1/27 - 6am - What a Mess!

Good morning! Since JCPS is closed, I thought that I'd post an early morning update.

First off, don't drive if you don't have to today. Snow and sleet totals around the area are in the 2-3" range around town and we are far from finished. We got mostly sleet in the Metro, but that mixed with the snow is making for a nasty layer of gunk on the roads.

Temperatures at 850mb (5000 feet) are going to rise today, changing our sleet and snow to freezing rain. I'll be blunt: We are going to see a major ice storm tonight with this changeover. This is the kind of precipitation that knocks out power and downs trees. Temperatures today will most likely stay just below freezing, so don't expect things to get much better before we descend into part 2 of this storm. Temperatures at 850mb will cool later tonight, which should change the freezing rain to snow. Expect another 2 inches of snow by Wednesday morning once this happens.

I've been watching the local morning news shows and the live shots they're broadcasting from the interstates are quite interesting. I didn't think the interstates would get that bad this morning, so please be careful if you have to be on the roads.

1/26 - 9pm - Video Update

Here's the video update... everything is coming together on the radar quite well at this point.

1/26 - 4:30pm - More Ice, Less Snow

WINTER STORM WARNING - 10pm tonight until 1am Wednesday.

Here's how things stand at the moment for tomorrow during morning rush hour:



I think the heaviest snow will be just north of Louisville, with temperatures staying just below freezing at the lower levels up there. Here in Louisville, I expect 3 to 4 inches by tomorrow morning. This is down just a bit because I think we'll transition to ice earlier than previously thought, meaning some of that 3 to 4 inches will be sleet on the ground. We could pick up another inch of sleet and snow throughout the day on Tuesday before the snow picks up again on Tuesday night. I'm thinking we'll have another inch or two of snow out of that by Wednesday. The total snow/sleet accumulation for Louisville should top out at around 5-6 inches by the time Wednesday morning rolls around. Points south of Louisville will see 2 to 3 inches tonight, but a transition to sleet will happen sooner in the morning. Freezing rain in the afternoon down there could trigger dangerous ice storm conditions as well.

Now... if we get even warmer at the upper levels, we'll see lower amounts of snow and more ice. Freezing rain is not out of the question either. The general gist is that we'll see more sleet, but snow should be the dominant precipitation tonight and early tomorrow morning. We should stay below freezing all day tomorrow, but that's subject to change. If things trend colder at 85omb (5000 feet), which I do not think will happen, then expect more snow. Either way, driving will be messy tomorrow morning and there will be numerous school closures.

1/25 - 8:30pm - Quick Snow Forecast Update

The models have been going a bit to the north with this system over the course of today, meaning we'll see some sleet and maybe freezing rain. We're still looking good for 5 inches or so, but the amount of ice on top of that is increasing with each model run. The heaviest snow will fall just to our north in Indiana, with 8 or more inches there. If we start seeing colder temperatures at 850mb in the model runs tomorrow, we're in for some heavier snow. For now, I think this will be a moderate snow event tomorrow night with an icy mess on top by Tuesday afternoon. We're still on for a little bit of snow on Tuesday night and Wednesday morning as well, so an inch or two could be appended on to the current 5 inch estimate. There's still plenty of time for things to shift tomorrow, so keep up to date!

1/25 - 1pm - WINTER STORM WATCH

The National Weather Service has issued a Winter Storm Watch for the area starting tomorrow night. At this point, I think we're going to get more ice than previously thought. Snow accumulations should total up to around 5" in the Metro by Tuesday evening, with ice accumulations of .25" or higher. Having just one of these components is bad enough, but having both will make conditions worse.

The reason for the enhanced ice is a warm layer of air a few thousand feet up that will come from the south on Tuesday afternoon. This is called an overrunning event. Surface temperatures will stay below freezing, but liquid precipitation will fall and freeze either on the surface (freezing rain) or just before it hits the ground (sleet). Here's how the 6z GFS played out with this:

Click any image for a larger view.

On the surface chart, the 0 degree line stays near the KY/TN border on Tuesday morning, meaning below freezing temperatures at the surface.


On this 850MB (5000 feet) chart, the 0 degree line is just south of Louisville, and should go slightly north of the city by Tuesday afternoon. The longer this line stays north of here and surface temperatures stay below freezing, the more ice we get.

The NAM model is going colder with this storm, suggesting all snow for us. I don't know if I buy that because it seems to be portraying an outlying solution compared to the GFS and Euro. With that in mind, I still think we'll see 4-5" in Louisville by Tuesday afternoon, with a fairly thick layer of ice to top that off. More snow is possible on Tuesday night and Wednesday morning, but I don't think we'll see more than an inch or two from that. Southern Indiana will get more snow than ice; Central and Southern Kentucky will get more ice than snow.

So, we're dealing with a mixed winter storm at the moment. If the 850MB charts change, we'll see either a larger snow portion or a larger ice portion of this storm. Either way, it's going to be a mess. I'll post tonight if anything changes in the models.

1/24 - 5pm - New Forecast Video

Looks like we're going to see our first major accumulating snow of the season next week! As an area of low pressure passes to our south, snow will overspread the area on Monday night and Tuesday. At this point it looks like more than 4 inches is possible, but a little bit of sleet on Tuesday could limit those accumulations slightly. A system coming through on Wednesday and Thursday could also bring some snow, but it looks like more of a rain-maker at the moment. Any shift south in that storm's track would likely bring us all snow. Stay tuned throughout the weekend!



EDIT (6pm): The 18z GFS is giving us all snow for both systems now. I'm upping my estimate to 5+ inches, with amounts up to 8 inches possible. The HPC is also putting us under a MODERATE Risk of 4+ inches of snow and a SLIGHT Risk for 8+ inches of snow.

1/23 - 4:45pm - Snow Shovels?

I think we may need to use snow shovels on Tuesday. After taking a look at the latest GFS runs, they've started going toward the HPC's solution of the low passing to our south. This means we'll see all snow on Monday night through Wednesday morning if this track holds. Snow amounts are tricky right now because the 6z GFS had us getting pummeled with quite a bit of moisture, but the 12z backed off. This will vary over the next couple days, so we needn't worry about snow amounts yet.

The Wednesday-Thursday storm looks like rain to me at the moment, but I'm still going to keep an eye on it. If the next storm corrects southward on the models like the one for Monday-Wednesday, look out. Obviously none of this is set in stone, so we'll have to wait for successive model runs to determine the details. I've have more details in the video forecast tomorrow afternoon!

Enjoy the last of the warm air this evening! Temperatures in the 30s are in store for the weekend after this cold front passes tonight.