US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
505 PM EDT Wed Jul 22 2020
 
Valid Saturday July 25 2020 - Wednesday July 29 2020
 
Hazards:
- Heavy rain across portions of the Central Plains, the Central Rockies, the Lower Mississippi 
Valley, the Central Great Basin, the Southern Rockies, the Northeast, the Southeast, the Central 
Appalachians, the Southern Plains, the Ohio Valley, and the Southwest, Mon-Tue, Jul 27-Jul 28.
- Heavy rain across portions of the Central Plains, the Lower Mississippi Valley, the Northern 
Plains, the Upper Mississippi Valley, the Southern Plains, and the Southwest, Sat-Sun, Jul 25-Jul 
26.
- Heavy rain across portions of the Central Plains, the Northeast, the Northern Plains, the 
Tennessee Valley, the Middle Mississippi Valley, the Mid-Atlantic, the Southern Appalachians, the 
Upper Mississippi Valley, the Southeast, and the Southern Plains, Wed, Jul 29.
- Flooding occurring or imminent across portions of the Central Plains and the Northern Plains.
- Excessive heat across portions of the Central Plains, the Middle Mississippi Valley, the Upper 
Mississippi Valley, and the Northern Plains, Sun, Jul 26.
- Excessive heat across portions of the Central Plains, the Upper Mississippi Valley, and the 
Northern Plains, Sat, Jul 25.
- Excessive heat across portions of the Middle Mississippi Valley, the Lower Mississippi Valley, 
and the Ohio Valley, Mon, Jul 27.
- Excessive heat across portions of the Lower Mississippi Valley, the Tennessee Valley, the Middle 
Mississippi Valley, the Mid-Atlantic, the Southeast, and the Ohio Valley, Mon-Tue, Jul 27-Jul 28.
- Much above normal temperatures across portions of the Central Plains, the Middle Mississippi 
Valley, the Great Lakes, the Upper Mississippi Valley, and the Northern Plains, Sat-Sun, Jul 25-Jul 
26.
- Much above normal temperatures across portions of the Great Lakes, the Mid-Atlantic, the 
Northeast, and the Central Appalachians, Mon-Tue, Jul 27-Jul 28.
- Much above normal temperatures across portions of the Great Lakes, Sat-Mon, Jul 25-Jul 27.
- Heavy rain across portions of the Alaska Panhandle and mainland Alaska, Sun-Tue, Jul 26-Jul 28.
- Heavy rain across portions of mainland Alaska, Mon-Tue, Jul 27-Jul 28.
 
Detailed Summary:

An expansive upper-level high will dominate much of the mainland U.S. through the medium range 
period Wednesday, July 29th as upper-level troughing tracks across from the Pacific Northwest to 
the North-central U.S. With this pattern in place, monsoonal moisture will transport northward 
through parts of the Southwest/Rockies and then curve through the Northern/Central Plains. Diurnal 
heating and the influx of moisture will result in localized heavy rainfall across parts of the 
Southwest/Southern Rockies. Across the Northern U.S., a cold front will move through and interact 
with the monsoonal moisture pooling over the central U.S. and trigger thunderstorms capable of 
producing heavy rain across parts of the Plains and Midwest. Meanwhile, showers and thunderstorms 
ahead of an exiting cold front should result in heavy rainfall on Friday across eastern North 
Carolina.

The National Hurricane Center continues to monitor the potential of a tropical cyclone forming in 
the Gulf to the south of the upper-level high, as the cyclone generally tracks west or 
west-northwest across the western Gulf Coast into southern Texas late this week into the weekend. 
The threat for heavy rainfall with this particular feature will increase across southern 
Texas/western Gulf Coast.

Although the upper-level high will expand across the eastern two-thirds of the country, the 
associated heat underneath the high is not expected to be too extreme, with forecast high 
temperatures staying below the 100 degrees through the extended period. Much above normal 
temperatures are expected from the Northern Plains to the Great Lakes Friday into the weekend ahead 
of the cold front. Increasing humidity ahead of the front will result in high heat indices during 
the afternoon over the northern Plains on Friday, gradually working its way southward into the 
lower Mississippi Valley by next Tuesday. Excessive heat have been highlighted on the Hazards map 
for these areas. Meanwhile, westerly winds descending from the Appalachians combining with 
increasing humidity will raise the likelihood of much above normal temperatures for parts of the 
Mid-Atlantic early next week.

In Alaska, a heavy rain area has been introduced for parts of the southern Interior on the 
27th-28th while the heavy rain area continues for Southeastern Alaska. Some of the heavy rain could 
briefly spill into the southern coastal area of Alaska and then further inland across southern 
Alaska.

Hurricane Douglas, per the latest track from the National Hurricane Center, is forecast to clip the 
Big Island on Sunday. Heavy rain, strong winds, coastal flooding and storm surge may impact the 
state this weekend and beyond.
Kong/Campbell