US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
500 PM EDT Fri Aug 27 2021
 
Valid Monday August 30 2021 - Friday September 03 2021
 
Hazards:
- Heavy rain across portions of the northern Plains as well as from the central Gulf Coast 
northward through the Tennessee Valley into the Ohio Valley, Mon-Tue, Aug 30-Aug 31.
- Heavy rain from portions of the Tennessee Valley, across the central/southern Appalachians, and 
into the Mid-Atlantic states; and from the northern Plains to the upper Midwest; as well as much of 
Arizona, Wed-Thu, Sep 1-Sep 2.
- Heavy rain across southwestern Colorado, Thu-Fri, Sep 2-Sep 3.
- Heavy rain across portions of the upper Midwest, Fri, Sep 3.
- Flooding possible across portions of the central Gulf Coast states.
- Flooding likely across portions of central Wisconsin.
- High winds across much of the central Gulf Coast and into the lower Mississippi Valley, Mon, Aug 
30.
- Much above normal temperatures across much of the central High Plains, Mon-Wed, Aug 30-Sep 1.
- Much above normal temperatures for a good portions of North Carolina and into South Carolina, 
Mon-Tue, Aug 30-Aug 31.
- High significant wave heights for coastal portions of Louisiana into Mississippi, Mon, Aug 30.
- Heavy rain across portions of southern Alaska, Wed-Thu, Sep 1-Sep 2.
 
Detailed Summary:

Hurricane Ida will likely be the top weather story as we begin the medium range period (from 
Monday, Aug 30 to Friday, Sept 3).  The latest projection from the National Hurricane Center places 
the eye of Ida over south-central Louisiana shortly after making landfall on the coast of 
southeastern Louisiana as a major hurricane around midnight early on Monday.  Torrential rain 
driven by destructive hurricane-force winds can be expected to push further inland on Monday.  
Model guidance shows above normal agreement on a relatively slow recurvature of the hurricane into 
the lower Mississippi Valley Monday into Tuesday.  This could prolong the impacts of high winds 
along the central Gulf Coast and possibly farther inland across southern Louisiana into Mississippi 
as the hurricane at such intensity at landfall will likely take extra time to spin down over land.  
In addition to the prolonged threat of high winds, the relative slow motion of the hurricane will 
likely increase the chance for more prolific rainfall to bring life-threatening flash flooding 
across Louisiana into the lower Mississippi Valley.  There is also a chance for isolated tornadoes 
to develop over land on the northeastern quadrant of Ida.

Following recurvature, Ida is forecast weaken further as it continues to track northeastward across 
the Tennessee Valley on Wednesday.  Thereafter, models begin to diverge on how fast the tropical 
moisture is carried downstream across the eastern U.S. from the middle to late next week.  
Nevertheless, heavy rain can be expected to overspread the central/southern Appalachians and into 
the Mid-Atlantic Wednesday into Thursday as the tropical moisture interacts with a frontal system 
dipping south from New England.  By Friday, the faster model guidance favors pushing the tropical 
moisture off the East Coast while the slower guidance is in the process of pushing the 
post-tropical circulation of Ida toward the Mid-Atlantic coast.

In addition to Ida, tropical cyclone Nora in the eastern Pacific is forecast to make its impact 
across the western U.S. next week.  Latest projection from the National Hurricane Center brings the 
eye of Hurricane Nora into the Gulf of California early next week.  Nora is then forecast to track 
further northwest towards the southwestern U.S. midweek.  Tropical moisture ahead of Nora is 
expected to surge northward and reach the southwestern U.S. due to the presence of an upper-level 
low to the west of Baja California.  Showers and locally heavy downpours are forecast to reach 
southern Arizona later on Monday, spreading further north on Tuesday.  The bulk of the heaviest 
rainfall is now forecast to overspread much of Arizona on Wednesday into Thursday.  In addition, 
the moisture plume is forecast to stream further northeast across the central Rockies bringing an 
increasing threat of heavy rain into the region especially southwestern Colorado late next week.

Outside of the tropics, the northern Plains into the upper Midwest will be under a threat of heavy 
rainfall as well--first ahead of a warm front early next week, followed by the next frontal system 
moving into the region later next week when some of the upper-level moisture from Nora could be 
injected into the system.

Over Alaska, the start of September looks stormy as another occluded cyclone is expected to impact 
the state, this time generating moderate to heavy rainfall over the Aleutians, east towards the 
upper Peninsula, and along the west-central Gulf coast, together with some gusty winds.  Conditions 
should improve late week as the system moves further off to the east.

Kong