Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 348 AM EDT Fri Jul 16 2021 Valid 12Z Fri Jul 16 2021 - 12Z Sun Jul 18 2021 ...Showers and thunderstorms to produce the threat of flash flooding between the Lower Great Lakes and Southern Plains today before entering the Northeast on Saturday... ...Additional rounds of heavy rain and thunderstorms found throughout the Southwest... ...Excessive heat builds into the Northern Plains and Intermountain West this weekend... The focus for much of the thunderstorm activity east of the Rockies over the next few days will be associated with a slow-moving cold front currently located between the Lower Great Lakes and Southern Plains. The main hazard along this frontal boundary is expected to be in the form of heavy rain as thunderstorms develop within a warm and very moist airmass. A Slight Risk (level 2/4) of Excessive Rainfall has been issued through Saturday morning to include parts of the Lower Great Lakes, Ohio Valley, Middle Mississippi Valley, and Southern Plains. Flash Flood Watches are also in effect across southeast Kansas, northeast Oklahoma, and southwest Missouri. A few isolated thunderstorms may turn severe and produce damaging wind gusts. By Saturday, the aforementioned frontal boundary is forecast to enter waterlogged portions of the Northeast and stall over southern New England. This will help spark numerous showers and thunderstorms, which may pass over locations currently experiencing an extremely wet July. In fact, much of New England and parts of the Northeast have seen 5-10+ inches of rain so far this month, more than double the normal rainfall for the first half of July. Thus, any additional heavy rain will likely lead to increased runoff and the potential for flash flooding. Rain will also continue to make headlines across the Southwest as monsoonal moisture brings much needed rainfall to this section of the country. However, instances of flash flooding will remain a concern throughout parts of Arizona and New Mexico into the weekend. Additional isolated rainfall totals up to 1 inch are possible today across central and southeastern Arizona, where Flash Flood Watches have been issued to highlight the potential hazard. Elsewhere, the next heat wave of the summer is set to impact the Northern Plains and eventually parts of the Great Basin by the end of the weekend. The pattern behind the upcoming stretch of oppressive heat is associated with a strong upper-level ridge that is forecast to strengthen and situate over the Rockies. High temperatures into the triple digits are likely for several consecutive days throughout eastern Montana, extending into the lower elevations of the Northern Rockies and Great Basin by Sunday. A few daily high temperature records could fall. Highs into the low-to-mid 90s are forecast along the U.S.-Canada border through North Dakota and Minnesota as well. Additionally, elevated fire weather will continue to be a concern throughout much of the Intermountain West due to the combination of above average temperatures and extreme drought. Snell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php