US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 344 PM EDT Fri Jun 25 2021 Valid Monday June 28 2021 - Friday July 02 2021 Hazards: - Heavy rain across portions of the Southern Rockies and the Southern Plains, Mon-Tue, Jun 28-Jun 29. - Heavy rain across portions of the Great Lakes, the Ohio Valley, the Central Appalachians, the Mid-Atlantic, and the Northeast, Wed-Fri, Jun 30-Jul 2. - Heavy rain across portions of the Great Lakes and the Ohio Valley, Wed, Jun 30. - Heavy rain across portions of the Southern Plains, the Lower/Middle Mississippi Valley, the Tennessee Valley, the Ohio Valley, the Great Lakes, and the Central/Southern Appalachians, Thu-Fri, Jul 1-Jul 2. - Flooding possible across portions of the Central Plains, the Middle/Upper Mississippi Valley, the Great Lakes, and the Ohio Valley. - Flooding likely across portions of the Middle Mississippi Valley. - Excessive heat across portions of California, the Pacific Northwest, the Great Basin, and the Northern Rockies, Mon-Fri, Jun 28-Jul 2. - Excessive heat across portions of California, the Pacific Northwest, the Great Basin, and the Southwest, Mon, Jun 28. - Excessive heat across portions of the Great Basin, the Northern Rockies, and the Northern Plains, Tue-Fri, Jun 29-Jul 2. - Much above normal temperatures across portions of the Northeast, Mon-Tue, Jun 28-Jun 29. - Heavy rain across portions of mainland Alaska and the Aleutians, Wed-Fri, Jun 30-Jul 2. - High winds across portions of mainland Alaska and the Aleutians, Wed-Thu, Jun 30-Jul 1. Detailed Summary: The medium range forecast period (Monday, June 28 to Friday, July 2) will feature a pretty stagnant upper-level pattern, with a persistent and strong upper-level high initially centered over southwestern Canada and moving into the northwestern U.S., upper-level troughing over the central U.S., and another upper high gradually shifting from near the Mid-Atlantic coast eastward. The anomalous upper high over the West is expected to continue causing much above average and likely widespread record-breaking temperatures Monday through Friday, with persistent hot weather in the Great Basin to Northern Rockies. The Pacific Northwest and the Desert Southwest should see their hottest temperatures from the short range period into Monday, before the upper high pivots eastward a bit and portions of Idaho, Montana, and Utah see increasing heat around Tuesday through late in the week. Temperatures in the 100s and even 110s will be common in the West, generally 15 to 30 degrees above normal. While fire danger is not expected to be too widespread due to modest winds, some fires could occur, and the hot and dry conditions will serve to worsen the drought in the Northwest and prime soils for fire spread as the summer progresses. Farther south, however, the back end of a front slowly progressing across the central U.S. is forecast to pass through the Southern High Plains early in the workweek, which should lead to cooler temperatures and even heavy rain for parts of Colorado, New Mexico, and western Texas early in the week, and some showers could spread into Arizona as well. Any rain would likely be welcomed there due to drought conditions. Much of the central and eastern U.S. are likely to see scattered showers and thunderstorms through the week as the upper-level low/trough persists and a couple of slow-moving fronts provide areas for abundant moisture from the Gulf of Mexico to focus. Multiple days of moderate rainfall are possible in portions of the south-central U.S., but at this point it appears that higher rainfall totals may be likely by the latter part of the week, when a front helps to focus rainfall shifting slowly from the Great Lakes region southeastward into the Northeast, Ohio and Tennessee Valleys, and back into the Southern Plains. The rain could cause flooding and flash flooding issues especially over areas that see heavy rainfall during the short range period as well. Coastal Texas could see locally moderate to heavy rain for the beginning of the week, while the Florida Peninsula will also see a wet pattern during the period. The northeastern U.S. can expect a warm period for the first part of the workweek due to the upper high centered near the Mid-Atlantic coast bringing in warm air. Temperatures are expected to be generally in the 90s, which will be most anomalous for portions of New England. Temperatures are forecast to slowly moderate closer to normal from midweek onward as the upper high shifts away and the cold front and rain approach. In Alaska, a series of low pressure systems are forecast to meander near and potentially cross the Aleutians next week, setting up a moist southerly flow pattern into the Alaska Peninsula and surrounding areas. Moderate to locally heavy rain is likely to result, with chances increasing Wednesday in the Aleutians to Alaska Peninsula and spreading eastward into the Kodiak Island/Lower Cook Inlet area by Friday. The lows could also produce high winds and some anomalously high waves for this time of year. Additionally, farther north, moderate precipitation is expected for portions of the North Slope and Brooks Range for the first half of the workweek associated with a cold front. As the front brings cooler than normal temperatures there, some precipitation especially in higher elevations could be in the form of light snow. Tate