 Strengthening high pressure means that places from California's Central Valley to interior Southern California, the Las Vegas area, and even Phoenix can reach 110 degrees daily through the weekend under sunshine. On a wetter note, a large part of the country east of the Mississippi River stands at least some risk for an afternoon thunderstorm as a front essentially washes out overhead from the Ohio Valley into the northeast. With stormy conditions possible, not out of the question from New England to Tennessee,