GOOD GOLLY MISS MOLLY...
Often times, a pattern that is unusually cold is preceded or followed by one that is just the opposite. A highly amplified jet stream structure that creates extremes means somebody's bad weather is somebody else's good weather. The natural order of our atmosphere is for it to balance the imbalances. That is why unusually cold temperatures are often preceded or followed by ones that are significantly warmer as the pressure gradient reverses and the pattern progresses.
That is the situation we will find ourselves in the next few days as a strong return flow of southerly winds replaces the cold northerly ones that have recently chilled us. When I say chilled, I certainly mean it as lows in much of the area were in the upper teens to low 20s Wednesday morning. Cedar Rapids hit 16 breaking their record low for the date of 19, set in 1972.
Sheldon, Iowa (in the northwest) was one of the coldest spots in the state with their low down to 10 degrees. That's really impressive for October and no snow cover. Here's the 7:00am observations Tuesday morning.
Winds chills as you can see were even worse with the NWS in the Quad Cities at 11 degrees.
Better days lay ahead of us as winds are already returning to the west indicating the ridge (core of the cold air) has shifted to the east. The cold cyclonic flow is being replaced by SW flow and good golly Ms. Molly, is that going to make a difference in our temperatures this weekend. Highs by Saturday and Sunday are likely to be 55 to as much as 60 degrees warmer than the lows we experienced Wednesday.
To get there, we have one more chilly day to deal with Thursday with highs remaining in the mid to upper 50s in most areas, maybe 60 in the far west and south. Then the lid goes off Friday and it's up up and away for temperatures. The national model blend shows highs in the Quad Cities reaching the mid 70s Friday, Saturday, and Sunday.
Both Saturday and Sunday highs could be as much as 25 degrees above normal with those mid 70s.
Out in western Iowa and much of the central Plains, highs could go well into the 80s.
It will take some time, but the sustained SW flow and southerly winds will serve to increase moisture over the weekend. So much so, that showers and storms are expected to develop ahead of a vigorous storm system situated over Nebraska. This will be our next weather maker as it and its cold front ejects into the area late Sunday night and Monday. The key factor for my immediate area in terms of rainfall is the timing of the front, something models are struggling with. More in that in a minute.
Of great importance is the serious need for rainfall. Much of the central and western United States is currently experiencing abnormally dry to extreme drought conditions.
Here in Dubuque, only 0.86 inches of rain has fallen over the past 50 days. These are the rainfall departures since September 1st around the Midwest.
Unfortunately, there is a big disparity between the EURO and GFS as to what will happen Monday. There is high confidence in a strong storm, however low confidence on the timing which is important. The faster EURO is drier, the slower GFS wetter. Here's what models suggest from our next potential rain maker Monday.