What Are the Lehigh Valley's Natural Hazards?

Earlier this week, I told you that both Lehigh and Northampton County Emergency Management agencies are in the process of updating the Lehigh  Valley Hazard Mitigation Plan Hazards. It identifies both natural and man-made hazards. Below is a listing of the natural hazards considered here in thye Lehigh Valley, which include a summary of past occurrences and an estimate of the likelihood of recurrence.  I'll list man-made hazards on Friday. 

Drought: "Predicting the frequency of droughts is challenging. However, droughts appear to be cyclical, implying they'll reoccur in the future. In fact, periodic droughts are commonplace in almost all U.S. climates."

Earthquake: "Based on the Lehigh and Northampton County Emergency Management Agencies’ operational viewpoint, as well as previous historical earthquake events, the probability of occurrence for earthquake events in the Lehigh Valley is considered Unlikely (less than 1% annual probability), as defined in the Methodology Section."

Extreme temperature: "The highest temperature ever recorded in the region was 105°F on the 4th of July weekend in 1966, while the lowest temperature ever recorded was -15°F on January 21, 1994. Since 1996, the Lehigh Valley was subject to more than 196 extreme temperature events. ... Over the 27 years of record keeping of extreme temperature events (1996-2023), there have been 196 recorded events, an average of 7.25 events per year. In the last 10 years, 2013 – 2023, there has been an extreme temperature event in 7 of the 10 years. As such, the probability that the Lehigh Valley will experience an extreme temperature event in any given year is Highly Likely."

Flood, Flash Flood, Ice Jam: "The Lehigh Valley has a long history of flooding events. According to NOAA’s National Centers for Environmental Information (NCEI) Storm Events Database, the Lehigh Valley experienced 235 flood events between January 1, 1996, and March 31, 2023. These floods resulted in one death, four injuries, an estimated $145.75 million in property damages, and approximately $2 million in crop damages. ... Based on the Lehigh and Northampton County Emergency Management Agencies’ operational viewpoint, the probability of occurrence for flood events in the Lehigh Valley is considered Highly Likely with a higher than 90% probability of annual occurrences as defined in the Methodology Section."

Hailstorm: "Hailstorms can occur as a routine part of severe weather in the Lehigh Valley. The potential for hail exists throughout the Lehigh Valley, with a few minor incidents recorded each year. ... Based on historical occurrences of hailstorm events retrieved from NCEI, the probability of occurrence for hailstorm events in the Lehigh Valley is considered Highly Likely, greater than 90% annual probability as defined in the Methodology Section."

Invasive Species: "Invasive species have been entering the Lehigh Valley for quite some time, though not all occurrences have required government action. Specific occurrences and quantified losses were not identified for these invasive species in the Lehigh Valley. ... Based on the Lehigh and Northampton County Emergency Management Agencies’ operational viewpoint, the probability of occurrence for invasive species impacting the Lehigh Valley is considered ‘highly likely’ (higher than 90% probability) as defined in the Methodology Section."

Landslide: "Pennsylvania has frequently been a hotspot for significant landslide occurrences due to its unique blend of a humid climate, locally intense topography, and the varied erosion and weathering characteristics of its sedimentary rocks. Additionally, human endeavors, including commercial, residential, and industrial development, along with transportation and mining projects, often intensify the susceptibility to landslides. ... From the perspective of the Lehigh and Northampton County Emergency Management Agencies, the probability of landslides occurring in the Lehigh Valley is categorized as 'unlikely'."

Lightning Strikes: "Defined as a lightning strike resulting in death, injury, or damage to property or crops, a lightning "event" has specific consequences. From 1993 to 2023, the Lehigh Valley registered 86 such events, with Northampton County accounting for 60 and Lehigh County for 26, as documented by NOAA-NCEI. ... Based on the Lehigh and Northampton County Emergency Management Agencies’ operational viewpoint, the probability of occurrence for lightning strike events is considered ‘highly likely’ as defined in the Methodology Section."

Pandemic and Infectious Disease: Includes data concerning incidence of COVID-19, influenza, West Nile virus and lyme disease. "Influenza is among the most common and recognizable diseases within the Lehigh Valley, the Commonwealth of Pennsylvania, and the U.S. as a whole. Influenza virus infections are detected year round in the U.S., although cases typically increase during “flu season” in the fall and winter months. ... Based on the Lehigh and Northampton County Emergency Management Agencies’ operational viewpoint, the probability of occurrence for pandemic and infectious disease events in the Lehigh Valley is considered ‘likely’ as defined in the Methodology Section."

Radon Exposure: The LV is in a "Zone 1" radon zone, "which means that the average indoor radon levels are likely to exceed 4 pCi/L (picocuries per liter). The EPA recommends that all homeowners who have radon concentrations of 4 pCi/L or greater take remedial actions to reduce the presence of radon. ... Radon is a constant threat throughout the Lehigh Valley. As a naturally occurring element, radon has been present in the ground across the Lehigh Valley since long before the area was settled. Overall, Pennsylvania is an area with historically high radon levels due to shear fault zones in the state that contain large amounts of uranium which eventually decays into radon. ... Radon exposure is inevitable given present soil, geologic, and geomorphic factors across Pennsylvania. In the future, the overall likelihood of radon exposure in the Lehigh Valley will remain high."

Subsidence/Sinkholes: "The Pennsylvania Department of Conservation and Natural Resources’ Sinkhole Inventory Online Database, along with the 2023 Pennsylvania State Hazard Mitigation Plan, recorded 470 sinkholes in Lehigh County and 677 in Northampton County between 2010 and 2013. Additionally, local data from the Lehigh and Northampton County Knowledge Center databases for 2012 and 2017 indicate 101 sinkhole incidents across 23 municipalities. Bethlehem Township experienced the highest number of sinkholes (28), followed by Palmer Township (19), Easton (12), Hanover Township in Northampton County (6), and Lower Saucon Township (5). ... . From the perspective of the Emergency Management Agencies of Lehigh and Northampton Counties, the likelihood of subsidence and sinkhole incidents in the Lehigh Valley is categorized as 'likely,' in accordance with the definition provided in the Methodology Section." 

Wildfire: "The Pennsylvania 2023 State Hazard Mitigation Plan notes reported wildfires and acres burned in the Lehigh Valley between 1992 and 2015. 122 wildfires in Lehigh County burned over 313 acres, while 87 wildfires in Northampton County burned more than 168 acres. 151 Wildfire events that were recorded in the National Centers for Environmental Information (NCEI) Storm Events ... with one death reported. In addition, Lehigh and Northampton County Knowledge Center databases identified 67 brushfires from 2012 to 2017. Information regarding damages, injuries or deaths was not available. ... Based on the Lehigh and Northampton County Emergency Management Agencies operational viewpoint, the probability of occurrence for wildfire events in the Lehigh Valley is considered ‘possible’ as defined in the Methodology Section.

Windstorm/Tornado: "Data from the NCEI Storm Events Database reveals a notable increase in tornado occurrences over recent decades. Comparing two periods, from 1950 to 1995, a span of 46 years, there were 493 tornadoes recorded. In contrast, a shorter period from 1996 to 2021, lasting only 26 years, saw a similar number of tornadoes at 497. This trend appears to be more pronounced regionally and might partly be attributed to advancements in reporting techniques. According to a 2018 report by the National Weather Service, part of NOAA, the overall frequency of tornadoes across the United States has been relatively steady since 1950, suggesting that the observed increase could be linked to more sophisticated and thorough reporting methods. ... From the perspective of the Lehigh and Northampton County Emergency Management Agencies, the probability of windstorm and tornado events occurring in the Lehigh Valley is categorized as 'possible,' as outlined in the Methodology Section. This classification underscores the need for continued vigilance and preparedness in the face of these natural phenomena."

Winter Storm: "Data from the National Oceanic and Atmospheric Administration and the National Centers for Environmental Information reveal that between 1993 and 2023, Lehigh County encountered 256 winter storm events, while Northampton County faced 257. These events led to property damages of approximately $3.8 million in Lehigh County and $2.25 million in Northampton County. ... . Based on assessments by the Emergency Management Agencies of both Lehigh and Northampton counties, the probability of winter storm events occurring in the Lehigh Valley is classified as 'likely'."