Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 354 AM EDT Thu Jun 15 2017 Valid 12Z Thu Jun 15 2017 - 12Z Sat Jun 17 2017 ...Severe thunderstorms and heavy rain possible for portions of the Plains, the Midwest and the Tennessee Valley... ...Heat wave across portions of California and the Desert Southwest... ...Cooler temperatures expected for the Mid-Atlantic and Northeast over the next couple days while the central U.S. remains above average... A low pressure system lifting through the Midwest, Upper Midwest and the Great Lakes region over the next couple of days will provide forcing for showers and thunderstorms to develop over the central and eastern states. Strong to severe thunderstorms will be possible, along with heavy rainfall, for some areas of the Central Plains and Midwest where the trailing front is nearly stationary. Slow storm motion and/or storms developing over the same area may lead to flash flooding. Please refer to products issued by the SPC for further details on the severe weather threat. As the northern portions of the system moves east today, showers and thunderstorms are expected to increase in coverage across portions of the lower Great Lakes, Ohio and Tennessee valleys, and the Mid-Atlantic. Some severe storms will once again be possible, especially across portions of the southern/central plains and the Tennessee valley. An approaching Pacific front will spread rain showers to the interior portions of the Pacific Northwest and Intermountain West. However, precipitation will largely diminish by Friday afternoon as the front weakens. Cooler air will continue to filter into the Northeast and Mid-Atlantic regions- resulting in a vast area topping out in the 70s for afternoon highs. For central portions of the U.S. temperatures will remain above normal, with several locations averaging 5 to 15 degrees above average. Temperatures across California and the Desert Southwest are forecast to be well above normal over the next few days. Daily records may be reached, or exceeded, into the weekend. Maximum temperatures may range from 100 to 120+. Portions of western Texas and Oklahoma could surpass 100 degrees by Friday. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php