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IntroductionThis page describes two studies of different convective cases; one over N. America associated with formation of severe tornadoes, the other over central Africa. Both cases are studied starting the forecast from the same date/time (initial conditions). The N.America case has strong large scale forcing whereas the centra African case is driven by the diurnal cycle.Two cases (US Tornado case and Africa case) - different types of convection US Tornado convection case (Arkansas)On the 27 April 7pm local time (00UTC 28 April), tornadoes hit towns north and west of Little Rock, Arkansas killing approx 17 people. (http://edition.cnn.com/2014/04/28/us/severe-weather/index.html?hpt=hp_c2). On the evening on the 28 April fatal tornadoes occurred over Mississippi (http://www.bbc.co.uk/news/world-us-canada-27199071). More information can also be found on the ECMWF Severe Event Catalogue 201404 - Convection - Arkansas U.S.
African diurnal deep convection (Central Africa) |
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Initial conditions
Case study: deep convection
On 27 April 7pm local time (00UTC 28 April), tornadoes hit towns north and west of Little Rock, Arkansas.
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- Understand the weather situation resulting in tornadoes
- Evaluate the control forecast and compare it to the analysis and observations
- What is the area of threat according to the control forecast?
- How does the convective adjustment process takes place and and what is the role of large scale forcing (why and where it happens)?
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Case study: diurnal variation of convection
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- Understand the weather situation over Africa.
- What difference and why does diurnal variation of convection make?
- Describe the phase and amplitude of (scaling) of the precipitation with the different experiments with respect to surface heat fluxes.
- What is it that scales precipitation flux?
Compare buoyancy flux with enthalpy. Think about the effect of local heating combined with atmospheric moisture.
What is the role of large scale in this case? - How important is the correct diurnal cycle of precipitation and radiation for 2m temperature and dewpoint forecast?
- Compare differences between Central Africa and other areas (e.g. Amazonia)
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