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Improving Prediction of Heavy Rainfall with Elevated Convection

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Improving Prediction of Heavy Rainfall with Elevated Convection 1/21/2017 THE PROGRAM FOR RESEARCH ON ELEVATED CONVECTION WITH INTENSE PRECIPITATION (PRECIP): AN OVERVIEW Patrick Market, University of Missouri Presented to the AMS Annual Meeting, 28th Conference on Weather Analysis and Forecasting Ronald W. Przybylinski Memorial Session on Elevated Convection 25 January 2017, Seattle, WA Acknowledgements Ron Przybylinski Ron encouraged our continued study of cold season (ROCS) and warm season (PRECIP) elevated convection Courtesy: NWA High Plains Chapter Webpage 1 1/21/2017 Acknowledgements Funding for PRECIP – National Science Foundation Dr. Neil Fox, Co-PI Students Laurel McCoy Katie Wunsch Joshua Kastman Marilyn Cummins Chasity Henson Katie Alexander Alzina Foscato Ryan Difani Collaborators Mike Bodner NOAA/NWS/WPC Dr. Scott Rochette SUNY-College at Brockport PRECIP Project Developed methods to predict where heavy-rain-producing elevated thunderstorms will occur Deployed teams to collect observational data from storm environment http://weather.missouri.edu/PRECIP or https://www.facebook.com/PRECIPresearchprogram 2 1/21/2017 Introduction Early work Colman (1990) initiated the modern era of elevated convection studies Showed the preferred region of elevated convection in US northeast of a surface cyclone north of its attendant warm front Moore et al. (2003) created composites 3 1/21/2017 Later work… Corfidi et al. (2008) examined the nature of altocumulus castellanus determined that the “…division between elevated and surface-based [convective] activity is rarely distinct.” Even later work… Parker (2008) Nowotarski et al. (2011) Marsham et al. (2011) Billings and Parker (2012) Schumacher (2015) PBL CAPE often still some degree of boundary layer air contributing to the convection If some amount of near-surface CAPE is available, even with significant CIN in the profile, then the convection is likely surface- based to some degree 4 1/21/2017 A Hierarchy of Elevated Convection Pure: τ > f -1 ex: wraparound Surface influences on mid-level parcels dramatically reduced or eliminated because of their 1) vertical location and/or 2) temporal history Hybrid: τ ~ f -1 ex: north of warm front Surface influences on mid-level parcels (if any) mitigated by their arrival over frontal inversion Mixed: τ < f -1 ex: warm sector castellanus Surface influences on mid-level parcels unrestricted A Hierarchy of Elevated Convection Pure Mixed 5 1/21/2017 Objectives Objectives Study historical events of EC with HP over Colman (1990) bullseye Create method for forecasting heavy-rainfall- producing elevated thunderstorms in this region Deploy observational assets to observe events in real time 6 1/21/2017 Scientific Questions Hypotheses Upright convection from the release of elevated PI is the dominant mode in elevated convection that produces heavy precipitation Elevated convection cells are more shallow, but longer lasting than convection rooted in the boundary layer Elevated PI results primarily from differential temperature advection 7 1/21/2017 Methods Ideal Deployment Method 2 radiosonde sites 2-hourly sampling typical Under the umbrella of 1-2 WSR-88D radar(s) 8 1/21/2017 Archived Case Selection Methodology Event criteria: Produced over 2” rain in 24 hrs. Local rainfall maximum within CWA boundary Used North American Regional Reanalysis (NARR) to evaluate event Archived Case Composite Method Composite events within following National Weather Service County Warning Areas (CWAs): Kansas City/Pleasant Hill (EAX) Springfield, MO (SGF) Tulsa (TSA) Wichita (ICT) Topeka (TOP) 9 1/21/2017 Results Composites – Plan View (McCoy 2014) 250-mb Jet Core > 70 kt Moisture – PWATs > 1.6” (~40 mm) Lifting – 250-mb DIV > 3 x 10-5 s-1 Instability – K Index > 32 10 1/21/2017 Composites – Cross Section (McCoy 2014) “The X” EC from PI (Market et al. 2015) IOP1 IOP2 IOP6 IOP7 11 1/21/2017 EC Threats (Kastman et al. 2015) Lightning and rainfall characteristics 8 elevated vs. 8 surface-based thunderstorm cases 2007 through 2010; central CONUS Areas of rainfall greater than 50.8 mm / 24 hours Elevated convection cases tend to produce more rainfall more total CG lightning flashes more positive CG lightning flashes than surface based thunderstorms EPEC Parameter (Foscato 2016; 2017) Excessive Precipitation with Elevated Convection EPEC = KINX + PWAT + (Div250 x 100,000) mm s-1 Units are neglected Originally estimated from mean and interquartile range plots from McCoy (2014) 12 1/21/2017 EPEC Parameter (Foscato 2016; 2017) Evaluated at WPC during FFaIR Adopted at SensibleWeather.com DCIN Parameter (Market et al. 2017) Downdraft Convective Inhibition DCAPE DCIN 13 1/21/2017 DCIN Parameter (Market et al. 2017) Downdraft Convective Inhibition Convergence Columns (Difani et al. 2017) Vertical structures within coherent areas of CONV that are derived from Doppler radar radial velocity volume scans When associated with ZDR columns, columns of convergence indicative of location of convective updraft 14 1/21/2017 Convergence Columns (Difani et al. 2017) Convergence at lowest observed height in elevated cases is significantly lower than in surface-based convection EC Characteristics (Wunsch et al. 2017) Elevated cells tend to have higher reflectivities, but lower echo top heights Indicates heavier rainfall rates, a known hazard w/EC Elevated cells have stronger convergence and thus stronger updrafts in the first 30-40 minutes of their lifetimes. 15 1/21/2017 Conclusions Conclusions Synoptic environment EPEC - Several parameters with low interquartile rangeshigher confidence for EC/FF events X “marks the spot” in cross sections DCIN - Sounding parameter to help define EC Storm-scale EC higher reflectivities, but lower echo top heights EC more rainfall EC more total CG lightning flashes EC more positive CG lightning flashes 16 1/21/2017 Thank you!! [email protected] http://weather.missouri.edu/PRECIP https://www.facebook.com/PRECIPresearchprogram References Billings J.M. and M.D. Parker, 2012: Evolution and maintenance of the 22-23 June 2003 nocturnal convection during BAMEX. Wea. Forecasting., 27, 279-300. Colman, R.C., 1990: Thunderstorms above frontal surfaces in environments without positive CAPE. Part I: A climatology. Mon. Wea. Rev., 118, 1103-1121. Corfidi S.F., S.J. Corfidi, and D.M Schultz, 2008: Elevated convection and castellanus: Ambiguities, significance, and questions. Wea. Forecasting, 23, 1280-1303. Difani, R.J., N. I. Fox and P. S. Market, 2017: Distinguishing elevated from surface-based convection using convergence columns identified from dual-polarization Doppler radar data. 28th Conf. on Weather Analysis and Forecasting. Foscato, A., P. S. Market, and N.I.Fox, 2017: EPEC: A tool for anticipating excessive precipitation with elevated thunderstorms. 28th Conf. on Weather Analysis and Forecasting. Foscato, A., 2016: An Index for Anticipating Excessive Precipitation with Elevated Thunderstorms. MS Thesis, University of Missouri, 69 pp. Kastman, J.S., P.S. Market, and A. Foscato, 2015: Rainfall-lightning ratio calculations for elevated thunderstorms with heavy rainfall. Seventh Conference on the Meteorological Applications of Lightning Data, Amer. Meteor. Soc., Phoenix, AZ. Market, P.S., S.M. Rochette, J. Shewchuk, R. Difani, J.S. Kastman, C.B. Henson, and N.I. Fox, 2017: Evaluating elevated convection with the downdraft convective inhibition. Atmospheric Science Letters, in press. Market, P.S., S. M. Rochette, M. Bodner, N. I. Fox, and J. S. Kastman, 2015: Stability tendency during elevated convection events with heavy rainfall. 40th Annual Meeting of the National Weather Association, Oklahoma City, OK. Marsham, J.H., S.B. Trier, T.M. Weckwerth, and J.W. Wilson, 2011: Observations of elevated convection initiation leading to a surface-based squall line during 13 June IHOP 2002. Mon. Wea. Rev., 139, 247–271. McCoy, L.P., 2014: Analysis of Heavy-Rain-Producing Elevated Thunderstorms in the MO-KS-OK Region of the United States. MS Thesis, University of Missouri, 208 pp. Moore, J.T., F.H. Glass, C.E Graves, S.M. Rochette, and M.J. Singer, 2003: The environment of warm-season elevated thunderstorms associated with heavy rainfall over the central United States. Wea. Forecasting, 18, 861–878. Nowotarski, C.J., P.M. Markowski, and Y.P Richardson, 2011: The characteristics of numerically simulated supercell storms situated over statically stable boundary layers. Mon. Wea. Rev., 139, 3139–3162. Parker, M.D., 2008: Response of simulated squall lines to low-level cooling. J. Atmos. Sci., 65, 1323–1341. Schumacher, R.S., 2015: Sensitivity of precipitation accumulation in elevated convective systems to small changes in low-level moisture. J. Atmos. Sci., 72, 2507–2524. Wunsch, K., N. I. Fox, and P. S. Market, 2017: A comparison of the life cycles of elevated and surface-based convection. 28th Conf. on Weather Analysis and Forecasting. 17.
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