US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
527 PM EDT Wed Jul 29 2020
 
Valid Saturday August 01 2020 - Wednesday August 05 2020
 
Hazards:
- Heavy rain across portions of the Southeast as well as the lower Great Lakes, Sat-Sun, Aug 1-Aug 
2.
- Heavy rain possible along much of the Eastern Seaboard up into New England, Mon-Wed, Aug 3-Aug 5.
- Flooding possible across portions of the central and northern Plains.
- Flooding occurring or imminent across portions of the central and northern Plains.
- Excessive heat across portions of the Desert Southwest, Sat-Sun, Aug 1-Aug 2.
- High winds across portions of Florida, Sat-Mon, Aug 1-Aug 3.
- Heavy rain possible across portions of eastern Alaska, Sun, Aug 2.
- Heavy rain possible across portions of coastal southern Alaska, Sat-Mon, Aug 1-Aug 3.
- Heavy rain possible across portions of the Alaskan Panhandle, Tue-Wed, Aug 4-Aug 5.

Detailed Summary:

For the medium range period (Saturday, August 1 - Wednesday, August 5), the eastern U.S. should 
become the main area of concern as a potential tropical cyclone could track across the region.  The 
initial setup over the eastern U.S. will be an omega blocking pattern over Canada with a 
positively-tilted longwave trough lingering across the eastern-central U.S.  A wave of low pressure 
forming along the associated frontal boundary should lead to heavy rain across the lower Great 
Lakes during the weekend, as Potential Tropical Cyclone Nine (PTC 9) is forecast to track up the 
vicinity of Florida Peninsula at tropical storm intensity.  Forecast uncertainty increases further 
for early next week as PTC 9 could track further up the East Coast or moving more slowly farther 
south.  The heavy rain area assumes some form of interaction between PTC 9 and a slow-moving 
frontal boundary that extends into New England.  Please consult the National Hurricane Center for 
the latest updates on PTC 9.

Meanwhile, an upper-level ridge will remain a dominant feature over the western U.S.   Temperatures 
should be about 5 to 10 degrees above normal across much of the interior western U.S. before an 
upper trough brings cooler air into the Pacific Northwest and the northern Rockies by early next 
week.  High temperatures are expected to reach 115 degrees in the Desert Southwest during the 
weekend before moderating slightly by early next week.  Over the northern and central Plains, much 
cooler than normal temperatures will remain in place behind the aforementioned slow-moving longwave 
trough.

Over Alaska, the pattern appears to get more active during the medium-range period as a couple of 
significant occluded cyclones are forecast to impact the southern periphery of the state.  The more 
active pattern also brings more uncertainty into the forecast.  Nevertheless, heavy rain is 
possible near the southern coastal sections of Alaska from late Saturday into Monday as the first 
occluded cyclone edges into the Gulf of Alaska.  By early next week, the next wave of moisture 
associated with the second occluded system should bring the threat of heavy rain farther south 
across portions of the Alaskan Panhandle.

Kong