the persistence and dissipation of lake michigan-crossing mesoscale convective systems
DESCRIPTION
Nicholas D. Metz* and Lance F. Bosart # * Department of Geoscience, Hobart and William Smith Colleges # Department of Atmospheric and Environmental Sciences, University at Albany E-mail: [email protected] Support Provided by the Provost Office at Hobart and William Smith Colleges - PowerPoint PPT PresentationTRANSCRIPT
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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, Hobart and William Smith Colleges# Department of Atmospheric and Environmental Sciences,
University at Albany
E-mail: [email protected]
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
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Motivation
MCS 1
MCS 2
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MCSs Crossing Lake Michigan
Johns and Hirt (1987)Laing and Fritsch (1997)
Frequency of Derechos
MCC Occurrences
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MCSs Crossing Lake Michigan
Graham et al. (2004)
68%24%
8%
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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
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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
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3.0°C 4.4°C 10.8°C 18.9°C 21.6°C 19.1°C
Monthly Climatological Distributionsn=110
LM LWT Climo
12
2121
17
28
11
43% = Persist 57% = Dissipate
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Hourly Climatological Distributionsn=110
21
14 1719
12 117 9
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Synoptic-Scale Composites
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Synoptic-Scale Composites
• 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
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Dynamic vs. Progressive
Dynamic Progressive
Johns (1993)
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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=31m s−1
m s−1
200-hPa
850-hPa
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Dynamic Persist vs. DissipateCAPE (J kg-1), 0–6 km Shear (m s-1)
Persist Dissipate
n=17 n=31
J kg−1CAPE
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Real Data Case Studies
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7–8 June 2008 - persist
4–5 June 2005 - dissipate
Case Studies
Source: SPC Storm Reports
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MCS 2105 UTC 7 June 08 - persist
Source: UAlbany Archive
1600 UTC 4 June 05 - dissipate
MCSSource: NOWrad
Composites
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Source: UAlbany Archive
MCS
MCS
Source: NOWrad Composites
2304 UTC 7 June 08 - persist
1800 UTC 4 June 05 - dissipate
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Source: UAlbany Archive
MCS
MCS
Source: NOWrad Composites
0001 UTC 8 June 08 - persist
1900 UTC 4 June 05 - dissipate
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Source: UAlbany Archive
MCS
MCS
Source: NOWrad Composites
0104 UTC 8 June 08 - persist
2000 UTC 4 June 05 - dissipate
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Source: UAlbany Archive
MCS
Source: NOWrad Composites
0302 UTC 8 June 08 - persist
2200 UTC 4 June 05 - dissipate
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23
26
26
23
20
2932
29
26
32
0408
12
1618
2000 UTC 7 June 08 - persist
SLP (hPa), Surface Temperature (C), and Surface Mixing Ratio (>18 g kg-1)
Source: UAlbany Archive
MCS
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20
23
26
29
04
08
12
16
02
Source: UAlbany Archive
MCS
1800 UTC 4 June 05 - dissipate
SLP (hPa), Surface Temperature (C), and Surface Mixing Ratio (>18 g kg-1)
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0000 UTC 8 June 08 - persist
Source: 20-km RUC
2100 UTC 4 June 05 - dissipate200-hPa Heights (dam), 200-hPa Winds (m s-1), 850-hPa Winds (m s-1)
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CAPE (J kg-1), 0–6 km Shear (m s-1)
0000 UTC 8 June 08 - persist 2100 UTC 4 June 05 - dissipate
Source: 20-km RUC
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Tair, Twater, p
Buoy 45007
T=6.2°C
Source: NDBC
Buoy meteogram
hPa
20Z/07 22Z/07 00Z/08 02Z/08
14
10
6
18
1006
1008
1010
1012
°C
Tair, Twater, pBuoy 45007
T=2.1°C
Source: NDBC
hPa
12Z/04 18Z/04 20Z/04 22Z/04
14
10
6
18
1006
1008
1010
1012
16Z/0414Z/04
°C
Persist
Dissipate
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WRF Modeling Results
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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
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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−1 4500 J kg−1
MUCAPE
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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
1012 10121004 1004
Actual Radar
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Control Run No Lake Michigan
2200 UTC 07 June 08 – 10-h forecast
10121012
1004
1004
Simulated Reflectivity (dBZ), SLP (hPa), and 2-m Wind (m s−1)
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Control Run No Lake Michigan
0000 UTC 08 June 08 – 12-h forecast
10121012
1004
1004
Enhanced Convection
Actual Radar
Simulated Reflectivity (dBZ), SLP (hPa), and 2-m Wind (m s−1)
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Control Run No Lake Michigan
0200 UTC 08 June 08 – 14-h forecast
10121012
1004
1004
Simulated Reflectivity (dBZ), SLP (hPa), and 2-m Wind (m s−1)
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Difference between No Lake Michigan and Control Simulations 15-h Total Accumulated Precipitation Difference (mm)
1200 UTC 7 June – 0300 UTC 8 June
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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
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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.
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Conclusions – 11 July 11
• 200-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
✔
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Conclusions – Broader Implications
Walters et al. (2008) Riemann-Campe (2009)
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Extra Slides
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Areal Coverage >45 dBZ
I II IIIIII
0
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Areal Coverage >45 dBZ
0
I II IIIIII
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Lake Interactions
LWA – South Haven
2130 Z 2200 Z
T, Td, p