Quinton E. Maximoff Weather

More Storms And Cool Temperatures Ahead

Hope you all are enjoying this pleasant cool-down this weekend. Looks as though the below-normal temperatures will continue for the eastern half of the U.S. and possibly even go cooler by next weekend after a wave of thunderstorms.

12Z NAM model guidance is suggesting an upper level shortwave with an associated surface cyclone moving through the IL/IN area on Monday 8/13, bringing some risk for severe weather with it. This severe threat will likely be in the form of a multicell/line structure initiating along a surface cold front, with hail and strong winds being the main hazards. Following the passage of this system, cooler temperatures will be maintained throughout the Great Lakes region, with little to no precipitation through Wednesday

Thursday (8/16), Latest GFS model output shows a stronger and more broad upper level trough amplifying southward from Canada into the Great Lakes region.

Accompanying this upper level trough will be a strong cold front extending from Quebec, across the Great Lakes, and through the central Plains. Ahead of this cold front will be quite moist air, with precipitatable water values(amount of water in the column of air if all liquid fell as precipitation) upwards of 2.2 inches as shown below. With this amount of moisture, thunderstorms and potentially heavy rainfall can be expected across the Great Lakes and central Plains on Thursday and Friday as the cold front moves eastward.

Behind this cold front will be more unseasonably cool air likely similar or even chillier than the temperatures this weekend. Here’s a look at 500 hPa height and surface temperature anomalies, giving us an idea of how cool this air will be:

As a result, most areas around the Great Lakes can expect high temperatures on Saturday and Sunday in the low 70s, with lows in the low 50s.

(Graphics courtesy of TwisterData.com and WeatherBELL Models)

Cool weekend ahead for Great Lakes region

As a lot of you may have heard, autumn-like temperatures are making their way into the Great Lakes region starting tomorrow. So, with that being said, how is this happening and how long will the cool temperatures last? Let’s take a look.

Above is a look at the upper level winds at the 200 mb (around 40,000 ft). This chart is used to assess the jet stream, or the “dividing line” between warm subtropical air and cool air originating from higher latitudes in Canada. In this chart above, an upper level trough, or dip in the jet stream is located directly over Lake Superior and Michigan. This signifies that cool air from Canada is being forced south over the area.

Another feature to notice in this chart is the location of jet streaks (stronger winds) with respect to the dip in the jet stream. Looking at the left side of the trough, you can notice wind speeds are around 70 knots, or around 80 miles per hour. When stronger winds are located on the left side of the trough, the trough will become more amplified and dip further south. This allows more cool, Canadian air to move into the region. This is important to understand when forecasting how long these fall-like temperatures will last.

So, the real question is, how long will people of the Great Lakes region experience these unseasonal temperatures?

This is the 0-7 day temperature anomalies according to the Global Forecast System (GFS) model. This goes until next Friday night. The blues and greens indicate departures from normal temperatures. This suggests that below average temperatures are expected through this upcoming week until next Friday. With this said, high temperatures should not exceed mid 80s for the duration of this upcoming week for most areas in the Great Lakes region. For this weekend (Fri, Sat, Sun), expect temperatures in the mid to upper 70s.

(Graphics and charts courtesy of Twisterdata.com and WeatherBELL Models)