A long‐lived supercell over mountainous terrain

Scheffknecht, Phillip; Serafin, Stefano; Grubı̆sı́c, Vanda

doi:10.1002/qj.3127

Cited by 20 publications

(11 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Some supercells that survived into the lee exhibited a brief enhancement in low-level rotation if they propagated over a cyclonic lee vortex. Other studies of mountain convection have found that enhanced lee-side vertical shear, owing to thermally induced plain-to-mountain flow, can promote supercell formation and/or maintenance [64,65].…”

Section: Orographic Impacts On Supercell Storm Environmentsmentioning

confidence: 95%

Moist Orographic Convection: Physical Mechanisms and Links to Surface-Exchange Processes

et al. 2018

Self Cite

View full text Add to dashboard Cite

This paper reviews the current understanding of moist orographic convection and its regulation by surface-exchange processes. Such convection tends to develop when and where moist instability coincides with sufficient terrain-induced ascent to locally overcome convective inhibition. The terrain-induced ascent can be owing to mechanical (airflow over or around an obstacle) and/or thermal (differential heating over sloping terrain) forcing. For the former, the location of convective initiation depends on the dynamical flow regime. In "unblocked" flows that ascend the barrier, the convection tends to initiate over the windward slopes, while in "blocked" flows that detour around the barrier, the convection tends to initiate upstream and/or downstream of the high terrain where impinging flows split and rejoin, respectively. Processes that destabilize the upstream flow for mechanically forced moist convection include large-scale moistening and ascent, positive surface sensible and latent heat fluxes, and differential advection in baroclinic zones. For thermally forced flows, convective initiation is driven by thermally direct circulations with sharp updrafts over or downwind of the mountain crest (daytime) or foot (nighttime). Along with the larger-scale background flow, local evapotranspiration and transport of moisture, as well as thermodynamic heterogeneities over the complex terrain, regulate moist instability in such events. Longstanding limitations in the quantitative understanding of related processes, including both convective preconditioning and initiation, must be overcome to improve the prediction of this convection, and its collective effects, in weather and climate models.

show abstract

Section: Orographic Impacts On Supercell Storm Environmentsmentioning

confidence: 95%

Moist Orographic Convection: Physical Mechanisms and Links to Surface-Exchange Processes

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…Supercells are the most intense storms in the spectrum of thunderstorms and have produced some of the largest short‐term rainfall rates in the United States (Bunkers & Doswell, ; Doswell et al, ; Giordano & Fritsch, ; Nielsen et al, ; Rogash & Racy, ; Smith et al, ). Recent studies are shedding light on both the dynamics and climatology of supercells in mountainous terrain (see, e.g., Bosart et al, ; Markowski & Dotzek, ; Scheffknecht et al, ).…”

Section: The Strangest Floods: the Blue Mountains Of Eastern Oregonmentioning

confidence: 99%

“…Eyewitness accounts of the storm suggest that it may have been a supercell thunderstorm, with one observer describing the storm as "a broad black streak almost straight north of us which seemed to be coming straight down from the sky" (Byrd, 2009). Supercells are the most intense storms in the spectrum of thunderstorms and have produced some of the largest short-term rainfall rates in the United States (Bunkers & Doswell, 2016;Doswell et al, 1996;Giordano & Fritsch, 1991 and climatology of supercells in mountainous terrain (see, e.g., Bosart et al, 2006;Markowski & Dotzek, 2011;Scheffknecht et al, 2017).…”

Section: Water Resources Researchmentioning

confidence: 99%

Strange Floods: The Upper Tail of Flood Peaks in the United States

Smith

Cox

Baeck

et al. 2018

Water Resources Research

138

View full text Add to dashboard Cite

We examine the upper tail of flood peak distributions through analyses of annual peak observations from more than 8,000 U.S. Geological Survey (USGS) stream gaging stations and through hydrometeorological analyses of the storms that produce the most extreme floods. We focus on the distribution of the upper tail ratio, which is defined as the peak discharge for the flood of record at a stream gaging station divided by the sample 10‐year flood magnitude. The 14 June 1903 Heppner storm, which produced an upper tail ratio of 200, was the product of a hailstorm that formed along the Blue Mountains in eastern Oregon, a region dominated by snowmelt flooding. A striking contrast between record flood peaks and the larger distribution of annual flood peaks in the United States is in the seasonality of flood occurrence, with record floods reflecting a much stronger contribution from warm season thunderstorm systems. Mountainous terrain and intense convective rainfall are important elements of the geography and hydrometeorology of extreme upper tail ratio flood peaks. The distribution of upper tail ratio values for USGS stream gaging stations does not depend on basin area, a result which is consistent with scaling results based on extreme value theory. Downscaling simulations with the Weather Research and Forecasting model are used to examine the storm environment of the 1903 Heppner storm, along with two other record flood peaks near the Blue Mountains of eastern Oregon from the USGS miscellaneous flood record, the July 1956 Meyers Canyon flood and the July 1965 Lane Canyon flood.

show abstract

“…In combination with horizontal advection towards mountainous regions, elevated stable layers may thus favour the accumulation of moist static energy within valleys and the establishment of convectively or potentially unstable conditions. Furthermore, wind shear across stable layers might aid convective organization and enhance storm longevity [215].…”

Section: Multiscale Interactionsmentioning

confidence: 99%

Exchange Processes in the Atmospheric Boundary Layer Over Mountainous Terrain

et al. 2018

Self Cite

View full text Add to dashboard Cite

Abstract:The exchange of heat, momentum, and mass in the atmosphere over mountainous terrain is controlled by synoptic-scale dynamics, thermally driven mesoscale circulations, and turbulence. This article reviews the key challenges relevant to the understanding of exchange processes in the mountain boundary layer and outlines possible research priorities for the future. The review describes the limitations of the experimental study of turbulent exchange over complex terrain, the impact of slope and valley breezes on the structure of the convective boundary layer, and the role of intermittent mixing and wave-turbulence interaction in the stable boundary layer. The interplay between exchange processes at different spatial scales is discussed in depth, emphasizing the role of elevated and ground-based stable layers in controlling multi-scale interactions in the atmosphere over and near mountains. Implications of the current understanding of exchange processes over mountains towards the improvement of numerical weather prediction and climate models are discussed, considering in particular the representation of surface boundary conditions, the parameterization of sub-grid-scale exchange, and the development of stochastic perturbation schemes.

show abstract

A long‐lived supercell over mountainous terrain

Cited by 20 publications

References 58 publications

Moist Orographic Convection: Physical Mechanisms and Links to Surface-Exchange Processes

Moist Orographic Convection: Physical Mechanisms and Links to Surface-Exchange Processes

Strange Floods: The Upper Tail of Flood Peaks in the United States

Exchange Processes in the Atmospheric Boundary Layer Over Mountainous Terrain

Contact Info

Product

Resources

About