US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
401 PM EDT Tue Jun 22 2021
 
Valid Friday June 25 2021 - Tuesday June 29 2021
 
Hazards:
- Heavy rain across portions of the Central/Southern Plains, the Upper/Middle Mississippi Valley, 
and the Great Lakes, Fri, Jun 25.
- Heavy rain across portions of the Southern Plains and the Middle/Lower Mississippi Valley, 
Sat-Sun, Jun 26-Jun 27.
- Heavy rain across portions of the Middle/Lower Mississippi Valley, the Great Lakes, the Ohio 
Valley, and the Tennessee Valley, Sat-Mon, Jun 26-Jun 28.
- Flooding occurring or imminent across portions of the Lower Mississippi Valley and the Ohio 
Valley.
- Flooding likely across portions of the Lower Mississippi Valley.
- Excessive heat across portions of the Pacific Northwest, the Northern Rockies, and the Northern 
Great Basin, Fri-Tue, Jun 25-Jun 29.
- Excessive heat across portions of the Pacific Northwest, California, the Southwest, the Great 
Basin, the Northern Rockies, and the Northern Plains, Sun-Tue, Jun 27-Jun 29.
- Heavy rain across portions of the Alaska Panhandle and mainland Alaska, Fri, Jun 25.
 
Detailed Summary:

The medium range forecast period (Friday, June 25 to Tuesday, June 29) will feature a persistent 
and strong upper-level high centered over the northwestern U.S. and southwestern Canada, while 
upper-level troughing will be centered over the Midwest/Great Lakes. The anomalous upper high is 
expected to cause above average and likely record-breaking temperatures this weekend into early 
next week in the West. Temperatures should begin to be 10 to 20 degrees above normal in Washington 
and Oregon on Friday and warm to 20 to 30 degrees above average Saturday, lasting through at least 
Tuesday. Seattle, for example, can expect several days in a row in the 90s, while Portland should 
see temperatures over 100 degrees. The hot temperatures are also forecast to expand eastward early 
next week eastward into Idaho and Montana, as well as southward into interior portions of 
California and the Intermountain West, with highs nearing or exceeding 100, depending on the region 
and elevation. Temperatures in the Desert Southwest are forecast to be in the low 110s--but this 
would only be a few degrees above normal, and not quite meeting hazardous criteria. Meanwhile, 
drought conditions remain extreme throughout the West and will undoubtedly continue or worsen over 
the next week given the heat and no expected rainfall in the medium range period.

Elsewhere, the upper-level trough is expected to slowly push a couple of fronts across the central 
and eastern U.S. late this week into early next week. Abundant moisture streaming into the vicinity 
should cause numerous showers and thunderstorms, while gusty winds are also possible with the 
fronts. The highest multi-day rainfall totals of several inches are likely to be focused across the 
Middle Mississippi Valley into the Upper Great Lakes region and Ohio Valley, as the initial front 
almost stalls there and another front catches up, providing areas for the moisture to focus and 
produce storms and possibly flooding. A round of heavy rain is also possible in the Southern Plains 
this weekend near the southwestern portion of the cold front. Fortunately, much of the Middle 
Mississippi Valley has been relatively dry over the last month or so, but areas from northern Texas 
into the Lower Mississippi Valley and Ohio Valley have seen wetter conditions. There is potential 
for scattered thunderstorms all the way to the Eastern Seaboard, but heavy rainfall is not expected 
to be widespread there. Though, there is currently some signal in model guidance for notable rain 
in the interior Northeast early next week, so this area will continue to be monitored, as frontal 
and upper trough timing become more clear. 

In Alaska, potentially heavy rain in the short range period could linger into Friday as a potent 
low pressure system churns over the eastern Aleutians and funnels moisture northward into the 
Southcentral region and the Alaska Panhandle. Another surface low is forecast to approach the 
Aleutians and Alaska Peninsula by next Monday and Tuesday, which could cause another round of heavy 
rain there, but the track of the surface low and thus rainfall amounts and location are still 
uncertain. Additionally, farther north, cool temperatures remain in the Brooks Range, and some 
precipitation there could be in the form of snow for the first part of next week.

Tate