SINGING SEPTEMBERS FINAL SONG...
As expected, Wednesday was another day of summer in September. While there was a late day increase in clouds most areas had enough sunshine to send highs into the mid and upper 80s. 90 degree readings were reported in Iowa City, Muscatine and Washington. Lowden and Vinton reached 91.
Most areas were about 17-20 degrees above normal. These are late afternoon departures and as you can clearly see the warmth was widespread over the central U.S.
With today being the last day of September, we'll send it out singing a summery song. There will be some passing clouds at times but I still think enough sunshine to get highs back in the low to mid 80s in most locations. Not including Thursday's highs, temperatures will end up well above normal for the month. Here's the temperature departures for the month through the 29th.
These are the rainfall totals for the the month through the 29th. Much of Iowa and northern Illinois struggled in the rain department. Outside of the southern third of my area, monthly rainfall totals will end up in the range of 1/2 to 2 inches.
That means a large region saw only 25-50 percent of September's mean rainfall.
In a nutshell, September goes into the record books as warm and dry...short and sweet.
With the arrival of October there is going to be an increase in rain chances but as I've been saying all week, the system was likely going to be slower than the GFS advertised and impacted by dry air that's trapped under a blocking ridge situated over the Ohio Valley. The EURO has been advertising the slower trend since Sunday and today the GFS finally got a good sniff of what's cooking.
That being the case I expect clouds to be on a gradual increase Thursday and Friday as the system slowly edges east. I will also introduce the chance of some warm advection showers later Friday night on a scattered basis into Saturday. These appear to be light and most widespread west of the Mississippi. A stronger round of forcing arrives Saturday night and at that time both the GFS and EURO show a new round of showers (maybe even a few thundershowers) spreading northeast. If we get into some beneficial rains this is the time frame that it's most likely. What rain develops should slowly transition out of the area from west to east Sunday morning or early afternoon.
The latest EURO has increased rainfall totals, especially Saturday night and Sunday and shows these totals Friday night through Monday.
The GFS is in reasonable agreement below. At least for the time being both models are showing a trend towards heavier amounts. Even so, I'm being very cautious about buying into these totals considering our dry soils and the ongoing drought in many areas. When you are in a drought cycle it's tough to break continuity with existing storm tracks and rainfall patterns. I fear the models are being too aggressive with amounts. We are still 60 hours away from the best rain potential and things could change. Even so, the latest guidance brings optimism with regards to at least moderate rainfall amounts for much of the region.
With additional clouds and eventually scattered rain Saturday and Sunday (more dry hours than wet ones), temperatures will begin a cooling trend with readings getting closer to normal by the end of the weekend and early next week. Here's the EURO ensembles meteograms depiction of coming temperatures.
Next week a closed upper air low develops that carves out a trough over the east-central Midwest. At the present time it's placement would not produce much more than stay showers and for the most part temperatures look to stay close to or slightly above normal the first half of the week.
I also wanted to mention that I have been working on my winter outlook which is becoming quite extensive. I'm waiting for a couple new pieces of information and should have the finished product out within the next week. Not to give anything away, but a couple months from now I suspect we'll be wishing fondly for spring and it won't even officially be winter. On that note, I will wrap this post up with a bow and wish you all a rock solid day. Roll weather...TS