Four Things To Know About Winter Storm Diego

Linda Lam
Published: December 8, 2018

Winter Storm Diego will take a slow track across the southern tier of the U.S., spreading a wintry mess from the southern Plains into the Ozarks and Southeast.  

(MORE: Winter Storm Central)

Below we take a closer look at what you need to know about this potent winter storm.

A Variety of Precipitation Types Expected

One of the biggest concerns with Winter Storm Diego is where and when exactly the different types of precipitation will fall. Small changes in the track of this system, along with small differences in temperature both at the surface and aloft, can mean big changes in the forecast.

Snow, sleet, freezing rain and rain are all expected as this storm tracks east. For more on the heavy rain and flood threat click here

Many locations will see an evolution in precipitation types throughout the storm. Some will see a change from rain to snow, while others will also see extended periods of sleet and freezing rain.


Hourly Forecast

When the changes in precipitation type occur makes a difference in how much sleet, snow or ice accumulates.

(MORE: Winter Weather 101)

As a result, the forecast details may continue to change, so be sure to check back for updates.

Impacts Will Last Into Next Week

Winter Storm Diego will track slowly across the southern tier of the U.S. into early next week. Precipitation may not end from this storm until late Monday or early Tuesday, especially near parts of the Southeast coast.

An area of low pressure will track slowly across the South.

Due to this slow movement, many locations will see an extended period of precipitation, especially in the Southeast.

A sluggish track combined with plentiful moisture is expected to result in heavy rainfall and snowfall.

Areas in the Southeast that receive snow and ice will also be slow to thaw out early next week. 


Forecast Morning Lows

High temperatures Monday will likely be stuck in the 30s for much of North Carolina and upstate South Carolina. Lows on Tuesday morning will drop into the 20s for these areas.

This will slow the melting of snow and ice.

Heavy Snowfall and Ice Are Concerns

There is the potential for heavy, impactful snowfall in western North Carolina and southwestern Virginia.

Some locations will see more than a foot of snow, which is not very common in this area. 


Snowfall Forecast

For example, Asheville, North Carolina has recorded only 12 snowstorms with at least a foot of snow since 1869, and there are indications that this event may add to this list.

In addition to the possibility of heavy snowfall, ice accumulation is also a concern.

A crippling ice storm is not currently anticipated but even small ice accumulations can cause slippery roads, damage to tree branches and power outages.

The National Weather Service has highlighted a broad strip from Oklahoma through the Ozarks and into the Southeast of having at least a low probability of experiencing 0.1 inch or more of ice accumulation. 


Ice Probability

Within this broad area, there are several pockets that could see at least a quarter-inch of ice, the threshold where impacts such as tree damage and power outages typically begin. One such pocket includes portions of northern Arkansas.

The other pocket of significant icing risk includes parts of far southern Virginia, western North Carolina, upstate South Carolina and far northeast Georgia.

(MORE: What Ice Storm Accumulations Mean)

Given the threat of heavy snow and ice, the National Weather Service in Greenville-Spartanburg, South Carolina noted in its forecast discussion earlier this week that this could be "a once-in-a-generation event for areas that experience mostly snow and ice."

Winter Storm Diego Will Likely Not Impact the Northeast

Fortunately for the Northeast, Diego will not have any effect, as it is expected to remain shunted to the south as a cold front from eastern Canada plunges south Sunday night and Monday.


Rain and snow forecast through Tuesday.

This would result in a dry stretch of weather in the Northeast, including the Interstate 95 corridor. Areas as far south as northern Virginia and the Washington, D.C. area are not expected to see any rain or snow from this system.

Check back with us at weather.com for the latest updates. 


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