Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 434 PM EDT Mon Jun 30 2014 Valid 00Z Tue Jul 01 2014 - 00Z Thu Jul 03 2014 ...Severe thunderstorms and flash flooding are possible through tonight across the Middle Mississippi Valley/Upper Great Lakes region... ...Heavy rainfall is likely along the eastern coast of Florida... The upper-level flow resembles a pattern more like late Spring as a deep and anomalous closed low positions itself across south-central Canada. A corridor of strong mid/upper level winds streaming through the Middle Mississippi Valley has been entering an environment characterized by abundant instability and ample moisture. The result has been numerous thunderstorm complexes which have been dropping very heavy rainfall and widespread reports of severe weather. The action will gradually shift eastward with potential impacts in some of the more populated regions of the Upper Great Lakes including Chicago and Milwaukee. The Storm Prediction Center has a moderate risk for severe thunderstorms in place from eastern Iowa/northeastern Missouri eastward into much of Illinois and sections of southern Wisconsin/northwestern Indiana. Based on their assessments, there may be a threat for a derecho which would bring a high-end wind threat to portions of the risk area. Of course the flash flooding concerns will also continue given the rainfall rates will be quite high in the stronger cells. For the latest information on the severe threat, please visit the following website: www.spc.noaa.gov. While the northern branch of the jet stream keeps the weather active across the Middle Mississippi Valley/Upper Great Lakes, a separate area of interest is located across the southeastern U.S. A wave of low pressure which has drifted southward toward the eastern coast of Florida has the potential to attain tropical characteristics. The latest National Hurricane Center outlook suggests an 80 percent of tropical development within the next 48 hours. Regardless, there will be a threat for heavy rainfall along eastern portions of Florida. Through Wednesday evening, WPC indicates 2 to 4 inches of rain will be possible along the immediate coastline. Localized pockets of heavier amounts are likely given the slow moving nature of the surface low and abundant moisture to work with. Elsewhere, showers and thunderstorms are forecast to break out along a stalled frontal zone stretching from the Ozarks back through the Southern Plains and into the Four Corners region. Looking further west, conditions will remain dry across the West Coast given the upper ridge building overhead. It will be quite toasty in the desert locales of the Southwestern U.S. with high temperatures into the lower 110s the next couple of days. Local forecast offices have already put excessive heat watches in anticipation of such temperatures. Rubin-Oster Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php