US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
350 PM EDT Wed Apr 15 2020
 
Valid Saturday April 18 2020 - Wednesday April 22 2020
 
Hazards:
- Heavy rain across portions of the Southeast, the Lower Mississippi Valley, the Southern 
Appalachians, and the Tennessee Valley, Sat-Sun, Apr 18-Apr 19.
- Heavy rain across portions of the Lower Mississippi Valley, the Tennessee Valley, the Middle 
Mississippi Valley, the Mid-Atlantic, the Southern Appalachians, the Southeast, the Southern 
Plains, and the Ohio Valley, Wed, Apr 22.
- Flooding occurring or imminent across portions of the Lower Mississippi Valley, the Northern 
Plains, the Tennessee Valley, the Middle Mississippi Valley, the Southern Appalachians, and the 
Upper Mississippi Valley.
- Much below normal temperatures across portions of the Central Plains and the Middle Mississippi 
Valley, Sat, Apr 18.
- Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Mon-Wed, Apr 
20-Apr 22.
- Heavy precipitation across portions of mainland Alaska, Sat-Sun, Apr 18-Apr 19.
- Much above normal temperatures across portions of mainland Alaska, Sat-Mon, Apr 18-Apr 20.
 
Detailed Summary:

The medium-range period will be highlighted by a large upper level trough over eastern Canada and 
extending south into the northeastern quarter of the CONUS. Meanwhile, a positive PNA phase will 
also take shape and help to dispense cooler temperatures into the Great Lakes and Northeast. 
Portions of the Central Plains and Middle Mississippi Valley will see one more day of much below 
normal temperatures before temperatures on Saturday. The cooler temperature regime in the Heartland 
will moderate and by early next week temperatures may rebound to seasonably mild levels.

The region with the most active weather across the Lower 48 looks to be the South as a pair of 
southwestern U.S. upper level disturbances traverse the southern states. The first cut-off upper 
low will track into Southern California on Friday then into the Southern Plains by Saturday. This 
disturbance will be responsible for generating additional showers and thunderstorms throughout the 
Southern Plains and Deep South. Both operational and ensemble guidance currently suggests areas 
from northern Louisiana to the Southeast coast could be most at risk for heavy rain and strong 
thunderstorms. These areas also have overly saturated soil and have recently felt impacts from 
heavy rainfall and severe storms, leading to additional concerns for flooding. To add insult to 
injury, a second upper-level trough will move from the Southwest to the South Central U.S. in 
forecast days 6-7. While guidance does differ in where the heaviest precipitation is located, the 
signal for heavy rainfall in the South and portions of the Middle Mississippi Valley is present 
with upper level troughing in the Southwest and high pressure positioned off the Southeast coast. 
This could lead to another chance for flooding in areas of the South and Mississippi Valley that 
have been drenched by storm systems in recent weeks.

Over Alaska, above average temperatures are expected to persist through much of the period, 
particularly for minimum temperatures. The highest anomalies are forecast throughout the northern 
half of the state but western and eastern regions can also anticipate abnormally warm conditions. 
Additionally, the jet stream pattern favors southerly flow with rich Pacific moisture advection 
over much of the mainland. Heavy precipitation is possible in the west-central portions of the 
state this weekend. As this round of precipitation exits, an upper trough swinging south of the 
Aleutians and into the Gulf of Alaska early next week will send high contents of atmospheric 
moisture into the Panhandle. The potential exists for heavy precipitation throughout the region the 
first half of next week but there is still some disagreement in model guidance as to how much 
precipitation there will be, when it arrives, and how long it sticks around.

Mullinax