US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
319 PM EST Wed Mar 04 2020
 
Valid Saturday March 07 2020 - Wednesday March 11 2020
 
Hazards:
- Heavy precipitation across portions of the Northern Great Basin, Sat, Mar 7.
- Heavy precipitation across portions of the upper Great Lakes, Mon, Mar 9.
- Heavy precipitation across portions of the Northeast, Tue, Mar 10.
- Heavy precipitation across portions of northwestern Arizona, western Idaho, and southern Sierra 
Nevada, Wed, Mar 11.
- Heavy rain across portions of the lower Mississippi Valley, coastal southern California, and 
parts of the eastern Gulf Coast, Mon-Tue, Mar 9-Mar 10.
- Heavy rain across portions of the southern Appalachians into the Mid-Atlantic, Wed, Mar 11.
- Heavy snow across portions of the northern Rockies near the Canadian border, Sat, Mar 7.
- Flooding occurring or imminent across portions of the Southeast and the Lower Mississippi Valley.
- Flooding likely across portions of the Northern Plains.
- Heavy precipitation from coastal southern Alaska down through the Alaska Panhandle, Mon-Tue, Mar 
9-Mar 10.
- Much below normal temperatures for central to eastern Alaska, Sat, Mar 7 and Tue-Wed, Mar 10-Mar 
11.
- Much below normal temperatures across western Alaska, Mon-Tue, Mar 9-Mar 10.
- Much below normal temperatures for the outer islands of western Alaska, Mon, Mar 9.
 
Detailed Summary:

The prevailing synoptic split flow pattern across the U.S. is forecast to persist through the 
medium range period. Beginning on Saturday, an intense low pressure system will be rapidly 
departing the East Coast into the Atlantic.  Any wintry precipitation in New England should be 
ending early on Saturday.  In the wake of the storm, a cold high pressure system will bring below 
normal temperatures across the eastern U.S. and down into the Deep South through much of the 
weekend.  However, the split flow pattern is expected to re-establish itself as the center of the 
high pressure system reaches the East Coast on Sunday.  In contrast, much warmer than normal 
temperatures are expected to overspread the northern Plains during the weekend ahead of a cold 
front.  Temperatures as much as 30 degrees above average could lead to issues related to snow melt 
across sections of the northern Plains, such as the Black Hills, and into the upper Midwest 
beginning on Friday and continuing through the weekend.  In addition to the anomalous warmth, dry 
and breezy conditions will exacerbate the lack of precipitation situation across parts of the 
northern Plains.

Behind the high pressure system, the split flow pattern will once again lead to moisture from the 
northern and southern streams to gather over the southern to central Plains.  The best chance for 
heavy rain appears to be over the lower Mississippi Valley and the eastern Gulf Coast Monday into 
Tuesday.  A good chance of rain is forecast to extend farther to the northeast ahead of a cold 
front.  However, the rainfall amounts do not appear to be heavy.  Farther north, a low pressure 
system should be tracking eastward across the lower Great Lakes.  Wintry precipitation appears 
likely across the upper Midwest into the upper Great Lakes from late Sunday through early on 
Tuesday.  The precipitation could be heavy in these areas depending on the strength of the low.  
Farther upstream, the persistent west-northwest upper flow arriving from the Pacific Northwest will 
bring a chance of heavy snow into the northern Rockies near the Canadian border and wet snow or 
mixed precipitation over western Idaho on Saturday.

Another low pressure system associated with the southern stream of the split flow pattern is 
forecast to approach the southwestern U.S. early next week.  Moisture ahead of the system is 
forecast to bring the chance of heavy rain along the coastal sections of southern California 
beginning next Monday and continuing into Wednesday, as the southern Sierra Nevada and northwestern 
Arizona could see heavy precipitation moving in as well. 

Over Alaska, below normal temperatures should moderate from west to east through the weekend as 
troughing relaxes.  However, another cold upper trough will bring the next episode of well-below 
normal temperatures into the western part of the state for early next week, spreading into the 
eastern part by next Wednesday.  Near the coast, frequent arrival of occluded cyclones will keep a 
good chance of heavy rain/snow along the southern coast of Alaska into the Alaska Panhandle early 
next week.

Kong