US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
437 PM EDT Thu Sep 02 2021
 
Valid Sunday September 05 2021 - Thursday September 09 2021
 
Hazards:
- Flooding possible across portions of the Mid-Atlantic and New England.
- Flooding occurring or imminent across portions of the Lower and Upper Mississippi Valley.
- Flooding likely across portions of the Northeast, New England, and the Upper Mississippi Valley.
 
Detailed Summary: 

The medium range forecast period (Sunday, Sep 5 to Thursday, Sep 9) may feature some instances of 
heavy rain, but no hazards outlook areas have been introduced at this time. At the beginning of the 
period, showers and storms are forecast to develop along a cold front moving southward through the 
eastern and central U.S., with the western portion across the Southern Plains and Lower Mississippi 
Valley expected to slow and remain relatively stationary on Sunday (Sep 5th) and Monday (Sep 6th). 
Instances of heavy rain may be possible from the southern Appalachians westward through the 
Tennessee Valley, Lower Mississippi Valley, and into the Southern Plains. However, there is not 
enough consistency amongst the model guidance on widespread, hazardous rainfall. 

Further into the period, an upper-level trough will dig across the Midwest. At the surface, a low 
pressure system will move from the Great Lakes on Tuesday (Sep 7th) east to New England on 
Wednesday (Sep 8th). Showers and storms appear likely in these areas as the associated fronts move 
east, but the forecast rainfall amounts do not look to be high and/or widespread enough currently 
for an outlook area. 

Finally, some showers and storms are possible along the central and western Gulf Coast as the cold 
front associated with the system in the Northeast continues southward at the end of the forecast 
period on Thursday (Sep 9th). There also appears to be some potential that a tropical system will 
approach this region which may lead to an increase in storms and heavy rain. However, there is not 
enough confidence in this scenario to introduce an outlook area at this time. While there are not 
included outlook areas for heavy rain, flooding will remain an ongoing threat in the northern 
Mid-Atlantic and southern New England due to recent heavy rainfall from the remnants of Ida. 

In Alaska, the potential for heavy rain is anticipated as two systems impact the state. On Sunday, 
an initial wave ahead of an occluding low pressure system over the Gulf of Alaska will lead to 
heavy rain across the southeastern Panhandle. As the deepening system approaches the Panhandle, 
showers will again increase on Tuesday. Several inches of rain are anticipated both days. On 
Thursday, a second occluding system is expected to approach the mainland Southwest from the Bering 
Sea. Widespread heavy rain of around 2 inches and locally higher is forecast along the southern 
Alaskan Peninsula, the southern Kenai Peninsula, and Kodiak Island. While there is some uncertainty 
in the development and progression of this system, the guidance has been consistent in showing a 
signal for heavy rain in these areas despite how the pattern evolves. However, given the region is 
entering the rainy season, opted not to highlight any outlook areas as the impacts from both 
systems are not expected to be particularly hazardous. In addition to the rain threat, high winds 
are also possible along Bristol Bay in advance of the Bering Sea system on Thursday. Given the 
uncertainty in the development of the system, though, have opted not to highlight an area here for 
now either, but this will be reassessed in the coming days. 
 
Putnam