The top graph shows the temperature (top curve) and dew point (bottom curve) plotted against universal time (UT, aka 'Z'). To convert to CST subtract 6 hours. When the dewpoint approaches the temperature we often have fog (symbol '='). Yellow dots mean rain and the funny squiggly symbol is a thunderstorm. Predicted precip amounts are in inches for each 3 hr interval.
The circles indicate cloud cover. An open circle is clear, and filled is cloudy. The flags attached to the circle show wind direction (top = north, right=east) and velocity in knots (a full flag equals 10 knots). Usually the dewpoint rises and it gets hazy (but perhaps better seeing) when the wind shifts to the south.
The second graph shows the predicted height of the cloud deck in feet. If only 20000 is indicated this is probably light cirrus that will cover the sky and lower transparency, but may give good seeing. Lower clouds are usually either fronts or the puffy varieties, which you may be able to observe through but beware of sudden showers.
The bottom graph is barometric pressure, not that useful for us.
Infrared satellite images often show cloud decks well. Sometimes by looking at a movie you can tell when a front will clear out the clouds. Another good source for weather movies is the NCAR Site.
A surface map is also sometimes helpful. In this case the number to the upper left of the cloud cover is the temperature, and the number to the lower left is the dewpoint. The flags are as in the meteogram. High pressure (clockwise circulation) is marked as blue H's, and lows are red L's. Cold fronts are blue, warm fronts red, stationary fronts dashed, occluded fronts in purple, and troughs in dashed yellow. You can even run a movie.
Really(!) clear areas are typically where the water vapor content is low - usually not us :(.
Lots of places give the 5-day forecast. My favorite tends to not have quite as many annoying ads and downloads faster than most. You can become a member for 5$ and the ads go away.
Happy Observing!