Key Parameters

  • Surface pressure depicts the overall synoptic environment where convective systems form and develop.
  • Wind at 850 hPa reveals low-level jets, which have an important role in the development of convection. They transport humidity from tropical regions (Amazon Basin) to extratropical regions (La Plata Basin and SSA).
  • Temperature advection at 850 hPa: warm temperature advection supplies the process of convection formation with energy.
  • Thickness (500 hPa/1000 hPa) gives the warmth of the lower layer (usually the bottom 5 km); high values mean warm air and low values cold.
  • Convective Available Potential Energy (CAPE) is the amount of energy a parcel of air would have if lifted a certain distance vertically through the troposphere. CAPE is effectively the positive buoyancy of an air parcel and is a indicator of atmospheric instability.
  • Streamlines and isotachs at 200 hPa and show the locations of high-level jets.

Surface pressure and 850 hPa wind
Schematic of the synoptic situation for the formation and development of MCCs. Low-level jet (LLJ), Northeast Argentinan Low (NAL) and a cold front passing southern South America.
Mean sea level pressure (hPa) and wind 850 hPa (m/s) overlayed on a GOES 11.0 IR image on 9 November 2008 at 06:00 UTC
Temperature Advection at 850hPa and Thickness (500hPa/1000hPa)
Temperature advection at 850 hPa (K/s) on 9 November 2008 at 06:00 UTC.
Thickness (500 hPa/1000 hPa) overlayed on a GOES 11.0 IR image on 9 November 2008 at 06:00 UTC.
Convective Available Potential Energy and Enhanced IR channel
CAPE - Convective available potential energy (J/kg) on 9 November 2008 at 06:00 UTC.
Enhanced infrared image from GOES 10 on 9 November 2008 at 06:00 UTC.
Divergence and isotachs - 200hPa Streamlines and isotachs at 200 hPa
Divergence (10-5 s-1) and isotachs at 200 hPa.
Streamlines (blue) and isotachs (yellow) at 200 hPa, presented together with LLJ (red).