The Rain & Chill To Return
by Cody Matz
April 25, 2012 7:39 PM
After a couple of phenomenal days across the Upper Midwest, we are all in for a rude awakening. The leading edge of cooler air (a cold front) dropped through the area Wednesday, which is starting our cooling trend that will last a couple of days. But its not going to be the cooling that’s the problem, but just how much we cool and how little sun is expected through the weekend that may startle a lot of us. A pretty potent storm will take shape on the eastern side of the Rocky Mountains Thursday, which will bring areas of rain and far cooler temperatures to the area from late Thursday all the way through Saturday. At first, this storm didn’t look all that impressive, but as it has gotten closer, the actual strength of this upcoming storm could rival our last one which dumped 1 to 3 inches of rain over much of the area. The exact timing and track of this storm is still unknown but here is what we are looking at.
As this storm rolls into the Midwest, it continues to strengthen. The image below shows you the very tight center of this system to our south. Typically the larger and more compact that ball of color is, the stronger the storm.
As this storm rolls through, winds will be out of the north and northeast allowing for temperatures to plummet as cool Canadian air shifts into our area. Check out the afternoon temperatures expected Friday, at least according to this forecast model.
Looks cold doesn’t it? Yea well it is, temperatures Friday afternoon will likely be in the 30’s and low 40’s if we actually end up with widespread light to moderate rain across the area. But just how much water are we talking about? Well, that’s still up in the air… no pun intended. But we are getting a better idea of how much you can expect. The next model goes back to our favorite subject in math…. Probabilities. This shows the probability of experiencing certain amounts of rain. This is shown in four mini pictures. The top left is the probability of getting at least a trace of rain from Thursday evening through Friday evening. The top right is receiving at least a quarter inch, the bottom left is a half-inch, and the bottom right is an inch.
According to this forecast, the entire area has a 100% chance of receiving at least a quarter inch of rain with an 80% chance of at least a half inch, and anywhere from a 40 to 80% chance of receiving at least an inch of rainfall. Well, it doesn’t take a genius to figure out that if these probabilities hold true, there could be a lot of water around here Thursday night and Friday.
Another avenue we can look at is the forecast by the Hydrological Prediction Center (HPC) that we show you fairly often. Here is their rainfall forecast for the 3-day period from Wednesday evening through Saturday evening.
The HPC seems to agree with the probability maps…. and then some. Widespread amounts of 1.5 to 2.5 inches are a possibility with this system. Yikes! There is no concern about flash flooding at the moment just because the ground is still reasonably parched, however, if we do receive this much rain then creeks, streams, and rivers will see a rise in flow so be careful around running water.
Unfortunately for those that don’t like the rain so much is that there is more in the forecast next week so looks like our unsettled pattern may stick around for a little while.