Geopotential height (tens of m) at 850 hPa (solid line) and Temperature (°C) at 850 hPa (coloured, dashed line) This chart helps to identify areas of densely packed isotherms (lines of equal temperature) indicating a front. Aside from this you can use the modeled temperature in 850 hPa (5000 ft a.s.l.) to make a rough estimate on the expected maximum temperature in 2m above the ground. However, this method does not apply to (winter) inversions.