1/15 - 8pm - Just Plain Rain for Starkville, but Snow Later?

While the Delta region has been plagued by an ice storm yesterday and today we've been lucky enough here in Starkville to just be experiencing plain rain and temperatures above freezing. It's 35 degrees in Starkville right now and it still looks like we'll keep above freezing for the remainder of the overnight hours. A Flash Flood Watch is still in effect through late tonight for the area due to all the heavy rain we've had. As this rain begins to move out tomorrow evening there's a chance that some of this could as snow. It's not real clear who will get the most snow and how much, but there's at least some potential for light snow as we go through Wednesday night into Thursday morning. That forecast will continue to be fine-tuned throughout the day tomorrow. Check out my video below for all you need to plan your week!

5/24 - 12:35am CDT - We're in... Iowa?

We didn't think we'd be in Iowa tonight. The storms that formed yesterday (Wednesday) rushed eastward as the cold front in the region decided to push further east than expected. Unfortunately none of these storms really did much because they formed in a linear fashion and didn't have the moisture necessary to get too severe. One of the southern cells in the line just west of Omaha, Nebraska managed to be isolated for a while and generated a wall cloud that triggered a tornado warning. Our only option in this environment was to cross the Missouri River in Omaha and wait for the storms to come to us because it would not be good to have the storms outrun us while trying to find a way across the river. The storms slowed down and died out pretty much at that point so we threw in the towel for the day.

Tomorrow will likely be a travel day back to Kansas or Southern Nebraska as we await Friday's potential chase setup. Storms tomorrow will be up near the Great Lakes in Wisconsin and Michigan and we just don't chase there due to the distance from the Plains and lack of good chase environment up there. Strong capping should keep storms from going up in the central and southern Plains, but we'll keep an eye on that in case that changes. Friday's setup may be decent if capping aloft doesn't ruin it. A deepening trough out in California and hopefully some better moisture return from the Gulf of Mexico should create potential for severe weather. A strengthening low in Southeast Colorado/Southwest Kansas should provide ample surface wind support for rotating storms should this pan out as forecast. The Storm Prediction Center already has a 5% risk area for this in their 3-day severe weather outlook. I'm crossing my fingers that this setup will yield some good storms because Friday is my last day chasing in the Plains until late June!

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5/15 - 11:30am CDT - Excitement in Southwest Texas Yesterday

My apologies for not having a blog post last night. We're in the Big Bend National Park area of Texas and there was little to no cellular data service where we stayed last night. Our travels along the Mexican border region of Southwest Texas yesterday were quite exciting though. We started off in Pecos, Texas and traveled south to Paradisio, Texas right on the border. We waited here for some storms to form before heading eastward to intercept them. Most of these storms were clustered together, but there were a couple cells that stayed independent that came toward us and crossed the border. The tornado threat wasn't realized yesterday because low-level shear did not play out as forecast due to unfavorable surface winds and multiple storms contaminating each other with cold outflow air. As we drove on the mountainous road along the Rio Grande river (yes there was a certain Duran Duran song of the same name stuck in my head) there was not much cell service so we had very limited radar updates. We drove east of Lajitas, Texas as the strongest cell at the time came at us rather quickly with no escape. Our vehicles pulled to the side of the road near a rock wall and that shielded us from the brunt of the golf ball size hail that came down.

This storm put down a huge amount of rain, so much so that the residents in this area that we talked to hadn't seen something like it in over four years. The deluge quickly overwhelmed the ground and widespread flash flooding took place. Our road east along the border was flooded by a foot of water at one point, so we stopped for an hour to let the water level drop. 6 or more inches of water is dangerous to drive through. The rushing rapids going over the road brought some pretty big rocks and debris, but luckily none of this was too big for a hand toss to the side of the road. Our group then continued on to a town just outside the Big Bend park area where we spent the night. I have some great video of the hail and flood yesterday that I'll try to upload once we get to a hotel with internet service.

Today's storm setup in Texas looks very marginal so we're touring the Big Bend area and then heading north so we can be ready for storms that may form in Eastern Colorado later on this week. With limited moisture in the Plains it might be hard to find some good storms over the next few days. We'll make the best of it!

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2/1 - 6:10pm - Severe Weather in North Mississippi

After a rainy start to the day and peeks of sunshine this afternoon, we're tracking a line of storms moving through the northern half of Mississippi. There is a Tornado Warning out for parts of Carroll and Grenada Counties due to some rotation present in that part of the storm. Severe Thunderstorm Warnings are in effect up and down this line right now, mainly for the strong wind threat they pose. The environment is not favorable for these storms to maintain their strength over the eastern half of Mississippi, so they should begin to fall apart soon.

A Severe Thunderstorm Watch is in effect for northeastern parts of Mississippi until 11pm CST:

While I do not have a full Mississippi State weather forecast today, I did record a "weather tease" in my broadcast meteorology class today. This is just a 45 second preview of a forecast that would come later in a newscast. Check it out below:

9/4 - 12:30pm - Yesterday's GMWT Video, TS Lee Update

Yesterday we began airing Good Morning West Tennessee for an additional hour starting at 8am. This means the Saturday show is now two hours, from 6-7am and again at 8-9am with Good Morning America airing in between. The forecast for West Tennessee still looks very wet today into tomorrow because of Tropical Storm Lee, but I think the rain should clear out as Labor Day rolls along. Check out some video from yesterday's broadcast below:

Lee is just hanging on to tropical storm status and should be downgraded to a depression later today as it moves inland. Just because it's weakening doesn't mean the risks from it will go away. Portions of Central Mississippi (I'm talking to you Starkville), Alabama, and even up through the Appalachian Mountains in North Carolina could see over eight inches of rain between now and Tuesday. Flooding is obviously a concern, so use caution while driving in these areas. Turn around, don't drown!

Tornadoes are also continuing a problem with Lee. There were 10 reports of tornadoes yesterday, some causing damage, along the Gulf Coast from Louisiana to Florida. Two tornado watches are in effect with about a half dozen warnings in them from Mississippi to Florida. The tornado risk from Lee should lessen as it continues to come onshore tonight and tomorrow.

8/25 - 4:15pm - Hurricane Irene's Fever Pitch

Hurricane Irene is certainly causing some drama both over the airwaves and along the East Coast where thousands are preparing for what could be that area's first hurricane strike in a while. This will also be the first hurricane to make landfall in the United States since Ike in 2008. States of emergency have been declared by the governors of North Carolina, Virginia, New Jersey, Maryland, and New York as the storm takes aim at the region. Areas from Wilmington, North Carolina to Cape Hatteras to Norfolk, Virginia will likely take the brunt of Irene as it makes landfall as a Category 2 or 3 storm on Saturday. A Hurricane Warning has been issued for the entire North Carolina coast and a Hurricane Watch is in effect from Virginia to New Jersey. On the satellite image to the top left you'll notice that Irene does not have a very apparent eye. This is because the storm has just completed an eyewall replacement cycle, which temporarily limits both the strength of the storm and the appearance of an eye. The eye will likely become much easier to see over the next 24 hours and the intensity of the storm will correspondingly increase.

The National Hurricane Center's 5pm EDT outlook for Hurricane Irene has the storm at Category 3 status with winds of 115 mph. For Tuesday and most of yesterday, it looked like Irene was going to miss much of the East Coast and curve back out to sea, but last night's and today's computer model runs have adjusted the storm's track quite a bit westward. This means hurricane force winds will be felt across a much larger portion of the North Carolina, Virginia coasts and even through to the Northeast and Delmarva Peninsula. To the right is a "spaghetti chart" showing all the computer model forecast tracks for Irene. There's a strong possibility that Irene may still be a Category 1 hurricane packing winds in excess of 75 mph and a storm surge up to 15 feet when it hits the New Jersey Shore, New York City, and Long Island areas on Sunday. While hurricanes that affect the Northeast aren't all that rare, the particular track of Irene and the intensity possible as it hits the area are causing great concern, especially about flooding. Folks from North Carolina to New England really need to pay attention to this storm this weekend and evacuate when instructed.

7/23 - 1:15pm - Heat Continues, No End in Sight

The entrenched heat we've had over the eastern half of the nation has been making headlines for quite some time now and it appears that it will continue for a while more. The strong ridge of hot, stagnant air is staying firmly in place and most forecast models are keeping it over the same area for at least the next week or two. A big portion of the Plains, Midwest, and East Coast is covered in heat advisories and warnings, which you'll see shaded in orange and purple on left.

Around Louisville, temperatures are going to stay in the 90's for the foreseeable future. For some perspective, we're hotter right now than Jackson, MS, Birmingham, AL, Memphis, TN, Jackson, TN, and Nashville, TN. Cloud cover, surface winds bringing in cooler air, and easterly flow aloft is keeping these locations cooler than Louisville even though they're all to the south. This really highlights the Midwest and Plains as being the primary target for the heatwave since we have been and will continue to be feeding off of the entrenched hot air from those regions.

A few pop-up showers and storms are possible today in Louisville, but a bigger chance for storms comes tomorrow as a "cool" front approaches the area that will cross through on Monday. I think tomorrow afternoon and evening will be the best time period for storms, most likely lasting into the early part of Monday. Behind this "cool" front temperatures won't really drop much, but dew points will take a tumble.

Check out the dew point output from the GFS for early Wednesday on the left. Those dew points are a good 15 degrees lower than the average this week and that translates to markedly lower humidity. That won't last long though... higher dew points with the same old hot temperatures will be back before the weekend. Until then, remember that an Excessive Heat Warning continues for the Louisville area until Sunday night. Stay safe!

7/21 - 2pm - Enough Excessive Heat to Go Around

93° in Louisville is hot on its own, but when you couple that with a very high 77° dew point (which puts relative humidity at 60%), you're talking about a heat index of 107°. We're well on our way to a high near 97° this afternoon. It's just hot. An Excessive Heat Warning, on left shaded in purple, remains in effect for the entire Louisville area until Saturday night as heat index values soar past 110° during the maximum heating of the day. Regardless of where you're from and the weather you're used to, your body cannot sustain itself in the hot, humid air we have in Louisville and much of the Midwest right now. Be sure to drink plenty of water and limit your activity outside this week to avoid heat-related illness.

Heat Index?

NC State Climate Office

I've been mentioning the term heat index for weeks now, so what exactly is the heat index you ask? Most people know it as the "feels like" temperature or what it feels like because of the humidity. That's basically it in a nutshell, but there's more to it. Mathematically, the heat index is a product of an equation that uses temperature and relative humidity. Factors like perspiration and body size averages are held constant, so the heat index is an educated guess at the "temperature" that most people are feeling. Don't let the "educated guess" usage fool you though, because higher humidity and in turn heat index values lessen the amount of evaporational cooling on your skin. If your body can't cool properly through this evaporation, you can overheat quite easily. It's interesting and useful to note that heat index values are based on what it feels like in the shade. Being in the sun can increase the heat index by up to 15°. Below is a table from NWS Pueblo, CO with heat index values and associated heat disorders:

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With the heat we'll have a chance for afternoon scattered storms, which will increase significantly as we get closer to the passage of a cold front on Monday. Today's storms have been and should be staying south of Louisville, so we'll see no relief from the heat today!

6/25 - 2:45pm - Tomorrow's Entertainment: An MCS

An MCS or Mesoscale Convective System is scheduled to move through Kentucky and Indiana tomorrow morning. An MCS is basically a large cluster of storms that normally has a distinct wind-driven line of strong to severe storms on the east side as it pushes along at a decent speed. Tornadoes can sometimes form in little notches or "eddies" that develop in the strong line of storms on the east or leading side of the MCS. Given that there will be some helicity (turning in the atmosphere) from Indianapolis to Bowling Green, KY as the MCS moves through, it would not surprise me to see a Tornado Warning or two issued since there could be a little rotation aloft. This will not be a tornado event though and I expect the probability of tornadoes to remain low. This will not be an event like Wednesday when we had five tornado touchdowns in the area because we will not have supercells developing. The Louisville area can expect storms to start sometime around 7am and possibly last into the mid afternoon hours. While the initial line of storms in the morning could be strong or severe, heating during the day could intensify storms by around noon. The main threats from this complex of storms will be damaging winds (especially in the morning) and hail. The 12z NAM model run (top left) seems to have a good handle on the storms.

These storms will be driven by a mid-level shortwave trough, which is basically just a ripple or wave in the atmosphere, and a warm front rising northward. Once this warm front passes to our north tomorrow, we can expect temperatures to exceed 90 degrees again next week.

We're under a Slight Risk tomorrow from the Storm Prediction Center (left) and on the very southern edge of another one on Monday (right) since another line of storms may try to come through early in the day:

Be sure to scroll down and read my exhaustive post on the Louisville tornadoes that happened on Wednesday.

6/23 - Expecting the Unexpected: The Louisville Tornadoes

A horse barn at Churchill Downs
Image: NWS WFO Louisville

The city of Louisville is recovering from an outbreak of tornadoes that even the most seasoned weather watchers didn't expect. As of this writing there have been four confirmed tornadoes (two EF-1's and two EF-2's) inside the Jefferson County/Louisville city limit. A fifth tornado in Harrison County, IN has been confirmed of EF-0 strength that started off the event. The iconic Churchill Downs received damage to barns, several power poles near the University of Louisville's Papa John's Cardinal Stadium were brought down, and buildings in Jeffersontown sustained damage along with massive tree damage as a result of three of the four tornado touchdowns in the county. Thankfully there were no reports of injuries or fatalities as these tornadoes ripped through a city containing three quarters of a million people.

Below is a rough map I've put together based on the NWS WFO Louisville storm survey page of the tornado tracks through Louisville . Purple tracks indicate EF-2 rated tornadoes (the indicated tornadoes only reached this strength briefly) and the red tracks indicate EF-1 rated tornadoes. Be sure to click the image for a larger view.

Timeline of Tornadoes

Information used in this section about each tornado can be found on NWS WFO Louisville's storm survey page.

Yesterday started off cloudy and even misting at times across the city as a cloud shield from overnight persisted well into the morning hours. The Storm Prediction Center had a Slight Risk for severe weather out for a good portion of the Mississippi and Ohio Valleys northward to Michigan, but this was a very conditional risk for Kentucky and Indiana because the cloud cover in the morning inhibited destabilization of the atmosphere. A cold front sagging southeastward from Indiana would be the trigger for any afternoon storms should they form as temperatures warmed. The clouds finally moved east of the Louisville area at around 2:30pm yesterday and temperatures topped 80 degrees by 3pm. By 6pm there were showers on the radar to the north of Louisville and a few specks on the radar to the west.

Just after 7:30pm a Tornado Warning was issued for Harrison County, IN and western portions of Jefferson County/Louisville because a tornado was spotted near Elizabeth, IN. The "storm" that triggered this warning was no more than a shower because it had no lightning strikes associated with it. I'll admit that I was skeptical of this tornado report because there was really no significant rotation on radar. I thought the report was an improper identification of moving scud clouds or even a gustnado. The storm seemed to weaken and spotters near the Shively area reported no funnel clouds, so the warning was allowed to expire. About ten minutes later the storm began to strengthen again in West Louisville and another Tornado Warning was issued just after 8pm for Jefferson County. Multiple reports of a tornado and associated damage began coming in from Churchill Downs around that time.
This time the storm had lightning and the visual tornadic hook echo with prominent rotation on radar, so it was clear at this point that this thing meant business. To the right is a radar image with the supercell and hook echo near Churchill Downs and below is the velocity data with the green/red couplet signifying where the rotation was at the time. Click either image to see a larger view:

This tornado strengthened briefly into an EF-2 with 120 mph winds near the intersection of Floyd and Central Avenue at the University of Louisville campus where the power poles came down. Here's a video from YouTube user kehdsh that was posted on the WAVE 3 Weather Facebook page this afternoon. It's a little far away, but it clearly shows the funnel cloud above and debris cloud on the ground near Churchill Downs. Note that a tornado does not need to have a visible funnel snaking all the way to the ground. The debris dust-up and tube near the ground verifies that a tornado is there. Watch the center of this video closely:

Bent light pole in Jeffersontown
Image: NWS WFO Louisville

The next three tornadoes to hit Louisville were actually from the same storm and you could argue that it was the same tornado that lifted and touched down three separate times. From 9:29pm to 9:41pm (a total of twelve minutes with two short breaks in between) these tornadoes pestered the Louisville incorporated city of Jeffersontown, the suburb of over 26,000 people in Jefferson

Tree on dentist office in Jeffersontown
Image: Ryan Hoke

County that I've lived on the southeastern fringe of for nearly ten years. The initial touchdown occurred in the neighborhood just behind (west of) the Meijer store on South Hurstbourne Parkway west of Jeffersontown. This is just due south of the Stonybrook Cinemas. The tornado continued eastward to downtown Jeffersontown and lifted at the St. Edward School and Church, causing EF-1 (95-100 mph winds) damage along the path. It dropped again just east of the school and went on to cause tree damage at Tully Elementary School and structural damage at an apartment complex and the Good Samaritan Center in downtown Jeffersontown. The Good Samaritan Center had EF-2 winds of 115 mph that tossed and flipped cars about 20 yards. The tornado then went on to cause significant damage at the industrial park just east of Jeffersontown before lifting again. It sat down again in the industrial park causing more warehouse damage and continued on toward the Gene Snyder Freeway (I-265) where it lifted just after damaging a bed and breakfast on Tucker Station Road. This storm wasn't as well-defined on radar as the Churchill Downs supercell because of the merger of multiple storms in the county. The embedded supercell structure with rotation was certainly there as you'll see with the red/green boundary of wind velocities north of the Jeffersontown dot in the image below:

Why it Happened

Caution: This section gets a little technical on the meteorology side of things.
I explain why I think tornadoes hit Louisville unexpectedly and in such a small area.

Nobody expected this rash of tornadoes in Louisville at all. This includes the National Weather Service, local media, and me. In my blog post yesterday morning I even stated: "The tornado risk for [Southern Indiana, Kentucky, and Tennessee] will be quite low." The Storm Prediction Center issued a Slight Risk with a 2% tornado risk area in the morning with mention of wind-driven linear storms possible across the Lower Ohio Valley. Later on in the day they issued a Mesoscale Discussion that indicated they may issue a Severe Thunderstorm Watch for a broad area from Cincinnati to Memphis if storms developed more, but they never did. Some folks are asking why they didn't issued a Tornado Watch as soon as the storms unexpectedly began producing a spotter-confirmed tornado in Central Louisville, especially when the tornado threat dragged on for roughly an additional two and a half hours. My guess is that the very small lead time they would give with the issued watch and the unknown end time for this already unexpected tornado outbreak led them to scrub any plans of issuing one. Not to mention that the watch would be extremely small given that tornadoes occurred across two counties. The National Weather Service office in Louisville did a very good job of handling all the reports and translating that information into warnings for folks in the path of these storms.

These storms formed in a highly speed-sheared environment meaning winds were very fast aloft, but much slower at the surface. The direction of the winds at the surface were forecast to be from the southwest according to most of the computer forecast models. Aloft at 18,000 ft the winds were forecast to be from about the same direction, but slightly more west. This means that there was little directional shear forecast, meaning the chances of storms rotating were slim. The setup was more favorable for damaging straight-line winds. Here's where things get interesting. At 2:43pm, surface observations showed southwest winds in Louisville as forecast. All is well, but watch that southerly wind vector (down-pointing flag) east of Evansville, IN in the top picture on the left. Just before 5pm this southerly surface wind vector is in Louisville as a south-southeast wind. This increased directional shear between the surface and 18,000 ft quite a bit. The timing also lines up with the development of small showers just to our west and north. The surface winds were from the south in Jefferson County between 5pm and just before 10pm. In between these times we had the tornado pandemonium in Louisville. The timing and location is just too perfect for these southerly winds to not be a contributing factor to this event. Low-level wind shear (the kind that produces tornadoes) would have been much higher in Jefferson County than the surrounding area with the surface wind out of the south given the winds aloft being from the southwest.

It's also interesting to note that the bulk shear output on SPC's mesoscale analysis had a 50 kt maximum right over Central Kentucky and Southern Indiana. I make no claim of being a research meteorologist, but this surface wind reasoning comes from my four years of chasing storms in the Plains and the experience I've gained from books on severe weather.

The RUC and NAM models yesterday morning did pick up on the fact that storms would indeed form in the afternoon near Louisville after the clouds cleared. The 12z RUC yesterday in particular seemed to pick out the linear nature of the storms that were to form less than twelve hours later. It was nowhere near perfect, but the timing and shape of the storms were in the ballpark. Check out the comparison of a live radar capture late last night and the aforementioned RUC reflectivity (simulated radar) output:

Finally, I wanted to point out that this all happened with less than 1500 J/kg of CAPE or instability. Usually you need a little more instability than that to get severe storms going, but I think the directional wind shear compensated for that. None of the other storms outside of the localized southerly winds around Louisville were severe. That plus the fact that we had a tornado touch down in Harrison County, IN (just west of Louisville) with little to no lightning present in the storm makes this a once-in-a-lifetime event that could have been much worse if people did not heed warnings. I'm extremely pleased that there were no reports of injuries or fatalities with these five tornadoes yesterday. Hopefully this event will be the last major population center to be hit by a tornado this year, which has seen tornadoes hit cities including Tuscaloosa, Birmingham, Joplin, MO, Oklahoma City, Springfield, MA, and now Louisville, KY.

Check out NWS WFO Louisville's storm survey page for more information on this tornado event.

6/15 - 6:45pm - KY/IN/TN Severe Weather Update

Severe weather has fired up across Kentucky, Indiana, and Tennessee this evening. A new Severe Thunderstorm Watch has been issued that includes Louisville and Bowling Green, KY as storms that have fired to the west of these cities have gone severe. Storms north of Evansville, IN could hit the Louisville area this evening, but they will have to fight the loss of heat that they'll encounter once the sun goes down. Severe thunderstorm warnings are being issued for the big complex of storms in Middle and Southwest Tennessee, but nothing greatly impressive is happening down that way.

The Storm Prediction Center has extended today's Slight Risk area northward as the warm sector between the warm front and cold front where these storms are setting up has moved further north. I don't think we'll be dealing with a tornado problem from these storms, but some brief and benign upper-level rotation is possible. Hail, high wind, and heavy rain should be the main threats as they develop and move through Southern Indiana and Kentucky. The storm threat should subside before midnight in these areas.

12/16 - 11:30am - Ice Accumulation Numbers

The temperature in Louisville got up to 32 at around 8am this morning, but we're now back down to 29 degrees. That's not good news at all because the accumulated ice simply won't melt with temperatures below freezing and cloud cover. Overall, Louisville did get around 0.5" of ice in places as expected, but the expected 1-2" of snow simply did not happen due to warm air advection aloft that traveled north quicker than expected. Here are some of the ice accumulation totals from the NWS in Louisville:

...ICE ACCUMULATIONS FROM OVERNIGHT AND EARLY THIS MORNING THROUGH 9 AM EST...

THE TOTALS BELOW ARE SEPARATED BY AMOUNT AND ARE NOT NECESSARILY
THE FINAL AMOUNT FOR EACH LOCATION.

*************************ICE ACCUMULATIONS**********************

ACCUM  LOCATION             ST   COUNTY               TIME
-----  --------             --   ------               ----

0.5"   VALLEY STATION       KY  JEFFERSON           500 AM EST
0.5"   ENGLISH              IN  CRAWFORD            900 AM EST
0.3"   BROWNSVILLE          KY  EDMONSON            200 AM EST
0.3"   CASEY                KY  BUTLER              200 AM EST
0.3"   TELL CITY            IN  PERRY               900 AM EST
0.3"   ANCHORAGE            KY  JEFFERSON           900 AM EST
0.3"   DOE VALLEY           KY  MEADE               900 AM EST
0.25"  HOLLAND              IN  DUBOIS              600 AM EST
0.25"  FRANKFORT            KY  FRANKLIN            645 AM EST
0.25"  GEORGETOWN           KY  SCOTT               730 AM EST
0.25"  ELIZABETHTOWN        KY  HARDIN              745 AM EST
0.25"  CORYDON              IN  HARRISON            705 AM EST
0.25"  SALEM                IN  WASHINGTON          600 AM EST
0.2"   NWS LOUISVILLE       KY  JEFFERSON           900 AM EST
0.2"   FERDINAND            IN  DUBOIS              530 AM EST
0.2"   PORTERSVILLE         IN  DUBOIS              530 AM EST
0.1    LEITCHFIELD          KY  GRAYSON             715 AM EST
0.1"   BOWLING GREEN        KY  WARREN                MIDNIGHT

I'll post some more photos of the ice later on today. Some of those icicles out there are pretty big! I think Louisville will stay dry for the rest of the day but areas near Lexington will receive just a little more freezing rain.

12/15 - 5:30pm - Louisville Winter Storm CRUNCH TIME!

The onset of Louisville's first major mixed precipitation winter storm of the season is just hours away and the forecast is still very difficult. The National Weather Service has extended tonight's and tomorrow's Winter Storm Warning to counties in Southern Indiana that were previously only in an advisory. The reason for this is the increase in precipitation totals that both the NAM and GFS have been hinting at today. Those areas in Indiana will see all snow and sleet, with accumulations up to six inches in places.

Here in Louisville the snow should start from the southwest near the 10pm hour and possibly mix with sleet before 1am, with accumulations of around 1-2". Based on the model guidance I've seen, I think we'll switch over to a period of sleet with some freezing rain mixed in after 1am. Freezing rain will become dominant in Louisville just a couple hours after that and last until around 7am with ice accumulations ranging from 0.25" to 0.5". The 18z GFS model (pictured top left) and the NAM both keep Louisville just below freezing at the surface during the entirety of the winter storm, but we're going to have to watch that. The snow we have on the ground will influence the surface temperatures across the area, so the computer models may be running too warm at this point. As I've said before, Downtown Louisville could get a degree or two above freezing during the afternoon and that will help road conditions improve tremendously. The 18z NAM BUFKIT output (second image on left) gives Louisville 1.7" of snow/sleet with a half inch of ice accumulation.

Even with all of this data nothing is set in stone. The storm is forming to our west right now and we're already seeing light snow and sleet falling to our west and southwest. Watching the radar trends and surface observations overnight (called nowcasting) will be crucial to see who gets what kind of precipitation. Louisville is historically the battleground between precipitation types and we'll be in that situation for sure tonight. The HPC (Hydrometeorological Prediction Center) has Louisville and areas south in a Moderate Risk for 0.25" of ice accumulation. Louisville and points north have been put under a Moderate Risk for 4"+ of snow accumulation as well, so we may very well end up with quite a bit of both snow and ice here in the city.


Should this system shift south just a few miles, Louisville would end up with mostly snow and accumulations would pile up to nearly half a foot. I've posted the 12z NAM snow accumulation output on the left just so you can see how incredibly close the heavy snow will be to Louisville, at least according to that model run. A shift northward would severely limit snow accumulations and put us in a mostly ice situation. Either way, Kentuckiana is set to get walloped by winter weather tonight. This will not be as bad as the January 2009 ice storm due to lesser ice accumulations and the potential for slightly above freezing temperatures during the daytime hours in Downtown Louisville and areas south of town as well. We'll see how it all plays out!