Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 403 PM EDT Tue Jun 12 2018 Valid 00Z Wed Jun 13 2018 - 00Z Fri Jun 15 2018 ...Severe thunderstorms are possible tonight for parts of the central Plains and upper Midwest, tomorrow across the Northeast, and Thursday in the northern Plains... ...Heavy rain and flash flooding possible for for portions of the central Plains and the lower Ohio Valley tonight... ...Heat wave to continue for portions of the Southwest with a warming trend expected across the Intermountain West and the central U.S.... Scattered showers and Thunderstorms can be expected across much of the Deep South, the Ohio Valley, and back into the central Plains tonight and into Wednesday ahead of a frontal boundary as it pushes slowly eastward. The boundary itself should serve a focus for heavier rainfall and strong to severe thunderstorms, particularly across portions of the lower Ohio Valley and the central Plains. WPC has slight risks for excessive rainfall/flash flooding highlighted across these regions through tonight, and the Storm Prediction Center is monitoring parts of the Texas and Oklahoma panhandles and southwest Kansas for the development of severe thunderstorms. To the north, a shortwave moving across the upper Midwest and the Great Lakes through tomorrow may spark a round of severe thunderstorms across the upper Midwest tonight, and again tomorrow for parts of the interior Northeast from northern West Virginia to upstate New York. The Storm Prediction Center has slight risks on their convective outlooks for both of these locations. Numerous showers and storms are likely by Wednesday afternoon across much of the Northeast and the lower Great Lakes ahead of the associated cold front. Persistent ridging in the upper levels will keep summer heat locked in across the Southwest with afternoon highs in the 90s and low 100s likely through Wednesday. These values are as much as 10 degrees above normal for this time of the year, and excessive heat warnings are in effect across parts of southern Arizona, eastern California and far southern Nevada. Temperatures are expected to moderate to near or below normal by Thursday as the upper ridging shifts eastward. Elsewhere, temperatures across the central U.S. and intermountain West will also be 10 to 15 degrees above normal ahead of a frontal boundary entering the Pacific Northwest by Wednesday. Santorelli Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php