US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
458 PM EDT Mon Sep 23 2019
 
Valid Thursday September 26 2019 - Monday September 30 2019
 
Hazards:
- Heavy precipitation across portions of the northern Cascades, Thu-Fri, Sep 26-Sep 27.
- Heavy precipitation across much of Montana and into portions of the northern Rockies, Sep 26-Sep 
30.
- Heavy rain across portions of the central Plains, the Midwest, and into the Great Lakes, Thu-Fri, 
Sep 26-Sep 27.
- Heavy rain across portions of the northern Plains, the upper Midwest and the western half of the 
Great Lakes, as well as southeastern Florida, Mon, Sep 30.
- Flooding possible across portions of the Southern Plains and the Northern Plains.
- Flooding occurring or imminent across portions of the Central Plains, the Middle Mississippi 
Valley, the Southern Plains, the Upper Mississippi Valley, and the Northern Plains.
- Flooding likely across portions of the Central Plains and the Middle Mississippi Valley.
- Much above normal temperatures across portions of the interior eastern and southeastern U.S., 
Thu-Mon, Sep 26-Sep 30.
- Much below normal temperatures across portions of northern California into the Great Basin and 
the Intermountain West, as well as the northern Rockies and the northern High Plains, Fri-Mon, Sep 
27-Sep 30.
- Heavy rain across much of southwestern Alaska, Sun, Sep 29.
- Heavy precipitation across portions of the Alaska Panhandle and southern Alaska, Mon, Sep 30.
 
Detailed Summary:

The upper-level flow pattern during the medium range period (Thursday 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 southeastern U.S. are likely in the interior sections of 
the southeastern U.S. starting on Thursday and continuing into the weekend.  The record high 
temperatures are forecast to spread further northeast into the interior Mid-Atlantic during the 
weekend.  Meanwhile, much colder temperatures are expected to overspread the interior Northwest 
beginning on Friday.  This cold air intrusion accompanied with a deepening upper low will likely 
bring the first significant winter weather event into the northern Rockies starting Friday and 
continuing through the weekend.  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 be slow to 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 Midwest on Thursday and Friday.  By next 
Monday, heavy rain will be a possibility from the northern Plains to the upper Midwest as a low 
pressure system is forecast to form along a strong front across the northern Plains.

In the meantime, as the strong upper ridge becomes firmly established over the Southeast, tropical 
cyclone Karen currently over the eastern Caribbean could eventually make a westward turn toward the 
northern Bahamas by early next week.  A heavy rain area is indicated for southeastern Florida for 
next Monday into Monday night per the latest track guidance from the National Hurricane Center.  It 
is to be noted that uncertainty is quite high regarding the long range track prediction of Karen.  
Hence, the potential impacts of Karen over the southeastern U.S. will be subject to change.

Over in 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 this weekend.  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 
addition, strong winds and high surf conditions are likely along the coast of southern Alaska 
through the weekend and into Monday.

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.

Kong