MCS cases Null cases - Colorado State Universitysaddleback.atmos.colostate.edu/esmei/interns/... ·...
Transcript of MCS cases Null cases - Colorado State Universitysaddleback.atmos.colostate.edu/esmei/interns/... ·...
FactorsthatInfluencetheGrowthofSupercellsintoMCSa8erSunsetKeenanEure1,JohnM.Peters2,RussShumacher2
1.UniversityofMaryland,CollegePark,CollegePark,MD2.ColoradoStateUniversity,FortCollins,CO
IntroducKon• Discrete,tornadoproducingsupercellso8enoccurina8ernoon
(stormswithrotaKngupdra8s)• ColdairouNlowsfromindividualcellsmergeandhelpform
MesoscaleConvecKveSystem(MCS)• O8enproducesflashflooding
• ConvecKontransiKonsfromsurfacebasedtoelevated• Lowest1-2kmofatmospherecools&stabilizesassunsetsand
warmairadvectsormovehorizontallyovercoolair(belowle8)• Southerlyfastmovingwinds,orlowleveljet(LLJ)hasa
maximumatnight(belowright)• Lowlevelwindshear&ascentincrease
Methods• 25casesofsupercelltoMCStransiKon(MCSevents)• 25casesofsupercellswithnoMCSa8erwards(Nullevents)• AnalyzedhourlyRapidRefresh(RAP)modeldataforeachcase
toanalyzethefollowingfrom18Zto9Z:• Meridionalwindcomponent–verKcalorsoutherlywind
component,toseethechangeintheLLJ• PotenKaltemperatureadvecKon–allowsustoseewarmair
advecKon;indicaKveoflowlevelascentorrisingmoKon• Divergence–similartopotenKaltemperatureadvecKon,
negaKvedivergenceshowsrisingmoKon/ascent• Bulkwindshear–Thechangeofthexandywindcomponents
withheight• ConvecKveAvailablePotenKalEnergy(CAPE)–measureof
instabilityforstormgrowthanddevelopment• DeltaZLevelofFreeConvecKon(LFC)–heightanairparcel
needstoreachtotheLFC,whereaparcelbecomesbuoyantandcontributestostormgrowth&development
• Tookcoordinatesforeachcasetomakeagridofareainfocus• Averagedvariablesoverthexandycoordinatesovereachlevel
ofatmosphere(37values,1foreachheight,37totalforeachhour)
• ProducedKmevs.heightplotsforeachparameterlistedabove• Createdplotsshowingdifferencebetweenspecifiedhourand
21Z,since21Zwastypicallythemostunstable&generallythemeanKmeoftornadoes
• Timevsheightmadeforeachcase,thencreatedcompositesoraveragesoftheMCSandnullcases,respecKvely
• PosiKvechangesinpotenKaltemperatureadvecKoninthe0Zto
5Zwindow(inthelowest1-2km)fortheMCScasesversusminimaloralmostnegaKvechangeindicatesmorelowlevelascentfortheMCScases
• SharpnegaKvechangesindivergencebetween0Zto6-7ZinMCScasesequatestoconvergence;asairconvergencesitleadstorisingmoKonaswell
• MeridionalwindcomponentchangeisindicaKveofastrongerLLJnocturnalmaximumforMCScases,comparedtoanabsenceofthisfornullcases
• CAPEvaluesfairlysimilarbetweenMCScasesandnullcases• DeltaZLFCvalues,orheightsparKcularlyhigherfornullcases,
meaningthattheseparcelsneededtoreachahigherheighttoreachtheirinstabilitylevel(LFC),whethertheparcelwasfromthegroundorelevated
Corfidi, Stephen F., Sarah J. Corfidi, and David M. Schultz. "Elevated Convection and Castellanus: Ambiguities, Significance, and Questions." Weather and Forecasting 23 (n.d.): 1280-303. 26 Apr. 2008. Web. 21 July 2016. Du, Yu, and Richard Rotunno. "A Simple Analytical Model of the Nocturnal Low-Level Jet over the Great Plains of the United States." American Meteorological Society 71 (2014): 3673-684. 22 Sept. 2014. Web. 21 July 2016. Markowski, Paul, and Yvette Richardson. Mesoscale Meteorology in Midlatitudes. N.p.: n.p., n.d. 17 Mar. 2010. Web. 21 July 2016. Moore, James T., Fred H. Glass, Charles E. Graves, Scott M. Rochette, and Marc J. Singer. "The Environment of Warm-Season Elevated Thunderstorms Associated with Heavy Rainfall over the Central United States." American Meteorological Society 18 (2003): 861-78. 1 Oct. 2003. Web. 21 July 2016. Nielsen, Erik R., and Gregory R. Herman. "Double Impact: When Both Tornadoes and Flash Floods Threaten the Same Place at the Same Time." American Meteorological Society 30 (2015): 1673-693. 17 Sept. 2015. Web. 21 July 2016. Parker, Matthew D. "Response of Simulated Squall Lines to Low-Level Cooling." American Meteorological Society 65 (2008): 1323-341. 1 Apr. 2008. Web. 21 July 2016. Peters, John M., and Russ S. Schumacher. "Dynamics Governing a Simulated Mesoscale Convective System with a Training Convective Line." American Meteorological Society 73 (2015): 2643-664. American Meteorological Society. American Meteorological Society, 24 June 2016. Web. 21 July 2016. Schumacher, Russ S., and Richard H. Johnson. "Organization and Environmental Properties of Extreme-Rain-Producing Mesoscale Convective Systems." American Meteorological Society 133 (2005): 961-76. Web.
ReferencesThisworkhasbeensupportedbytheNaKonalScienceFoundaKonResearchExperiencesforUndergraduatesSiteinClimateScienceatColoradoStateUniversityunderthecooperaKveagreementNo.AGS-1461270andAGS-PRF1524435.
FormoreinformaKon,[email protected]
IntroducKon
Methodology
Conclusions
Acknowledgements
References
Results
Discretesupercellsonthele8,organizedMCSontheright
MCScases Nullcases
18 19 20 21 22 23 0 1 2 3 4 5 6 7 8 90
500
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Time (Z)
Heig
ht a
bove
gro
und
leve
l (m
)
Potential Temp Advection Change from 21Z (K hr−1)
−1
−0.8
−0.6
−0.4
−0.2
0
0.2
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1
18 19 20 21 22 23 0 1 2 3 4 5 6 7 8 90
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Time (Z)
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t abo
ve g
roun
d lev
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Potential Temp Advection Change from 21Z (K hr−1)
−1
−0.8
−0.6
−0.4
−0.2
0
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Time (Z)
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t abo
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Divergence Change from 21Z (hr−1)
−0.1
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Time (Z)
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Divergence Change from 21Z (hr−1)
−0.1
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Meridional Wind Component Change from 21Z (m/s)
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Meridional Wind Component Change from 21Z (m/s)
−10
−8
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)
CAPE (J Kg−1) and Delta Z LFC (m)
1750
20002000
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2750
2750
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325032
3250350037504000
0
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Heigh
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CAPE (J Kg−1) and Delta Z LFC (m)
30003250
3500
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Caseanalyzedthatsawseveralflashfloodsandtornadoesincloseproximity