Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 222 AM EDT Tue Jul 08 2014 Valid 12Z Tue Jul 08 2014 - 12Z Thu Jul 10 2014 ...Showers and thunderstorms are expected across across the Northeast, Midwest, Great Lakes, and Mid-South... ...Summertime thunderstorms remain in the forecast for parts of the Southwest and the Southeast/Florida... The flow pattern over the next couple of days will feature an upper-level trough -- which keeps the weather unsettled across the Great Lakes -- and upstream ridging across the West allowing the development of a thermal low across the region. An upper level disturbance moving across northern Mexico from east to west should continue monsoon conditions across the Southwest into Thursday. Within the cool air aloft across the Great Lakes and Ohio Valley lie a couple of deep cyclones, which are expected to merge across western Quebec Wednesday morning to the southwest of a blocking ridge building across Labrador and northeast Quebec. Both will slowly urge a slow-moving cold front at the leading edge of the parent upper level trough across the Ohio Valley as well as the northern and eventually central Appalachians by Thursday morning, spurring thunderstorm development along the way near and ahead of the boundary as well as near the cyclone centers. Thunderstorms today into Wednesday morning could be severe from the Mid-Mississippi and Ohio Valleys northeastward into the northern Appalachians, per thoughts from the Storm Prediction Center. Reinforcements to the cooler air will be sponsored by cyclonic air flow from Hudson Bay and the Great Lakes through the period. Under the base of the warm core ridge out West, the summertime monsoonal flow lures distant Gulf of Mexico moisture into the Southwest and Great Basin, funneled in north of a retrogressive upper level disturbance moving from east to west across northern Mexico. This flow of moisture combined with daytime heating keeps scattered showers and thunderstorms in the forecast during the afternoon and evening hours. Across the Florida peninsula and portions of the Gulf coast, sea breeze convergence within a moist environment will allow for the development of showers and storms during the afternoon/evening hours caused by daytime heating. Roth Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php