THE STORM THAT KEEPS ON GIVING...
Just Looking at the 500mb jet stream pattern you would be hard pressed to think that some parts of eastern Iowa have had over 6 inches of rain the past few days (some estimates as high as 8"). There's ridging over much of the eastern U.S. with the majority of the upper air energy contained within a closed low centered over Colorado. At face value, not that exciting in my area..
However, the satellite tells a far different story. Around that circulation in Colorado a southwest flow is tapping moisture and thrusting it northward into the Midwest. A stationary boundary is stretched from Texas to Missouri into Ohio dividing our chilly air from a summery air mass to its southeast. This provides a natural area of lift (or forcing) for precipitation near and NW of the boundary. It's called over-running. The buoyant warm moist air rides over the dense cold air at the surface providing lift. The upper air low spinning in Colorado ejects spokes of energy that rotate out of the SW flow into the central Midwest. These pieces of vorticity come in waves and provide enhanced forcing for the rain that's been falling the past several days. It's the storm that keeps on giving!
This classic "warm conveyor belt" has effectively alleviated the drought conditions that had developed over the past 2 months, especially north of I-80. Here's the 7 day total rainfall which keeps going up.
This is the 7 day rain total percent of mean. Areas around the Quad Cities are 500 to 750 percent above normal over that period.
And guess what's on the way? Models are suggesting that another inch (maybe 2 in spots) could fall in some areas before this whole thing ejects on Sunday. These are some rainfall forecasts taking us through the weekend and the conclusion of this event.
The Canadian GEM
The 3k NAM
The 12K NAM
Temperatures will begin to moderate though as a warm front advance towards the region. Highs should end up around 60 in many areas Friday and then jump into the 70s both Saturday and Sunday. After that, drier and warmer days are here again. Roll weather...TS