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The Persistence and Dissipation of Lake Michigan-Crossing Mesoscale Convective Systems Nicholas D. Metz* and Lance F. Bosart # * Department of Geoscience,

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Presentation on theme: "The Persistence and Dissipation of Lake Michigan-Crossing Mesoscale Convective Systems Nicholas D. Metz* and Lance F. Bosart # * Department of Geoscience,"— Presentation transcript:

1 The Persistence and Dissipation of Lake Michigan-Crossing Mesoscale Convective Systems Nicholas D. Metz* and Lance F. Bosart # * Department of Geoscience, Hobart and William Smith Colleges # Department of Atmospheric and Environmental Sciences, University at Albany Support Provided by the Provost Office at Hobart and William Smith Colleges 20th Great Lakes Operational Meteorology Workshop Chicago, IL 14 March 2012 Acknowledge: Daniel Keyser and Ryan Torn – University at Albany Neil Laird – Hobart and William Smith Colleges Morris Weisman – NCAR

2 Motivation MCS 1 MCS 2

3 MCSs Crossing Lake Michigan Johns and Hirt (1987) Laing and Fritsch (1997) Frequency of Derechos MCC Occurrences

4 MCSs Crossing Lake Michigan Graham et al. (2004) 68% 24% 8%

5 Purpose Present a climatological and composite analysis of MCSs that encountered Lake Michigan Describe two MCSs, one that persisted and one that dissipated while crossing Lake Michigan, and place them into the context of the composites Discuss two simulations of the persisting MCS to identify the effects of Lake Michigan

6 MCS Selection Criteria MCSs in this study: –are from the warm seasons (Apr–Sep) of 2002–2007 –are ≥[100  50 km] on NOWrad composite reflectivity imagery –contain a continuous region ≥100 km of  45 dBZ echoes –meet the above criteria for >3 h prior to crossing Lake Michigan 47 out of 110 (43%) MCSs persisted upon crossing Lake Michigan

7 3.0°C 4.4°C10.8°C 18.9°C21.6°C19.1°C Monthly Climatological Distributions n=110 LM LWT Climo % = Persist 57% = Dissipate

8 Hourly Climatological Distributions n=

9 Synoptic-Scale Composites

10 Constructed using 0000, 0600, 1200, 1800 UTC 1.0° GFS analyses Time chosen closest to intersection with Lake Michigan –If directly between two analysis times, earlier time chosen Composited on MCS centroid and moved to the average position

11 Dynamic vs. Progressive Dynamic Progressive Johns (1993)

12 Dynamic Persist vs. Dissipate Persist Dissipate 200-hPa Heights (dam), 200-hPa Winds (m s -1 ), 850-hPa Winds (m s -1 ) n=17 n=31 m s −1 200-hPa 850-hPa

13 Dynamic Persist vs. Dissipate CAPE (J kg -1 ), 0–6 km Shear (m s -1 ) Persist Dissipate n=17 n=31 J kg −1 CAPE

14 Real Data Case Studies

15 7–8 June persist 4–5 June dissipate Case Studies Source: SPC Storm Reports

16 MCS 2105 UTC 7 June 08 - persist Source: UAlbany Archive 1600 UTC 4 June 05 - dissipate MCS Source: NOWrad Composites

17 Source: UAlbany Archive MCS Source: NOWrad Composites 2304 UTC 7 June 08 - persist 1800 UTC 4 June 05 - dissipate

18 Source: UAlbany Archive MCS Source: NOWrad Composites 0001 UTC 8 June 08 - persist 1900 UTC 4 June 05 - dissipate

19 Source: UAlbany Archive MCS Source: NOWrad Composites 0104 UTC 8 June 08 - persist 2000 UTC 4 June 05 - dissipate

20 Source: UAlbany Archive MCS Source: NOWrad Composites 0302 UTC 8 June 08 - persist 2200 UTC 4 June 05 - dissipate

21 UTC 7 June 08 - persist SLP (hPa), Surface Temperature (  C), and Surface Mixing Ratio (>18 g kg -1 ) Source: UAlbany Archive MCS

22 Source: UAlbany Archive MCS 1800 UTC 4 June 05 - dissipate SLP (hPa), Surface Temperature (  C), and Surface Mixing Ratio (>18 g kg -1 )

23 0000 UTC 8 June 08 - persist Source: 20-km RUC 2100 UTC 4 June 05 - dissipate 200-hPa Heights (dam), 200-hPa Winds (m s -1 ), 850-hPa Winds (m s -1 )

24 CAPE (J kg -1 ), 0–6 km Shear (m s -1 ) 0000 UTC 8 June 08 - persist2100 UTC 4 June 05 - dissipate Source: 20-km RUC

25 T air, T water, p Buoy  T=6.2°C Source: NDBC Buoy meteogram hPa 20Z/0722Z/0700Z/0802Z/ °C T air, T water, p Buoy  T=2.1°C Source: NDBC hPa 12Z/0418Z/04 20Z/0422Z/ Z/0414Z/04 °C Persist Dissipate

26 WRF Modeling Results

27 Model Configuration WRF–ARW v.3.2, initialized at 1200 UTC NARR initialization and boundary conditions 4-km domain with explicit convection MYJ PBL and WSM6 microphysics schemes Control Run No Lake Michigan Water converted into land with properties consistent with surrounding land surface

28 2000 UTC 07 June 08 – 8-h forecast Surface Temperature (°C) and Wind (m s −1 ) Control Run No Lake Michigan No Marine Cold Pool 2500 J kg − J kg −1 MUCAPE

29 Simulated Reflectivity (dBZ), SLP (hPa), and 2-m Wind (m s −1 ) Control Run No Lake Michigan 2000 UTC 07 June 08 – 8-h forecast Actual Radar

30 Control Run No Lake Michigan 2200 UTC 07 June 08 – 10-h forecast Simulated Reflectivity (dBZ), SLP (hPa), and 2-m Wind (m s −1 )

31 Control Run No Lake Michigan 0000 UTC 08 June 08 – 12-h forecast Enhanced Convection Actual Radar Simulated Reflectivity (dBZ), SLP (hPa), and 2-m Wind (m s −1 )

32 Control Run No Lake Michigan 0200 UTC 08 June 08 – 14-h forecast Simulated Reflectivity (dBZ), SLP (hPa), and 2-m Wind (m s −1 )

33 Difference between No Lake Michigan and Control Simulations 15-h Total Accumulated Precipitation Difference (mm) 1200 UTC 7 June – 0300 UTC 8 June

34 Concluding Discussion MCS that dissipated progressed into a less favorable synoptic-scale environment and was associated with a weaker near-surface inversion than MCS that persisted MCS

35 Concluding Discussion MCS that dissipated progressed into a less favorable synoptic-scale environment and was associated with a weaker near-surface inversion than MCS that persisted WRF simulations suggest that MCS persistence was primarily a function of the large-scale environment, with Lake Michigan modulating MCS strength within favorable large-scale envelope.

36 Conclusions – 11 July hPa jet 850-hPa LLJ Downstream CAPE Over-lake inversion ✔ ✔ ✔ Buoy air temperature = 21.0°C Buoy water temperature = 18.9°C Inversion Strength = 2.1°C ✔

37 Conclusions – Broader Implications Walters et al. (2008) Riemann-Campe (2009)

38 Extra Slides

39 Areal Coverage >45 dBZ I II III 0

40 Areal Coverage >45 dBZ 0 I II III

41 Lake Interactions LWA – South Haven 2130 Z 2200 Z T, T d, p


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