12/28 - 1:30am EST - Kentuckiana Winter Storm Number 2

Wednesday's winter storm didn't give much snow to folks in the Louisville area and instead confined heavy snow to areas of Southern Indiana. While differences in the models did exist over whether Louisville would get any accumulating snow or not, the overall situation was handled pretty well from a forecast standpoint. The highest snow report in NWS Louisville's coverage area was 7.2 inches in Washington County, IN while Louisville received a trace to a half inch.

The next storm on the heels of the last one is less than 24 hours away as a system arrives from the southwest and stays to our southeast as it moves through the region. This will start as some rain for the Louisville area but as colder air filters in we'll switch over to snow during the later evening hours. This exact time for switchover depends on how warm we get during the day tomorrow (lower 40's versus upper 30's makes a difference!) and how fast the cold air comes in. The 0z NAM that came in earlier tonight has about 3" for the city and after comparing this with other models I'm thinking this may be a number we'll see most commonly reported by Saturday morning in Louisville. Higher totals will be possible just a bit further north from Louisville.

But even as I say this there's a small fly in the ointment. The 3z RPM model is in and it has the possibility of 4-6" of snow just due east of the city and a few very small totals like this scattered throughout areas near the Ohio River. This suggests that totals closer to 4" might be more widespread than previously thought. You can click the RPM output on the left for a larger view. We've seen the trend of increasing snow totals today on the models and this run of the RPM just continues this. We'll need to watch for this trend tomorrow morning to see if other models catch on. Right now this isn't really a factor in my forecast since it's just one model. Below is my snow forecast map for the region. Realize that, like the last storm, a small shift in track or more/less cold air will change things for some folks drastically.

Also worth noting is that the Hyrdrometeorological Prediction Center (HPC) has us in a Slight Risk of a 4" snowfall (think of this like the Slight, Moderate, and High severe weather risks) while areas closer to Cincinnati are in a Moderate Risk. Expect to see Winter Weather Advisories being issued tomorrow for portions of Kentuckiana. There may also be a few Winter Storm Watches issued as well depending on if forecast amounts of 4" or more look to be more widespread. You can keep up with the latest on this storm tomorrow by following me on Twitter and Facebook. Good luck, snow lovers!

12/21 - 2pm - I'm Dreaming of a White (Day After) Christmas

How about that snow last night around Kentuckiana? Most places saw a dusting but areas in Southern Indiana near Orange County picked up about 3 inches since a snow band set up there for a few hours during the overnight. Here at my house in Southeast Louisville we picked up a dusting of snow that blew around a bit in the wind. Temperatures today aren't going to make it out of the mid 30's in Louisville today thanks to the cold air behind the front that passed through yesterday. Seems appropriate given that it's the first day of winter!

Temperatures will moderate for the weekend with southerly flow returning but an area of low pressure moving through will bring rain and even warmer temperatures for Christmas Eve. Booooo! Luckily Christmas Day isn't looking like a washout with just a few clouds and highs in the lower 40's. That's a different story further South in Mississippi, Alabama, and Georgia where rain will be setting up.

Now... onto the fun part. Over the past couple of days the forecast models have been jumping onto the idea of an area of low pressure moving from the Gulf states to the western side of the Appalachian Mountains the day after Christmas. This is concerning because this track favors a snow event for Kentuckiana and even some of West Tennessee. You need to be on the north and west side of these low pressure systems if you want to see some snow since that's where the cold air is confined to. The past few systems we've been on the south and east sides of the lows moving though so that has meant thunderstorms and warm weather lately.

The latest 3 runs of the GFS for this particular post-Christmas storm have been fairly consistent with the low track, which is good! The problem has been that there's been trouble determining how much cold air there will be to work with and how strong/large the low moving through will be. These issues have affected how much snow the Louisville area gets. The graphic on the left is a comparison of the last 3 runs of the GFS for December 26th. For entertainment purposes only, the 0z run had just shy of 8" of snow for Louisville, the 6z had about 3", and the 12z had around 2.5". It is still way, way too far out for specific totals and to worry about the cold air issues yet since things will change likely on the models between now and then. I will say though that the 6 and 12z runs seemed to have difficulty keeping the low as a single, compact system once it matured and instead wanted to go with an elongated large low that tries to interact with another low that develops east of the Appalachians. I've seen this kind of thing happen on the GFS earlier this year with the Nor'easters that we had. Eventually, based on what happened with these Nor'easters, these elongated lows should give way to more concentrated, compact lows on the GFS as we get closer to the actual event. This should help to clear up some of the murkiness with the cold air issues too.

The Euro has been fairly consistent with the track of the low as the GFS has been, but has also experienced a few issues of its own like the GFS. Yesterday's 12z run of the Euro had a blockbuster snow event in the Louisville area while the 0z last night backed off on that prospect thanks to, you guessed it, a more elongated low and trouble with cold air. I can't post the precipitation output from the Euro model since it's behind a paywall and copyrighted, but I can at least show you what the 0z run did with the low after it moved through. Lots and lots of cold air will be behind this system if you couldn't tell by the deep blues and purples on the map!

UPDATE 2:20pm - Today's 12z Euro model run is in and it has a blockbuster storm track for snow for us here in Kentuckiana and West Tennessee. That is quite a strong low in East Tennessee on the left-hand map compared to previous runs. Sheesh.

The CMC and the JMA, which are the Canadian and Japanese models, aren't worth showing here right now. The CMC has the storm running off the east coast and the JMA has a nice low track for some snow in Louisville. It's worth noting that this system might disappear all together on the models or make a radical change. It's still too far out for much certainty.

Also, West Tennessee may see snow from this storm should it take the track that we're seeing. It wouldn't be much snow but certainly more than an inch or so isn't out of the realm of possibility, especially in Northwest Tennessee. Once we get closer to time this will become a bit more clear.

The NAO, which is the North Atlantic Oscillation, frankly isn't agreeing that there will be support for this storm. A negative NAO means blocking near Greenland allows for cold air to flow into the Eastern US and stay locked in place. The current forecast is for a positive NAO during this time, but it has been flipping between negative and positive over the past couple of days. This storm doesn't have to have a negative NAO to happen, but it would help to have it for cold air support and for a storm track that rolls up to the northeast. This will, like the aforementioned models, sort itself out over the next few days.

 

Finally, NWS Louisville has been on board with this storm since yesterday. They're being cautious like they should be but mentioning at length the potential for this at 5 days out is something that they don't do very often. Here's their latest statement:

A much more significant weather system will arrive on the 26th. Both the 00z GFS/ECM and ensembles track a strong low pressure system just to the west of the Appalachian spine which may set us up for our first significant snow. If the low pressure system takes its current forecast track, precipitation would enter the area Wed morning with the bulk of precip occurring Wed during the day and then exiting late Wed night or Thurs morning.

Although there is still much uncertainty in the track of this weather system 6 days out, the possibility is there for significant snow based on the low track and anticipated thermal profiles. BUFKIT GFS showed 8 inches at SDF with a little more than 0.5 inch of qpf. The soundings denote a classic heavy snow sounding with subzero and deep isothermal layer super saturated. The synoptic features of interest are a 110 kt jet max entering a the base of a deepening trough.

For now will have 60% pops on the 26th with rain in the morning and then snow in the afternoon and Wed night. Bing Crosby`s I`m dreaming of a White Christmas may happen, just 24 hours later.

Stay tuned for upcoming forecast updates as this weather system may put a kink in holiday travel plans.

 

This will be a fun system to watch over the weekend. Hopefully there's some snow in our future!

 

12/11 - 10:30pm - Be Careful When Wishing for Snow... You Might Get it!

With all the warmth much of the eastern portion of the nation has been experiencing lately some folks are beginning to get antsy over whether we'll be able to fall into a more winter-like pattern in time for the holidays. The cold front that rolled through earlier this week has helped to assuage some of those fears as it brought much cooler temperatures and even some light snow/sleet to parts of Kentucky and Indiana.

So... What's next? First up is a system that will move through the region this weekend as a warm one. A low will travel from the Plains to Lake Michigan and keep the eastern half of the nation warm as it spreads rain from the Great Lakes to the South. This makes sense because the North Atlantic Oscillation (NAO) will be going neutral during this time, which generally means that cold air won't be able to spill down into the Eastern US from Canada. The Arctic Oscillation will be negative to support cold air coming out of the north, but that doesn't matter too much for us when the NAO isn't negative as well.

The system behind this weekend's is the one that is drawing some concern. A low will be moving across the South during the day on Tuesday and potentially spread some snow to areas that are north of it. At this point anywhere from West Tennessee to the Louisville area is in a potential corridor for snow. This all depends on the exact track of the low and how much cold air it will be able to bring down from the north. This scenario is supported by the NAO and AO both going negative during this time. The GFS model takes the storm along the southern border of Tennessee right to the Carolinas. The ECMWF (European) model starts out with the low a little further south along the Mississippi River but has it exit off the coast in about the same location as the GFS. The low would then become a storm that would ride up to the Northeast just off the coast. With the previous system pulling up toward the Chicago area, this low will likely stay suppressed to the south. So... the broad, general nature of this low's track isn't in too much question. My preliminary (read: subject to change!) thinking is that this will be a rain to light snow situation for portions of Tennessee and Kentucky since cold air would plunge in as the system is exiting to the east. Accumulations would be very light to none.

But here's an issue. The snow cover over the Northern Plains and Upper Midwest has expanded tremendously over the past week as a storm pummeled those areas with quite a bit of snow. We're now at 31.4% snow cover over the United States. Air moving from the north over that snow won't warm as quickly as it would over bare land and the computer models generally have a difficult time resolving that. With this snow cover, the air in place over us and the air coming down from the north may be a little cooler than the computer models think it will be at the moment. That could mean more snow from this system. We're still a week away from this event so while details are sketchy, it's now obvious that this is a system to watch. This likely won't be the only storm we'll have to contend with between now and the new year since a pattern is setting up that will allow cold air to sit close by to the Ohio and Tennessee Valleys while lows track through and just to the south of the region. There's hope for a white Christmas in the region but it will depend on whether we can get enough cold air and a storm to move through just before the 25th. It'll be fun to watch!

12/26 - 12:30pm - Post-Christmas Snow Chance?

While many did not have a white Christmas yesterday, it certainly was a nice day across much of the East US with warm temperatures. We now turn our attention to a system that will be bringing much of the Southeast rain and possibly some snow as you head northward. This system is brewing in the Gulf Coast states right now and will bring West Tennessee rain this afternoon through tomorrow and the Louisville area rain tonight through tomorrow. While West Tennessee will likely stay all rain throughout the duration of this system due to warmer temperatures, Kentuckiana may have to deal with some snowfall during the afternoon tomorrow. The track of this storm from Tennessee to Eastern Kentucky is usually one that gives us our bigger snow events during the winter, but this time that won't be the case because of the lack of cold air we'll have to work with.

The forecast for snow is a tough one because we'll be dealing with colder air coming in on the backside of this system to give us our snow. This means that the atmosphere will cool from top to bottom and while snow will be falling it will likely not accumulate much, if any, because the air at the surface will still be warm while the upper atmosphere cools down. Nevertheless, a switchover to snow in the Louisville area will likely happen sometime tomorrow during the early to mid afternoon hours as cold air penetrates enough of the atmosphere to keep snow falling all the way to the surface. The NAM (left) seems to be the most aggressive on this switchover right now due to the surge of cold air it brings in early on in the afternoon in Louisville but the forecast sounding, or a vertical snapshot of the atmosphere at a given time, still indicates that we'll have temperatures just above freezing near the surface. This means that snow will be making it to the ground, but will likely melt on contact or accumulate lightly on the grass and elevated areas in heavier snow bands. Speaking of banding, that's another issue we could face. Snow banding is when you get a thin strips of heavy snow falling that look like bands due to winds coming together in these areas. These bands can produce snow accumulations even when temperatures are above freezing, just like in Jackson, Tennessee earlier this month when over an inch of snow accumulated with temperatures just above freezing.

Overall, I think areas in and close to Louisville can expect a dusting and maybe up to an inch of snow on grassy and elevated surfaces at some point tomorrow evening. If cooler air does not come in as quickly as expected this will remain a rain/snow mix or even just plain rain. Areas north and west of the Ohio River have the best shot for a light accumulating snow as they'll be slightly cooler and have an earlier switchover during the late morning hours. Most of the models are agreeing that we'll stay above freezing during most of this event, but we will be dipping down below that mark late Tuesday evening. This may create slick spots if any roads are wet from the snowfall during the afternoon. The 12z NAM (top left) is indeed the most aggressive on snowfall totals around here by looking at the snowfall output map, which you can see a larger view of by clicking. The 0z GFS (bottom left) is less aggressive, which is typical for it lately, and the Euro (which I cannot post here to copyright policies) keeps the snowfall along and north of the Ohio River. There are still a lot of small variables like exactly how fast the precipitation will move out of here and how much cold air will actually work into this process, so little details like these can drastically alter who gets snow and how much.

12/10 - 12:30pm - Crazy Weather on the Way in Louisville!

I'm back home in Louisville after a long drive from Mississippi last night. My third semester at MSU is over after going through my final exams and now it's time to move on to more important things, like a potential accumulating snow here in Louisville this weekend!


The Latest
The computer forecast models have had a very difficult time trying to forecast this weekend's storm across the Upper Midwest and Ohio Valley. Earlier this week there were vast differences in where the low pressure center of this storm would track. Some models had the low moving into central Tennessee or central Kentucky before cutting northward to Ohio/West Virginia, and others had it moving into Wisconsin, Illinois, and Indiana before cutting north to the Great Lakes. The Tennessee/Kentucky track is the one that would give Louisville a snowstorm, but it appears a more northerly track will take place. The HPC's (Hydrometeorological Prediction Center) depiction of the northern track is on the right image. Luckily, for you snowlovers out there, this is not the end of our snow chances for this storm here in Kentuckiana!

As the cold air behind this storm catches up with the back end of the rain we'll see on Saturday, we may see a brief burst of wet snow on Saturday night. Then, light snow will wrap around the back end of the storm and impact us from the north on Sunday, possibly into Monday. By the time this is all said and done, I think Louisville will have 2-3" (isolated 4") of snow on the ground with lower amounts south and higher amounts north of here. The 6z GFS model seems to be picking up on these totals well and I've posted its forecast snowfall accumulation map to the left. You can click the image for a larger view if needed.

Here's what the National Weather Service in Louisville says about all of this:

THE COLD FRONT LOOKS TO PUSH THROUGH THE AREA SATURDAY EVENING BEFORE MIDNIGHT OVER MOST LOCATIONS.  DEPENDING ON HOW FAST THE COLD AIR CAN CATCH UP TO THE PRECIP...THERE MAY BE A BRIEF CHANGE OVER TO SNOW ESPECIALLY IN THE BLUEGRASS BEFORE WE GET INTO A BRIEF DRY SLOT EARLY SUNDAY MORNING. WRAP AROUND LIGHT SNOW WILL THEN PUSH THROUGH THE AREA ON SUNDAY.  LAKE ENHANCED LIGHT SNOW WILL CONTINUE SUNDAY NIGHT THROUGH MONDAY BECOMING MORE CONFINED TO OUR SOUTHEAST INDIANA COUNTIES AND THE BLUEGRASS BY MONDAY AS MOISTURE SLOWLY PULLS AWAY FROM THE REGION.  TOTAL SNOW ACCUMS LOOK TO BE BETWEEN 1-3 INCHES FROM SAT NIGHT THROUGH MONDAY WITH THE HIGHEST ACCUMS EXPECTED OVER SOUTHEAST INDIANA AND THE BLUEGRASS REGION.

Even though we have a general track somewhat ironed out now, there are a couple of details that could increase our snow totals. While the GFS/ECMWF (European)/NAM/CMC models all generally agree on a northern track to this storm, the UKMET model is still taking a more southerly track near the Ohio Valley. At this point I think it's an outlier solution, but nevertheless there is a sliver of a chance that the low could take a little jog southward and impact our snow totals. There's also a chance that a secondary low could form well to the south of the primary storm and the implications of that are pretty substantial on our snow totals. Chances for that look slim as well as most computer models either don't have it or get rid of it before it exits Texas. Again, these are just a couple little things to watch that could affect us if they come to fruition by some outside chance.

As if the snow wasn't enough, we'll also have to contend with gusty winds of 25-35mph on Sunday which will blow the drier snow around and create visibility issues. Temperatures will also plummet during the storm as a cold front comes through, meaning we'll see highs only in the 20's for Sunday and Monday here in the Metro. Factor those chilly temperatures in with the winds and you've got yourself below zero windchills. That's dangerous weather in itself... stay warm out there!

I'll be posting updates on my Facebook and Twitter accounts today if there are any updates.

1/2 - 7pm - Snow Chances Going Up!

Snow chances are on the rise as confidence and agreement among the computer models increases for next week. Right now it looks like snow could fall from Chicago to Mississippi on Thursday. With cold air in place, problems with ice or rain look very unlikely for all points north of Central Alabama, Arkansas, and Mississippi. As far as snowfall totals go, I think we could see some fairly impressive numbers come out of this system. The GFS model had been very conservative with precipitation amounts up until the 18z run this afternoon, which mirrors the ECMWF (Euro) more closely with increased precipitation (I do not have access to precipitation amounts for the ECMWF, but local NWS discussions highlighted what was going on with this model). I would say that Louisville could get 3 to 5 inches of snow out of this system if the GFS keeps this trend up. Remember that it will be very cold when the precipitation reaches the area, so liquid rain to snow conversion ratios will be much higher.

I'm heading back to Mississippi State on Monday, and this same system may spread snow across the northern half of the state on Thursday! I was a bit worried that it may not be cold enough down there for this system to stay all snow, but the GFS and Euro have been consistent in keeping things cold enough for snow north of I-20. The current 18z GFS run spits out over 4 inches of snow for the Starkville, Columbus, West Point area, so we may see a good accumulating snow if things keep up on the models. 4 inches may be a little too optimistic, but I'd say at least an inch or two. There's certainly room for things to change between now and Thursday, but I think chances are getting better for snow in Mississippi. We'll see how it goes!

12/28 - 2pm - A Difficult Snow Forecast

Hope that everyone in Louisville enjoyed the dusting of snow that came last night. Here's a little 6-inch snowman I was able to put together as the snow was falling:


The New Year's snow chance is still on the maps. The computer models are having difficulties trying to hammer down a track for this storm, but I think we may have a shot at 1-4" of snow. The precipitation amounts are different on all of the models right now, so that's about the best estimate I can offer at this point.

The 12z NAM run is a little warm for us in Louisville, but the track of the low is sufficient to generate a good snow around here if temperatures cooperate. There's a coastal low that may form as well, and that could impact how much precipitation we receive and the storm track.

The 12z GFS run is similar to the NAM, but the low is further east by a few miles. This helps to lower our temperatures a little bit, so we wouldn't have as much rain before the precipitation changes to snow. That coastal low shows up on the GFS as well.

The 12z ECMWF (Euro) is difficult to read because of the large time difference between frames this many days out, but you can see that it favors the low pushing further east and pushing off the coast.

Here's what the NWS in Louisville says about this system:

SO...WHAT KIND OF PRECIPITATION WILL IT BE? THAT IS A DIFFICULT QUESTION TO ANSWER AT THIS TIME. TAKING OUR BEST SHOT...FOR WEDNESDAY THROUGH THURSDAY IT LOOKS LIKE THE NORTHERN SECTIONS OF THE AREA /SOUTHERN INDIANA AND NORTHERN KENTUCKY/ COULD SEE PRIMARILY SNOW WITH SOME RAIN MIXING IN DURING THE WARMEST AFTERNOON HOURS. CENTRAL PORTIONS LOOK TO BE A RAIN/SNOW MIX...AND SOUTHERN KENTUCKY SHOULD SEE MOSTLY RAIN WITH SOME SNOW MIXED IN WEDNESDAY NIGHT.

....

CANNOT SAY WITH CONFIDENCE YET JUST HOW MUCH SNOW WILL FALL...BUT IT DOES LOOK LIKE ACCUMULATING SNOWS WILL BE POSSIBLE LATER THIS WEEK JUST ABOUT EVERYWHERE. STAY TUNED.

From what I've seen, I think we may start with a period of light rain on Wednesday evening as the low approaches the area. Cooler temperatures should filter in and change everything to snow by late Thursday as the low moves to our east. How much snow falls on Thursday and Friday will be determined by the track of the low as it moves northward. If this storm rides up the west of the Appalachians, expect more snow than if the storm moves out to sea or if the coastal low overpowers it. I still say this will be a widespread light snow event, but there's still quite a bit of wiggle room for precipitation amounts and storm track at this point.

12/26 - 2:15pm - Still Watching for New Year's Snow

I hope that everyone had a wonderful Christmas yesterday and that the lack of snow around here didn't get anyone down in the dumps.

As we shift our focus to the new year, we may also have to shift our focus to a chance of snow in Louisville. Over the past week, the long-range GFS computer model has been showing a storm tracking through the Gulf states. While the moisture and precipitation with this storm has been suppressed to the south on most model runs, I'm starting to see the (this) season-typical northward trend in the track of this storm.

The Euro model has this storm tracking from the Gulf Coast to Virginia, which would be a fairly decent track for us to have snow in Kentuckiana if enough moisture accompanies the storm. My worry is that there may not be enough cold air in place to counter the warm air being brought north by the storm, and this may negatively affect our snow chances. It's still too early to tell if this will indeed be a problem, but at least the storm track is good at this point.

Basically, the graphic from the last post with the potential storm tracks of this system still applies. There are a lot of factors like phasing, the polar vortex, and model-to-model differences that need time to get hammered out. I'd say this is our best chance for snow so far this season, and I think this is certainly a system that bears watching.

12/12 - 11:45pm - Looking for Snow

I know many of us here in Kentuckiana are waiting for the first big snow of the season. While we generally don't see much snow around Louisville in December, the pattern right now in my opinion is very ripe for an early season snowfall. The long range computer models (GFS & Euro) heat things up this weekend and early next week, but temperatures quickly turn downhill again by the middle of next week. We may even see a small bit of snow next weekend with a possible clipper system. The southern storm track, the one that brings most of our snowfall, has been and will continue to be very active throughout the arrival of this new batch of arctic air next week. Receiving snow in Louisville is all about timing, which means we have to have an abundance of cold air in place as a low pressure system tracks to our south and east, preferably along the mountains of Eastern Kentucky. Having one of these components out of place would mean rain or ice for us here in Louisville.

Many have asked: Does it look like we'll have a white Christmas? The answer is maybe. The possibility for light snow between now and the 25th looks pretty good right now, but getting a big storm in here will be tough. The GFS computer model has been hinting at some sort of snow event around Christmas for a couple days now, but accuracy that far out is very low. I'd say our chances for a white Christmas are probably the best since 2004, when we had a crippling snow/sleet system dump over a foot of snow in Louisville and Southern Indiana on the 22nd and 23rd of December. Just keep in mind that the pattern is ripe for snow, but that the specifics are blurry at this point.

If you're desperate to see some snow, head across the Ohio River to Paoli Peaks in Southern Indiana. They've been able to generate enough machine-made snow to open for skiing this weekend and they should be able to keep that snow on the ground through the warm spell we'll see early next week. Guess it's time to hit the slopes!

[Courier-Journal | "Paoli Peaks to open for skiing early"]

1/30 - 4:30pm - Models Having Difficulties

The models I mentioned earlier are still going way off to the east with this Monday storm, except for the NAM now:



That's a definite westward shift from earlier runs of the NAM, so we'll see if this spreads to other models. I still smell something fishy. The way that just about every model shifted this storm way off to the east in one model run really doesn't make sense. I think we'll see flip-flopping over the next few runs, but the easterly solution that the GFS and ECMWF are portraying probably won't stay. We'll have to see if this reverts back to where we were last night or if this stays just to our east.

For the time being, we'll warm up tomorrow into the 30s and into the mid 40s on Sunday. LG&E is now reporting 174,000 without power, which is up a bit due to trees falling in the wind and other factors. I've been listening to the Mayor's press conference, and he's really emphasizing safety with generators and carbon monoxide problems. Remember: Do not use generators or grills inside your house or garage. Keep those appliances away from your home and windows to avoid carbon monoxide poisoning. There have been fatalities in the area due to carbon monoxide, so be very careful if you are using a generator or other similar appliance. There probably aren't very many people reading this blog who do not have power (unless on a mobile device), but pass this information along to those who don't have power if you can.

1/30 - 10:15pm - Monday Snow Going East?

The latest GFS, NAM, and even the ECMWF (Euro) are taking our storm on Monday well to the east now. It's strange how all the models changed at once last night with this shift. I'm not sold on the far eastern track that it's taking, but I'm beginning to think that the models I posted yesterday are too far west. We'll see how this shapes up today and tomorrow.

The latest numbers from LG&E show that 172,000 are still without power and 11,329 lines are down. Still looks like 7-10 days before everyone gets power back.

1/29 - 9pm - Monday Looking Increasingly Interesting

First off, LG&E is reporting 190,000 without power right now. This is up a bit from last check due to more trees falling as the day went on. For a map of the current power outage estimates in Jefferson County, click here. A state-wide map can be found here.

On to the next storm, which could be a whopper if things fall into place. An area of low pressure surging north from the Gulf of Mexico should cool things down on Monday from the near 50 degree temperatures we'll have on Sunday. The accompanying precipitation with this storm will be impressive to say the least, maybe even historic. Here's the latest model outputs:


18z GFS


12z ECMWF (European)


18z DGEX

Notice how all three of these models offer a similar track for the intense low, which is west of where it was forecast to go yesterday. The Canadian (posted yesterday) looks about the same, but has shifted west slightly. You're probably looking at the darker greens and blues on the GFS and DGEX and saying "Uh-oh." I'm saying the same thing. Look at this preliminary accumulation estimate taken from the GFS for this storm:



Yeah, that's 6-8" at a 10:1 rain/snow ratio. Here's the problem: we'll be operating at a ratio that could get higher than 12:1 during the coldest part of the storm, when the freezing line at the surface sinks way south of here. These totals could be nearing 12" if that happens.

We're still four days away, so things could change. The daunting issue is that the models are agreeing on this storm pretty well. I think there is a chance that it could correct eastward, but I'm only seeing westward trends at this point. If this low track changes slightly and pulls up more moisture from the Gulf, we could be dealing with a historic storm. It will be interesting to see what happens. Again, whatever happens on the models this weekend will be the deciding factor on whether Louisville, Lexington, or somewhere further east gets the brunt of this storm.

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.

1/22 - 5pm - All Over the Place

There's a word I like to hear when we have a storm in the forecast: model convergence. I haven't heard it or said it once today. This system next week that could bring us a ton of snow, a nasty ice storm, or a boatload of rain just cannot be forecast accurately at this point using our 21st century technology. The GFS gives us a smattering of snow on Tuesday before cranking up the rain for Wednesday and Thursday. I'm getting a similar gist from the Euro as well.

I just looked at the HPC's low track and they have the low tracking through Tennessee. The DGEX model seems to agree with that to some degree. The thing I've seen the most on all of these models has been a depletion of moisture on Monday and Tuesday to the storm (two systems going on here) on Wednesday-Thursday. I also noticed that the Louisville NWS is sticking to their guns with an all snow solution for both systems on our local forecast package, although they note how difficult they are being forecast-wise. I think we'll know by Sunday if we're going to get socked by this thing or not. Don't get your hopes up.

What I can bet on is warm weather for tomorrow! After a high in the 50s today, we'll see mid 50s for tomorrow. The reality of Winter will set in by the weekend, with lower 30s for both Saturday and Sunday.

1/21 - 7:30pm - Still Watching Next Week

I think most of us are ready for a break in these cold temperatures around here! Luckily, both tomorrow and Friday will rise into the 40's and maybe touch 50 for a high temperature. There could be a few sprinkles of rain on Friday as well, but overall not an active weather pattern for late week and the weekend.

Next week is still looking ominous and complex. The fact that somewhere in the region will see a moderate to major ice and snow event is pretty much agreed upon, but where is the real question. The GFS has trended slightly colder and further south over the course of today, but we'll see how that works in the 0z tonight and subsequent runs tomorrow. The Euro is similar, but wants it to come through slower. At any rate, nobody really knows if this will be a mix (my bet), all snow, ice, or rain for us.

The GFS has waffled around with precipitation potential today as well. Earlier runs had a moderate amount of precip, but the 12z and 18z sucked alot of moisture out of the area. I really wouldn't lose sleep over that fact at the moment because it's too far out. I'm unsure if the low precipitation bias on the GFS still exists, so we'll have to see how this acts on the models. There's a possibility that this could be an ice storm or snowstorm, so everyone needs to keep up with the latest forecast.

12/4 - 10pm - It's Cold Now and We're Just Getting Started

It is going to be downright frigid for tomorrow as our temperatures won't get much above freezing. We're still on for some snow showers on Saturday, but the big question is early next week.

There are some foreign forecast models (Euro, etc.) that have been saying we could get one mighty snowstorm on Tuesday-Wednesday, but I don't buy it. From what I see, we're going to be too warm for this. I like the local NWS office forecast of some possible snow on Tuesday night, but the rest would be rain. The low pressure track seems to be going in the right direction for us to get this "mighty" storm, but our surface temps won't cut it. Unless there's a correction in the US models that would bring in a colder batch of air, I'm going to stick with mostly rain on this one. We got burned last week when we had a storm on the GFS for us, and then it got too warm on subsequent runs. The Euro and other foreign models continued to show a snowstorm for a couple more runs than the GFS, so I'm going to assume this is a similar situation. It does concern me that the low track would indicate a good batch of precipitation and that the freezing line is not too far off, so we'll just have to watch for any changes.

Speaking of next week, get ready for some really cold air after the front associated with that Tuesday-Wednesday system goes through. Highs could struggle to get into the 30's after Thursday, so get out your big jackets if you haven't done so already! I think this cold air could support a snowstorm for us and the GFS agrees, so keep in mind that we could be dealing with accumulations after next weekend.

12/20 - 9pm - Well That's Annoying.

The GFS has vaporized our Christmas storm. What gives? The Euro still shows a low near here, but I can't see if there's any precip with it. I don't know what the GFS is thinking by playing with storm manifestation this close to the storm. I smell a rat... AccuWeather seems to be having the same problem right now trying to decide whether a storm will materialize. They say just to cool off and wait until tomorrow. I agree.

Until then, we'll see 50's and a chance for some showers tomorrow. A better chance for rain comes on Saturday night, with snow showers on the end of the storm by Sunday. Keep an eye on that Christmas forecast.

Christmas Snow Chance: 30%

12/10 - 7pm - Here's the Deal...

***DISREGARD ALL CURRENT GFS MODEL RUNS (0z-18z).***

Just do it. Please. Everyone. Yes, that means you media outlets.

I've just had enough of the inadequacies showing up on the GFS for the past few days. That forecast model is worthless right now. The problem is that the Euro, Canadian, JMA, and whatever else model you can throw at me are predicting a SNOWSTORM (you heard right) on the 15-16th (17th storm for NE US that I've been talking about) for the Louisville area. Right now the GFS is taking the low that is to produce this storm right off the coast into the Atlantic and then blowing it up into a monster. Not gonna happen folks. Nope. Here's why...

• The NAM is going deeply negative (red lines on bottom graphic): This simply means that there will be higher than normal pressure in the North Atlantic, signaling a shield of sorts to deflect all low pressure to staying within the East Coast, and not going straight out to sea.

• The GFS (I JUST saw the 18z run when writing this post and it brought the storm back, but placement is still an issue) is still taking the low too far south and making a huge storm in Alabama, which is just not the right solution given the current dry pattern there. The low wouldn't want to infiltrate that dry high down there, instead it would want to skirt along the northern edge, which is just a couple hundred miles north of the GFS forecast location on the 16th.
• Henry Margusity at Accuweather is actually putting us in the center of a snowfall potential map. He's been pretty good forecasting the recent storms in the Northeast and he's been doing well down this way as well (although there was the storm a couple weekends ago that surprised a lot of people and went north on us, which was a close call to begin with)

(Read Margusity's blog here)

• John Belski at WAVE-TV is going out on a limb (I'm behind you 100% on this) that we'll see snow on Saturday with this low. He gave the three possible low tracks (out to sea, S. Alabama, and N. Georgia) and said "I see the potential for a snowstorm". In other words, he's the only one in the local TV market calling for this (WDRB is 40 degrees and slight chance of rain/snow, WLKY is mix and snow with 30's, WHAS is cloudy and upper 30's.)

So here's my thinking, let's wait until Thursday and see what the models look like. If we're in the same or similar boat, I'm going to go ahead and call for a storm. Otherwise we'll just see what happens. Throughout the next few days we'll see fluctuations in the models, but overall I think this is the best shot we've had so far at some appreciable snow this season.


Now, shorter range (Don't you just love how I think in reverse-chronological order?)

We will see highs near or at 70 tomorrow with little rain expected. What a deal in December! The saying in Louisville is, "If you don't like the weather today, wait a little bit." That's just a little urban folklore there, but hey, 70's and snowstorms can happen in the same week!

Ahh... Now we get some numbers!

Finally! I've got numbers for you. My current thinking is:

• 2 to 4 INCHES OF SNOW (At the moment...)
  

You may say this is not too much but I'm thinking we will get the higher end of that estimate. This will occur over three periods of snow, Wednesday night, Thursday night, and Friday morning. Thursday night will be the heaviest time with a possible 1 to 3". The other two times will be an inch or two.

Now there are some risks still. It could go north/south of us. It could "miraculously" warm up like the last two disasters. The snow may not even show up.

With recent modeling though, this looks slim. The GFS is still trashed and NAM is weak so we're depending on the Euro/Canada/Japan bunch here. This estimate could change dramatically within 36 hours, but for now looks fairly solid. If anything, I think the snow totals could go up with a weaker model run biasing forecasts.

If it doesn't come, there are still many more significant snow chances on the way. But, as they say, the third time is a charm...

If things get really out of hand tomorrow (say, maybe a huge increase in accumulation estimates), I'll make the very first Ryan Weather Emergency Severe Weather Video. Again, only if I see a real change or at least a very solid forecast for over 3-4".