US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
341 PM EDT Fri Apr 23 2021
 
Valid Monday April 26 2021 - Friday April 30 2021
 
Hazards:
- Heavy rain across portions of the Middle/Lower Mississippi Valley, the Tennessee/Ohio Valley, the 
Great Lakes, the Mid-Atlantic, the Southern Appalachians, the Southeast, the Southern Plains, and 
the Ohio Valley, Tue-Thu, Apr 27-Apr 29.
- Severe weather across portions of the Central Plains and the Southern Plains, Tue, Apr 27.
- Flooding occurring or imminent across portions of the Lower Mississippi Valley.
- High winds across portions of the Central Plains, and the Central Rockies, Mon, Apr 26.
- Much above normal temperatures across portions of the Northern/Central Great Basin, California, 
and the Southwest, Wed-Fri, Apr 28-Apr 30.
- Much above normal temperatures across portions of the Mid-Atlantic, the Northeast, and the 
Central Appalachians, Tue-Wed, Apr 27-Apr 28.
- Enhanced wildfire risk across portions of the Southern Rockies, the Southern Plains, and the 
Southwest, Mon, Apr 26.
- Heavy precipitation across portions of the Alaska Panhandle, Wed-Thu, Apr 28-Apr 29.
 
Detailed Summary:

The main upper-level feature causing impactful weather in the medium range period (Monday, April 26 
- Friday, April 30) will be an upper trough/low dropping southward through the Northwest and 
continuing eastward through the central U.S. through the middle part of the week, while a potent 
frontal system moves just ahead of the trough. These features will spread precipitation to much of 
the U.S. along with other hazards. First, precipitation is likely across the Intermountain West. 
Higher elevation heavy snow is expected in higher terrain. Locally heavy precipitation is also 
possible across portions of the Northern/Central Rockies. Meanwhile, winds are expected to increase 
ahead of the trough on Monday, with much of southern Colorado seeing the possibility for high 
winds. Along with the windy conditions, low relative humidity and dry ground will likely lead to 
dangerous fire weather conditions for the Southern High Plains on Monday.

As the upper-level trough and front move east, Gulf of Mexico moisture will be steered into the 
central U.S. and enhance rainfall amounts near and ahead of the front and associated surface lows. 
Current forecasts show heavy rain progressing eastward from the Southern Plains Tuesday into the 
Middle/Lower Mississippi Valley as well as the Tennessee/Ohio Valley Wednesday, with some rain 
spreading into the Southeast and Southern Appalachians on Thursday. Heavy rain amounts could also 
stretch into the Midwest to Upper Great Lakes region as a surface low and warm front move north, 
with Wednesday looking to be the most active day, though some rain is also possible (and 
potentially a bit to the West) on Tuesday. Rain showers will spread into the eastern third of the 
country by Friday despite there being less signal for heavy amounts to continue into that day. 
Severe weather is also a possibility given the pattern, and the Storm Prediction Center has 
outlook-ed the potential for severe weather on Tuesday across the Southern/Central Plains. Some 
areas across the southern tier will be sensitive to additional rainfall after the heavy rainfall 
event late this week, as well as rainfall events earlier this month.

Temperatures will generally be cooler than average behind the cold front and upper-level trough, 
with above normal temperatures ahead of the front and underneath the upper-level ridges in both the 
east and west coasts. We could reach much above normal temperatures in the Northeast and West mid 
to late next week as model trends appear to signal at strengthening ridges over those respective 
sides of the country.

An additional threat early next week will be a fairly deep surface low moving as a nor'easter and 
impacting the northeastern U.S. Sunday into Monday. The tight pressure gradient could cause a 
period of gusty winds along coastal New England on Sunday, and as the low tracks into southeastern 
Canada Monday, enhanced winds are possible especially across higher terrain areas of northern New 
England. Precipitation in the form of rain is likely at least for eastern portions of Maine as well.

Then toward midweek next week, chances for precipitation increase in the Northwest. Details 
regarding the timing and amounts of this precipitation remain in question at this point, so while 
it is possible that some areas especially in the Cascades could see heavy amounts, no area is 
depicted at this time.

Over Alaska, the anomalously warm temperatures being experienced especially into the North Slope in 
the near term/short range timeframe will be gradually cooling closer to normal by early next week. 
Some periods of precipitation are possible for the Aleutians and Alaska Peninsula, but below 
hazardous criteria. Heavier precipitation amounts with the possibility for coastal rain and inland 
snow are possible for southeastern parts of the Alaska Panhandle around Wednesday as moisture 
increases there.

Kebede/Tate