I hear the joke about meteorologists all the time – “I wish I got paid for being right only half the time”. Despite the misperception by some, the forecasting skills at the NWS offices are very good. Skills have improved over the years, not only for routine forecasts of temperature and precipitation, but also for critical severe weather. There are still meteorological surprises every once in awhile, but most of the “it came without warning” cases did indeed have warnings associated with them.
Here is an example where the National Weather Service did a good job of forecasting when and where the rain would fall from this last system over a 5-day period. It is a product called the quantitative precipitation forecast (QPF). I’ve really been impressed with this product over the past few years and rely on it routinely. The first map is the potential 5-day rainfall totals made on July 1. The second map is the actual 5-day rainfall totals over the forecasted period (July 1-5).
Unfortunately, the color schemes is different between the two maps. In general, the areas in red in the first map were expected to receive 2 to 5 inches of rain, while the areas in yellow and red in the second map did receive 2 to 5 inches of rain. Overall, the amounts and overall pattern match up well. Kudos to the folks at NWS.
By the way, more rain is likely on the way over the next five days (last map), with amounts of 1 to 2 inches expected across Illinois.
You can monitor the NWS quantitative precipitation forecasts (QPF) at http://www.wpc.ncep.noaa.gov/qpf/day1-7.shtml