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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
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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
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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
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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
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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
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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
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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
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Methods
Ideal Deployment Method
2 radiosonde sites 2-hourly sampling typical
Under the umbrella of 1-2 WSR-88D radar(s)
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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)
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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
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Composites – Cross Section (McCoy 2014)
“The X”
EC from PI (Market et al. 2015)
IOP1
IOP2
IOP6
IOP7
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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)
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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
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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
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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.
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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
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Thank you!!
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.
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