Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 357 AM EDT Fri Jun 18 2021 Valid 12Z Fri Jun 18 2021 - 12Z Sun Jun 20 2021 ...Severe thunderstorms and heavy rain producing flash flooding are possible throughout the Ohio Valley on Friday... ...Dangerous and record-breaking heat will continue across a large portion of the western U.S. and the central Plains... ...Tropical rains and an increasing threat for flash flooding are expected along the Central Gulf Coast beginning Friday... Heatwave continues. Excessive Heat Warnings and Heat Advisories remain in effect across much of California, Nevada, Arizona, and Utah. Temperatures are expected to once again reach record-breaking highs across much of the region, with several records likely to fall on Friday and Saturday as well. Additionally, Heat Advisories are also in effect for portions of the Central Plains/Middle Mississippi Valley on Friday. Well-above normal temperatures are expected across the region, with record-breaking highs expected from Kansas to Iowa and Missouri. While a front dropping into the region is expected to offer some relief, temperatures are forecast to remain well-above average on Friday and into Saturday. Severe thunderstorms will develop across portions of the Middle Mississippi/Ohio Valleys. The Storm Prediction Center has issued an Enhanced Risk for severe thunderstorms across the Ohio Valley through Saturday morning. The main hazards with these storms are frequent lightning, severe thunderstorm wind gust, large hail, and a few tornadoes. There is a 10% or greater probability of wind gust of 65 knots or greater over parts of the Ohio Valley. Furthermore, heavy rain associated with the thunderstorms will produce areas of flooding. Therefore, the WPC has issued a Moderate Risk of excessive rainfall with these thunderstorms. The associated heavy rain will create numerous areas of flash flooding. Furthermore, many streams may flood, potentially affecting larger rivers through Saturday morning. On Saturday, the severe thunderstorms and the excessive rainfall threat will decrease. However, showers and thunderstorms will occur along and near the front on Saturday into Sunday. Heavy rainfall and windy conditions are expected to develop along the Central Gulf Coast on Friday before spreading over the Southeast on Saturday and Sunday. Abroad area of low pressure over the Gulf of Mexico continues to become better organized. This system is expected to move generally to the north, and a tropical depression is likely to form over the west-central Gulf of Mexico on early Friday. As a result, the National Hurricane Center has indicated a Tropical Storm Warning across portions of the Central Gulf Coast. Furthermore, heavy rain will develop over the area on Friday and Saturday. As a result, the WPC has issued a Slight Risk of excessive rainfall over the Central Gulf Coast. The heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, and small streams are the most vulnerable through Saturday morning. Then on Saturday, the WPC has increased the excessive rainfall threat to a Moderate Risk through Sunday morning. The associated heavy rain will create numerous areas of flash flooding. Furthermore, many streams may flood, potentially affecting larger rivers on Saturday into Sunday morning. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php