A strong and persistent atmospheric ridge that has been in place over the Southeast for more than a week will begin to break down as this week progresses, allowing temperatures to return to near-normal values for late May and early June.
The death ridge has delivered abnormally hot and abnormally dry weather to the region, while also helping steer storm systems that have delivered devastating tornadoes to the Plains and Midwest.
Despite the unusually hot weather, Oneida has not officially hit 90 degrees yet. The hottest the temperature has been in Oneida was 89 degrees on Saturday, setting a record for the date. Temperatures were near 90 again on Sunday and Monday, though coming up just short. In 2018, Oneida record its first temperature of 90 or hotter on May 15. In a typical summer, Oneida hits 90 for the first time in the middle of June.
As several weak impulses of energy roll towards the region later in the week, the ridge will be weakened. That will allow the region to come under the influence of a northwest flow, which generally means cooler temperatures and better rain chances during the summer months. As a result, Wednesday should be the last day of abnormally hot temperatures. After that, temperatures across the Cumberlands will be much closer to normal for this time of year — ranging from the upper 70s to the lower 80s — for the next week.
Despite the slightly cooler temperatures, it does not look like much-needed rain is in store. Lower level ridging will hamper rain chances. There will be a slight chance of thunderstorms each day for the next week over the northern plateau, but no single day will bring significant rain chances.
Oneida last saw appreciable rainfall on May 11-12, when about two inches of rain fell across a two-day period. The combination of a lack of rain and hot temperatures since then have lawns wilting and gardeners forced to water their plants. Oneida has received 3.7 inches of rain for the month and is poised to end May about one inch below normal.
While year-to-date rainfall is still well above normal, topsoil moisture levels have been depleted by the influence of the so-called death ridge. Unless something changes, it could be at least another week — and perhaps closer to two weeks — before significant rainfall is seen again.