The total is the amount of rainfall forecast during the 12 or 24 hours immediately preceding the verification time in the lower lefthand corner of the map. Comparison with the 540 thickness line in panel 2, and the 0 C isotherm in panel 4 can give a good indication of the dividing line between snow and rain. Panel 4 850mb Temperature, Humidity and Winds Colored contours indicate the air temperature at the 850 millibar level, in degrees Celsius. The 0 C contour is highlighted, as this is also often used as a divider between rain and snow. The green shading indicates the relative humidity percentage at the 850 millibar level.
High values indicate the availability of moisture.
The barbs indicate the direction and speed of the wind, in meters per second. The direction of the wind is parallel to the shaft with the barbs pointing into the wind. Advection of moisture by the wind can be inferred by noticing the direction and rate at which moist areas appear to be blown. Similarly, temperature advection can be inferred by noticing whether the wind is blowing cold air toward a warm region, or warm air toward a cold region. Panel 5 200mb Winds Purple shading indicates the speed of the winds at the 200 millibar level, in meters per second.