Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Tue Jul 04 2017 Valid 12Z Tue Jul 04 2017 - 12Z Thu Jul 06 2017 ...Dry and hot over the western U.S. but cool and pleasant over the Great Lakes and the Northeast... ...Scattered thunderstorms across much of the eastern two-thirds the country through Independence Day... The upper-level pattern across the U.S. mainland will continue to favor a broad trough in the northeastern U.S. while a ridge begins to strengthen over the western U.S. This means that heat is forecast to intensify over the West while cool and pleasant weather will continue from the Great Lakes eastward into New England. In the meantime, summertime heat and humidity with scattered thunderstorms are expected to continue for the rest of the country through Independence Day. The heaviest thunderstorms that have been focusing in the central Plains for the past few days will begin to shift eastward towards the mid-Mississippi Valley during the next couple of days. It appears that the severe weather nature of these storms will gradually shift to more of a heavy rain nature as a subtle convective low pressure system that is forecast to form in the central Plains in association with the thunderstorm clusters begins to interact and move east-northeast along a weak front. This subtle low pressure system, which has been suggested by computer models for the past few days, can help focus or enhance precipitation as it moves into the mid-Mississippi Valley on Wednesday before reaching the Ohio Valley on Thursday. Elsewhere, thunderstorms are more scattered in nature in the vicinity of a slow-moving front from across the Mid-Atlantic, central Appalachians, and across the Midwest into Wednesday. By Thursday morning, the thunderstorms will be scattered across the upper Midwest, the Great Lakes and into upstate New York. In the western U.S., a persistent upper-level ridge is forecast to strengthen during the next few days. The strong July solar radiation will heat up the interior mountains, and high temperatures are expected to gradually increase each day. Some locations in the Intermountain region will reach the upper 90s into the lower 100s. Meanwhile, temperatures are expected to soar into the 110s across much of the Desert Southwest. The fire danger will remain at very high levels under these conditions. The heat is expected to trigger only a few showers and thunderstorms over the interior mountains from the afternoon to the early evening hours. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php