US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
303 PM EDT Tue Sep 24 2019
 
Valid Friday September 27 2019 - Tuesday October 01 2019
 
Hazards:
- Heavy precipitation across portions of the Northern/Central Rockies, the Northern/Central Great 
Basin, and the Northern Plains, Sat-Mon, Sep 28-Sep 30.
- Heavy rain across portions of the Central Plains, the Upper/Middle Mississippi Valley, the Great 
Lakes, and the Ohio Valley, Fri-Sat, Sep 27-Sep 28.
- Heavy rain across portions of the Great Lakes and the Upper Mississippi Valley, Sun-Mon, Sep 
29-Sep 30.
- Flooding possible across portions of the Central/Southern Plains, the Great Lakes, and the 
Upper/Middle Mississippi Valley.
- Flooding occurring or imminent across portions of the Plains, the Upper/Middle Mississippi 
Valley, and the Great Lakes.
- Flooding likely across portions of the Middle Mississippi Valley and the Southern Plains.
- Much above normal temperatures across portions of the Central/Southern Appalachians, the 
Tennessee Valley, the Mid-Atlantic, the Southeast, the Great Lakes, and the Ohio Valley, Fri-Tue, 
Sep 27-Oct 1.
- Much below normal temperatures across portions of the Northern/Central Great Basin, the Northern 
Plains, the Northern Rockies, California, and the Pacific Northwest, Sat-Tue, Sep 28-Oct 1.
- Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Mon-Tue, Sep 
30-Oct 1.
- Heavy rain across portions of mainland Alaska, Sun, Sep 29.
 
Detailed Summary:

The upper-level flow pattern during the medium range period (Friday to Monday) is forecast become 
highly amplified, with a deep trough over the Western U.S. coupled with a strong ridge over the 
Southeastern U.S. This will set the stage for much below normal daytime temperatures across the 
interior Northwestern U.S. while heat is expected to expand across the interior Eastern U.S. In 
fact, record high temperatures across the interior sections of the Southeastern U.S. are likely 
starting on Friday and continuing into Monday.  Meanwhile, much colder temperatures are expected to 
overspread the interior Northwest beginning on Saturday. This cold air intrusion accompanied with a 
deepening upper-level low will likely bring the first significant winter weather event into the 
Northern Rockies starting Saturday and continuing through the Tuesday.  Precipitation will likely 
be in the form of heavy snow across the higher elevations of the Northern Rockies in the morning 
hours on Saturday and Sunday, culminating on Monday morning, while mixed precipitation is expected 
for the lower elevations. On Monday, the wintry weather should begin spreading slightly eastward 
into the Northern High Plains as the deep upper low is expected to slowly move out of the western 
U.S.

To the east of the deep upper low, moisture lifted ahead of a cold front is expected to bring the 
chance of heavy rain from the Central Plains to the Great Lakes on Friday and Saturday.  On Sunday, 
heavy rain will be a possibility from the Upper Mississippi Valley to the Upper Great Lakes as a 
low pressure system is forecast to form along a strong front across the Central High Plains.

Over Alaska, moisture associated with a cut-off low from the Central Pacific, combining with the 
remnants of former tropical cyclone Tapah from the Western Pacific, is expected to impact Southwest 
Alaska on Sunday.  It appears that total rainfall of 2 inches or more is possible for Southwest 
Alaska.  By Monday, more rain is expected to spread toward Southeastern Alaska with wintry 
precipitation farther inland.  Total precipitation could exceed 2 inches near the coast.

In Hawaii, an axis of tropical moisture is forecast to become nearly stationary across the western 
islands for the latter half of this week, leading to the potential for heavy rainfall to impact the 
area.

Ziegenfelder