US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
339 PM EDT Wed May 15 2019
 
Valid Saturday May 18 2019 - Wednesday May 22 2019
 
Hazards:
- Heavy precipitation across portions of the Central Great Basin, California, and the Southwest, 
Sat-Sun, May 18-May 19.
- Heavy precipitation across portions of California, the Northern Plains, and the Northern Rockies, 
Sat, May 18.
- Heavy precipitation across portions of the Central Great Basin, the Northern Rockies, and the 
Northern Great Basin, Sun, May 19.
- Heavy precipitation across portions of the Central Rockies, the Northern Plains, and the Northern 
Rockies, Sun-Mon, May 19-May 20.
- Heavy precipitation across portions of the Northern Plains, Wed, May 22.
- Heavy rain across portions of the Central Rockies, California, the Pacific Northwest, and the 
Central Plains, Mon-Tue, May 20-May 21.
- Heavy rain across portions of the Central Plains, the Lower Mississippi Valley, the Northern 
Plains, the Great Lakes, the Middle Mississippi Valley, the Upper Mississippi Valley, the Southern 
Plains, and the Ohio Valley, Sat-Wed, May 18-May 22.
- Heavy rain across portions of the Black Hills of South Dakota, Wed, May 22.
- Severe weather across portions of the Central Plains, the Middle Mississippi Valley, the Lower 
Mississippi Valley, the Southern Plains, and the Upper Mississippi Valley, Sat, May 18.
- Severe weather across portions of the Middle Mississippi Valley, the Lower Mississippi Valley, 
the Great Lakes, the Ohio Valley, and the Tennessee Valley, Sun, May 19.
- Severe weather across portions of the Central Plains and the Southern Plains, Mon, May 20.
- Severe weather across portions of the Central Plains, the Middle Mississippi Valley, the Lower 
Mississippi Valley, the Southern Plains, and the Ohio Valley, Tue, May 21.
- Flooding possible across portions of the Northern Great Basin.
- Flooding occurring or imminent across portions of the Lower Mississippi Valley, the Northern 
Plains, the Great Lakes, the Northern Rockies, the Middle Mississippi Valley, the Upper Mississippi 
Valley, the Southeast, the Southern Plains, and the Ohio Valley.
- Flooding likely across portions of the Northern Rockies and the Northern Great Basin.
- Much below normal temperatures across portions of the Central Plains, the Central Great Basin, 
the Northern Plains, the Northern Rockies, the Central Rockies, California, the Northern Great 
Basin, the Pacific Northwest, and the Southwest, Sat-Wed, May 18-May 22.
- Much below normal temperatures across portions of the Central Plains, the Upper Mississippi 
Valley, the Great Lakes, the Northern Plains, and the Northern Rockies, Sat-Tue, May 18-May 21.
 
Detailed Summary:

An amplified upper-level pattern will likely bring active weather across much of the Great Plains 
for the medium range period (May 18-May 22). Meanwhile, heat and humidity are forecast to establish 
across the Southeast into the Mid-Atlantic as chilly conditions continue over much of the western 
U.S. and across the northern Plains.

Persistent upper-level troughing will bring multiple rounds of snow across the higher elevations of 
the western U.S. The Sierra Nevada will likely see 1-2 feet of snow during the weekend as the first 
system moves through the region. Some addition snowfall can be expected by Tuesday and Wednesday as 
the next system moves in. The higher peaks of the northern Rockies will likely see periods of 
accumulating snow through the medium range period. By next Wednesday, the Black Hills of South 
Dakota may see some snowfall as well.

Meanwhile, the cold upper trough will also keep chilly conditions across much of California into 
the Great Basin and across the northern Plains. In fact, the cold conditions are most pronounced 
during the day due to considerable clouds and precipitation. They are highlighted on the WPC 
hazards chart where high temperatures are forecast to be 10 to more than 20 degrees below normal.

As pieces of energy from the western U.S. upper trough eject into the Plains, severe weather will 
be possible daily through May 21. The prime area of focus will vary each day but should generally 
be located to the west of the Mississippi Valley. Please refer to the Storm Prediction Center for 
more specific details. In addition to the severe weather threat, a large area of heavy rain will 
encompass much of the Great Plains through the medium-range period where highest rainfall totals 
could exceed 5 inches.

Alaska and the eastern U.S. will remain relatively quiet through the medium-range period. However, 
some heat and humidity is forecast to build across the Southeast into the Mid-Atlantic where high 
temperatures could reach the mid-90s with dew points forecast to reach the upper 60s. These high 
temperatures are marginal for the much-above-normal temperature criteria at the moment.

Kong