US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 358 PM EDT Tue Aug 31 2021 Valid Friday September 03 2021 - Tuesday September 07 2021 Hazards: - Flooding possible across portions of the Northeast, the Central Appalachians, the Tennessee Valley, the Mid-Atlantic, the Southern Appalachians, the Southeast, the Great Lakes, and the Ohio Valley. - Flooding occurring or imminent across portions of the Lower Mississippi Valley, the Tennessee Valley, the Middle Mississippi Valley, the Upper Mississippi Valley, the Southeast, and the Great Lakes. - Heavy rain across portions of mainland Alaska, Fri, Sep 3. Detailed Summary: The medium range period (Friday, Sep 3 to Tuesday, Sept 7) will begin with flash flooding potential across the Northeast due to heavy rain from Ida. A heavy rain area wasn't added because the threat has now moved into the short range period. That being said, flooding remains a possibility into the medium range for parts of the Mid-Atlantic, Ohio Valley and Northeast. Waves of low pressure riding along an upper-level trough will bring rain to the Midwest over the medium range period. The Friday and Tuesday systems don't seem strong enough at this time to exceed our heavy rain threshold. A heavy rain threat exists along a thermal boundary over the Central Plains and Middle Mississippi Valley next Tuesday as potential convection may lead to elevated rain amounts. We'll monitor this moving forward. Over Alaska, an occluded cyclone edging closer to the southern coast should bring heavy rainfall mainly on the eastern portion of the Kenai Peninsula Peninsula and nearby areas just to the east on Thursday and into Friday. Some heavy rainfall could move into the southern end of the Alaska Panhandle but uncertainty is currently a bit too high for specifying a heavy rain area. Kebede/Kong