Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 406 PM EDT Fri Jun 04 2021 Valid 00Z Sat Jun 05 2021 - 00Z Mon Jun 07 2021 ...Early season heatwave across the northern Plains will expand into the Northeast and Mid-Atlantic this weekend... ...Additional heavy rain expected to spread eastward into the central Gulf Coast this weekend... Impressive early season heat is expected to continue across much of the northern tier of the U.S. into Saturday as a strong upper level ridge dominates the weather pattern across the region. Highs well into the 90s to near 100 degrees are likely to break some old-standing records across portions of the Dakotas and Minnesota Saturday afternoon. Meanwhile, much cooler air associated with an upper-level trough is moving into the Pacific Northwest. A cold front will move steadily eastward across the northern Rockies tonight and could trigger some strong to severe thunderstorms for the northern High Plains through tonight into Saturday morning. Cooler air behind the front will bring temperatures down to normal levels for the northern High Plains on Sunday. However, the upper Midwest will remain hot on Sunday as the heat expands eastward into the Northeast and the Mid-Atlantic this weekend where high temperatures in the low to mid 90s could challenge some daily records. Over the Mid-Atlantic, some thunderstorms this afternoon into this evening may become severe. Expect the rain chances to decrease during the weekend as a surface trough tends to move toward and off the Mid-Atlantic coast. Meanwhile, additional heavy rainfall is forecast for the western half of the Gulf Coast region as an upper-level trough/low forms over the southern Plains and interacts with tropical moisture from the Gulf of Mexico. The highest chance of heavy rain is expected to be across coastal Texas through tonight but the heavy rain is expected to shift toward Louisiana on Saturday as the upper trough is forecast to lift toward the northeast. By Sunday, the threat of heavy rain could spread further inland across the lower Mississippi Valley. Total rainfall of 2 to 4 inches may result in some instances of flooding especially across southern Louisiana during the weekend. Over the Pacific Northwest, damp and cool condition will return for the weekend under cool and moist onshore flow associated with the upper trough. In contrast, it will remain quite warm across the interior West with 100+ degree readings expected for the lower elevations across the Desert Southwest. Some scattered thunderstorms are forecast across the Great Basin into this evening, shifting into the central and southern Rockies during the weekend, and possibly over the central to southern High Plains Sunday afternoon. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php