Different Weather Pattern

Over the past several days, models have continued to indicate the arrival of a very cool air mass into the United States. For this to occur, several things must happen first. For one thing, the large upper level low over the lower Mississippi Valley and Deep South will be "kicked" out of the United States by a large upper level wave moving southward out of Canada and into the Northern Rockies. This upper level wave will deepen and cause the formation of a surface low pressure system along a developing strong baroclinic zone (temperature changing over a given distance or a temperature gradient). This low pressure system will move in a hook shape, first moving southeast into South Dakota, and then making a sharp turn to the northeast and moving into Minnesota and Canada. At the current time, models are forecasting that the air will be cool enough to cause a significant snowfall over Northern Minnesota and North Dakota. But that is another story. As for here, I expect that the storm system will drag a cold front through the area by Thursday night.. Ahead of the strong cold front, temperatures will warm into the upper 70's for Thursday afternoon. At the same time, it could get fairly breezy. Thursday night, the cold front will be strong enough to generate a few showers and possibly a thunderstorm with the available moisture. As the cold front passes, temperatures will drop rapidly and then remain steady in the lower 50's.. On Friday, lingering cloud cover and lake effect rain showers will keep temperatures below 60. For the weekend, a secondary cold front will move through the region, reinforcing the initial shot of cold air, and causing temperatures to drop again. This will cause another lake response, causing widespread cloud cover for Saturday and possibly Sunday. This will limit highs to the lower and middle 50's! In fact, conditions may be just cloudy and breezy enough to limit highs below 50, making for quite a chilly weekend. Both Saturday and Sunday night look to bring a high potential frost. In fact, if the wind is light enough and cloud cover is limited during the night, we could be seeing the first FREEZES of the season. This will be quite early for this area, and if realized could be one of the earliest in many years. In any case, I expect a widespread frost both Saturday and Sunday nights, and possibly Monday night.

After the weekend, model solutions diverge, with some models holding the cold air mass across the region, and some moving it away rather quickly. This will all depend on the transition of the longwave pattern. At this time, I would lean more towards the models that hold the cold air mass in the region, due to the strength of the blocking ridge of high pressure in the Gulf of Alaska. Time will tell, but the next several weeks look to be rather cool across the area.

Map of forecasted temperature anomalies.. As you can see, there is a large area of below normal temperatures across the Midwest and Great Lakes regions.