Search Results

You are looking at 11 - 20 of 21 items for :

  • Plains Elevated Convection At Night (PECAN) x
  • All content x
Clear All
Kevin R. Haghi, Bart Geerts, Hristo G. Chipilski, Aaron Johnson, Samuel Degelia, David Imy, David B. Parsons, Rebecca D. Adams-Selin, David D. Turner, and Xuguang Wang

a bore over the Gulf Coast. (c) “Morning Glory” seen from Virgin Australia flight (courtesy of Virgin Australia, @VirginAustralia). (d) GOES-16 water vapor channel (courtesy of NOAA). (e) Radar reflectivity images of an undular bore over Oklahoma, (courtesy of Noah Brauer, @NOAABrauer). (f) Images of a bore developed from a sea/land breeze interaction (courtesy of @Weatherology Twitter account). Disclaimer: data from GOES-16 data are preliminary. Past studies on organized convection captured

Open access
David J. Bodine and Kristen L. Rasmussen

-dimensional community mesoscale model developed by the National Center for Atmospheric Research with many user-contributed physics parameterizations. The platform supports many options for microphysics, land surface, cumulus and shallow convection, planetary boundary layer, surface layer, and radiation parameterizations. The WRF Model has been used extensively to model weather and climate phenomena, thus these parameterizations have been reasonably well tested. For this study, the following parameterizations were

Full access
Alan Shapiro, Evgeni Fedorovich, and Joshua G. Gebauer

LLJ), or along or north of the intersection of an LLJ with a cold front, are more or less clear, but the mechanisms that force ascent on a lateral flank of an LLJ are still not well understood. In this regard, we believe that the recent Pu and Dickinson (2014) explanation for such a mechanism is not wholly satisfactory. In a study of vertical motions in Great Plains LLJs using a North American Regional Reanalysis (NARR) June–July climatology, Pu and Dickinson (2014) suggest that after midnight

Full access
Thomas R. Parish and Richard D. Clark

the vertical sawtooth profiling was conducted. A vertical grid of 84 sigma levels was used with increasing resolution toward the surface. Key parameterizations used for the run are the following: Lin (Purdue) microphysics scheme, the new Goddard scheme for longwave and shortwave radiation physics, MM5 surface layer similarity with the unified Noah land surface model, and the Yonsei University boundary layer physics scheme. For this simulation, the model was initialized at 1200 UTC 19 June 2015

Full access
Aaron Johnson, Xuguang Wang, and Samuel Degelia

forecasts, as described in Part I . The forecast ensemble microphysics and boundary layer parameterization configurations in Table 2 follow the “MULTI” configuration from Part I because this configuration provided the best combination of forecast performance and ensemble spread of the three configurations considered in Part I (see also Johnson et al. 2011 ). All ensemble members used the Noah land surface model, Goddard shortwave radiation, and RRTMG longwave radiation schemes. b. Forecast

Full access
Tammy M. Weckwerth, John Hanesiak, James W. Wilson, Stanley B. Trier, Samuel K. Degelia, William A. Gallus Jr., Rita D. Roberts, and Xuguang Wang

of remote sensing profilers, like PISAs deployed during PECAN, have aided in recent NCI studies (e.g., Wilson et al. 2018 ). A nationwide network of these systems ( National Research Council 2009 ) should have mesoscale spacings of ∼50 km to provide critical thermodynamic and wind observations to be used for enhanced understanding, for data assimilation and for improving convective weather forecast skill. A recent experiment, Land–Atmosphere Feedback Experiment (LAFE; Wulfmeyer et al. 2018

Full access
Manda B. Chasteen, Steven E. Koch, and David B. Parsons

developed near the terminus of the LLJ and triggered both gravity waves and bores, which initiated subsequent convection. During the morning, this elevated convection evolved into a surface-based MCS. Trier et al. (2011) examined this case using a WRF-ARW simulation and found that mesoscale processes were important for conditioning the inflow environment of the MCS and that the system lacked a well-defined cold pool until midmorning, which suggests that it had been maintained via elevated convergence

Full access
Matthew D. Parker, Brett S. Borchardt, Rachel L. Miller, and Conrad L. Ziegler

soundings are shown in Fig. 3 . The observed PECAN soundings were passed through a simple vertical smoother (the same procedure used by Parker 2014 ) to remove noise before plotting. Fig . 3. CAPE, CIN, and required lifting depth (Δ z LFC ) as a function of a parcel’s original level. CIN and Δ z LFC are only plotted for parcels with CAPE > 0 J kg −1 . All data from the 0300 UTC 26 Jun 2015 PECAN observation are plotted in blue. All data from the 0430 UTC 26 Jun 2015 PECAN observation are plotted in

Free access
Shushi Zhang, David B. Parsons, and Yuan Wang

lies above the southerly peak. Parsons et al. (2019) found that on average this westerly layer was favorable for deep convection with significant CAPE and lower convective inhibition (CIN). Nocturnal MCSs that are maintained by lifting of this potentially unstable air at and above the level of the NLLJ are typically considered to be “elevated.” We do note, however, that different definitions have been used for the term “elevated” and Corfidi et al. (2008) showed that even surface-based systems

Free access
David B. Parsons, Kevin R. Haghi, Kelton T. Halbert, Blake Elmer, and Junhong Wang

region with a nocturnal convective maximum ( Fig. 1a ) so that the composited vertical profiles of CAPE, CIN, and horizontal winds allow insight into both bores and the nocturnal convective maximum. Given that nocturnal convection can be elevated and fed by CAPE above the stable boundary layer [see Geerts et al. (2017) and references within], the use of the vertical profile of CAPE and CIN provides greater insight into the relationship between convection and the environment than can be obtained

Full access