Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 347 AM EDT Mon Jun 10 2019 Valid 12Z Mon Jun 10 2019 - 12Z Wed Jun 12 2019 ...Near-record to record breaking heat developing across portions of the West... ...Much colder air spilling across the southern High Plains on Monday... ...Moderate to heavy rains, with possible flash flooding spreading north through the Mid Atlantic into the Northeast on Monday.... Strong high pressure developing aloft will support an expanding area of above-normal temperatures across the western U.S. through midweek. On Monday, daytime highs are forecast to reach 10-20 degrees above normal across much of California and western Oregon, with triple digit readings expected within the interior valleys of central and northern California. Well-above normal temperatures will continue to expand farther north on Tuesday into the Pacific Northwest, with temperatures topping off more than 20 degrees above normal across portions of western Oregon. Excessive Heat Warnings and Heat Advisories are in effect on Monday across many of the interior valleys of central and northern California. An Excessive Heat Warning is in effect for portions of southwestern Oregon on Tuesday. Excessive Heat Watches beginning Tuesday have been raised for portions of interior southern California, southern Nevada and southwestern Arizona, including the Las Vegas and Phoenix metro areas. In contrast to the West, colder air will continue to filter in behind a front that is pushing east through the upper and mid Mississippi valley, while dropping south through the southern Plains on Monday. In contrast to Sunday's highs, temperatures will be 20-30 degrees colder on Monday across portions of the southern High Plains, with daytime highs expected to reach only in the 60s to lower 70s across much of eastern New Mexico and West Texas. The slow-moving system that has brought multiple rounds of heavy rain to portions of the Southeast will begin to lift out ahead this approaching front - bringing moderate to heavy rains with possible flash flooding farther north into the northern Mid Atlantic and Northeast on Monday into early Tuesday. The front is expected to move offshore, with high pressure and dry conditions forecast for the Northeast and northern Mid Atlantic Tuesday night into Wednesday. However, conditions across the Southeast will remain unsettled as the front remains in place, with a series of weak surface lows supporting additional showers and storms through midweek. Showers and storms associated with a developing low pressure system are forecast to return and progress east across the northern Plains into the upper Midwest Tuesday and Wednesday. Pereira Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php