** GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing **

** especially the derived products **

http://cimss.ssec.wisc.edu/goes/shortcourse/kansascity2017_dphandson.html



15 July 2017 - Where may strong convection develop?

You are responsible for providing a short term (3-6 hour) forecast of where strong thunderstorms may erupt. Conventional model data, radar data, and surface observations are unavailable, you only have access to GOES-16 soundings products from 5:02 UTC to 17:02 UTC. The products for those times and descriptions follow:

Convective Available Potential Energy (CAPE)

GOES-16 CAPE [click to play MP4 animation] **Click to play** A measure of the amount of energy available for convection. CAPE is directly related to the maximum potential vertical speed within an updraft; thus, higher values indicate greater potential for severe weather. Observed values in thunderstorm environments often may exceed 1000 joules per kilogram (J/kg), and in extreme cases may exceed 5000 J/kg. However, as with other indices or indicators, there are no threshold values above which severe weather becomes imminent. CAPE is represented on an upper air sounding by the area enclosed between the environmental temperature profile and the path of a rising air parcel, over the layer within which the latter is warmer than the former. (This area often is called positive area.) See also CIN. (from https://forecast.weather.gov/glossary.php?word=cape)

K-Index (KI)

GOES-16 KI [click to play MP4 animation] **Click to play** The K-Index or George's Index is a measure of thunderstorm potential in meteorology. According to the National Weather Service, the index harnesses measurements such as "vertical temperature lapse rate, moisture content of the lower atmosphere, and the vertical extent of the moist layer." (from https://en.wikipedia.org/wiki/K-index_(meteorology))

Lifted Index (LI)

GOES-16 LI [click to play MP4 animation] **Click to play** A common measure of atmospheric instability. Its value is obtained by computing the temperature that air near the ground would have if it were lifted to some higher level (around 18,000 feet, usually) and comparing that temperature to the actual temperature at that level. Negative values indicate instability - the more negative, the more unstable the air is, and the stronger the updrafts are likely to be with any developing thunderstorms. However there are no "magic numbers" or threshold LI values below which severe weather becomes imminent. (from https://forecast.weather.gov/glossary.php?word=lifted+index)

Showalter Index (SWI or SI)

GOES-16 SI [click to play MP4 animation] **Click to play** A stability index used to determine thunderstorm potential. The SWI is calculated by lifting an air parcel adiabatically from 850 mb to 500 mb. The algebraic difference between the air parcel and the environmental temperature at 500 mb represents the SWI. It is especially useful when you have a shallow cool airmass below 850 mb concealing greater convective potential aloft. However, the SWI will underestimate the convective potential for cool layers extending above 850 mb. It also does not take in account diurnal heating or moisture below 850 mb. As a result, one must be very careful when using this index. (from https://forecast.weather.gov/glossary.php?word=showalter+index)

Total-Totals Index (TT)

GOES-16 TT [click to play MP4 animation] **Click to play** A stability index and severe weather forecast tool, equal to the temperature at 850 mb plus the dew point at 850 mb, minus twice the temperature at 500 mb. The total-totals index is the arithmetic sum of two other indices: the Vertical Totals Index (temperature at 850 mb minus temperature at 500 mb) and the Cross Totals Index (dew point at 850 mb minus temperature at 500 mb). As with all stability indices there are no magic threshold values, but in general, values of less than 50 or greater than 55 are considered weak and strong indicators, respectively, of potential severe storm development. (from https://forecast.weather.gov/glossary.php?word=Total-Totals+index)

Total Precipitable Water (TPW)

GOES-16 TPW [click to play MP4 animation] **Click to play**