Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 255 PM EDT Sun Jul 27 2014 Valid 00Z Mon Jul 28 2014 - 00Z Wed Jul 30 2014 ...Severe weather and flash flooding possible across the Ohio Valley...Central Appalachians and Middle Atlantic states... ...Another round of cooler and drier Canadian air with a large cell of high pressure will spread south and eastward through the Central and Eastern U.S.... ...Heavy rain and flash flooding are possible later in the forecast from the Front Range of the Rockies into the Southern Plains.... A strong upper level disturbance combined with a moist and unstable airmass is capable of producing severe weather including large hail, damaging winds and a few tornadoes today across the eastern Ohio Valley...Central Appalachians into the Middle Atlantic states. More widespread but scattered heavy showers and thunderstorms are also likely across the Ohio Valley...Midwest...Middle Atlantic and Northeast US through Sunday night. Some heavy rains will continue across portions of Pennsylvania...New York and New England on Monday although the threat of severe weather will be diminishing. As the upper disturbance continues to move north and eastward...a cold front will be ushering in another cooler and drier airmass across much of the eastern half of the nation over the next several days...likely lasting through the end of the month. Some instability showers are likely to remain across the Midwest especially on Tuesday and Wednesday afternoon...while comfortable temperatures and relatively low humidity cover the nation from the central and northern Plains eastward to the Atlantic coast. The cold front is expected to drop as far south as the Gulf Coast and northern Florida...with showers and thunderstorms along and south of the front. A strong Canadian surface high will push southward into the north central states and will remain for several days and continue to bring relatively cooler and drier air across the Central and Eastern US. Easterly flow around the surface high will help produce upslope flow across the Front Range of the Rockies. Meanwhile...monsoonal moisture will continue to fuel widespread convection across the Southwest and Central Rockies Sunday and Monday afternoons. The combination of upslope flow and monsoonal moisture will fuel localized areas of heavy rainfall from the Central Rockies to the southern Plains late in the forecast...where flash flooding could become a threat. Farther north...temperatures will be on the rise in the Northern Rockies and Northern Intermountain West as an expansive upper ridge sprawled across the south central U.S. builds northward through the region. Kocin Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php