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!
The warm weather we've been seeing across the region hit record-breaking levels this afternoon. Here is a list of some broken temperature records today:
Jackson, TN: High 84° | Previous Record 80°
Memphis, TN: High 82° | Previous Record 80°
Chattanooga, TN: High 83° | Previous Record 81°
Louisville, KY: High 82° | Previous Record 80°
Paducah, KY: High 82° | Previous Record 78° Evansville, IN: High 82° | Previous Record 77°
Indianapolis, IN: High 81° | Previous Record 79°
Many other cities in came close to breaking records, especially in Alabama and Middle Tennessee. The ridge over the Eastern US that's funneling all the remarkably unseasonable temperatures into the area will stay put through the weekend, but a few shortwave disturbances aloft will bring storm chances to much of West Tennessee, North Mississippi, and even into Central Kentucky tomorrow and Friday. These storms will be more organized than the spotty ones that developed in eastern portions of West Tennessee and even up through Western Kentucky this afternoon. The crazy-warm temperatures are going to last at least another full week as this strong ridge stays put, so I think to say that spring (or even summer) has sprung before winter officially ended!
It's still cold out there in Mississippi after a frigid morning with temperatures in the 30's. A cold front that passed through yesterday is to blame for the chill, but fear not, temperatures will be back to around 60 for highs by tomorrow afternoon. Quick turnaround, huh? Some rain and a few storms will be possible Friday night into Saturday with temperatures still increasing. A shot of severe weather may be possible sometime around the middle of next week, so keep watch for more updates on that forecast as it becomes clearer. Today's Mississippi State University forecast video is below:
Brownsboro Rd in Louisville
The count of yesterday's confirmed tornadoes in Kentucky and Indiana has now reached seven according to the National Weather Service in Louisville. The strongest of these was an EF-2 in Simpson and Allen Counties in Kentucky. Two of these tornadoes with winds of up to 100 mph occurred in highly-populated portions of the city of Louisville in Jefferson County. NWS Louisville is updating a webpage continuously with information about these tornadoes as it becomes available from their damage surveys.
A cold front sliding southward through Indiana and Kentucky this morning has triggered some thunderstorms in Southwest Indiana that likely won't make it to the Louisville area this afternoon, but more storms could develop later on. While any storm that forms this afternoon could have heavy rain, lightning, and some gusty winds, most if not all will stay below severe limits. Temperatures are already in the upper 80's around the Louisville area, so a high near 93 today looks good at this point.
How about those Fourth of July forecasts? Hot and humid will be the rule for most locations, but scattered afternoon thunderstorms covering quite a large area could drench a few of those outdoor barbecues. The storms will be large in coverage due to a trough hanging around the eastern half of the US and a stationary front near the Ohio River.
Here are some Independence Day forecasts for selected regional locations from the National Weather Service:
Had enough storms already? We have one more round to go before we clear things out for a while around Kentucky and Indiana. A few non-severe storms have already moved through the Louisville area this morning and the storms that are still well off to the west are weakening and beginning to take a more southerly turn.
The bit of clearing we'll see this afternoon after this morning's storms pass off to the east should help to destabilize the atmosphere in preparation for development of severe storms this afternoon. If this clearing doesn't materialize and we stay more cloudy than sunny across the area, the severe threat will be much lower. These storms should fire up in the mid afternoon across southwest Indiana and Western Kentucky and impact the Louisville area this evening. While most of these will be your run-of-the-mill severe storms with 60mph winds and hail, a few could have supercell structures or bowing segments. The embedded or isolated supercell structures will be powered by the small amount of wind shear (changing wind direction and speed with height - see 5pm NAM model output left) and helicity (turning in the atmosphere) we'll have in the area as storms form. This means a couple isolated tornadoes are possible.
The bowing segments could produce wind damage as a cold pool of air collects behind some of the more linear storms. These storms will likely last well into the evening and overnight hours and be out of the Louisville area by mid morning tomorrow or earlier. Since there is the risk for wind damage and an isolated tornado or two, the Storm Prediction Center has issued a Slight Risk area for most of Kentucky, Southern Indiana, and portions of Middle Tennessee. A 5% tornado risk exists from Chicago and St. Louis to along the Ohio River, while a 2% risk extends further southward.
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:
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.
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.
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.
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!
