2023 05/25
Dr. Jason Keeler Mobile Mesonets Research

Before the meeting officially began, Dr. Jason Keeler provided attendees with a show-and-tell of Central Michigan University’s Mobile Mesonet. He explained many of the instruments installed on the vehicle and talked about his experience with lake breeze measurement campaigns performed in Michigan’s Lower Peninsula near Lake Michigan.

Dr. Keeler’s presentation focused mainly on the research performed with Mobile Mesonets, both at CMU as well as other campaigns that have taken place over the years. For the Michigan campaigns, they focus on three points:

- Warmer air does always equal more instability

- Instability can exist on the cool side of boundaries as long as there is enough moisture present

(this has also been observed in the southern US on the cool side of a dry line that taps into

moisture coming up from the Gulf of Mexico)

- Research question: how often does this happen in West Michigan?

Before covering those topics, Dr. Keeler provided the group with a brief history of Mobile Mesonets. He explained that the word “Mesonet” stands for “Mesoscale Network” and was developed for the VORTEX campaign in the 1990s which took place one year before the movie, Twister (which was loosely based on aspects of the VORTEX campaign)! Weather stations are located all over the US but there are quite a few data gaps, especially in the Great Plains where severe weather is most common. It was determined that a vehicle outfitted with weather sensors could complement the fixed weather stations’ weather data and could therefore improve the ability to forecast impactful weather.

Dr. Keeler also noted that the placement of sensors is important. The first vehicles that were used in the VORTEX campaign featured the sensors on top of the car. Later, it was shown that there was less turbulence and potential for sensor contamination (e.g., heat from an idling engine when the vehicle is stopped) at the front of the vehicle.

The second half of the presentation was dedicated to CMU’s lake breeze studies and the characterization of a “classic” vs. “non-classic” lake breeze.

Dr. Keeler shared numerous case studies from multiple days of observations performed with CMU students and the Mobile Mesonet. Before sharing the results of their campaign, Dr. Keeler spent a little time discussing Theta-E (Equivalent Potential Temperature) values. Theta-E is the temperature a parcel of air would have if it was lifted to the point of saturation, all water vapor was condensed out and then returned to a pressure of 1,000 mb without a loss of heat or mass (NWS Glossary). Theta-E is an important component observed during a rare weather event known as a MAHTE which stands for Mesoscale Air mass with High Theta-E.

Out of eight cases of lake breeze events observed during the campaign, three clear-cut MAHTE conditions were observed and two borderline cases.

After the data was analyzed and applied to very high-resolution model scenarios (grid spacing of 0.1 km), it was determined that MAHTE can be predicted and could have important implications on impactful weather prediction in non-traditional storm environments. Dr. Keeler plans to continue this research and hopes to provide additional data sets with the intention of continuously improving our forecast abilities.

You can view his slides below.