US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
500 PM EDT Wed Jun 17 2020
 
Valid Saturday June 20 2020 - Wednesday June 24 2020
 
Hazards:
- Heavy rain across portions of the Lower Mississippi Valley, the Southern Plains, and the 
Tennessee Valley, Tue, Jun 23.
- Heavy rain across portions of the Central/Southern Plains, and the Middle Mississippi Valley, 
Sun-Mon, Jun 21-Jun 22.
- Flooding occurring or imminent across portions of the Middle Mississippi Valley, the Lower 
Mississippi Valley, and the Northern Plains.
- Flooding likely across portions of the Northern Rockies.
- Much above normal temperatures across portions of California, the Northern/Central Great Basin, 
and the Pacific Northwest, Mon-Wed, Jun 22-Jun 24.
- Much above normal temperatures across portions of the Northeast, Sat-Mon, Jun 20-Jun 22.
 
Detailed Summary:

An upper-level ridging ahead of an upper-level trough over the Northern Plains will build into the 
Upper Great Lakes and into parts of the Northeast as an upper-level low over the Mid-Atlantic will 
slowly weaken on Saturday into Sunday.  The building upper-level ridging will allow temperatures to 
become 12 degrees above normal over the Northeast on Saturday into Sunday.  On Saturday the 
upper-level trough over the Northern Plains will begin to move into the Northeast. These conditions 
met the criteria for depicting and area of much above normal temperatures over the region on 
Saturday into Sunday.

Another area of much above normal temperature will develop over parts of the Pacific Northwest, 
Great Basin, the Northern Intermountain Region, and parts of Northern California will develop on 
Monday into Wednesday.  As the upper-level trough moves away from the Northern Plains, upper-level 
ridging will develops over the region starting on Monday and building into Tuesday.  On Wednesday, 
upper-level troughing will move over the Pacific Northwest reducing the effects of the upper-level 
ridging.  The ridging will aid in allowing temperatures to reach the criteria for an area of much 
above normal temperatures on Monday into Wednesday.

A front associated with the upper-level troughing over the Northern Plains will extend from the 
Upper Great Lakes to the Southern High Plains and will move eastward to the Lower Great Lakes to 
the Southern Plains and stalling over the Central Plains into the Lower Great Lakes. A plume of 
moisture will move northward from the Western Gulf of Mexico northward over the Southern Plains on 
Sunday into Monday that will overrun the front. Showers and thunderstorms and maybe a convective 
system will develop along the front that will produce enough rain to meet the criteria for heavy 
rain over parts of the Central Plains/Middle Mississippi Valley on Sunday into Monday. The front 
will slowly dissipate Monday night into Tuesday morning.  With another front over the Upper Midwest 
that will put the Lower Mississippi Valley, the Southern Plains, and the Tennessee Valley in the 
warm sector.  Conditions will favor the development of an MCS type convective system that will 
produce an area of precipitation from parts of the Southern Plains, Lower Mississippi Valley, and 
the Tennessee Valley that will meet the criteria for heavy rain on Monday.      

No hazards are delineated over Alaska. There will be rain over the Alaska Panhandle yet the rain 
will not meet the criteria for heavy rain over the area.

Ziegenfelder