Search Results

You are looking at 1 - 10 of 38 items for :

  • Mesoscale forecasting x
  • Plains Elevated Convection At Night (PECAN) x
  • All content x
Clear All
Jonathan E. Thielen and William A. Gallus Jr.

1. Introduction Mesoscale convective systems (MCSs) play a crucial role climatologically in precipitation across the central United States. These systems account for roughly 30%–70% of the precipitation that occurs during the April–September period (warm season) in this region ( Ashley et al. 2003 ) and are therefore key phenomena of interest when seeking to improve the quantitative precipitation forecast (QPF) skill of models ( Fritsch et al. 1986 ). While this rainfall is essential to

Full access
John M. Peters, Erik R. Nielsen, Matthew D. Parker, Stacey M. Hitchcock, and Russ S. Schumacher

featured an outer domain with a 15-km grid spacing, an inner domain with a 3-km grid spacing ( Fig. 8a ), a one-way feedback from the outer domain to the inner domain, and was run from 0000 UTC 24 June to 1200 UTC 25 June 2015 with lateral boundaries updated every hour. The third WRF simulation was configured with the North American Mesoscale Forecast System (NAM) analysis at 0000 UTC 24 June 2015 as ICs, and the subsequent 6-hourly NAM analyses as LBCs [this simulation is hereafter referred to as the

Full access
Matthew D. Flournoy and Michael C. Coniglio

. Knopfmeier , 2016 : Impact of assimilating preconvective upsonde observations on short-term forecasts of convection observed during MPEX . Mon. Wea. Rev. , 144 , 4301 – 4325 , . 10.1175/MWR-D-16-0091.1 Cotton , W. R. , M. S. Lin , R. L. McAnelly , and C. J. Tremback , 1989 : A composite model of mesoscale convective complexes . Mon. Wea. Rev. , 117 , 765 – 783 ,<0765:ACMOMC>2.0.CO;2 . 10

Full access
Rachel L. Miller, Conrad L. Ziegler, and Michael I. Biggerstaff

-based CL. The dynamics that support formation of a surface-based cold pool are probably critical for understanding the difference in propagation between elevated and surface-based storms. It is hypothesized that knowledge of the existence of surface-based mesoscale cold pools along with strong CLs and expansive TS regions would assist forecasters in anticipating the risks of flooding and severe surface winds in nocturnal MCSs. In the 26 June MCS case, the initial wind damage report at 0521 UTC was

Free access
W. G. Blumberg, T. J. Wagner, D. D. Turner, and J. Correia Jr.

1. Introduction The radiosonde is widely considered to be the gold standard for measuring vertical profiles of thermodynamic and kinematic variables. The in situ nature of radiosonde observations allows scientists to obtain a high-vertical-resolution (roughly every 10 m) picture of the atmosphere. Because of this, radiosondes are used for several different applications. Meteorologists use these profiles to understand the current atmospheric state, initialize models, verify model forecasts, and

Full access
Brian J. Carroll, Belay B. Demoz, David D. Turner, and Ruben Delgado

on the LLJ, and its role in convection. Modeling the evolution of LLJ wind speed has been greatly improved in recent years from an analytical and theoretical perspective (e.g., Du and Rotunno 2014 ; Shapiro et al. 2016 ) and optimized in terms of model setup using the Weather Research and Forecasting (WRF) Model (e.g., Klein et al. 2016 ; Smith et al. 2018 ). Modeling LLJ moisture transport in the mesoscale environment of NCI and MCS events has received relatively little attention, though

Restricted access
Stacey M. Hitchcock and Russ S. Schumacher

, . 10.1175/MWR-D-16-0403.1 Bryan , G. H. , and J. M. Fritsch , 2002 : A benchmark simulation for moist nonhydrostatic numerical models . Mon. Wea. Rev. , 130 , 2917 – 2928 ,<2917:ABSFMN>2.0.CO;2 . 10.1175/1520-0493(2002)130<2917:ABSFMN>2.0.CO;2 Chappell , C. F. , 1986 : Quasi-stationary convective events . Mesoscale Meteorology and Forecasting , P. S. Ray, Ed., Amer. Meteor. Soc. , 289 – 309 , https

Restricted access
Aaron Johnson, Xuguang Wang, and Samuel Degelia

doing the DA on a coarser mesoscale grid without radar observations. Wheatley et al. (2015) focus on Warn-on-Forecast time and space scales and limit the forecast lead times to about 1 h. Both of these studies focus on severe weather prediction, which occurs primarily during the day. The prediction system described in this paper is unique in its focus on nocturnal convection. Furthermore, multiscale cycled EnKF is conducted using radar observations on the convection-permitting grid, and

Full access
Samuel K. Degelia, Xuguang Wang, and David J. Stensrud

moist layer that is key to generating nocturnal CI. Peters et al. (2017) connect errors in mesoscale convective system (MCS) forecasts to moisture biases, and in the simulations with negative moisture biases the models produce errors in both CI timing and location due to the parcels requiring additional residence time within the lifting regions. Assimilating kinematic and thermodynamic observations can improve many of the above issues related to forecasting nocturnal CI. Recently, Degelia et al

Full access
Samuel K. Degelia, Xuguang Wang, David J. Stensrud, and Aaron Johnson

. 1979 ) that often result in more deaths in the United States per year than any other severe weather-related hazard ( NOAA 2004 ). Considering the well-documented nocturnal maximum in precipitation in the Great Plains of the United States ( Wallace 1975 ; Surcel et al. 2010 ), improving forecasts of nocturnal convection during the summer is crucial. Previous studies have related the nocturnal precipitation maximum to the eastward movement of mesoscale convective systems (MCSs) that initiate over

Full access