MCS and Mountain Interaction Forecast Practices

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MCS and Mountain InteractionForecast Practices

• National Weather Service
• Greenville-Spartanburg Airport
• Greer, SC

CSTAR RFP Meeting Raleigh, NC August 2-3, 2006
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0401 UTC 25 Oct 01
0633 UTC
0803 UTC
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1701 UTC 3 May
03 1933 UTC
2103 UTC
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Forecast (and Warning) Practices

• Primary questions regarding mesoscale convective
  systems approaching mountains from the west
• If severe, will severe weather continue in the
  mountains?
• If not severe, will severe weather develop in the
  mountains?
• What will happen to strength and organization of
  convective storms as they descend from the
  mountains and move across the Piedmont?
• Primary considerations
• Environment (i.e., stability and energy, wind
  structure, forcing by dynamics across the
  spectrum of scales)
• Terrain Influences

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Portion of Western North Carolina in the
Knoxville Quadrangle (1250,00)
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TN/NC
NC/SC
Terrain Cross Section Knoxville to north of
Spartanburg
Terrain is complex both vertically and
horizontally
AWIPS screen capture of HiResTopo image of
southern Appalachians. Thin northwest/southeast
line approximates terrain cross section above.
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Conceptual model of channeled flow from northwest
Location of windward and leeward slopes during
periods of northwest flow (Perry 2006)
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Operational Considerations

• Evaluate environmental characteristics
• Impose conceptual model of convective storm
  structure upon terrain
• Rear inflow jet and cold pool
• Most of the time expect East TN severe weather
  to continue into first tier of NC counties
• Thereafter observe radar trends
• Wary of redevelopment east of mountains

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Conceptual ModelBorrows from recent work at Penn
State(Markowski and Grumm 2004 Frame and
Markowski 2006)
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References
Frame, J., and P. Markowski, 2006 The
interaction of simulated squall lines with
idealized mountain ridges. Mon. Wea. Rev.,
134, 1919-1941. Markowski, P., and R. Grumm,
2004 Bow echo development associated with the
interaction of convection with complex terrain
Blending observations with idealized simulations.
Final Report, Cooperative Program for
Operational Meteorology, Education, and Training
(COMET) Outreach Program, 9 pp. Available online
at www.comet.ucar.edu/outreach/abstract_final/0238
661_PSU.pdf Perry, L.B., 2006 Synoptic
climatology of northwest flow snowfall in the
southern Appalachians. Ph.D. Dissertation,
Department of Geography, University of North
Carolina Chapel Hill, 176, pp.
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The End