US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
310 PM EDT Mon Sep 09 2019
 
Valid Thursday September 12 2019 - Monday September 16 2019
 
Hazards:
- Heavy rain across portions of the Great Lakes, the Upper Mississippi Valley, and the Northern 
Plains, Thu-Fri, Sep 12-Sep 13.
- Flooding possible across portions of the Upper Mississippi Valley and the Northern Plains.
- Much above normal temperatures across portions of the Lower Mississippi Valley, the Central 
Appalachians, the Tennessee Valley, the Middle Mississippi Valley, the Southern Appalachians, the 
Southeast, the Great Lakes, and the Ohio Valley, Thu-Fri, Sep 12-Sep 13.
- Heavy rain across portions of the Alaska Panhandle and mainland Alaska, Thu-Fri, Sep 12-Sep 13 
and Sun-Mon, Sep 15-Sep 16.
 
Detailed Summary:

The medium range period (Thursday-Monday) will mostly feature upper-level troughs in the western 
and north-central U.S. and upper-level ridging in the Southeast. The biggest threat of heavy rain 
will be across the Upper Midwest and Great Lakes on Thursday and Friday as a low-pressure system 
moves across the region and exits into southern Ontario. Additional rainfall amounts around 1 to 2 
inches are possible across northern Minnesota and Wisconsin, with locally higher amounts. Heavy 
rain will also be possible along the cold front across central Oklahoma Thursday and Friday, but 
rainfall amounts appear too low to include a highlighted hazard area. Another area that could see 
heavy rain is the Southeast and Gulf Coast. A tropical wave is forecast to cross the Florida 
Peninsula on Saturday and reach the central Gulf Coast by Monday. This could bring the threat of 
widespread showers and thunderstorms, but confidence on where exactly the heaviest rain will occur 
is low. 

Upper-level ridging over the southeastern U.S. will result in above normal temperatures across much 
of the Ohio and Tennessee valleys on Thursday and Friday. The highest maximum temperature anomalies 
are expected to be around 10 to 15 degrees above normal from central Tennessee to southern Ohio. 
High temperatures are forecast to reach the mid-to-upper 90s across the Southeast and Tennessee 
Valley, with low-to-mid 90s across the Ohio Valley. Even though it will be hot, heat indices are 
forecast to remain below 105F due to relatively dry air and lower humidity.

In Alaska, a pair of low pressure systems are forecast to impact the southern coast during the 
medium range period. The first is forecast to bring heavy rain on Thursday and Friday, with the 
second entering the region on Sunday. Both systems could bring rainfall totals over 2 inches in 24 
hours, prompting a heavy rain area on the hazards graphic.

Snell