More Unsettled WeatherJuly 3rd, 2013 at 8:22 am by Jamie Jarosik under Weather
Our weather pattern over the past nearly 2 weeks has been unsettled with showers and thunderstorms and the pattern looks to continue through the remainder of this week. All of this unsettled weather in influenced by an unusually deep trough/upper level low that has been situated over the Ohio Valley and Mississippi Valley. This is an map of 500 mb or about 18,000 ft aloft shows the upper level low over the Ohio Valley:
This upper level low is also referred to as a cold pocket of air aloft. With cold air aloft and the strong July sunshine to heat the lower levels of the atmosphere, this causes instability which leads to the development of showers and thunderstorms. Also small disturbances rotate around this upper low which helps to enhance these showers and thunderstorms. And because the upper level winds have been weak, these thunderstorms have been slow to move causing flash flooding in some areas. This map from the Midwestern Regional Climate Center shows rainfall over the past 7 days. Over 2 inches has fallen over the western and northern Miami Valley, of course some areas received locally higher amounts of 4-5″ inches.
This upper level low will gradually weaken over the next few days, however our chances of thunderstorms will continue right through the 4th, unfortunately. Between the upper low and a strong area of high pressure over the eastern Atlantic Ocean this creates a strong southerly flow right out of the Gulf of Mexico. This satellite image shows this stream of tropical moisture right out of the Gulf of Mexico:
This stream of tropical moisture, has brought heavy rains to the East Coast, will shift westward into the Ohio Valley. This is expected to bring even more showers and thunderstorms to our area late Wednesday night and continue throughout the 4th of July holiday. This southerly flow will continue right though the weekend with increasing humidity levels, which will keep the chances for showers and thunderstorms right through the first part of next week.
Have a great afternoon and happy 4th!