Tomorrow’s Asthma Forecast: How Meteorologists are Attempting to Predict Thunder Asthma
“Tomorrow’s Forecast: Thunderstorms with a chance of asthma.” This could be an actual weather report coming to a future newscast near you. Following close on the heels of my recent post “Thunderstruck!” I happened on a report at rtmagazine.com highlighting new research aimed at understanding the storm conditions most likely to spawn epidemic and even fatal episodes of thunder asthma, such as occurred in Melbourne Australia in late 2016.
Watching the Radar
The storm events known to precipitate thunder asthma fall into the weather category of Mesoscale Convective Systems (MCS). Briefly, these severe weather events occur when thunderstorms aggregate to form a collection of thunderstorms that act as a system. They typically occur in late spring and mostly at night or early morning. Per the National Oceanic and Atmospheric Administration MCS’s include three main storm types:
- Mesoscale convective complex (MCC) – a large, circular, long-lived cluster of showers and thunderstorms identified by satellite that often emerge out of other storm types.
- Mesoscale convective vortex (MCV) – A low-pressure center within an MCS that pulls winds into a circling pattern, or vortex that can take on a life of its own, lasting hours after the parent MCS has dissipated. An MCV that moves into tropical waters, such as the Gulf of Mexico, can serve as the nucleus for a tropical storm or hurricane.
- Derecho – is a widespread, long-lived wind storm that is associated with a band of rapidly moving showers or thunderstorms with an associated large area of straight line wind damage. A weather event may be classified as a derecho if the wind damage swath extends more than 240 miles (about 400 kilometers) and includes wind gusts of at least 58 mph (93 km/h) or greater along most of its length.
Diagnosing the Storm
Forecasting thunder asthma involves diagnosing the combined elements of any of these mesoscale convective processes. ScienceDaily.com, cites the UGA and Emory University study published in the Journal of Applied Meteorology and Climatology noting this assessment includes “the combination of rainfall, winds and lightning from thunderstorms in conjunction with pollen or mold spores”. The fateful mixture of these factors may result in weather related asthma events reaching epidemic proportions:
- Rainfall and high humidity rupture bioaerosols, particularly rye grass pollen grains
- Thunderstorm electrical activity contributes to further pollen fragmentation
- Gusty winds can spread pollen granules ahead of the storm
Cross referencing forecasting models that predict the amalgam and severity of these stormy elements may lead to early warning systems for healthcare agencies and those likely to be affected in the tempest targeted population. The AMS journal study abstract details the forecasting methodology: “The authors investigated the utility of several mesoscale products derived from atmospheric soundings such as downdraft convective available potential energy (DCAPE) and indices
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for predicting surface wind gusts such as microburst wind speed potential index (MWPI) and a wind gust index (GUSTEX). These results indicate that DCAPE levels reached “high” to “very high” thresholds for strong downdraft winds in the lead-up to the thunderstorm, and the MWPI and GUSTEX indices accurately predicted the high maximum surface wind observations. This information may be useful for diagnostic and prognostic assessment of epidemic thunderstorm asthma and in providing an early warning to health practitioners, emergency management officials, and residents in affected areas.”
While the methodology is not yet ready for prime-time the research holds promise for asthmatics and non-asthmatics alike in areas where mesoscale convection systems are prevalent, such as the plains states, southeast U.S. and midwest. The well-loved weatherman Willard Scott who quipped “Everyone complains about the weather, but nobody ever seems to do anything about it” may soon be proven wrong.