EVEN COLDER NEXT WEEK...

Since the middle of August, temperatures have been on a downward trend thanks to the development of an east coast trough. That's turned upper level winds in from the NW, sending cool Canadian air our way. Look at how dramatically readings have fallen since August 16th. Today was the 5th consecutive day with highs in the 70s and the 3rd straight day with a low in the 40s at the NWS office in the Quad Cities.

For some perspective, here are the temperature departures for the last 3 days. It is abundantly clear that the core of the cool air has been directly over the Midwest.

While we will see a more seasonal day Thursday, there's a significant reservoir of cool air to tap, and we've got at least another 10 days of below normal temperatures in our future. In fact, the EURO shows an even colder air mass than the one we are currently experiencing, arriving the middle of next week. Here's the trough that will deliver it Wednesday, September 3rd. Let me say this, if the EURO verifies, this push of cool air will get your undivided attention.

A pattern such as this has all the earmarks of what's known as a negative EPO (Eastern Pacific Oscillation). Compare the similarity of the 500mb chart above to the graphic below. The big ridge over the NE Pacific buckles the jet and allows a downstream plunge that delivers air directly from the Polar regions of North America. Fortunately it's not January, or we would be in line for a deep freeze. Even so, it's going to be quite fresh.

Indeed, looking at teleconnections, the EPO is shown going strongly negative and remaining in that state through September 11th on the EURO ensemble. That's a big signal for at least a week of below normal temperatures that reach their lowest mid to late next week.

To prove it, next Thursday the 500mb heights on the EURO are shown to be 4 standard deviations below normal, indicating this is likely to be a rare event for early September.

Thursday, September 4th (a week from today) the EURO paints some healthy temperature departures centered on my region.

A closer inspection reveals readings that are up to 20 degrees below the norms.

That translates to highs September 4th in the mid 50s. The 57 shown in the Quad Cities would be the average high for October 29th.

850mb temperatures (about a mile up) are shown, dropping to +1C in spots. The rule of thumb for snow to reach the ground at the surface, is for 850 readings to be 0C. (32 degrees) or colder. That's getting pretty close.

While I don't see any snow, it is possible that lows next Friday morning reach the 30s in parts of my area. The GFS is seeing that trend, indicating this for lows the morning of September 5th. That could very well challenge existing record lows that are in the low to mid 40s.

With the air so cold aloft, steep lapse rates are likely that will generate clouds and instability showers in the wrap around circulation associated with the upper air low. Things are going to get a little ugly for a few days next week, just so you know.

Often times when an unusually strong event like this occurs in late summer, it's followed by a nice warm-up as the atmosphere recovers and attempts to re-balance. I am seeing some signs of that possibility as early as September 7th.

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THE HERE AND NOW...

Meantime, a front slips through the region Thursday morning, but all indications point to a dry frontal passage. However, the cooler air associated with the front lags until later in the day. When it arrives it could spark some clouds and a few spotty light showers in the north. Before then, highs should range from 76 north to about 80 in the south.

After that, high pressure locks in for the holiday weekend, keeping things dry, temperatures comfortable, and humidity low through Sunday. It looks like a full on go for outdoor activities during this period. Days will be mild in the low to mid 70s and nighttime lows pleasantly cool in the low to mid 50s. We'll take it. Roll weather...TS