US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
500 PM EDT Tue Aug 25 2020
 
Valid Friday August 28 2020 - Tuesday September 01 2020
 
Hazards:
- Heavy rain possible across the interior Deep South, portions of the Tennessee and Ohio Valleys, 
the lower Great Lakes, the Appalachians, and from the Mid-Atlantic to much of the Northeast, 
Fri-Sat, Aug 28-Aug 29.
- Heavy rain possible from the upper Midwest down into the Mid-Mississippi Valley and the nearby 
central Plains, Sun-Mon, Aug 30-Aug 31.
- Heavy rain possible from the central Plains northeastward across the Midwest into the lower Great 
Lakes, Tue, Sep 1.
- Severe weather possible across the Midwest into portions of the lower Great Lakes and 
northwestern Pennsylvania, Fri, Aug 28.
- Severe weather possible across the northern Mid-Atlantic and nearby central Appalachians into 
central New England, Sat, Aug 29.
- Flooding possible west of the lower Mississippi Valley and into southeastern Texas.
- Excessive heat across portions of far southern Texas, Fri-Sat, Aug 28-Aug 29 and Mon-Tue, Aug 
31-Sep 1.
- Excessive heat across portions of southern Texas, Fri, Aug 28.
- Much below normal temperatures across portions of northwestern Wyoming, Tue, Sep 1.
- Heavy rain across the Alaska Peninsula and the Aleutians, Fri-Sun, Aug 28-Aug 30.
- Heavy rain across southern Alaska, Sun-Tue, Aug 30-Sep 1.
- Heavy rain across the Alaska Panhandle, Mon-Tue, Aug 31-Sep 1.
- High winds across portions of southwestern Alaska and the Aleutians, Sun-Mon, Aug 30-Aug 31.
 
Detailed Summary:

It appears that the eastern two-thirds of the country will be relatively active in terms of 
rainfall during the medium range period (Friday, August 28 - Tuesday, September 1).  Hurricane 
Laura currently in the Gulf of Mexico is forecast to strengthen into a major hurricane before 
moving inland and recurving toward the northeast across Arkansas by Friday.  Model guidance 
continues to show a significant amount of variability regarding the track, forward speed and 
strength of Laura as it begins to interact with an approaching cold front from the northwest.  If 
Laura is able to maintain a well-defined circulation while traversing the interior Deep South 
toward the Mid-Atlantic as suggested by the ECMWF, a period of gusty winds and heavy rainfall could 
impact the mid-Mississippi Valley on Friday, then moving into parts of the Mid-Atlantic on 
Saturday.  Meanwhile, a low pressure system developing along a stationary front across the northern 
tier states will track quickly across the Midwest on Friday and then across the Northeast on 
Saturday.  This will likely bring a period of enhanced rainfall across these areas as what remains 
of Laura will likely be pushed off the East Coast later on Saturday.

Across the northwestern U.S., the next frontal system and the associated upper trough should be 
heading across the northern Rockies toward the northern Plains during the weekend.  A low pressure 
system forecast to develop over the northern Plains could bring a swath of heavy rain from the 
upper Midwest down into the Mid-Mississippi Valley and the nearby central Plains Sunday into 
Monday.  Behind the developing low pressure system, a rather cool Canadian air mass will be ushered 
into the northern Plains and the northern Rockies early next week.  This will likely bring the 
first freeze of the season for the coldest locations Monday morning.  By Tuesday morning, 
temperatures across much of northwestern Wyoming could be below freezing.

In contrast, excessive heat and humidity will appear to persist across southern Texas where 
afternoon heat indices could exceed 110 degrees through the medium-range period.

For Alaska, a rather stormy period appears to be in store during the medium-range, as a rather 
intense low pressure system is forecast to track from the Aleutian islands toward western Alaska.  
This system will likely produce gale to possibly storm-force winds across the eastern Aleutians and 
southwestern Alaska Sunday and Monday.  In addition, heavy rain associated with the system will 
progressively spread from west to east from the Aleutians across the southern portion of the state 
before reaching the Alaska Panhandle by early next week.

Kong