TURNING UP THE HEAT...
The central Midwest has enjoyed several days of sensational weather characterized by sunshine, low humidity, and comfortable temperatures. That's all going to change Saturday as southwesterly winds drive a typical late summer heat wave into the region.
One issue that's come up that may impact just how warm we end up will be smoke from western wild fires. This has the potential to limit incoming solar radiation enough to keep readings in the upper 80s to near 90 if the smoke is as extensive as the HRRR vertically integrated product verifies. Here's what it shows around mid-day Saturday.
Accounting for the smoke, the HRRR maintains a much cooler look than other models with highs only in the mid to upper 80s.
The GFS goes hog wild on deep mixing, lower dew points, and a SW wind to create a very warm temperature signal. I doubt if its on the right track with its toasty readings.
To give you some perspective on just how warm the GFS temperatures are I included this graphic from the Iowa Mesonet. It shows that over a period of 129 years the temperature in Cedar Rapids has reached 95 on September 11th just 2 times. It also shows that a 95 degree or greater high has occurred just once after September 19th in that same 129 year time frame. After September 15th, 90 degree heat is pretty hard to achieve in my area.
The NBM ( a model blend) is more of a middle ground approach Saturday and may be a good compromise. You can see its more in line with the 3K NAM and EURO below in the 88-92 degree range.
The 3K NAM
However it turns out, Saturday is going to be very warm day with highs at least 15 degrees above September 11th levels. These are the projected departures.
Based on the latest models is seems our new found warmth is going to be a feature of our weather into Tuesday of next week, especially in my central and southern counties where highs Sunday through Tuesday are projected to be in the range of 85-90. The far north around HWY 20 may fair better as highs will be impacted by a front that could generate some periods of clouds and even a few showers and storms. Readings 80-84 may prevail here.
As for the showers and storms, the first window for rain is most likely Sunday night and early Monday across the HWY 20 corridor. Further south a healthy cap should keep storms at bay until later Tuesday or Tuesday night in the rest of my area when a front that sits over northern Iowa decides to make inroads into the region. It's this second precipitation window that holds the greatest potential for precipitation coverage in my area. That said, the timing of the frontal passage and mesoscale details will dictate when and where storms develop (if at all in a given area). Here are some rainfall forecasts Sunday night through Tuesday night.
The WPC forecast.
Time will tell how it all plays out. Meantime, I know where I'll be Saturday afternoon. I'll be sitting in the air conditioning somewhere watching the Iowa Iowa State football game. I'm unable to watch it at my place as Mediacom and WQAD can't reach an agreement on rates so even though I'm paying for WQAD programming, all I have is a black screen. Isn't that special! Oh well, I'll figure it out. Have a sensational weekend and roll weather...TS.