Extratropical Synoptic-Scale Processes and Severe ConvectionOver viewSynoptic FactorsTopographical influencesSolenodial circulationsMonsoonsVertical ShearFeed Backs to the synoptic scaleFeed backs con.Examples of Severe convective events500 hPA chart, 0000UTC 29 Aug 1990Sounding at Peoria IL, 0000UTC 29 Aug 1990Surface Analysis for 1500 UTC on 27 Mar 1994Sounding and hodograph for 1700 UTC on 27 Mar 1994 for Jackson, MS500 hPa analysis at 1200 UTC on 17 Aug 1994Surface analysis at 1800 UTC on 17 Aug 1994a) Ground relative and b) storm relative wind profiles850hPa analysis at 0000 UTC on 7 June 1982500-300 hPa Layer averaged Q-vector divergence field at 000 UTCTopeka, KS. Sounding at 0000 UTC on 7 June 1982500 hPa Analysis at 0000 UTC 15 June 1990Surface Analysis at 0000 UTC 15 June 1990500 hPa at 0000 UTC 10 June 1972Surface analysis at 0000 UTC 10 June 1972Slide 25Any questions?Extratropical Synoptic-Scale Processes and Severe ConvectionPart 1 Elizabeth Polito Pg ( 27- 43 )Part 2 Terrance Seddon pg ( 44-64 )Over view•Synoptic Factors Associated with Severe convection–Topographic influences–Solenoidal Circulations over simple Terrain–Monsoons•Feedbacks to the synoptic scale•Examples of severe convective events from a Synoptic perspectiveSynoptic Factors•Vertical motion in convective storms is ~10 m/s•Vertical motion on synoptic scale is ~10 cm/s•Sub synoptic scale process need to provide the lift to produce the convective stormsTopographical influences•Orographic effects–Leeward side, flat terrain, import of low level moistuer•Other Topographic effects–Seasonal changes in the effects they have•Air Mass Characteristics–High lapse rates, low level mositureSolenodial circulations•The flow associated with solenoidal circulations–Classic fronts–Land-sea breeze–Convective outflow–Inhomogeneties in underline terrain–Dry linesMonsoons•Defined as a season shift in the surface flow•Does not directly initiate convection•Does however initiate process that do initiate convection–Upslope flows–Embedded solenoidal drive flows•Also the shift in the wind patterns can provide the low level moisture so important to DMC.Vertical Shear•The presence or absence of vertical shear can be the difference between a severe storm, and a short heavy rain shower•It is difficult to predict the exact effects of vertical shear and helicity on a storm, as the storm’s initial path is not known.Feed Backs to the synoptic scale•While synoptic scale processes have been associated with helping to initialize DMC, it is also found that DMC affects synoptic processes.–Ex. US Warm and autumn season effects–Ex. Mediterranean Autumn vs. Spring–Ex. Australian variationFeed backs con.•Qualitatively DMC is important to a global heat balance•Single events of DMC are in themselves are too brief to affect Synoptic scale processes•However, it is not uncommon for an event of DMC to develop until it is a mesoscale Convective system, which lasts for days.•These MCSs have the longevity required to affect the synoptic scale processes.Examples of Severe convective events•28 Aug 90 Plainfield Il•27 Mat 1994 Palm Sunday Outbreak•17 Aug 1994 Lahoma, OK•7 June 1982 Kansas City, MO•14 June 1990 Shadyside OH•9 June 1972 Rapid City, SD500 hPA chart, 0000UTC 29 Aug 1990Plainfield, Il An isolated Tornado eventSounding at Peoria IL, 0000UTC 29 Aug 1990Plainfield, Il An isolated Tornado eventSurface Analysis for 1500 UTC on 27 Mar 1994Palm Sunday Tornado outbreakSounding and hodograph for 1700 UTC on 27 Mar 1994 for Jackson, MSPalm Sunday Tornado outbreak500 hPa analysis at 1200 UTC on 17 Aug 1994Lohoma, OK an Isolated intense wind and hail stormSurface analysis at 1800 UTC on 17 Aug 1994Lohoma, OK an Isolated intense wind and hail storma) Ground relative and b) storm relative wind profilesLohoma, OK an Isolated intense wind and hail storm850hPa analysis at 0000 UTC on 7 June 1982Kansas City, MO a derecho500-300 hPa Layer averaged Q-vector divergence field at 000 UTCKansas City, MO a derechoTopeka, KS. Sounding at 0000 UTC on 7 June 1982Kansas City, MO a derecho500 hPa Analysis at 0000 UTC 15 June 1990Shadyside, OH A challengeSurface Analysis at 0000 UTC 15 June 1990Shadyside, OH A challenge500 hPa at 0000 UTC 10 June 1972Rapid City, SD A western eventSurface analysis at 0000 UTC 10 June 1972Rapid City, SD A western event500 hPa at 0000 UTC 10 June 1972Rapid City, SD A western eventAny