THE CIRCLE IS UNBROKEN...
Tuesday night's satellite image pretty much tells the story. It shows an arc of clouds extending from Michigan to Illinois and Missouri. They represent showers and thunderstorms along a cold front which eased through the region during the day. Behind the front, high pressure is building into the upper Midwest ensuring more dry weather will be with us now the rest of the work week and potentially through the entire weekend.
Monday night you can see some rain developed up north but as expected remained just out of my immediate area.
Those showers and storms fizzled and dissipated by Tuesday morning then kicked in again towards evening. By then the forcing was south of my area leaving us high and dry once again. The circle remains unbroken! Below the 24 hour rainfall estimates show the break in precipitation bands, one north and the other south.
At any rate, there was a pretty good drop in temperatures behind the front Tuesday. In my northern counties highs never got out of the low to mid 70s. Further south there was time for some decent heating and from about I-80 south highs reached the low to mid 80s. You can see the 24 hour change in temperatures at mid-afternoon.
With high pressure entrenched directly over the area Wednesday, outstanding weather is anticipated with sunny skies and highs in the upper 70s to low 80s. Furthermore dew points will only be in the range of 45-50 which means no issues with humidity. Really, it should be a near perfect day considering winds will be10 mph or less.
Thursday as the high moves off to the east, winds return to the south and summer weather begins to build back into the area just in time for the weekend. As warm advection intensifies Friday night, there may be just enough over-running and forcing along a warm front to spark some showers and storms. Models at this time are underwhelming but do show the potential for at least some light amounts of rain. We'll have a better idea on how this sets up in the next 24-36 hours but the way things are going I would not be surprised if this threat dried up all together. As it stands now, here's what the GFS and EURO are showing for rain totals out of this event.
As for temperatures, readings remain pleasant through Thursday but with the return of southerly winds temperatures will increase daily by 2-3 degrees through Sunday. That means low 80s Thursday, mid 80s Friday, upper 80s Saturday and perhaps 90 or a wee bit better Sunday. Once we reach that level we should hold there Monday and Tuesday of next week. The 5 day temperature departures on the GFS look like this Friday through Tuesday. Toasty!
The 500mb jet stream and sea level pressure pattern Saturday clearly shows the westerly flow aloft that drives the unseasonal warmth.
Wednesday of next week some significant changes are showing up that could bring a rather abrupt end to the summery conditions and initiate a pattern change. At 500mb a a potent closed low is shown digging into the upper Midwest.
It in turn generates a significant storm center that draws warm moist air into its center. As it swings a sharp cold front across the region models are at least showing the potential for a decent band of precipitation proceeding it.
Behind the storm the first real push of fall-like air is looking more and more likely. In NW Minnesota and NE North Dakota readings are shown far below normal Wednesday.
That chilly air sweeps southeast across the Midwest on brisk winds Thursday and by Friday morning the GFS shows lows that are dipping well into the 30s.
Since this is a good week away there are lots of details to iron out before the full impacts are known. However, I do think some significant temperature changes are coming next week. The MJO is also shown going into phase 4 which is conducive to a cool down in September. We'll take a deeper look at the overall set-up in coming days. Meantime, enjoy the spectacular day ahead and roll weather...TS