US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 159 PM EDT Tue Jun 01 2021 Valid Friday June 04 2021 - Tuesday June 08 2021 Hazards: - Flooding possible across portions of the Central and Southern Plains. - Flooding occurring or imminent across portions of the Southern Plains. - Flooding likely across portions of the Central Plains, the Northern Rockies, and the Northern Great Basin. - Heavy rain across portions of the Southeast and the Mid-Atlantic, Fri, Jun 4. - Heavy rain across portions of the Southern Plains, Fri-Sat, Jun 4-Jun 5. - Heavy rain across portions of the Lower Mississippi Valley and the Southern Plains, Sun-Mon, Jun 6-Jun 7. - Heavy rain across portions of the Middle and Lower Mississippi Valley, Tue, Jun 8. - Much above normal temperatures across portions of the Pacific Northwest, California, the Northern/Central Great Basin, the Northern/Central Rockies, the Northern/Central Plains, the Upper Midwest, and the Northern Great Lakes, Fri-Tue, Jun 4-Jun 8. - Much above normal temperatures across portions of the Northeast and Central Appalachians, Sun-Tue, Jun 6-Jun 8. Detailed Summary: During the medium range period (Friday, June 4th - Tuesday, June 8th), an upper level cut-off low positioned over the Southern Plains will be the main driving force behind the very active weather forecast for the region. Beginning on Friday, moist return flow off the Gulf of Mexico will help to enhance instability at the surface, priming the atmosphere for the development of multiple rounds of convective precipitation. Rainfall totals up to and exceeding 2" in 24 hours have been forecast for much of southeast Texas Friday and Saturday. On Sunday and Monday the upper level low is expected to track northeast, pushing the heavy rainfall into eastern Texas and western Louisiana before it spreads north into Oklahoma and Arkansas on Tuesday. With the soils heavily saturated in each of these affected areas due to recent above average rainfall, the potential for flash flooding associated with these heavy rain events will be a significant concern. Other locations where heavy rainfall may become hazardous on Friday are the Mid-Atlantic and Southeast. As an upper level shortwave moves a frontal boundary into warm air settled over the regions showers and thunderstorms may develop and deposit rainfall totals up to and exceeding an inch throughout the contoured area. Temperature wise, much of the western US and Northern Tier will experience much above normal temperatures this weekend and into early next week. Ridging over the western half of the CONUS will allow daily high temperatures throughout the Intermountain West, Northern Rockies, and the Northern Plains to soar near 100, 20 to 30 degrees warmer than normal. Towards the beginning of next week, the upper level ridge is expected to progress eastward, spreading the wealth to the Great Lakes and the Northeast where daily highs will likely reach the 80s and, in some areas, the low 90s. Though no hazards have been posted for Alaska, two precipitation events occurring within the medium range period are worth mentioning. The first event is some rainfall over the southeastern Mainland that is expected to develop on Friday in association with a stationary front and low pressure wave over the area. While the current guidance indicates some heavy precipitation with 1.5 to isolated 2 inch rain totals is possible, it is toeing the hazardous threshold line and is therefore not indicated on this graphic. A second event over the northwestern Mainland later in the period has also been decidedly excluded in the graphic today as the storm total rainfall may not reach hazardous levels and the models cannot agree on where the heaviest precipitation will occur. Finally, it is worth noting that daily high temperatures across the state will hover between 5 and 15 degrees below normal throughout the period. Zavadoff