The models since the recent weekend have trended toward a mild and toasty scenario for much of the country next week. It’s been a cold April with widespread temperature anomalies of over 10 degrees below average for the Central US. That is beginning to change as a more traverse pattern takes place with frequent ridges and troughs, or small dips in the jet stream, passing through the Lower 48.
Based on the great agreement among the model guidance for next week, we are confident that temperatures will become way above average for several days across most of the Eastern two-thirds of the US. Before we get to next week, let’s chat about this week: It’s going to be a relatively-hot week for the Western US with temperatures up to 35 degrees above average, especially in the Northwest. According to the National Weather Service office in Seattle, “the odds of having 3 consecutive days of 70 degrees or higher in April are 1 in 345 or about a 0.3% chance.” This week’s heat is definitely unusual, and even record-breaking Tuesday and Wednesday. About a dozen of record daily high temperatures are forecast to be broken on both days. This includes cities like Seattle, Portland, and Needles, CA. Needles will actually soar into the 100s through at least Friday. Keep in mind, their average high for this time of the year is 87 degrees, so yes, the deserts will be baking as well. The reason for this week’s heat in the West is due to a strengthening ridge of high pressure slowly drifting to the east while an upper-level low sits off the West Coast. This eastward movement will eventually lead to warmth for the East next week. This ridge wants to share the love!
Speaking of next week, this ridge will move to the east before eventually reaching the East Coast by Wednesday while further intensifying. The heat from this ridge will first be felt in the Central US, where temperatures will become above average this weekend. Highs up to 25 degrees above normal in the Great Plains and Upper Midwest will translates to actual high temperatures in the 70s for most locations. It’s taken the last weekend of April for this to happen, but it’s finally happening. For a city like Minneapolis, typically the first 70+ degree day occurs on April 12th, but that is yet to happen this year. The record latest first 70+ degree day for the city is May 17th, which occurred in 1875 and 1892.
This heat will slowly direct toward the East Coast. The above average temperatures will reach the coast by Tuesday the latest. The only areas in the East that will remain seasonable or even below average will be Florida and the Carolina coast. On Monday, high temperatures will be up 25 degrees above normal in the Central Plains and Upper Midwest before a cold front ushers in a new cool air mass from the north and west. Then on Tuesday and Wednesday, the warmest of air relative to average will be found in the Northeast. Temperatures may be over 30 degrees above average, and many cities may record highs in the 80s. You can thank the combination of the ridge or amplification in the jet stream as well as a strong dome of high pressure just off the coast. This high is called the ‘Bermuda High,’ which is more common in the summer and is often responsible for the extreme heat waves in the Northeast.
Unfortunately, by the end of the week, cooler temperatures will return to the Northern Plains and much of the Midwest, but the warmth should persist from the Southern Plains through the East Coast. The Western US will experience seasonable weather with temperatures generally between 5 degrees above and below average.