Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 357 PM EDT Tue Aug 18 2020 Valid 00Z Wed Aug 19 2020 - 00Z Fri Aug 21 2020 ...Record heat and fire danger will be persistent in the Southwest, but ease in the Northwest by Thursday... ...Scattered showers and thunderstorms are expected for the southeastern quadrant of the country... Across the West, a mid/upper-level ridge of high pressure has been causing widespread record heat, which persists today. The heat is expected to gradually ease in the Northwest and California in particular, bringing temperatures closer to normal by Thursday, though still above average in California. However, Wednesday will be another hot day, with temperatures in the 90s, with some areas nearing 100 in the interior Northwest, and exceeding 100 in the California valleys. Meanwhile farther south, the Desert Southwest can expected widespread record-breaking heat to continue, with many locations surpassing 110 degrees in what would normally be monsoon season. Elevated to critical fire danger is also a threat for northern California into the Great Basin and Northern Rockies over the next couple of days. While isolated thunderstorms could cause light precipitation, some thunderstorms could be almost or completely dry, so lightning strikes could ignite wildfires. The western U.S. is covered in Excessive Heat Warnings, Heat Advisories, and Red Flag Warnings. A few isolated thunderstorms could be strong to severe in the High Plains on Wednesday and Thursday. Meanwhile in the East, temperatures near or below normal are forecast underneath upper-level troughing. A couple of frontal systems should help trigger showers and thunderstorms in a moist air mass from the Tennessee and Ohio Valleys to the Mid-Atlantic and Southeast. Scattered rain totals over the next couple of days could be over an inch, and isolated flooding or flash flooding is possible, but storms there are not expected to be severe. Tate Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php