US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
319 PM EDT Fri Apr 02 2021
 
Valid Monday April 05 2021 - Friday April 09 2021
 
Hazards:
- Heavy snow across portions of the Northern Rockies and the Northern Great Basin, Mon, Apr 5.
- Heavy rain across portions of the Upper Midwest, the Middle Mississippi Valley, and the Northern 
Plains, Wed-Thu, Apr 7-Apr 8.
- Heavy rain across portions of the Tennessee Valley, the Southern Appalachians, the Southeast, and 
the Ohio Valley, Thu, Apr 8.
- Heavy rain across portions of the Southeast, Fri, Apr 9.
- Flooding occurring or imminent across portions of the Middle/Lower Mississippi Valley and the 
Ohio Valley.
- Much above normal temperatures across portions of California and the Southwest, Mon, Apr 5 and 
Thu, Apr 8.
- Much above normal temperatures across portions of Southern Texas, Wed-Fri, Apr 7-Apr 9.
- Much below normal temperatures across portions of mainland Alaska, Tue-Fri, Apr 6-Apr 9.
 
Detailed Summary:

During the medium range period (Monday, April 5th - Friday, April 9th), ridging aloft on Monday 
will keep the weather relatively quiet precipitation-wise while simultaneously opening the door for 
temperatures to soar well above normal for a significant portion of the CONUS. From the Desert 
Southwest to the Upper Midwest temperature departures ranging from 15 to 25 degrees above average 
are expected Monday, potentially breaking a handful of daily high temperature records. Though the 
greatest temperature anomalies are forecast for the Central and Northern Great Plains they are not 
anticipated to be hazardous, as highs will only reach into the 70s and 80s. Conversely, in the 
Desert Southwest highs are expected to reach the high 90s and may hit triple digits in some areas. 
High temperatures will begin to moderate over the southwest and north-central CONUS on Tuesday as 
the upper-level ridge progresses eastward, giving the South and East their own taste of warm 
weather for a few days, though abnormally high temperatures in the mid to upper 90s will return to 
the Desert Southwest briefly on Thursday. Beginning on Wednesday, unaffected by a cold front 
passing to the north and aided by warm air advection via southerly flow, southern Texas is forecast 
to get its own bout of hot weather as highs consistently reach the upper 90s through Friday. 
Residents of southwestern Arizona, southeastern California, and southern Texas should exercise 
caution when outside to prevent dehydration and heat stroke.

With the arrival of an upper-level cut-off low over the Pacific Northwest comes the return of wet 
weather over the lower 48 after a short reprieve. To the south and east of this low an extended 
frontal boundary is expected to pass through the West and Northern Tier, bringing with it a mix of 
light to moderate rain. High elevation snow will also be likely and may become heavy at times, 
particularly over the Northern Great Basin and Northern Rockies late Monday into Tuesday. As a 
portion of this frontal boundary breaks off into a singular, mature low pressure system on 
Wednesday it will begin ingesting air with a higher moisture content, increasing rain rates over 
the Plains and the Upper Midwest. In stark contrast to yesterday's guidance the models have begun 
to agree on the storm track as well as an area where the highest rainfall totals will likely occur 
in that region, which is outlined by the heavy rain contour. Ushered to the south and east by the 
cut-off upper-level low, this system is anticipated to continue producing moderate to heavy rain 
along its path, with the current guidance indicating the heaviest totals may fall in the Tennessee 
and Ohio Valleys on Thursday and in portions of the Southeast on Friday. Though more heavy rain 
areas have been drawn today, it is worth noting that there is still a sizable degree of uncertainty 
between the models regarding the evolution of this system. As such, these areas should not be 
considered absolutes for where the heaviest rain will occur and are subject to change over the 
coming days as predictability increases and the guidance comes into better focus. Elsewhere, a pair 
of cold fronts moving onshore into the Pacific Northwest and through northern California Thursday 
and Friday will likely bring moderate rain to low lying coastal areas, high elevation snow to the 
Cascades, and mixed precipitation to the Sierra Nevada.

In Alaska, a stationary front is forecast to settle along the southern coast of the mainland Monday 
into Tuesday. Forcing produced by this boundary working in tandem with shortwave energy is expected 
to bring moderate to heavy, though non-hazardous, mixed precipitation to the northern half of the 
Panhandle Monday into Tuesday. Afterwards, high pressure at the surface is anticipated to build to 
the north and west of the state, driving cold, arctic air into the Interior as well as portions of 
the Southwest and Far North, causing temperatures to plummet 20 to 35 degrees below normal. With 
lows sitting around or well below zero, residents are urged to take caution when outside, keeping 
skin covered to prevent frostbite and dressing warm to stave off hypothermia.


Zavadoff