US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
341 PM EDT Thu Aug 22 2019
 
Valid Sunday August 25 2019 - Thursday August 29 2019
 
Hazards:
- Heavy rain across portions of the Central/Northern Plains, the Middle/Upper Mississippi Valley, 
and the Upper Great Lakes, Sun-Tue, Aug 25-Aug 27.
- Flooding possible across portions of the Central Plains, and the Middle Mississippi Valley.
- Flooding occurring or imminent across portions of the Northern Plains.
- Flooding likely across portions of the Central Plains and the Middle Mississippi Valley.
- Excessive heat across portions of the Southern Plains, Sun-Mon, Aug 25-Aug 26.
- Much above normal temperatures across portions of the Pacific Northwest, Tue-Thu, Aug 27-Aug 29.
- Enhanced wildfire risk across portions of the Central Rockies, and the Northern Great Basin, Sun, 
Aug 25.
- Heavy rain across portions of the Alaska Panhandle, Sun-Mon, Aug 25-Aug 26.
 
Detailed Summary:

Amplified upper level troughing across the Northern tier states will push a cold front from the 
Northern Plains on Sunday to the Midwest/Upper Great Lakes by Tuesday. Heavy rainfall and possibly 
strong thunderstorms will shift east with the boundary from eastern portions of the 
northern/central Plains on Sunday to the northern/middle Mississippi Valley and western Upper Great 
Lakes on Monday. The front may be slower to move across parts of eastern Kansas into Missouri 
presenting an additional heavy rain threat through Tuesday. For simplicity, a large heavy rain area 
was drawn encompassing all of the mentioned regions spanning from Sunday, Aug 25 to Tuesday, Aug 
27. 

Farther south, lingering tropical moisture will keep a good chance for showers and storms from the 
central Gulf Coast to the Southeast and Florida. While pockets of heavy rainfall are possible, 
confidence isn't high enough to place an area on the medium range hazards chart. Enhanced moisture 
associated with a tropical wave/surface low moving just off the Southeast coast will also need to 
be monitored for the potential for heavy rainfall to clip coastal regions from eastern Florida to 
the Carolinas, though at this time, the best rainfall should remain offshore.  

In terms of temperatures across the CONUS, the northern U.S. will remain cool most of the period as 
a cool Canadian airmass settles in. Because it is summer, this does not necessarily present a 
hazard, though daytime highs could be 10 to 15 degrees below normal for this time of the year. From 
the West to the Southern Plains, temperatures will be warm underneath of mid to upper level 
ridging. A much above normal temperatures hazard was drawn across parts of western Oregon and 
Washington for daytime highs near or above 90 degrees, which is as much as 10 to 15 degrees above 
normal. Temperatures across the interior Valley of California and into the Southwest should tend to 
increase next week, but at this point appear to be marginal for the excessive heat criteria. 
Farther east into the Southern High Plains/western Texas, daytime highs near and above 100 degrees 
likely presents an excessive heat hazard. Heat and humidity also across parts of South Texas may 
bring heat indices near or above 105 degrees in some spots, but the threat may not be widespread 
enough to warrant an excessive heat hazard area on the chart.

In Alaska, heavy rainfall is expected across parts of the Alaska Panhandle Sunday and into Monday 
over a previously drought-stricken region. The complex terrain across this region may also make it 
more susceptible to flash flooding. The next occluded cyclone is forecast to bring another round of 
rainfall to parts of the southern coast, though there remains enough model uncertainty for whether 
this represents a heavy rain hazard.

Santorelli