest)
Station Name Precipitation
(inches)		 Normal Precip
(inches)		 Rank
(wettest)
No top 20 rankings set in June.
July Precipitation Rankings (wettest)
Station Name Precipitation
(inches)		 Normal Precip
(inches)		 Rank
(wettest)
Binghamton, New York 9.82 3.80 1
Harrisburg, Pennsylvania 8.00 4.74 9
Williamsport, Pennsylvania 6.99 4.64 10
July Precipitation Rankings (driest)
Station Name Precipitation
(inches)		 Normal Precip
(inches)		 Rank
(wettest)
Charlottesville, Virginia 2.52 3.37 18
Dulles Airport, Virginia 2.43 4.15 19
Norfolk, Virginia 2.63 6.08 19
August Precipitation Rankings (wettest)
Station Name Precipitation
(inches)		 Normal Precip
(inches)		 Rank
(wettest)
Binghamton, New York 6.23 4.10 6
Washington National, DC 9.07 3.25 9
Scranton, Pennsylvania 6.13 3.85 12
Dulles Airport, Virginia 4.93 3.53 15
Charlottesville, Virginia 7.26 3.87 16
Harrisburg, Pennsylvania 5.88 3.77 18

Source: Northeast Regional Climate Center, 2021 (http://www.nrcc.cornell.edu). Used with permission.

Part 3: Fall 2021 Outlook

Temperature and Precipitation

As of August 19, 2021, the NOAA Climate Prediction Center forecasts a 40-60-percent chance of above-normal temperatures for the majority of the Chesapeake Bay watershed and Mid-Atlantic region for September, October, and November 2021.71 The precipitation forecast shows an equal chance of wetter than, drier than, or near-normal conditions across the region for the same period.72

Drought Incidence

The U.S. Seasonal Drought Outlook identifies how drought might change across the United States and categorizes areas by whether drought could develop or become more or less intense. As of August 31, 2021, the outlook indicates no ongoing drought within the Mid-Atlantic region, with drought removal likely along the portions of the border between Virginia and West Virginia.73

Atlantic Hurricane Outlook

Researchers at Colorado State University (CSU) have predicted an above-average probability for major hurricanes for the 2021 Atlantic hurricane season.74 As of August 5, 2021, CSU’s forecast anticipates 18 named storms and 8 hurricanes for 2021, with a 65-percent chance of at least one major hurricane (category 3–5) making landfall on the eastern U.S. coastline.75 NOAA’s Climate Prediction Center, which issues a hurricane outlook for the Atlantic at the end of each spring season, is forecasting a 65-percent chance of an above-normal 2021 Atlantic hurricane season. NOAA’s outlook forecasts 15-21 named storms, 7-10 hurricanes, and 3-5 major hurricanes.76 According to NOAA, “an average hurricane season produces 14 named storms, of which seven become hurricanes, including three major hurricanes.”77

NOAA’s Climate Prediction Center, which monitors the likelihood of occurrence of El Niño and La Niña climate phenomena, has a La Niña Watch active as of August 12, 2021.78 The occurrence of La Niña can result in near- to slightly above-normal temperatures and near- to slightly below-normal precipitation during winter in parts of the Mid-Atlantic.79

Part 4: Growing Degree Days

Growing Degree Days (GDDs) measure the number of degrees that accumulate over a given year, as a metric of the heat available for various needs (i.e. crops, insects) and are an important metric for agricultural management.80 GDDs help estimate when different plants and insects will arrive at various life stages, which is useful for determining when to plant crops and when to protect plants from various pests.81 Generally, a larger number of GDDs indicates warmer growing conditions.82 Research has shown that GDDs are increasing across the continental United States, which may reduce crop yields across the United States, particularly for corn, soybean, sorghum and wheat.83

GDDs can be calculated in a number of ways, but for this analysis we use the following equation:

Growing Degree Days Gained = Average Daily Temperature – Baseline Temperature

with a baseline temperature of 50 degrees F. This number is calculated for each day of the year and each positive number is added together to get the total annual GDDs. If GDDs are negative for a given day, which occurs when the average daily temperature is below 50 degrees F, it is not included in the annual total. To calculate the GDDs for a specific crop, a different baseline temperature is usually selected. For example, a baseline temperature of 40 degrees F is typically used for wheat, barley or rye, while 50 degrees F is used for corn, sorghum or rice.84

The number of GDDs varies with geography, with more southern or lower elevation areas typically having more GDDs in a given year and northern or higher elevation areas having fewer GDDs.

Increases in GDDs over time indicate either more days with average temperatures above 50 degrees F, or an increase in the average temperatures on days that were already above 50 degrees F, or some combination of the two. Therefore, increases in GDDs could potentially indicate an increase in the length of the growing season.

Changes in the accumulation of GDDs over the course of a year can also shift the timing of various crops and insect cycles. This could create a situation where crops reach vulnerable stages in their development at a time of year where frosts are still possible or when precipitation is less available.

Figures 4 and 5 display an analysis of historic (Figure 4) and future projected (Figure 5) growing degree days across the Mid-Atlantic.

Key Findings

  • Across all observed historic observations and the future modeled time periods, the southeastern portion of the region (Eastern Maryland and Central and Eastern Virginia) experiences the greatest number of GDDs.
  • The average annual number of GDDs has increased from 1981 to 2020 according to historic observations (Figure 4).
  • The average annual number of GDDs is projected to continue to increase in the future, for both the low and high emissions scenarios (Figure 5).
  • In a high emissions future, portions of Eastern Virginia and Coastal Maryland may experience increases in average annual GDDs greater than 40 percent (Figure 5).

Figure 4. Average Annual Number of Growing Degree Days from Historic Observations

How to Use the Tool

Selecting Time Periods
Use the Time Period slider bar to adjust the decade used to calculate the average annual growing degree days.

Viewing Variability Within a Location
Hover or tap over a point of interest. A window will pop up that displays changes in growing degree days by decade. You can also use the Geography filter to the right of the map to zoom into a location of interest.

Technical Notes

NOTE: In this analysis, growing degree days are calculated for each day using the following formula: Growing Degree Days Gained = Average Daily Temperature – Baseline Temperature. In our calculations, the baseline temperature is 50 degrees F. Positive numbers from each day of the year are added together to create a total Growing Degree Days number for the year. For the historical data, we plot the average of this number over a 10-year period, using 1981–1990 to represent the baseline period.

These maps were generated with gridded temperature estimates from the PRISM Climate Group at Oregon State University. Parameter-Elevation Regressions on Independent Slopes Model (PRISM) daily mean temperature data are available at a 4-km resolution for the coterminous United States. Data were processed by the Northeast Regional Climate Center. More information on PRISM data can be found at http://www.prism.oregonstate.edu.

Figure 5. Average Annual Number of Growing Degree Days from Global Climate Model Data

How to Use the Tool

Selecting Time Periods and Future-Emissions Scenarios
Use the slider to the right of the maps to adjust the 30-year period used to calculate the average annual number of growing degree days. Users can also select the future-emissions scenario (Low or High Emissions).

Viewing Variability Within a Location
Hover or tap over a point of interest. A window will pop up that displays changes in growing degree days by decade. You can also use the Geography filter to the right of the map to zoom into a location of interest.

Technical Notes

NOTE: Localized Constructed Analogs (LOCA) is a downscaled climate data product available at 1/16-degree (6-km) resolution over the continental United States. LOCA data sets85 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, Representative Concentration Pathway (RCP) 4.586; and a high-emissions future, RCP 8.587. For this study, we used LOCA data over the Chesapeake Bay watershed from 1991–2100 (or 2099 for some models). Access LOCA datasets and learn more about the methodology.

Data were processed by the Northeast Regional Climate Center to calculate the average annual growing degree days. In this analysis, growing degree days are calculated for each day using the following formula: Growing Degree Days Gained = Average Daily Temperature – Baseline Temperature.

In our calculations, the baseline temperature is 50 degrees F. Positive numbers from each day of the year are added together to create a total Growing Degree Days number for the year. For the future projected data, we plot the average of this number over a 30-year period and use 1991–2020 to represent the historic period. Note that the final future period is only 20 years long, due to availability of climate model data. These values were calculated for a low-emissions future (RCP 4.5)88 and a high-emissions future (RCP 8.5)89. A weighted average was provided by the Northeast Regional Climate Center to average across climate models for each grid cell in the LOCA data set.90 The LOCA data sets were masked to the boundaries of the Mid-Atlantic region.

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The Mid-Atlantic Regional Integrated Sciences and Assessments (MARISA) Seasonal Climate Impacts Summary and Outlook is a quarterly series produced by the MARISA program, a collaboration funded by NOAA through the RAND Corporation 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 data sets for the benefit of policymakers, practitioners, residents, and community leaders in the Mid-Atlantic region. Projections of weather and climate variability and change in the Mid-Atlantic region 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), Jessica Spaccio (Cornell University), Samantha Borisoff (Cornell University), and Arthur T. DeGaetano (Cornell University).

Citation: Miro, Michelle E., Krista Romita Grocholski, Jessica Spaccio, Samantha Borisoff, and Arthur T. DeGaetano, Mid-Atlantic Regional Climate Impacts Summary and Outlook: Summer 2021. Santa Monica, CA: RAND Corporation, 2021.

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Footnotes

  1. https://www.spc.noaa.gov/climo/reports/210603_rpts.html Return to text ⤴

  2. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=LSRLWX&e=202106040038 Return to text ⤴

  3. https://www.weather.gov/akq/Jun_11_2021_Flooding Return to text ⤴

  4. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=PNSLWX&e=202106121637 Return to text ⤴

  5. https://www.cbs19news.com/story/44126580/major-rain-event-caused-partial-dam-failure-in-westmoreland-county Return to text ⤴

  6. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=PNSLWX&e=202106121637 Return to text ⤴

  7. https://www.weather.gov/akq/Jun_11_2021_Flooding Return to text ⤴

  8. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=LSRLWX&e=202106110259 Return to text ⤴

  9. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=LSRCTP&e=202107010237 Return to text ⤴

  10. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=LSRLWX&e=202107010333 Return to text ⤴

  11. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=PNSLWX&e=202107022328 Return to text ⤴

  12. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=PNSLWX&e=202107022328 Return to text ⤴

  13. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=PNSLWX&e=202107022328 Return to text ⤴

  14. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=PNSLWX&e=202107031830 Return to text ⤴

  15. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=PNSAKQ&e=202107021717 Return to text ⤴

  16. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=PNSAKQ&e=202107021717 Return to text ⤴

  17. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=PNSCTP&e=202107180303 Return to text ⤴

  18. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=PNSCTP&e=202107122000 Return to text ⤴

  19. https://www.baltimoresun.com/weather/bs-md-storms-saturday-20210717-jztm3uns6fb25b6nmriudwkgma-story.html Return to text ⤴

  20. https://www.pahomepage.com/news/local-news/bradford-county-deals-with-flooding-damage-after-monday-night-storms/ Return to text ⤴

  21. https://wbng.com/2021/07/12/in-photos-flood-damage-across-broome-county/ Return to text ⤴

  22. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=LSRLWX&e=202107181232 Return to text ⤴

  23. https://www.wric.com/news/one-person-injured-after-citgo-gas-station-roof-flies-off-fueling-station/ Return to text ⤴

  24. https://www.progress-index.com/story/news/2021/07/26/national-weather-service-issues-flood-storm-watch-petersburg/5377129001/ Return to text ⤴

  25. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=LSRAKQ&e=202107270046 Return to text ⤴

  26. https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=LSRAKQ&e=202107270046 Return to text ⤴

  27. https://twitter.com/NWS_BaltWash/status/1420584900923596800 Return to text ⤴

  28. https://www.spc.noaa.gov/climo/reports/210728_rpts.html Return to text ⤴

  29. https://www.weather.gov/ctp/20210729_Myerstown_Tornado Return to text ⤴

  30. https://nwschat.weather.gov/p.php?pid=202107302155-KLWX-NOUS41-PNSLWX Return to text ⤴

  31. https://www.weather.gov/ctp/20210729_Myerstown_Tornado Return to text ⤴

  32. https://nwschat.weather.gov/p.php?pid=202107302155-KLWX-NOUS41-PNSLWX Return to text ⤴

  33. https://www.spc.noaa.gov/climo/reports/210729_rpts.html Return to text ⤴

  34. https://nwschat.weather.gov/p.php?pid=202107302155-KLWX-NOUS41-PNSLWX Return to text ⤴

  35. https://www.weather.gov/akq/Jul_29_2021_Supercell Return to text ⤴

  36. https://www.spc.noaa.gov/ Return to text ⤴

  37. http://mesonet.agron.iastate.edu/wx/afos/p.php?pil=LSRLWX&e=202108140408 Return to text ⤴

  38. http://mesonet.agron.iastate.edu/wx/afos/p.php?pil=LSRLWX&e=202108150013 Return to text ⤴

  39. https://www.washingtonpost.com/local/storms-fairfax-dominion-power-montgomery/2021/08/10/3f97ac4a-fa36-11eb-9c0e-97e29906a970_story.html Return to text ⤴

  40. https://wjla.com/news/local/lightning-strike-likely-cause-for-attic-fire-at-montgomery-county-apartment Return to text ⤴

  41. https://www.wric.com/news/local-news/richmond/flash-flood-warning-in-effect-in-chesterfield-as-heavy-rains-move-through-the-area-on-sunday/ Return to text ⤴

  42. https://www.washingtonpost.com/local/alexandria-flash-flood/2021/08/15/7c05d54a-fdcd-11eb-a664-4f6de3e17ff0_story.html Return to text ⤴

  43. https://twitter.com/NWS_BaltWash/status/1426767098060185601 Return to text ⤴

  44. http://mesonet.agron.iastate.edu/wx/afos/p.php?pil=LSRLWX&e=202108281634 Return to text ⤴

  45. https://www.spc.noaa.gov/climo/reports/210827_rpts.html Return to text ⤴

  46. https://www.spc.noaa.gov/climo/reports/210828_rpts.html Return to text ⤴

  47. http://mesonet.agron.iastate.edu/wx/afos/p.php?pil=LSRLWX&e=202108290229 Return to text ⤴

  48. http://mesonet.agron.iastate.edu/wx/afos/p.php?pil=LSRLWX&e=202108281634 Return to text ⤴

  49. http://mesonet.agron.iastate.edu/wx/afos/p.php?pil=LSRLWX&e=202108282342 Return to text ⤴

  50. https://www.nhc.noaa.gov/archive/2021/CLAUDETTE.shtml Return to text ⤴

  51. https://www.pilotonline.com/weather/storms/vp-nw-flash-flood-warning-as-claudette-strengthens-20210621-s2nsshusmbbkzjbgoky6tyidte-story.html Return to text ⤴

  52. https://www.nhc.noaa.gov/archive/2021/ELSA.shtml Return to text ⤴

  53. https://www.weather.gov/akq/DetailedSummary_Elsa_Jul82021 Return to text ⤴

  54. https://www.weather.gov/akq/DetailedSummary_Elsa_Jul82021 Return to text ⤴

  55. https://www.weather.gov/akq/DetailedSummary_Elsa_Jul82021 Return to text ⤴

  56. http://mesonet.agron.iastate.edu/wx/afos/p.php?pil=PNSAKQ&e=202107110234 Return to text ⤴

  57. https://www.weather.gov/bgm/pastFloodAugust202021 Return to text ⤴

  58. https://www.democratandchronicle.com/story/news/2021/08/19/steuben-county-ny-declares-state-emergency-after-flooding/8193587002/ Return to text ⤴

  59. https://www.spc.noaa.gov/climo/reports/210818_rpts.html Return to text ⤴

  60. https://twitter.com/NWSEastern/status/1429806738820288514 Return to text ⤴

  61. http://mesonet.agron.iastate.edu/wx/afos/p.php?pil=LSRBGM&e=202108231413 Return to text ⤴

  62. https://droughtmonitor.unl.edu/data/png/20210601/20210601_va_trd.png Return to text ⤴

  63. https://droughtmonitor.unl.edu/data/png/20210713/20210713_va_trd.png Return to text ⤴

  64. https://droughtmonitor.unl.edu/data/png/20210727/20210727_va_trd.png Return to text ⤴

  65. https://droughtmonitor.unl.edu/data/png/20210810/20210810_usdm.png Return to text ⤴

  66. https://www.nvdaily.com/nvdaily/drought-conditions-continue-to-strain-regions-farmers/article_4f9c0c83-65ae-5e38-88a5-59c9d8a41432.html Return to text ⤴

  67. https://www.whsv.com/2021/08/13/harrisonburg-encourages-residents-conserve-water/ Return to text ⤴

  68. https://droughtmonitor.unl.edu/data/png/20210824/20210824_rcc_northeast_cat.png Return to text ⤴

  69. https://droughtmonitor.unl.edu/data/png/20210824/20210824_va_cat.png Return to text ⤴

  70. 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 1991–2020 average. See https://www.ncdc.noaa.gov/data-access/land-based-station-data/land-based-datasets/climate-normals#:~:text=Climate%20Normals%20are%20three%2Ddecade,variables%20including%20temperature%20and%20precipitation. Return to text ⤴

  71. For more information on how NOAA defines at, above or below normal and determines percent chances, see: https://www.cpc.ncep.noaa.gov/products/predictions/long_range/seasonal_info.php Return to text ⤴

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

  73. https://www.cpc.ncep.noaa.gov/products/expert_assessment/season_drought.png; The Mid-Atlantic has experienced severe to extreme droughts in the past, most notably in the mid-1980s, the late 1990s, and the 2000s. https://onlinelibrary.wiley.com/doi/pdf/10.1111/1752-1688.12600 Return to text ⤴

  74. https://tropical.colostate.edu/forecasting.html Return to text ⤴

  75. https://tropical.colostate.edu/forecasting.html Return to text ⤴

  76. https://www.noaa.gov/news-release/atlantic-hurricane-season-shows-no-signs-of-slowing Return to text ⤴

  77. https://www.noaa.gov/news-release/atlantic-hurricane-season-shows-no-signs-of-slowing Return to text ⤴

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

  79. https://www.weather.gov/lwx/research_dcbalt_lanina Return to text ⤴

  80. https://newa.cornell.edu/index.php?page=about-degree-days Return to text ⤴

  81. https://ag.umass.edu/landscape/fact-sheets/growing-degree-days-for-management-of-insect-pests-in-landscape Return to text ⤴

  82. http://climatesmartfarming.org/tools/csf-county-climate-change/ Return to text ⤴

  83. https://www.nature.com/articles/s41598-018-25212-2#Tab1 Return to text ⤴

  84. https://mrcc.illinois.edu/gismaps/info/gddinfo.htm Return to text ⤴

  85. https://loca.ucsd.edu/ Return to text ⤴

  86. More information on RCP 4.5 can be found in: https://loca.ucsd.edu/ Return to text ⤴

  87. More information on RCP 8.5 can be found in: https://doi.org/10.1007/s10584-011-0149-y Return to text ⤴

  88. More information on RCP 4.5 can be found in: https://doi.org/10.1007/s10584-011-0151-4 Return to text ⤴

  89. More information on RCP 8.5 can be found in: https://doi.org/10.1007/s10584-011-0149-y Return to text ⤴

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

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