US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
315 PM EDT Thu Jun 24 2021
 
Valid Sunday June 27 2021 - Thursday July 01 2021
 
Hazards:
- Heavy rain across portions of the Central/Southern Plains, the Middle/Lower Mississippi Valley, 
and the Ohio Valley, Sun-Thu, Jun 27-Jul 1.
- Heavy rain across portions of the Great Lakes and the Ohio Valley, Sun, Jun 27.
- Heavy rain across portions of the Southern Plains, Sun-Mon, Jun 27-Jun 28.
- Heavy rain across portions of Florida, Tue-Thu, Jun 29-Jul 1.
- Flooding possible across portions of the Central Plains, the Upper/Middle Mississippi Valley, the 
Great Lakes, and the Ohio Valley.
- Excessive heat across portions of the Pacific Northwest, California, the Northern/Central Great 
Basin, the Northern Rockies, and the Southwest, Sun-Thu, Jun 27-Jul 1.
- Excessive heat across portions of the Pacific Northwest and the Northern Great Basin, Sun-Mon, 
Jun 27-Jun 28.
- Excessive heat across portions of the Northern/Central Great Basin, the Northern Rockies, and the 
Northern Plains, Tue-Thu, Jun 29-Jul 1.
 
Detailed Summary:

The medium range forecast period (Sunday, June 27 to Thursday, July 1) will feature a persistent 
and strong upper-level high initially centered over southwestern Canada and moving into the 
northwestern U.S., while upper-level troughing will be centered over the Midwest. The anomalous 
upper high is expected to cause much above average and likely widespread record-breaking 
temperatures this weekend into next week in the West. Temperatures should warm to 20 to 30 degrees 
above average beginning in the short range period Saturday across Washington and Oregon. Seattle, 
for example, can expect several days nearing 100 degrees, while Portland should see temperatures in 
the 100s. The hot temperatures are also forecast to expand southward by Sunday into interior 
portions of California and the Intermountain West, with highs nearing or exceeding 100, depending 
on the region and elevation. Temperatures in the Pacific Northwest are forecast to gradually 
moderate on Tuesday into Thursday as the upper high pivots a bit east, but will remain persistently 
hot through midweek and beyond in the Great Basin. The shifting high will also lead to increasing 
heat in Idaho and Montana beginning around Tuesday. Temperatures in the Desert Southwest are 
forecast to be in the low 110s early next week--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 in the Northwest given the heat 
and no notable expected rainfall in the medium range period. However, some welcomed moisture is 
likely to impact New Mexico/Colorado next week, and some showers may occur in Arizona by around 
midweek as well.

Elsewhere, the upper-level trough is expected to slowly push a couple of fronts across the central 
U.S. next week. Abundant moisture streaming into the vicinity should cause numerous showers and 
thunderstorms. Rainfall will begin during the short range period across the Middle Mississippi 
Valley and Midwest, and the slow initial frontal push will spread rainfall from the Southern High 
Plains toward the Ohio Valley early in the week. Rain totals could be particularly heavy compared 
to normal around eastern New Mexico, with cool temperatures as well there behind the back end of 
the cold front. Then, rounds of additional potentially heavy rain are expected to remain across 
portions of the central U.S. (currently expected from around eastern Oklahoma into portions of 
Arkansas/Missouri into the Ohio Valley) as another frontal boundary catches up to the initial 
front, providing areas for the moisture to focus. Multi-day rainfall totals of a few inches could 
produce flooding and flash flooding. Fortunately, the last couple of weeks have somewhat dried out 
much of the Southern Plains and Lower Mississippi Valley, but farther north, the short range period 
should see such wet conditions that additional rainfall would exacerbate any flooding problems. 
There is potential for scattered thunderstorms all the way to the Eastern Seaboard. Heavy rainfall 
is possible in the East, but appears that it should be more localized than widespread in most 
areas. The exception could be the Florida Peninsula, which may see tropical moisture cause rain 
amounts of 1-3 inches there around midweek. The Northeast will also continue to be monitored for 
heavy rain potential ahead of a frontal boundary meandering in southern Canada.

In Alaska, a couple of surface lows are forecast to approach and cross the Aleutians by next Monday 
into Thursday, setting up a moist flow pattern into the Alaska Peninsula. This should lead to at 
least moderate rainfall there, but whether or not rainfall amounts will be heavy or hazardous is 
still uncertain. Gusty winds are also possible with the low pressure systems. Additionally, farther 
north, cool temperatures return to the Brooks Range early next week, and some precipitation there 
could be in the form of light snow.

Tate