US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
338 PM EDT Mon Apr 05 2021
 
Valid Thursday April 08 2021 - Monday April 12 2021
 
Hazards:
- Heavy rain across portions of the Lower Mississippi Valley, the Tennessee Valley, the 
Mid-Atlantic, the Southern Appalachians, the Southeast, and the Southern Plains, Fri-Sat, Apr 9-Apr 
10.
- Flooding occurring or imminent across portions of the Middle Mississippi Valley, the Lower 
Mississippi Valley, and the Ohio Valley.
- Flooding likely across portions of the Lower Mississippi Valley.
- High winds across portions of the Central Rockies, the Central Plains, the Central Great Basin, 
and the Northern Plains, Thu, Apr 8.
- Much above normal temperatures across portions of the Southern Plains, Thu-Fri, Apr 8-Apr 9.
- Heavy snow across portions of the Alaska Panhandle, Thu, Apr 8.
- High winds across portions of mainland Alaska, Thu-Fri, Apr 8-Apr 9.
- Much below normal temperatures across portions of the Alaska Panhandle and mainland Alaska, 
Thu-Sun, Apr 8-Apr 11.
 
Detailed Summary:

During the upcoming Day 3-7 period (Thursday, April 8 through Monday, April 12), the weather across 
the lower 48 will be predominantly influenced by a series of Pacific systems advancing across the 
northwestern states and swinging through a broad upper trough over the central U.S.  On Thursday, a 
fast-moving upper system and associated surface front will dive southeastward through the northern 
Rockies and northern High Plains.  The system will be accompanied by some precipitation, but the 
main concern will be locally strong winds behind the front.  The highest winds are expected over 
southern/central Wyoming, though could extend northward into eastern sections of Montana.  On 
Friday, the higher winds will shift into the Dakotas due to a strong pressure gradient between a 
low over the upper Mississippi Valley and high pressure building behind the aforementioned cold 
front.  The forecast winds are a little below our criteria (sustained winds greater than 34 mph), 
but gusts are likely to exceed this value at least for part of the day.  Over the weekend, it looks 
like a repeat occurrence of high winds is possible over the northern Rockies/High Plains as another 
cold front quickly crosses the region.

Farther east and downstream of the central U.S. trough, southerly flow will allow deep Gulf of 
Mexico moisture to stream northward into the lower Mississippi Valley, southeastern states and 
sections of the Mid-Atlantic region later this week and weekend. This moisture will interact with a 
mid-upper level system transiting the southern tier of states, resulting in a broad area of 
moderate to heavy rainfall.  The general consensus among our guidance suggests that the heaviest 
precipitation will occur in the Friday to Saturday period.  On Friday, itâ€s likely to be mostly 
confined to around and just north of the Gulf Coast.  Then as this system lifts northeastward 
around the central U.S. trough, the heavier rainfall may tend to shift into the southern/central 
Appalachians region Saturday.  There is still a lot of uncertainty with the exact placement of 
heaviest precipitation, especially Saturday, but given the above normal recent rainfall across the 
southern/central Appalachians, itâ€s worth keeping an eye on as the week progresses.  

Elsewhere, across southern sections of Texas, there will still be a couple more days of much above 
normal temperatures early in the period (with highs locally reaching 100-105).  A general increase 
in upper troughing, along with associated weak surface fronts will result in some moderation of the 
hot temperatures during the weekend into early next week.  Temperatures over the Desert Southwest 
will be on the order of 10-12 degrees above average Thursday, with highs reaching the mid 90s, but 
given the warmer weather over the past weekend and today, felt that this was at best a marginal 
hazard.  

Over Alaska, winter is maintaining a firm grip, as Arctic air entrenched over much of the mainland 
keeps temperatures much below normal through the end of the week and into the weekend.  
Temperatures will range from 20-30 degrees below normal, with a potential to set a few new records 
for early April.  There will be some overall moderation to the temperatures by late in the weekend 
into early next week.  In addition to the cold temperatures, the gradient between a strong high in 
eastern Siberia and a powerful low moving into the Gulf of Alaska Thursday-Friday will result in 
strong winds across Bristol Bay, the Alaskan Peninsula and Cook Inlet.  The highest winds, greater 
than 40-50 mph, will be offshore north and south of Kodiak Island.  Farther east, this same strong 
Gulf low will bring abundant moisture and heavy precipitation into the Panhandle region Thursday.  
Temperatures are expected to be cold enough so that much of this precipitation will be heavy, wet 
snow (locally a foot or more), though a transition to rain is possible, especially near the coast 
and over southern sections.  

Klein