US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
442 PM EDT Mon Apr 12 2021
 
Valid Thursday April 15 2021 - Monday April 19 2021
 
Hazards:
- Heavy rain across portions of the Southeast and the Lower Mississippi Valley, Sun-Mon, Apr 18-Apr 
19.
- Heavy rain across portions of the Mid-Atlantic and the Northeast, Thu-Fri, Apr 15-Apr 16.
- Heavy snow across portions of the Central Rockies, the Central Plains, and the Northern Plains, 
Thu-Fri, Apr 15-Apr 16.
- Flooding possible across portions of the Middle Mississippi Valley.
- Flooding occurring or imminent across portions of the Middle Mississippi Valley and the Lower 
Mississippi Valley.
- Flooding likely across portions of the Middle Mississippi Valley.
- High winds across portions of the Mid-Atlantic and the Northeast, Thu-Fri, Apr 15-Apr 16.
 
Detailed Summary:

In the medium-range forecast period, the Hazards Chart has an area of heavy rain near the 
Southeast/Central Gulf Coast, heavy rain over parts of the Northeast/northern Mid-Atlantic, heavy 
snow over parts of the Central Rockies/Central High Plains, and high wind along parts of Southern 
New England Coast/Mid-Atlantic Coast.   Low pressure along the Mid-Atlantic Coast on Thursday will 
deepen just south of Long Island and move to near the coast of Massachusetts on Friday.  The low 
will move out over the Atlantic on Saturday.  The low will stream moisture off the Atlantic into 
the Northeast, producing heavy rain over parts of the northern Mid-Atlantic and Southern New 
England on Thursday.  The heavy rain will taper off over parts of the northern Mid-Atlantic on 
Thursday night into Friday. The heavy rain will linger over eastern Massachusetts on Friday.  The 
pressure gradient associated with the low will produce high winds along the coast of Southern New 
England and the Mid-Atlantic on Thursday and Friday.

Additionally, the associated front extending from along most of the East Coast and parts of the 
Gulf Coast on Thursday will move southward over the Florida Peninsula, stalling out halfway down 
the peninsula on Saturday.  Also, on Saturday, a wave of low pressure will develop along the front 
over the Gulf of Mexico.  The low will move onshore over northeast Florida on Sunday.  The boundary 
will start to move southward, again, over the peninsula on Monday.  Moisture will be pooling along 
the front producing heavy rain over parts of Florida and parts of the Central Gulf Coast on Sunday 
and Monday. 

A wave of low pressure on the western end of the front will develop over parts of the Great Basin 
and move southward into parts of the Southern High Plains by Friday.  The low and upper-level 
energy will help produce heavy snow over parts of the Central Rockies and Central High Plains on 
Thursday into Friday. 

For Alaska, an upper-level low over the mainland will move southward over the North Pacific by 
Saturday.  Upper-level ridging will build over the mainland through Monday, when upper-level 
troughing will dip over the Far North.  Temperatures over the Far North will get above freezing for 
a short period, but at this time, will not be a hazard.   A deep low over the North Pacific will 
stream moisture into parts of the Gulf of Alaska that will produce precipitation along the coast 
and Prince William Sound region on Sunday into Monday.  At this time, it appears the precipitation 
will not be heavy enough to be included as a hazard.

Ziegenfelder