US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
448 PM EDT Thu Sep 03 2020
 
Valid Sunday September 06 2020 - Thursday September 10 2020
 
Hazards:
- Heavy rain across portions of the Central/Southern Plains, and the Middle/Lower Mississippi 
Valley, Tue-Wed, Sep 8-Sep 9.
- Flooding occurring or imminent across portions of the Lower Mississippi Valley and the Southern 
Plains.
- Excessive heat across portions of the Central Great Basin, California, and the Southwest, 
Sun-Tue, Sep 6-Sep 8.
- Much above normal temperatures across portions of California, the Central Great Basin, the 
Pacific Northwest, the Northern Great Basin, and the Southwest, Sun-Mon, Sep 6-Sep 7.
- Much above normal temperatures across portions of the Northern/Central Plains, and the 
Upper/Middle Mississippi Valley, Sun, Sep 6.
- Much below normal temperatures across portions of the Plains, the  Rockies, the Mississippi 
Valley, the Central Great Basin, the Great Lakes,  the Ohio Valley, and the Southwest, Mon-Thu, Sep 
7-Sep 10.
- Heavy precipitation across portions of mainland Alaska, Sun-Mon, Sep 6-Sep 7.
- Heavy rain across portions of the Alaska Panhandle and mainland Alaska, Sun-Wed, Sep 6-Sep 9.
- High winds across portions of mainland Alaska, Sun-Mon, Sep 6-Sep 7.
 
Detailed Summary:

Upper-level high over the over the Rockies extending into the Northwest will weaken as an 
upper-level low dives southward out of Western Canada on Monday.  The upper-level high will allow 
temperatures to become 12 degrees or greater above normal over parts of the Great Basin into the 
Northwest/Northern California on Sunday into Monday. The eastern part of the upper-level high will, 
likewise, produce temperatures 12 degrees or greater above normal over parts of the Central High 
Plains eastward to the Middle Mississippi Valley on Sunday.  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.  Furthermore, heavy rain will develop along the cold front while moving southward over 
the Southern Plains/Middle Mississippi Valley on Tuesday and Wednesday. 

For Alaska, deep low pressure over the North Pacific will move northward into the Bering Sea on 
Monday and will continue to move northward to the Far Northwestern mainland by Tuesday.  The deep 
low will bring strong wind to the Southwestern portion of the mainland on Sunday and Monday when 
the wind will be 35 knots or greater.  The low will aid in producing an area of heavy precipitation 
over parts of Southwestern mainland on Sunday into Monday.  In addition, the storm will bring a 
plume of moisture into the Alaska Peninsula and the Gulf of Alaska Coast producing an area of heavy 
rain from the Alaska Peninsula eastward to near Yakutat from Sunday into Monday.  

Ziegenfelder