This list is currently a work in progress. In time, it will contain links to and brief summaries of all published work by our group, presented in chronological order. Thanks for your patience as we build this list!
Nevius and Evans (2018, Wea. Forecasting) - The influence of vertical advection discretization in the WRF-ARW model on capping inversion representation in warm-season, thunderstorm-supporting environments
Capping inversions forecast by the WRF-ARW model are well-known to be too smooth as compared to their observed counterparts. This study tested the hypothesis that damping (or smoothing) tied to the finite-difference approximation used to compute vertical advection is the primary cause of overly smooth forecast capping inversions. Over the sample considered, however, the data do not support this hypothesis. Single-column model experiments for strong capping inversions suggest that parameterized turbulent vertical mixing has a greater control on inversion structure, though all are too smooth compared to observations.
Evans et al. (2018, Wea. Forecasting) - An evaluation of paired regional/convection-allowing forecast vertical thermodynamic profiles in warm-season, thunderstorm-supporting environments
This study evaluated the performance of paired regional and convection-allowing models at forecasting vertical thermodynamic profiles at short lead times (0-24 h) in warm-season, thunderstorm-supporting environments. Despite grid spacings in the terra incognita of numerical modeling, where boundary layer turbulence begins to be resolved by the numerical model, we find that convection-allowing models are equally skillful to their regional counterparts over the sample considered. The research has important implications for SPC operations, namely that convection-allowing models can satisfy all SPC short-lead use cases.
Prince and Evans (2018, J. Appl. Meteor. Climatol.) - A climatology of extreme South American Andean cold surges
This study created a climatology of intense South American cold surges that traveled toward the Equator in the lee of the Andes Mountains. Intense cold surges were defined relative to the local climatology using standardized anomalies. These events, which occur approximately twice per year, significantly modulate the wind and temperature fields across the Amazon basin for two to eight days after forming. The composite cold surge reaches to the Equator and, in a unique finding, weakens first at and near the surface due to strong sensible heating from the underlying Amazon basin.
Keclik et al. (2017, Mon. Wea. Rev.) - The influence of assimilated upstream, pre-convective dropsonde observations on ensemble forecasts of convection initiation during the Mesoscale Predictability Experiment
This study tested the hypothesis that assimilating upstream, pre-convective, meso-alpha- to synoptic-scale dropsonde observations is sufficient to improve the predictability of convection initiation over the set of fifteen cases sampled by 2013's Mesoscale Predictability Experiment. Both deterministic and probabilistic verification indicate negligible impact to forecast skill from assimilating these observations, likely because they were targeted to improve accumulated precipitation forecasts (which are only partially related to convection initiation) and did not effectively sample boundary-layer variability important to convection initiation.
Evans et al. (2017, Mon. Wea. Rev.) - The extratropical transition of tropical cyclones. Part I: cyclone evolution and direct impacts
This review paper documents advances in our understanding of extratropical transition since the early 2000s. Particular focus is given to extratropical transition climatologies and diagnostic identifiers, direct observations of structural change during the transformation stage of extratropical transition, improved understanding of the physics and dynamics for strong winds, large waves, and heavy precipitation accompanying transition events, and assessments of transition-related predictive skill. A companion paper describes advances in understanding of the downstream impacts of extratropical transition.
Burlingame et al. (2017, Wea. Forecasting) - The influence of PBL parameterization on the practical predictability of convection initiation during the Mesoscale Predictability Experiment (MPEX)
This study examined the influence of varying the planetary boundary layer parameterization on the practical predictability of convection initiation in WRF-ARW short-range ensemble forecasts for three MPEX events. Varying the planetary boundary layer parameterization exerts a significant control on the number of initiation events, with cooler, moister parameterizations resulting in more initiation events, but does not change predictive skill due to the duality of error between hits and false alarms. Convection initiation is only predictable to within ~100 km and ~1 h over the set of events considered.
Grunzke and Evans (2017, Mon. Wea. Rev.) - Predictability and dynamics of warm-core mesoscale vortex formation with the 8 May 2009 "super derecho" event
During the early morning of 8 May 2009, an intense warm-core mesoscale vortex formed on the northern end of a derecho-producing convective system, resulting in significant damange from southeast Kansas through central Kentucky. In this study, the predictability of the parent convective system was high, but that of the warm-core vortex was very low. Successful vortex forecasts required an initial elevated MCS to form in northwest Kansas ~6-9 h prior to vortex formation; unsuccessful forecasts did predict MCS initiation, but not until later over south-central Kansas due to an alternative forcing mechanism.