Model: GFS (Global Forecast System) Global Model from the "National Centers for Environmental Prediction" (NCEP)
Update: 4 times per day, from 3:30, 09:30, 15:30 und 21:30 GMT
Greenwich Mean Time: 12:00 GMT = 13:00 BST
Parameter: Geopotential height (tens of m) at 850 hPa (solid line) and Temperature (°C) at 850 hPa (coloured, dashed line)
Description: 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.