US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 354 PM EDT Wed Jul 08 2020 Valid Saturday July 11 2020 - Wednesday July 15 2020 Hazards: - Heavy rain across portions of the Great Lakes and the Upper Mississippi Valley, Mon-Wed, Jul 13-Jul 15. - Heavy rain across portions of the Northeast, Sat, Jul 11. - Flooding occurring or imminent across portions of the Northern Plains. - Excessive heat across portions of California and the Southwest, Sat-Mon, Jul 11-Jul 13. - Excessive heat across portions of the Central Plains, the Lower Mississippi Valley, the Tennessee Valley, the Middle Mississippi Valley, the Southeast, and the Southern Plains, Sat-Wed, Jul 11-Jul 15. - Excessive heat across portions of the Central Plains, the Middle Mississippi Valley, and the Lower Mississippi Valley, Wed, Jul 15. Detailed Summary: The medium range period (Saturday, July 11 - Wednesday, July 15) will feature a very summer-like pattern dominated by expanding heat and isolated chances for heavy rain. A low pressure system currently off the coast of the Carolinas is forecast to move northward and into southern New England by Saturday. As a result, heavy rain will be possible across the region from Massachusetts to Maine. Current forecast rainfall amounts are between 1 to 2 inches, with locally higher amounts possible depending on the eventual strength of the system. Scattered thunderstorms will be possible across the remainder of the Northeast on Saturday and Sunday, but impacts from heavy rain will be isolated. Another area that could see heavy rain/flash flooding will be across the Northern Plains and Upper Midwest between Monday, July 13 and Wednesday, July 15. A cold front will swing across the Northern Plains on Monday and run into a very warm and humid airmass. Thunderstorms are expected to break out across North Dakota and Minnesota on Monday, followed by repeated rounds of storms Tuesday and Wednesday as the front very slowly crosses the Upper Great Lakes. There is too much uncertainty to discuss specific rainfall amounts, but ensemble guidance shows moderate confidence in at least 1 inch of rain across the highlighted region. Portions of Minnesota, including Duluth and Minneapolis, could actually use the rain given how dry the last 30 days have been. The most widespread weather hazard in this time-period will be the expanding area of Excessive Heat across the Southwest, Southern/Central Plains, Deep South, and into the Middle Mississippi Valley. Across the Southwest, high temperatures are forecast to soar well above 100 degrees and into possible record territory through Monday. In fact, Phoenix and Tucson, Arizona are forecast to tie or break their daily record high temperature on both Sunday and Monday. Temperatures are expected to cool slightly across the Southwest on Tuesday as the center of the upper-level ridge moves into the Southern Plains. Record-breaking heat is also in store across much of Texas, however heat indices will make it feel much hotter through the middle of next week east of the High Plains. Widespread heat indices greater than 110 degrees will be found from Texas and Oklahoma eastward to southern Alabama. This relentless heat will remain in place through Wednesday, as it also begins to expand further north and east into Missouri and the Middle Mississippi Valley. Therefore, expect the current Excessive Heat area on the Hazards Outlook graphic to expand eastward over the next couple of days. Another aspect of this heat wave will be low temperatures remaining well above average across this region, with temperatures only dipping into the 70s and low 80s, making it even harder to cool off at night if no A/C is available. Above average temperatures will begin to enter the Great Lakes and Ohio Valley on Wednesday, leading to highs in the mid-90s. No widespread weather hazards are expected across Alaska between Saturday and Wednesday. Temperatures are expected to remain below average with chances of rain and high elevation snow showers. An area of low pressure could reach the western Aleutian Islands by Wednesday, but confidence in any impacts is low at this time. Snell