Highlights

• The Spring season saw a high number of tornadoes—nearly 40—across the Chesapeake Bay region, breaking records in many states.
• Spring precipitation was up to double historical averages in the northern Chesapeake Bay.
• Spring temperature was above average for most of the Chesapeake Bay watershed.
• The region could expect normal to near-normal hurricane activity for the 2019 summer to fall hurricane season in the Atlantic Ocean.
• An analysis of multi-decadal changes in seasonal precipitation shows that the region has experienced increases in summer seasonal precipitation, as well as increases in the variability of fall precipitation.
• An analysis of future projections of seasonal total precipitation suggests that increased precipitation, compared to historical averages, could continue.

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Part 1: Significant Weather Events

On March 21 and 22, a coastal storm brought snow and heavy rain to the region. Some areas received heavy rain, with the greatest 24 hour rainfall totals of up to 3.90 inches in southern Pennsylvania, Maryland, and northern Virginia.¹ On March 21, Dulles Airport, Virginia, received 2.69 inches of rain², its wettest March day on record (since 1960), which led to flooding, closed roads and stranded vehicles.³ Higher elevations received up to 10 inches of snow. A road in the Blue Ridge Mountains of Virginia was closed for several hours because dozens of vehicles became stuck due to snow and ice.⁴

On April 14 and 15, a severe weather outbreak occurred. Nine tornadoes touched down in Pennsylvania, five of which were in the Chesapeake Bay Watershed and included one Enhanced Fujita (EF) scale EF-0 tornado, three EF-1s, and one EF-2.⁵ In addition, there was one EF-0 tornado in Maryland, one EF-1 tornado in New York, and two tornadoes in Delaware, an EF-1 and an EF-2.⁶ The storms also produced straight-line winds⁷ of up to 105 mph, ping pong ball-sized hail, and over 2.50 inches of rain in some areas.⁸ Dozens of homes and buildings were damaged. Numerous trees were snapped and uprooted, and power lines were downed, leading to power outages and road closures.⁹

A few days later, on April 19, Virginia had its third largest single-day tornado outbreak with 16 tornadoes: nine EF-0s, four EF-1s, two EF-2s, and one EF-3.¹⁰ The EF-3 touched down in Franklin County, VA, the fourth recorded EF-3 tornado in the Blacksburg National Weather Service forecast area.¹¹ In addition, five tornadoes, three EF-1s and two EF-2s, touched down in southern Pennsylvania; Fulton County had its first April tornado on record.¹² Straight-line winds of up to 100 mph also occurred in the region. The storms damaged homes and other structures, destroyed outbuildings, and uprooted and snapped trees.¹³ Heavy rain caused flash flooding in parts of Virginia, closing some roads. With 14 tornadoes during April, Pennsylvania had its greatest number of April tornadoes since records began in 1950.¹⁴

A third round of severe thunderstorms downed wires and dozens of trees and caused damage to homes and buildings in the Mid-Atlantic on April 26.¹⁵ An EF-1 tornado touched down in north-central Maryland, mainly snapping and uprooting trees.¹⁶

On May 11, two EF-1 tornadoes touched down in Virginia, damaging trees and at least a dozen homes.¹⁷ An EF-1 tornado in south-central Pennsylvania on May 19 snapped and uprooted numerous trees, leading to a temporary closure of the Pennsylvania Turnpike.¹⁸ A few days later, on May 23, two tornadoes touched down in the region: an EF-0 in Pennsylvania and EF-1 in Maryland.¹⁹ Severe thunderstorms on May 25 and 26 produced a funnel cloud and golf ball-sized hail, as well as damaging wind gusts, in northern Virginia.²⁰

From May 28 to 31, ten weak (EF-0 or EF-1) tornadoes touched down in the Chesapeake Bay region: eight in Pennsylvania and two in Maryland, accompanied by straight-line winds of up to 90 mph, softball-sized hail, and flash flooding.²¹ Storm reports indicated roofs were lifted off of several structures and hundreds of trees were downed, some of which fell on buildings.²² Pennsylvania had one of its most active Mays for tornadoes on record (since 1950), with 16 tornadoes.²³ The state had 30 tornadoes during the spring season, which is six times greater than average.²⁴

Part 2: Seasonal Temperature and Precipitation

Temperature

An analysis of Spring 2019 average temperature, shown in Figure 1, compared to the average from 1976 to 2005, indicates above-average departures from average historical temperature for most of the Chesapeake Bay watershed, including increases above 2°F in spring temperatures in the greater Baltimore metropolitan region and in western Virginia.

Note: Historical average temperature is based on temperature data from 1976-2005. Red indicates above-average temperature.

Source: Northeast Regional Climate Center, 2019.

Precipitation

From March 1 through May 31, 2019, precipitation departures from average historical precipitation for the period 1976 to 2005 show that the region experienced both increases and decreases in precipitation compared to historical average precipitation, as shown in Figure 2. Western Virginia, southern and central Pennsylvania and northern Maryland experienced the highest rates of precipitation departures—up to 200 percent of the historical average. Southern Maryland and Eastern Virginia experienced decreases in precipitation up to 75 percent of average.

Note: Historical average seasonal precipitation is based on precipitation data from 1976-2005. Brown indicates below-average seasonal precipitation.

Source: Northeast Regional Climate Center, 2019.

Part 3: Summer 2019 Outlook

Temperature and Precipitation

As of May 16, 2019, NOAA’s Climate Prediction Center forecasts a 40–60% chance of temperatures above normal for the majority of the Chesapeake Bay Watershed. The precipitation forecast shows a 33–40% chance of precipitation above normal in the Southern half of the watershed for June–August 2019 in the Mid-Atlantic region.²⁵

Drought Incidence

The United States Seasonal Drought Outlook identifies how drought may change across the United States, and categorizing areas by whether drought could develop or become more or less intense. As of May 16, 2019, the outlook indicates no likelihood of drought for the Chesapeake Bay Watershed.²⁶ The Chesapeake Bay region has experienced severe to extreme droughts in the past, most notably in the mid-1980s, the late 1990s and the 2000s. ²⁷

Atlantic Hurricane Outlook

NOAA’s Climate Prediction Center, which issues a hurricane outlook for the Atlantic at the end of each spring season, is forecasting a normal hurricane season with 9–15 named storms, 4–8 hurricanes and 2–4 major hurricanes.²⁸ Researchers at Colorado State University (CSU) have predicted an average 2019 hurricane season in the Atlantic. As of June 4, 2019, CSU's total seasonal forecast calls for 14 named storms and 6 hurricanes for 2019, with a 32 percent chance of at least one major hurricane (category 3-5) making landfall on the eastern U.S. coastline.²⁹

Part 4: Seasonal Precipitation Trends and Projections

The following figures provide detail on how the total precipitation occurring each season has changed over time (Figure 3) and could change into the future (Figure 4). For a visual analysis of these changes across the Chesapeake Bay Watershed, please see Winter 2018-2019 Climate Summary.