US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
408 PM EDT Fri Sep 04 2020
 
Valid Monday September 07 2020 - Friday September 11 2020
 
Hazards:
- Heavy rain across portions of the Central Plains, the Upper/Middle Mississippi Valley, the Great 
Lakes,  and the Ohio Valley, Mon, Sep 7.
- Heavy rain across portions of the Central/Southern Plains, and the Middle/Lower Mississippi 
Valley, Tue, Sep 8.
- Heavy rain across portions of the Great Lakes and the Southern Plains, Wed, Sep 9.
- Heavy snow across portions of the Northern/Central Plains, the Rockies,  and the Central Great 
Basin,  Mon-Wed, Sep 7-Sep 9.
- Flooding occurring or imminent across portions of the Lower Mississippi Valley and the Southern 
Plains.
- High winds across portions of the Central/Southern Plains, the Central Great Basin, the 
Central/Southern Rockies, California, and the Southwest, Tue-Wed, Sep 8-Sep 9.
- Much above normal temperatures across portions of California, the Central Great Basin, the 
Pacific Northwest, and the Southwest, Mon-Tue, Sep 7-Sep 8.
- Much below normal temperatures across portions of the Plains, the Rockies, the Mississippi 
Valley, the Central Great Basin, the Great Lakes, the Northern Great Basin, and the Southwest, 
Mon-Thu, Sep 7-Sep 10.
- Heavy rain across portions of mainland Alaska, Mon, Sep 7.
- Heavy rain across portions of the Alaska Panhandle and mainland Alaska, Tue-Wed, Sep 8-Sep 9.
- High winds across portions of mainland Alaska, Mon-Tue, Sep 7-Sep 8.
 
Detailed Summary:

Upper-level high over the over the West Coast will weaken as an upper-level low dives southward out 
of Western Canada on Monday into Tuesday to the four corners region.  The upper-level high will 
allow temperatures to become 12 degrees or greater above normal over parts of the Great Basin into 
the Northwest and most of California on Monday. 

In contrast, as the upper-level low digs southward to the four corners region by Tuesday and 
Wednesday. The associated front will race southward to Northeastern Mexico by Wednesday. Cold air 
behind the front will aid in allowing temperatures to become 12 degrees or greater below normal 
over parts of the Northern High Plains on Monday expanding into the Northern/Central Plains and the 
Central Rockies by Tuesday. The below normal temperatures will continue to expand southward into 
the Southern Plains/Rockies by Wednesday into Thursday as the temperatures will start to moderate 
by Friday. The temperatures will be cold enough to bring snow to the highest elevations of the 
Northern/Central Rockies into parts of the Southern Rockies on Monday into Wednesday. 

Furthermore, heavy rain will develop along the cold front while moving southward over the Great 
Lakes into the Middle Mississippi Valley on Monday.  On Tuesday, the heavy rain will move to, 
mainly, the Southern Plains as the front continues to settle southward. By Wednesday, the heavy 
rain will settle to parts of the Southern Plains/South-Central Texas. In addition on Wednesday, 
heavy rain will return to the Great Lakes near the boundary.  On Thursday into Friday there is too 
much uncertainty where or if there will be heavy rain over the CONUS. 

High pressure at the surface over Northwest Canada will settle over the Norther High Plain/Northern 
Rockies on Tuesday and into the Central Plains on Wednesday and Thursday before beginning to weaken 
on Friday.  The strong high pressure will aid in producing strong wind over the Central/Southern 
Plain and Rockies and extending into parts of the Southwest and Southern California through 
Wednesday. 

For Alaska, deep low pressure over the Bering Sea on Monday will move northward into the Far 
Northwestern mainland by Tuesday. The deep low will bring strong wind to the Southwestern portion 
of the mainland on Monday and Tuesday when the wind will be 35 knots or greater. The low will aid 
in producing an area of heavy rain over parts of Southwestern mainland on Monday. In addition, the 
storm will bring a plume of moisture into parts of the Gulf of Alaska Coast producing an area of 
heavy rain over parts of the Northeast Gulf of Alaska Coast eastward to near Yakutat from Tuesday 
into Wednesday. After Tuesday high pressure will build over the Bering Sea and expand onto the 
mainland through Friday. 


Ziegenfelder