US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
346 PM EDT Tue Jul 14 2020
 
Valid Friday July 17 2020 - Tuesday July 21 2020
 
Hazards:
- Heavy rain across portions of the Great Lakes, the Upper Mississippi Valley, and the Northern 
Plains, Fri-Sat, Jul 17-Jul 18.
- Flooding possible across portions of the Middle/Upper Mississippi Valley and the Great Lakes.
- Flooding occurring or imminent across portions of the Northern Plains.
- Flooding likely across portions of the Upper Mississippi Valley and the Northern Plains.
- Excessive heat across portions of the Plains, the Mississippi Valley, the Great Lakes, the Ohio 
Valley, the Central Appalachians, the Tennessee Valley, and the Southeast, Fri-Mon, Jul 17-Jul 20.
- Excessive heat across portions of the Mid-Atlantic, the Northeast, and the Central Appalachians, 
Sun-Tue, Jul 19-Jul 21.
 
Detailed Summary:

The medium range period (Friday, July 17 - Tuesday, July 21) will continue to feature a summer-like 
pattern with expanding heat across the Southwest into the central/eastern U.S. as high pressure 
persists south of the jet stream located across the northern states. Hot temperatures combined with 
high dewpoints will lead to high heat indices over much of the Plains, Mississippi Valley, the 
Tennessee/Ohio Valleys, and Southeast. Warm overnight lows are expected as well, exacerbating the 
heat threat. The heat in the central U.S. is expected to subside somewhat as a front pushes through 
over the weekend, but remain across the Southern Plains/Lower Mississippi Valley into early next 
week. Additionally, high heat indices over 100, even over 105, are forecast across the Mid-Atlantic 
region for the first half of next week, leading to an Excessive Heat area there. The Desert 
Southwest should also remain hot, but around normal for this time of year.

Rain and thunderstorms are possible in the vicinity of fronts moving through north-central and 
eastern parts of the country through the period. For now, it seems the best likelihood of heavy 
rainfall is across the Upper Midwest late this week, where model guidance has the best potential 
for organized storms. Some potential remains for heavy rain after that, but there is too much 
uncertainty at this time in terms of amounts and position of the heaviest amounts to delineate 
other Heavy Rain hazard areas. Another area to watch for rainfall is the Florida Keys and the 
southwestern peninsula as a tropical wave moves through, but heavy rainfall amounts may stay 
offshore.

Over Alaska, the weather looks to be active through early next week, but not necessarily in terms 
of hazards. Moisture streaming ahead of a low pressure system tracking across the southern coast 
could lead to heavy rainfall for south-central Alaska into the Panhandle for early next week, but 
confidence in rainfall amounts is low since models vary. Showers are also likely over interior 
Alaska, but organized heavy rainfall is not expected there. A cold upper-level trough will lead to 
cooler than normal conditions across much of the state through the period, but especially over the 
North Slope, where high temperatures could be up to 30 degrees below average.

Tate