top of page
thumbnail_1 ts baner, future in your hands.png


It's not too often that I get surprised like I did Tuesday (thank GOD)! Outside of my far southern counties, way down around Ft. Madison and Keokuk, I expected a dry day. Instead, rain fell in just about all of my region with some spots picking up 4 inches plus! Needless to say, I'm eating humble pie which tastes like crap but is certainly effective when it comes to staying grounded. Essentially I was rode hard and put away wet...

So how did this happen you ask? Well, I wanted answers to that question myself so I went back in time to when I created my post Monday night. My routine is to always wait for the 0Z model runs which come down between 10 PM and 2:00 AM so I can have fresh "reliable" data for those reading it later that night or early the following morning. I wanted to make sure there wasn't something glaring in that data that I missed in my analysis.

With that in mind I called up the 0Z runs of the EURO, GFS, and 12K NAM which is what I used to formulate my opinions. They all depicted an MCS (mesoscale convective system) but its rains were shown well west and south, perhaps just grazing my southernmost counties in SE Iowa and WC Illinois. Since the event was less than 12 hours away it appeared pretty cut and dry that 95% of my area would remain dry. See below.


The 12K NAM

Well, instead of quiet rain free radar, the Doppler looked like this at 5:00 PM with flash flood warnings in effect for parts of the Quad Cities and surrounding counties to the southeast. Compare that to what was indicated by the modeling above.

Now if you follow this page, you know that in recent weeks I have made numerous remarks about how mesoscale details can alter a forecast, especially beyond 24 hours. In this case, we didn't even get beyond 12 hours when what's known as an MCV formed. An MCV is a mid-level low pressure center that develops within the stratiform region of a mesoscale convective system (MSC) as it releases latent heat over a period of hours. The low pressure develops a circulation that ranges in diameter from (30 to 125 miles). An MCV can persist and sustain precipitation for 12 hours or more after its parent MCS has dissipated.

Anyway, if you are still with me, the MCS alone would likely have missed my region as models suggested. However, the energy associated with the MCS created the MCV which (was not) anticipated. The creation of the mid level vortex is where everything went haywire. Not only did it bring rain but it altered the temperatures which ended up substantially cooler than anticipated.

Here's some of the rain totals from the area that just 12 hours earlier was expected to be dry. Amounts in the various shades of green range from 1/2 inch to 2 inches. The yellows and pinks go from 2 to as much as 6 inches. Much of it came in a very short period of time.

Just for kicks, here are the QPF (quantitative precipitation forecasts) from Monday night which I based my post on for Tuesday. You can compare the model output below to what actually happened above.


The 0Z GFS

The 0Z 12K NAM

Dang it, that's a terr