FLYING Magazine Pilot Proficiency Weather

Know Your Convective Outflow Boundaries

Pay particular attention to those strong, gusty winds before attempting a landing at an airport when storms are approaching.

Thursday, September 19, 2024 at 12:50 PM ET

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As a thunderstorm evolves, it will bring in warm, moist air to feed the intense updraft providing fuel for it to intensify. [iStock]

Key Takeaways:

Convective outflow boundaries (gust fronts) are mesoscale cold fronts formed by descending thunderstorm air, posing hazards like severe turbulence, strong winds, and low-level wind shear, especially when moving in advance of convection.
Pilots can detect gust fronts on surface analysis charts, ground-based NEXRAD radar (as low reflectivity), and sometimes visible satellite imagery, but should note that datalink weather often filters them out and distant radar may overshoot them.
These low-level events (typically below 6,500 ft AGL) involve rapid and extreme shifts between strong updrafts and downdrafts, creating sudden, jarring turbulence that pilots must recognize and avoid using all available weather information.

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Surface analysis charts are issued every three hours by meteorologists at the Weather Prediction Center (WPC). On some you may have seen a tan dashed line with a label “OUTFLOW BNDRY” nearby. This is what meteorologists call a convective outflow boundary.

This Article First Appeared in FLYING Magazine

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Scott Dennstaedt, Ph.D

Scott resides in Charlotte, North Carolina, and flies regularly throughout the Mid-Atlantic and Southeast U.S. He is a CFI and former NWS meteorologist. Scott is the author of "The Skew-T log (p) and Me: A Primer for Pilots" and the founder of EZWxBrief.