Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 359 AM EDT Fri Aug 04 2017 Valid 12Z Fri Aug 04 2017 - 12Z Sun Aug 06 2017 ...Excessive heat across the West Coast expected to continue... ...A strong cold front sweeping the eastern U.S. to bring showers and thunderstorms with it... ...Severe thunderstorms possible for portions of the Central/Northern Appalachians... ...Heavy rainfall expected across the Gulf Coast... Portions of the Pacific Northwest will continue to have oppressive heat today - much of western Washington and Oregon have excessive heat warnings and heat advisories in effect. This area will have afternoon highs soaring in the 100 to 110+ range today. As the strong upper-level ridge begins to weaken this weekend the temperatures will cool slightly in response - with most areas peaking in the upper 90s. In the Desert Southwest and Central/Southern Rockies, monsoonal moisture along with daytime heating will generate showers and thunderstorms during the afternoon and evening hours. Any of these storms could have isolated heavy downpours; which would increase the threat of flash flooding. A vast portion of the central and eastern U.S. will have showers and thunderstorms over the next few days. Heavy rain will be possible, along with an increased risk for flash flooding, across the Gulf Coast states. Warm, moist air from the Gulf of Mexico is expected to stream northward over a stalled front boundary along the Gulf Coast. This boundary will act as a focus for convection during the afternoon and evening hours due to daytime heating. Amounts of 1 to 2 inches are forecast through the weekend for this region, with isolated amounts of 3+ will be possible. Additionally, a warm front attached to a surface low will travel northward across the Carolinas, which may generate showers and thunderstorms along the coastline; however, the heaviest rainfall will remain offshore. A frontal system is forecast to track southward from the Northern/Central Rockies and out into the Central/Southern Plains. Scattered to widespread showers and thunderstorms will generate along and east of this frontal boundary. With the slow nature of this system, many areas may have multiple rounds of precipitation. Much of eastern Oklahoma, eastern Kansas, Arkansas and Missouri will get the highest amounts, which has areal averages of 1 to 3 inches. A strong cold front will continue to track eastward into through the Ohio/Tennessee Valleys today. As the front stretches from the lower Great Lakes to the southern Plains, showers and thunderstorms will fire off ahead of this boundary. There is a possibility of severe weather primarily for the lower Great Lakes and Ohio Valley region on Friday. By Saturday, the front reaches the East Coast--with most of the precipitation occurring in the Northeast. Behind the front, much cooler temperatures can be expected for the entire region east of the Rockies. Campbell/Reinhart Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php