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SimInAria: Prof. William Gallus - Numerical Weather Prediction of Mesoscale Convective Systems in the U.S. (and Italy): What Have We Learned?

lunedì 19 dicembre 2016 ore 15, Bologna - Viale Silvani 6, piano terra , sala 5

Prof. William Gallus

 

Numerical Weather Prediction of Mesoscale Convective Systems in the U.S. (and Italy): What Have We Learned?

 

ABSTRACT

Organized mesoscale convective systems (MCSs) produce much of the warm season rainfall in the Central United States, and often cause damage and flooding around the world, but remain poorly forecast even after many years of efforts to improve the forecasts.  Several recent projects exploring better prediction of these systems will be discussed.  First, the impact of assimilation of radar data on Weather Research and Forecasting (WRF) model forecasts of extreme rainfall will be addressed.  Improvements have been found to be restricted to the first 6-12 hours of the forecast and are case-dependent.  Second, the relationship between accuracy in forecasting the nocturnal low-level jet (LLJ) and the skill of rainfall forecasts for MCSs will be discussed.  The relationship is found to be much stronger for synoptically-forced LLJs than for those driven primarily by the inertial oscillation.  Finally, issues related to forecasting storm morphology will be presented.  For the most poorly forecast type of thunderstorm system, bow echoes, it is found that problems exist even in 1 km grid spacing ensembles, and spread in the details of the systems is large even when spread in position of the general system is not.  There may also be a tendency for systems to move faster in 1 km simulations than in 3 km simulations.

 

WILLIAM A. GALLUS, JR.

Professor of Meteorology, Department of Geological and Atmospheric Sciences, Iowa State University

 

RECENT RELEVANT PUBLICATIONS

Lawson, J., and W. A. Gallus, Jr., 2016a: On contrasting ensemble simulations of two Great Plains bow echoes. Wea. Forecasting, 31, 787-810.

Squitieri, B. J., and W. A. Gallus, Jr., 2016a:  WRF forecasts of Great Plains nocturnal low-level jet-driven MCSs.  Part I: Correlation between low-level jet forecast accuracy and MCS precipitation forecast skill.  Wea. Forecasting, 31, 1301-1323.

Squitieri, B. J., and W. A. Gallus, Jr., 2016b:  WRF forecasts of Great Plains nocturnal low-level jet-driven MCSs.  Part II: Identifying the differences between strongly and weakly forced low-level jet forecast environments.  Wea. Forecasting, 31, 1491-1510.

Parodi, A., L. Ferraris, W. A. Gallus, Jr., M. Maugeri, L. Molini, F. Siccardi, and G. Boni, 2016: Ensemble cloud-resolving modelling of a historic back-building mesoscale convective system over Liguria: The San Fruttuoso case of 1915.  Climates of the Past.

Jahn, D., E. S. Takle, and W. A. Gallus, Jr., 2016a: Improving numerical wind forecasts of wind ramps at 100m height in the stable boundary layer.  Bound. Layer Met., (conditionally accepted).

Jahn, D., E. S. Takle, and W. A. Gallus, Jr., 2016b: Wind ramp forecast sensitivity to boundary layer scheme closure parameters.  Bound. Layer Met., (conditionally accepted).

Geerts, B., D. Parsons, C. Ziegler, T. Weckwerth, D. Turner, J. Wurman, K. Kosiba, R. Rauber, M. Parker, R. Schumacher, M. Coniglio, K. Haghi, M. Biggerstaff, W. A. Gallus, Jr., B. Demoz, K. Knupp, R. Ferrare, X. Wang, J. Hanesiak, J. Pinto, and J. Moore, 2016: The 2015 Plains Elevated Convection at Night (PECAN) field project.  Bull. Amer. Meteor. Soc.

Lawson, J., and W. A. Gallus, Jr., 2016: Adapting the SAL method to evaluate model reflectivity forecasts of summer precipitation in the central United States.  Atmos. Sci. Letters, doi:10.1002/asl.687.

Yan, H., and W. A. Gallus, Jr., 2016: An evaluation of QPF from the WRF, NAM and GFS models using multiple verification methods over a small domain.  Wea. Forecasting, 31, 1363-1379.

Moser, B. A., W. A. Gallus, Jr., and R. Mantilla, 2015: An initial assessment of radar data assimilation on warm season rainfall forecasts for use in hydrologic models.  Wea. Forecasting, 30, 1491-1520 (published Dec. 2015).

Snively, D. V., and W. A. Gallus, Jr., 2014: Prediction of convective morphology in near-cloud permitting WRF model simulations. Wea. Forecasting, 29, 130-149.

Walton, R. A., E. S. Takle, and W. A. Gallus, Jr., 2014: Characteristics of 50-200 m winds and temperatures derived from an Iowa tall tower network.  J. Appl. Mteor. and Clim., 53, 2387-2393.

Duda, J. D., and W. A. Gallus, Jr., 2013: The impact of large-scale forcing on skill of simulated convective initiation and upscale evolution with convection-allowing grid spacings in the WRF. Wea. Forecasting, 28, 994-1018.

Schaffer, C. J., W. A. Gallus, Jr., and M. Segal, 2011: Improving probabilistic ensemble forecasts of convection through the application of QPF-POP relationships. Wea. Forecasting, 26, 319-336.

Clark, A. J., W. A. Gallus, Jr., D. J. Stensrud, and M. L. Weisman, 2010: Neighborhood-based verification of precipitation forecasts from convection-allowing NCAR WRF model simulations and the operational NAM. Wea. Forecasting, 25, 1495-1509.

Clark, A. J., W. A. Gallus, Jr., M. Xue, and F. Kong, 2010:  Growth of spread in convection-allowing and convection-parameterizing Ensembles.  Wea. Forecasting, 25, 594-612.

Duda, J. D., and W. A. Gallus, Jr., 2010:  Spring and summer Midwestern severe weather reports in supercells compared to other morphologies.  Wea. Forecasting, 25, 190-206. 

Clark, A. J., W. A. Gallus, Jr., M. Xue, and F. Kong, 2010: Convection-allowing and convection-parameterizing ensemble forecasts of a mesoscale convective vortex and associated severe weather. Wea. Forecasting, 25, 1052-1081.


Email
siminaria@arpa.emr.it

Nodi organizzatori: Struttura Idro-Meteo-Clima


Tipologia: > Siminaria


Interesse: Internazionale