FIRST ALERT: A breakdown of our potential for rain changing to snow on Sunday

Sunday is a First Alert Weather Day due to the potential of a winter storm which could have a big impact in North Alabama and Middle Tennessee.

Rain will change to snow this evening before ending from west to east. The biggest concern for most areas overnight and for the Monday morning commute will be patches of black ice as wet roads will freeze in some areas. 

In the higher terrain of northeast Alabama and Middle Tennessee the travel problems will be more widespread due to higher snowfall totals.

Morning lows will be in the upper 20s.  Highs will stay in the 30s for Monday with scattered snow showers possible into the afternoon.  Little additional accumulation is expected tomorrow.  Below normal temperatures can be expected for much of the next 10 days.  Rain chances return Wednesday.

Here is a breakdown of what we know.

A Winter Storm Warning has been issued for all counties in Middle Tennessee and now includes Jackson and DeKalb counties. As confidence is much higher now that there will be great impacts north of the Tennessee/Alabama Stateline, not only has this Warning been issued, but also a Winter Weather Advisory for the rest of North Alabama.

WHAT WE KNOW:

As has been the case all week, the beginning of the event for those of us here in the Tennessee Valley will be during the middle of the day and into the afternoon on Saturday. This will be all be rainfall. Temperatures on Saturday will be way too warm for any winter precipitation to be possible. We expect temperatures to stay into the mid to upper 40s most of the day which is well above freezing. This is due to a strong wind out of the southeast at 10 to 20 mph.

Overnight Saturday into Sunday morning is when the dynamics of the system will change as the center of the low-pressure system nears and the colder temperatures begin to move in.

WHAT WE ARE WATCHING:

The biggest questions that remain with this system is the track of the low pressure system as well as the timing for when the rain will change over to snow. We really won’t have an exact answer to these questions until the event itself, but unlike earlier this week, models are more in line for the path of the low. The latest trends are to keep this further to our south. The further south the center is, the more likely we will see snow here in North Alabama.

Above is a snapshot of a comparison between the EURO and the GFS models. They are much more consistent with the placement of the low pressure center over Georgia Sunday morning. It also looks like we will see a secondary low pressure system develop to our east, or northeast, which will aid in the dynamics for this event. This is called a “double barreled low,” as there will be two center of low pressure with this storm. As this happens, we will have potential for more significant snow bands to develop. This could lead to localized very heavy snowfall, with snowfall rates of one inch or more per hour.

The changeover from rain to snow is another major question that needs to be answered with this system. The earlier the changeover the more snow and vice versa. Right now it looks like the changeover will happen at some point during the morning on Sunday starting in Middle Tennessee and the Shoals. This will likely also occur over Northeast Alabama and Sand Mountain earlier than the Metro due to that potential second low pressure.

Currently (as seen above), the thought is that many in North Alabama will see a slushy 1-2″ of snow from this with the heavier totals north of the Tennessee River. Some portions of Northeast Alabama in the higher elevations could see more than 5 inches. Heavier snowfall is also more likely into Middle Tennessee with areas between Fayetteville and Nashville seeing 3 to 7 inches. However, snow totals for most are still part of the uncertainty so keep checking back for future snow forecast changes and updates

IMPACTS:

No matter what happens regarding the snow, you will see some sort of impact to your weekend. Rainfall will be heavy at times and that means we could see some minor flooding, especially since we have seen some heavy rain over the last few weeks. Soils are already soaked so additional water could lead to some flooding, and some areas could see as much as two inches of additional moisture this weekend.

As we change from rain over to snow we will also begin to see sleet and snow accumulation increase. This will start to create some major road impacts. Travel will start to be difficult by late Sunday morning and will continue to deteriorate into the afternoon and evening. Something different with this evening compared to the snow that we saw earlier in the month is that earlier this month we were coming off of record warmth in December and on New Year’s Day. The ground and road temperatures for that event were much warmer to start with, which made roads less icy. That won’t be the case this time around. The last week or so has been cooler than normal and Saturday’s temperatures ill be into the mid to upper 40s, much lower than the 60s, 70,s & 80s we had before our last storm.

Places into Middle Tennessee will probably experience impossible travel conditions by midday. I have received a lot of questions about travel to Nashville, Chattanooga, as well as Gatlinburg and the Smokie Mountains for this weekend. If you had travel plans for those areas this weekend, make plans to be there until at least Monday or Tuesday. Snow will begin much earlier in the day Sunday, possibly even the very early morning/overnight hours on Sunday.

Temperatures overnight into Monday will continue to fall and will make their way into the mid-20s. This means that whatever is on the roads Sunday will still be there until at least Monday morning. Travel conditions will likely be dicey for Monday morning’s commute. The good news is that most schools are already out because of Martin Luther King Jr. Day. However, there will still likely be travel issues.

Another issue with this weekend’s snow is the potential for more power outages. Similar to our snow on January 2, this snow will be a dense, heavy, wet snow which will put a strain on trees that are already compromised after the previous snow and rain. Wind will be gusting at 15 to 20 mph at times with this event which will stress these trees even more. I would expect to hear about more downed trees and power by midday Sunday. With this potential you will want to have a backup plan regarding power.

You can stay up to date using our 48 Weather App as well as on our streaming apps wherever you stream us! You can find us on Roku, Apple TV, & Amazon Fire devices! We will also be posting updates on our Facebook and Twitter pages! Keep checking back in those areas for the latest updates on the system and more clarity we move through the weekend.

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