Characterizing Thunderstorm Gust Fronts Near Complex Terrain

Nicholas Luchetti, Katja Friedrich, Christopher Rodell, Julie Lundquist

Research output: Contribution to journalArticlepeer-review

10 Scopus Citations

Abstract

Fire safety, aviation, wind energy, and structural engineering operations are impacted by thunderstorm outflow boundaries or gust fronts (GFs) particularly when they occur in mountainous terrain. For example, during the 2013 Arizona Yarnell Hill Fire, 19 firefighters were killed due to sudden changes in fire behavior triggered by a passing GF. Knowledge of GF behavior in complex terrain also determines departure and landing operations at nearby airports, and GFs can induce exceptional structural loads on wind turbines. While most examinations of GF characteristics focus on well-organized convection in areas such as the Great Plains, here the investigation is broadened to explore GF characteristics that evolve near the complex terrain of the Colorado Rocky Mountains. Using in-situ observations from meteorological towers, as well as data from wind-profiling lidars and a microwave radiometer, 24 GF events are assessed to quantify changes in wind, temperature, humidity, and turbulence in the lowest 300 m AGL as these GFs passed over the instruments. The changes in magnitude for all variables are on average weaker in the Colorado Front Range than that typically observed from organized, severe storms in flatter regions. Most events from this study experience an increase in wind speed from 1 to 8 m s-1, relative humidity from 1 to 8 %, and weak vertical motion from 0.3 to 3.6 m s-1 during GF passage, while temperature drops by 0.2 to 3° C and turbulent kinetic energy peaks at > 4 m2 s-2. Vertical profiles reveal that these changes vary little with height in the lowest 300 m.
Original languageAmerican English
Pages (from-to)3267-3286
Number of pages20
JournalMonthly Weather Review
Volume148
Issue number8
DOIs
StatePublished - 2020

NREL Publication Number

  • NREL/JA-5000-75211

Keywords

  • complex terrain
  • gust fronts
  • thunderstorm
  • wind energy

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