US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 340 PM EDT Thu Jul 09 2020 Valid Sunday July 12 2020 - Thursday July 16 2020 Hazards: - Heavy rain across portions of the Great Lakes, the Upper Mississippi Valley, and the Northern Plains, Mon-Wed, Jul 13-Jul 15. - Flooding occurring or imminent across portions of the Southern Plains and the Northern Plains. - Excessive heat across portions of California and the Southwest, Sun-Mon, Jul 12-Jul 13. - Excessive heat across portions of the Southeast, the Middle/Lower Mississippi Valley, the Central/Southern Plains, and the Tennessee/Ohio Valley, Sun-Thu, Jul 12-Jul 16. Detailed Summary: The medium range period (Sunday, July 12 - Thursday, July 16) 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. Heavy rain associated with the system will occur over northern Maine on Sunday before beginning to wind down. Current forecast rainfall amounts are between 1 to 2 inches, with locally higher amounts possible depending on the strength of the system. Scattered thunderstorms will be possible across the remainder of the Northeast on Sunday, but impacts from heavy rain will be isolated. The Northern Plains and Upper Midwest could also see some heavy rain and thunderstorms 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 may 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. Around 1 inch of rain is possible with locally higher amounts. 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 the medium range will be the 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. Other potential record breaking cities include: Las Vegas, Albuquerque and San Antonio. 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 felt 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 Tuesday, with highs likely to breach 90 degrees by Wednesday. No widespread weather hazards are expected across Alaska between Sunday and Friday. 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, behind a receding ridge, but impacts seem relatively minor at this time. Kebede/Snell