US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
346 PM EDT Fri Jul 17 2020
 
Valid Monday July 20 2020 - Friday July 24 2020
 
Hazards:
- Heavy rain across portions of the Upper/Middle Mississippi Valley and Central Plains, Mon, Jul 20.
- Flooding possible across portions of the Northern Plains.
- Flooding occurring or imminent across portions of the Upper/Middle Mississippi Valley, the Great 
Lakes, and the Northern Plains.
- Flooding likely across portions of the Central Plains.
- Excessive heat across portions of the Mid-Atlantic, the Middle/Lower Mississippi Valley, the 
Central Appalachians, the Tennessee Valley, the Northeast, the Southeast, and the Ohio Valley, 
Mon-Wed, Jul 20-Jul 22.
- Heavy rain across portions of the Alaska Panhandle, Mon, Jul 20.
 
Detailed Summary:

The medium range period (Monday, July 20 - Friday, July 24) will continue to feature a summer-like 
pattern with 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 parts of the Middle/Low Mississippi Valley, and the 
Tennessee/Ohio Valleys early in the week. Warm overnight lows are expected as well, exacerbating 
the heat threat.  Heat indices over 105 could remain across the Lower Mississippi and Tennessee 
Valleys through Wednesday.  Additionally, high heat indices over 110, even approaching 115 in some 
places, are forecast across the Mid-Atlantic region to the New York City area for the first half of 
next week, leading to an Excessive Heat area there.  The Desert Southwest, southern Texas, and the 
Florida peninsula should also remain hot, but all those areas are around or just a few degrees 
above normal for this time of year. The main consistent spot where temperatures could be below 
normal is the Northern Plains on the cool side of a front.

Rain and thunderstorms are possible in the vicinity of fronts moving through north-central and 
eastern parts of the country through the period.  On Monday an area of organized convection  will 
develop along front that is forecast to stall over the Middle Mississippi Valley and Central 
Plains. Heavy rain could occur as moisture from the Gulf of Mexico will flow over the boundary.  
The exact placement of the heavy rainfall amounts will change depending on the positioning of the 
front.  Rain and thunderstorms are also expected along the Eastern Seaboard, but model guidance is 
not currently consistent on areas where the rain could focus to become heavy. Southwestern Florida 
could see heavy rainfall on Tuesday, but heavy amounts may remain offshore. Another area to watch 
for heavy rain potential is eastern North Carolina on Thursday and Friday but model guidance 
continues to vary.

Over Alaska, moisture streaming into the Panhandle on Monday. Showers are also likely over interior 
Alaska through the period, but organized heavy rainfall is not expected there. Some rain may also 
spread into the Aleutians around midweek as another low pressure system moves across.  A cold 
upper-level trough will lead to cooler than normal conditions across much of the state, but 
especially over the North Slope, where high temperatures could be as much as 30 degrees below 
average through Tuesday, and low temperatures could be below freezing.

Ziegenfelder