Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 406 PM EDT Tue Jul 17 2018 Valid 00Z Wed Jul 18 2018 - 00Z Fri Jul 20 2018 ...There is a slight risk of severe thunderstorms over parts of the Central Plains and the Northeast States... ...Heavy rain possible over portions of Arizona, Northern New Mexico and Southern Colorado, as well as parts of the northern High Plains and the Northeastern states... ...Hot temperatures expected across the southern Plains and southern Mississippi Valley, as well as for the portions of the western states... A large frontal system currently extends from New England southward across the Central Appalachians and westward through the Tennessee Valley into the Southern Plains. The eastern portion of this front will continue to shift off shore into the Atlantic through Wednesday. Meanwhile, the southern extent of the front will push southward into the Southeast through the remainder of the week, while a low pressure system deepens across the Southern Plains and begins to transition northeast as a warm front for the remainder of the week. During this time, shower and thunderstorm development is expected along the extent of the frontal boundary. SPC has outlined a slight chance risk for severe thunderstorm development along the New England coast for this afternoon and tonight. Excessive rain and flash flooding is also ongoing in this area and will likely continue into the overnight, before the front shifts off the coast Wednesday. Meanwhile, upper level energy and a low pressure system over the Northern Plains is also resulting in the development of strong showers and thunderstorms. A slight chance for both excessive rain and severe thunderstorm activity will remain in place across portions of the Central and Northern Plains through tomorrow, transitioning eastward into the Mid and Upper Mississippi Valley by Thursday. The best threat for severe weather and excessive rainfall will be in the afternoon and evening hours during peak daytime heating. A strong push of warm air from the Gulf of Mexico is making its way into the Southern Plains and Lower Mississippi Valley ahead of the above mentioned frontal boundary. This is leading to excessive heat and humidity, with heat advisories in place in portions of this area through mid week. Out west, much of the Pacific Northwest, California, and the western portion of the Intermountain West are experiencing very dry conditions, which is aiding in boosting temperatures across this region. Wind is also adding to the concerns as well. Heat advisories, warnings, and Red Flag Warnings are all in effect across portions of these areas through at least midweek. Wix Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php