Speaker: Sam Lashley
This talk will examine past weather and climate trends, recent weather events, and potential future weather conditions across Indiana.
Sam Lashley is a veteran meteorologist with over 33 years of operational experience, culminating in his retirement in 2025 as the Warning Coordination Meteorologist for the National Weather Service (NWS) in Indianapolis. In that capacity, Sam served as the primary liaison for state and local partners, leading Impact-Based Decision Support Services (IDSS) to strengthen community resilience against severe weather and hydrological hazards. Today, Sam is the founder of Sunny Sam Enterprises LLC, a natural hazards consulting service specializing in preparedness and safety planning along with table top exercises focused on natural hazard event planning, operations, and recovery. Sam was born and raised in Crawfordsville, IN where he lives today with his wife Lesley.
Sponsored by Don Cummings.
Program: Indiana Weather and Climate: A Look at the Past, Present and Future
Speaker: Sam Lashley, BS, veteran meteorologist with NWS (retired) and founder of Sunny Sam Enterprises, a natural hazards consulting service, Crawfordsville, IN
Introduced By: Don Cummings
Attendance: NESC: 107; Zoom: 31
Guests: Alex Nelson, Kathleen Tobey
Scribe: Judy Weitzman
Editor: Carl Warner
Talk’s Zoom recording found at: https://www.scientechclubvideos.org/zoom/08102026.mp4
Today’s program was presented by Sam Lashley and dealt with Indiana climate and weather. Lashley is a retired National Weather Service meteorologist who now works part-time at the Indiana State Climate Office and runs a weather consulting business. His duties with the Climate Office include coordinating the Indiana Mesonet Site that hosts and deploys dense weather networks across the State to retrieve precise, localized weather data. The retrieval and cataloguing of this information is vital to providing accurate and timely weather reports, predicting weather events and maintaining data that allows us to recognize patterns and changes to those patterns.
There is a difference between weather and climate. Weather refers to short-term conditions that allow meteorologists to predict in-coming weather with 80-85% accuracy within 2 to 3 days. Climate is based on historical data and allows predictions based on past patterns. Lashley stressed several times that accurate reporting and recording of weather is vital to understanding climate and how it changes.
Historical records demonstrate that drought patterns and extreme wet conditions have routinely happened during our history. What we are seeing now is increased intensity in those events. A number of things can help explain this change.
- Because the earth’s atmosphere is warming it holds more moisture. This results in heavier rainfall and more extreme weather events, especially during hurricanes, leading to the increase in extreme rainfall events frequently reported in the news. In addition to that, our oceans are warming, helping to intensify the weather condition over the equatorial Pacific known as El Nino. The jet stream carries the effects of El Nino for thousands of miles. The warmth and increased moisture combine to create the extreme rain events.
- Besides carrying warm damp weather from the Pacific into the US, El Nino also locks in cold air to the north, resulting in milder winters in Indiana with below normal snowfall. Another effect of El Nino is to cause stronger upper-level winds over the Atlantic, thereby suppressing Atlantic hurricane activity.
- Teleconnection like the Arctic Oscillation and North Atlantic Oscillation cause short-term variability in weather, sometimes overriding El Nino effects temporarily. Polar vortex impacts are strongest during negative Arctic Oscillation phases when jet streams weaken and dip south.
And how does all of this affect us in Indiana?
These changes in weather from drought to extreme wet are brutal on farmers. Plants without water cannot grow, and fields that are too wet because of extreme rain are difficult to seed and maintain. Extreme rain has a bad tendency to cause soil erosion and nutrient run-off.
We have experienced an increase in weaker tornados (EF0-EF1) which rarely cause fatalities. Since 1980, 86% of Indiana tornadoes were weak, resulting in only 2 fatalities. However, stronger tornados (EF2-EF5), which occur in cycles, have increased over the last few years with EF3 and EF4 intensities.
Lashley strongly emphasized the need to accurately report and record weather related data. Mesonet (centralized in the Indiana Climate Office) and CoCoRaHS provide essential high quality data. CoCoRaHS is a grassroots volunteer network of backyard weather observers of all ages and
backgrounds working together to measure and map precipitation (rain, hail, and snow) in their local communities in the US, Canada and the Bahamas. We were all encouraged to visit their website (https://www.cocorahs.org/), learn more and maybe get involved.
Sam Lashley
