US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
411 PM EDT Wed Jun 24 2020
 
Valid Saturday June 27 2020 - Wednesday July 01 2020
 
Hazards:
- Heavy rain across portions of the Northern Plains and the Northern Rockies, Sun-Tue, Jun 28-Jun 
30.
- Heavy rain across portions of the Central Plains, the Middle Mississippi Valley, the Upper 
Mississippi Valley, and the Northern Plains, Tue-Wed, Jun 30-Jul 1.
- Heavy rain across portions of the Southeast, the Middle Mississippi Valley, the Lower Mississippi 
Valley, the Mid-Atlantic, and the Tennessee Valley, Wed, Jul 1.
- Heavy rain across portions of the Central Appalachians, the Tennessee Valley, the Middle 
Mississippi Valley, the Southern Appalachians, the Great Lakes, and the Ohio Valley, Sat-Sun, Jun 
27-Jun 28.
- Heavy rain across portions of the Tennessee Valley, the Middle Mississippi Valley, the Southern 
Appalachians, the Upper Mississippi Valley, the Great Lakes, and the Ohio Valley, Mon-Tue, Jun 
29-Jun 30.
- Heavy rain across portions of the Northeast and the Great Lakes, Sat, Jun 27.
- Flooding possible across portions of the Middle Mississippi Valley, the Great Lakes, and the 
Upper Mississippi Valley.
- Flooding occurring or imminent across portions of the Mid-Atlantic, the Upper Mississippi Valley, 
and the Northern Plains.
- Flooding likely across portions of the Middle Mississippi Valley and the Upper Mississippi Valley.
- High winds across portions of the Central Rockies, the Central Great Basin, California, the 
Northern Great Basin, and the Southwest, Sun, Jun 28.
- Much above normal temperatures across portions of the Central Plains, the Upper Mississippi 
Valley, and the Northern Plains, Sun-Mon, Jun 28-Jun 29.
- Heavy rain across portions of western mainland Alaska, Sat-Sun, Jun 27-Jun 28.
- High winds across portions of western coastal Alaska, Sat, Jun 27.
 
Detailed Summary:

As June ends and the calendar gets ready to flip over to July, heavy rain will be the most common 
hazard observed across the Lower 48. An area of low pressure over the northern Great Lakes and 
southern Ontario on Saturday. The cold front associated with this storm system should trigger 
strong thunderstorms and heavy rain in the Ohio Valley on north and east to northern New York on 
Saturday. Showers and thunderstorms remain in the forecast over the lower Ohio Valley and Tennessee 
Valley on Sunday where heavy downpours are possible. By Sunday and Monday, a weak upper-level 
disturbance will cut beneath a building upper level ridge over southern Canada. This feature may 
lead to more opportunities for heavy rainfall and strong thunderstorms from the Midwest to the 
Mid-South. Lastly, a frontal boundary pushing through the Southeast the first of July may cause 
more heavy showers and storms to develop across the region.

To the west, temperatures cool off this weekend because of an intensifying upper-level low tracking 
over the Pacific Northwest moving southeastward into the Great Basin and California early next 
week. The upper-level low will pull in moisture from the Pacific and the Plains into the Northern 
Rockies where heavy rain within embedded thunderstorms should develop over the region. Temperatures 
aloft are so cool for the time of year, however, that some precipitation may fall in the form of 
snow in the higher elevations of northern Idaho, western Montana, and northwestern Wyoming. To the 
south, a strong southwesterly jet sets the stage for potential high winds in the Great Basin and 
Intermountain West. Given recent history with dry humidity levels and wildfires, there could also 
be a heightened risk for fire weather in these regions early next week. Downstream of the upper 
trough, much above normal temperatures are possible in the Northern Plains and Upper Midwest by the 
end of the month, along with a threat for heavy rain and thunderstorms in the Dakotas and central 
Plains to open July.

Over Alaska, a robust upper trough diving from the East Siberian Sea to the northwest coast this 
weekend. Rainfall totals have increased on most of model guidance with the Baird mountains and the 
southern hills of the Seward Peninsula most at risk for heavy rainfall. In addition, a tight 
pressure gradient could lead to strong winds along the Seward Peninsula coast. There will be more 
chances for copious amounts of showers across much of the mainland as the upper trough tracks over 
the state, while simultaneously ushering in a fairly chilly air-mass for late June and early July.

Mullinax