Deep Convection, Severe Weather, and Appalachian Lee/Prefrontal Troughs Daniel B. Thompson, Lance F. Bosart and Daniel Keyser Department of Atmospheric and Environmental Sciences University at Albany, State University of New York NWS Focal Points: Thomas A. Wasula NOAA/WFO Albany, NY Matthew Kramar NOAA/WFO Sterling, VA CSTAR Spring Meeting: 6 May 2011 NOAA/CSTAR Grant # NA01NWS4680002
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Deep Convection, Severe Weather, and Appalachian Lee/Prefrontal Troughs
Deep Convection, Severe Weather, and Appalachian Lee/Prefrontal Troughs. Daniel B. Thompson, Lance F. Bosart and Daniel Keyser Department of Atmospheric and Environmental Sciences University at Albany, State University of New York NWS Focal Points: Thomas A. Wasula NOAA/WFO Albany, NY - PowerPoint PPT Presentation
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Deep Convection, Severe Weather, and Appalachian
Lee/Prefrontal Troughs
Daniel B. Thompson, Lance F. Bosart and Daniel Keyser
Department of Atmospheric and Environmental SciencesUniversity at Albany, State University of New York
NWS Focal Points: Thomas A. WasulaNOAA/WFO Albany, NY
Matthew KramarNOAA/WFO Sterling, VA
CSTAR Spring Meeting: 6 May 2011NOAA/CSTAR Grant # NA01NWS4680002
Importance
• Proximity of convective initiation region to densely populated Eastern Seaboard– Aviation impacts
• Forecasting Appalachian Lee Trough (ALT) convection can be challenging (especially in summer months during weak upper flow) with respect to:– Location– Mode– Severity
• Weak synoptic forcing shifts focus to mesoscale features (pressure troughs, boundaries, etc.)
Overview
1) Background and literature review
2) Data and methods
3) Preliminary results
4) Technology transfer
5) Next steps in research
Relevant Literature (1 of 2)
• Weisman (1990) Mon. Wea. Rev.: An observational study of warm season southern Appalachian troughs. Part II: Thunderstorm genesis zones– ALT present 40% of time from May-
September 1984-1985– Maximum in convection in late afternoon– Convective events stratified by strength of
forcing• Lee trough was not the focus for convection in 3
out of 4 forcing categories
Lee Trough Formation: PV Perspective
• PV = g(ζθ + f)(-∂θ/∂p)• d(PV)/dt = 0 for adiabatic flow• Need component of flow normal to mountain barrier• Flow across mountain barrier will subside on lee side