Step 1: Isobars. Locate all points of 1024 millibar (mb) pressure in the northwest United States. Similar to a dot-to-dot coloring book, use a black pen to connect all four of the 1024 mb points. Your line should start and end at the point of 1024 mb pressure in Utah. Repeat this procedure with the next isobar value until all the points on the map have isobars running through them. Be sure that no set of isobars crosses another. Remember that not all isobars will be closed circles. Label each of your lines with the last two digits of the pressure reading (24, for example). Step 2: Air Pressure. Locate the areas of the highest and lowest pressure on your map. Label these centers with a large blue letter H and a red letter L, respectively. Step 3: Weather Conditions. Based on air pressure, locate the regions where you would expect to see rain or snow and shade them in green. Then shade the regions where you would expect to see clear skies in yellow. Step 4: Wind Direction. Indicate the wind direction by drawing pink arrows around the letter H and around the letter L on your map.