Wednesday, January 21, 2015 9:53 PM

Late Week/Weekend Winter Storm Will Impact Many

Matthew Holliday

We’re finally getting some action across the United States. It’s either been very cold and dry or warmer and wet. Things have become a bit more active, and given that the overall pattern looks to remain active with several shots of Arctic air, I’d say the chances are quite high that many regions will get snow/ice over the next couple of weeks. This first storm will likely give wintry precipitation to many, but there will be a few regions further south that will have to deal with a cold rain (with possibly some wrap-around snow/sleet on the backend). I’ll be detailing that below.

Latest snowfall accumulation projection through Sunday from the NAM

Latest snowfall accumulation projection through Sunday from the NAM

Currently this system is pumping copious amounts of moisture across New Mexico, Oklahoma, and Texas. The snow is already starting to pile up across the panhandles of Texas/Oklahoma and over New Mexico. Heavy snowfall accumulations are likely over those regions. The moisture is going to continue to spread eastward, moving further into Texas and Oklahoma. Parts of southwestern and western Oklahoma into parts of central Oklahoma could also end up with some heavy snow before all is said and done.

I wouldn’t be surprised if regions near the Dallas/Ft. Worth area (particularly just north of there) ended up with a changeover to some heavy snow/frozen precipitation that could bring accumulations. Those regions are not currently under any winter weather advisories, but that could easily change. They may end up being in one of those surprise areas. It’s always important to realize that a degree or two can make a huge difference.

Moisture will begin to spread eastward over Louisiana and Arkansas tomorrow and then eventually east and northeastward into the Tennessee Valley and Gulf Coast states tomorrow night going into Friday. Cold air is going to rush in behind this system, so a changeover to heavy, wet snow is definitely possible over south and central Arkansas, northern Mississippi, and particularly over Tennessee. I wouldn’t even be surprised if a few wet flakes or ice pellets fell over northern Louisiana.

As this system moves along the Gulf Coast states on Friday, it will eventually cross over northern Florida and then up the East Coast, where this system will rapidly strengthen. As this system begins to pull up the coast Friday night, I wouldn’t be surprised at all if certain areas in northern Alabama and northern Georgia changed over to some frozen precipitation towards the end of the event. Parts of northern Upstate SC could also transition to some wet snow or frozen precipitation, and in fact, latest model guidance has some very light accumulations over the area. We’ll have to wait and see if anything comes of that, but given that cold air will be rushing in behind this system, I’d say that it’s definitely possible.

Bombogenisis is likely going to occur with this storm as it slides up the coast, meaning the pressure will likely drop over 24 millibars in a 24-hour period. This will pull copious amounts of moisture up the coast, and it’s going to all come down to the track of this system, which will determine who gets very heavy snow or just a cold rain. I’d say that from the western NC mountains, Tennessee/Kentucky and up through western and central Virginia into West Virginia has a decent shot at snow and/or ice. The highest risk area will be from the DC area up to around Boston. Again, a few mile jog west or east can change the entire forecast. That’s why it’s so hard to predict these kinds of systems when they go up the coast like this.

I hope this gives you a good idea as to what you can expect. This system is likely going to be bringing a big winter storm to many, and I wouldn’t even be surprised if it brought a little surprise to other areas, too. Generally this will be a very heavy rain event across the Gulf coast states, but like I mentioned, some regions could see a changeover to some frozen precipitation. I will monitor everything as the event unfolds.